Review of Meniscal Allograft Transplantation Focusing on Long-term Results and Evaluation Methods

Differences in Graft Tear Configurations in Medial and Lateral Meniscal Allograft Transplantation: Objective Evaluations Using Magnetic Resonance Imaging

BACKGROUND

Few studies have compared the characteristics of meniscal allograft tears between medial and lateral meniscal allograft transplantation (MAT) using bone fixation.

PURPOSE

To investigate the prevalence, location, and patterns of allograft tears after MAT with the bone fixation technique and compare tear patterns between medial and lateral compartments according to the time elapsed after surgery.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

The charts of consecutive patients who underwent primary medial or lateral MAT between December 1996 and June 2019 were retrospectively reviewed. The location, pattern, and postoperative periods during which allograft tears occurred were evaluated by reviewing all series of follow-up magnetic resonance imaging (MRI) scans, which were performed at 6 weeks, 3 months, 6 months, and 1 year postoperatively and every 2 years thereafter with the patient's agreement. Postoperative periods for allograft tears were defined as the time between surgery and the follow-up MRI scan in which the meniscal tear was first confirmed. Allograft tears were compared between the medial and lateral MAT groups.

RESULTS

A total of 327 consecutive patients who underwent MAT (55 medial, 272 lateral) with a minimum 2-year follow-up were retrospectively reviewed. The incidences of allograft tears after medial and lateral MATs were 32.7% and 30.9%, respectively. The mean times for tears were 80.1 ± 81.1 months and 48.9 ± 46.3 months in the medial and lateral MAT groups, respectively (P = .130). In both the medial and lateral MAT groups, allograft tears were observed mainly in the posterior horn, with complex tears being the most commonly identified tear type. In medial MATs, root tears were the second most common at 27.8%, with a significantly higher proportion than the lateral MATs (P = .014). On the other hand, in lateral MATs, meniscocapsular separation and radial tears were the second most common at 15.5% each, albeit not significantly more common than in medial MATs (P = .123 and P = .454, respectively). All root tears in medial MATs and meniscocapsular separations in lateral MATs were observed within 1 year postoperatively.

CONCLUSION

Significant differences in allograft tear patterns were identified between the medial and lateral MAT groups. The proportion of root tears in medial MATs was higher than that in lateral MATs; conversely, the proportion of meniscocapsular separation was more common in lateral MATs. Such tear patterns, which may require surgical repair or graft resection, were observed only within 1 year of surgery. Therefore, close observation and regular follow-up in the earlier postoperative period are necessary after medial or lateral MATs.

Survivorship of 157 Arthroscopic Meniscal Allograft Transplants Using Bone Fixation at a Mean of 7 Years and Prognostic Factors Analysis

BACKGROUND

Meniscal allograft transplantation (MAT) is an accepted and effective treatment option in the context of unsalvageable menisci, particularly in young and active patients. It has been shown to reduce pain and improve knee function in previously symptomatic patients. However, there is still limited knowledge about the long-term survival rates of allografts, the durability of clinical results, and the influence of patient-specific parameters, such as leg alignment, tibial slope, and preoperative International Cartilage Regeneration & Joint Preservation Society (ICRS) grade.

PURPOSE

To determine (1) the long-term clinical success rate after MAT with bony fixation in a large, single-center cohort of consecutive patients, and (2) if patient-specific and procedural variables influence the clinical, anatomic, and subjective outcomes and risk of failure.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Data on 185 consecutive knees undergoing MAT in a single institution were prospectively collected and screened for inclusion in this study. The minimum follow-up time was 2 years. Radiographic variables (ICRS grade and Kellgren-Lawrence grade) were assessed preoperatively and at follow-up. Subjective patient-reported outcome measures (PROMs) (Lysholm score, Knee injury and Osteoarthritis Outcome Score [KOOS] including subscores, International Knee Documentation Committee [IKDC] score, and visual analog scale [VAS] score) were collected preoperatively and at follow-up. Clinical failure was defined as revision surgery due to graft failure or conversion to total knee arthroplasty. Anatomic failure was considered a tear covering >20% of the allograft, any peripheral tear, and unstable peripheral fixation leading to dislocation of the graft. Subjective failure was defined as Lysholm score ≤65. Preoperative tibial slope and leg alignment were assessed. Survival analyses were performed using the Kaplan-Meier estimate. Univariate and multivariate analyses were performed to determine risk factors for clinical and anatomic failure.

RESULTS

A total of 157 knees met inclusion criteria. After a mean follow-up time of 7 ± 3.5 years, 127 (80.9%) knees were free of clinical, anatomic, and subjective failure. Fourteen (8.9%) knees experienced clinical failure, 26 (16.6%) knees were identified as having experienced anatomic failure, and 13 (8.3%) patients experienced subjective failure with a reported Lysholm score of ≤65 at a mean follow-up of 7 years. Concurrent osteochondral allograft transplantation was identified as a predictor of both clinical (hazard ratio [HR], 4.55; 95% CI, 1.46-14.17; P = .009) and anatomic (HR, 3.05; 95% CI, 1.34-6.92; P = .008) failure. Cartilage damage of ICRS grade 3 or 4 of the index compartment conveyed an increased risk for clinical (HR, 3.41; 95% CI, 1.05-11.01; P = .04) and anatomic (HR, 3.04; 95% CI, 1.31-7.11; P = .01) failure. High-grade cartilage damage preoperatively (HR, 10.67; 95% CI, 1.037-109.768; P = .046), patient age >25 years (HR, 5.44; 95% CI, 0.120-246.070; P = .384), and a body mass index >30 (HR, 2.24; 95% CI, 0.748-6.705; P = .149) were associated with subjective failure. PROMs including KOOS and IKDC were significantly improved at final follow-up compared with preoperative scores across all measurements (P < .005).

CONCLUSION

MAT showed good to excellent clinical results at a mean follow-up of 7 years. Low ICRS lesion grade was associated with a higher clinical and anatomic survival rate. Patients with concurrent OCA transplantation are at a higher risk of clinical and anatomic failure, but still report significantly improved PROMs. These results suggest that MAT has a lasting beneficial effect both in isolation and in complex cases with ≥1 concurrent procedures.

Early Graft Tear As a Major Risk Factor for the Clinical Failure of Lateral Meniscal Allograft Transplantation

BACKGROUND

Graft tears are often observed on magnetic resonance imaging after lateral meniscal allograft transplantation (MAT). Their characteristics, such as the location and configuration, are likely to be different depending on the timing of the injury. However, the clinical relevance of early and late graft tears has not been investigated.

HYPOTHESIS

(1) Both early and late graft tears would be associated with the clinical failure of lateral MAT, and (2) an early graft tear (ET) would lead to worse outcomes than a late graft tear (LT) or an intact graft.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 261 patients who had undergone lateral MAT between March 2000 and June 2019 were retrospectively reviewed. The graft tear was investigated using magnetic resonance imaging, which was performed routinely during the first postoperative year and every 2 years thereafter. The patients were classified according to the timing of the graft tear: no graft tear (NT) group, ET (≤1 year after surgery) group, and LT (>1 year after surgery) group. Clinical failure was defined as (1) reoperations including arthroplasty, realignment osteotomy, revision MAT, and meniscectomy (>50% of the graft or to the zone of the meniscocapsular junction) or (2) a Lysholm score of <65. Risk factors for a low survival rate were investigated using Cox regression analysis. A comparison of the Lysholm scores for each group was also performed.

RESULTS

There were 24 (9.2%) patients who had clinical failure at a mean follow-up of 7.5 ± 4.3 years. The overall survival rate at 5 years was 92.8% (95% CI, 91.1%-94.5%). A graft tear was noted in 80 patients: 23 patients in the ET group and 57 patients in the LT group. The most common tear pattern was a meniscocapsular tear in the ET group and a complex tear in the LT group. The hazard ratios for clinical failure in the ET and LT groups were 30.7 (95% CI, 9.4-76.4; P < .001) and 4.0 (95% CI, 1.3-12.9; P = .013), respectively. The Lysholm score of the ET group (82.7 ± 14.8) was significantly lower than that of the other 2 groups (NT: 87.6 ± 11.7; LT: 90.7 ± 9.0; P = .024).

CONCLUSION

An ET was a major risk factor for the clinical failure of lateral MAT. An LT was associated with a lower survival rate. An ET was also associated with worse clinical outcomes.

Bone bridge technique for lateral meniscal allograft transplantation: no difference in clinical outcome compared to the soft tissue technique

PURPOSE

There is considerable debate regarding the optimal method of fixation for lateral meniscus allograft transplantation (MAT), with bone bridge techniques technically harder but allowing maintenance of root attachments, while soft tissue techniques are potentially more challenging for healing. The aim of this study was to compare the clinical results of the bone bridge and soft tissue techniques for lateral MAT in terms of failure, re-operation rate, complications and patient reported outcomes.

METHODS

Retrospective analysis of prospectively collected data for patients undergoing primary lateral MAT with a minimum of 12-month follow-up. Patients following surgery utilising the bone bridge technique (BB) were compared with historical control patients who underwent MAT with the soft tissue technique (ST). Outcome was assessed by failure rate, defined as removal or revision of the meniscus transplant, survivorship by Kaplan-Meir analysis, re-operation rates, and other adverse event. Patient-reported outcome measures (PROMs) were compared using data at the 2-year point or 1 year if not reached 2 years.

RESULTS

One-hundred and twelve patients following lateral meniscal transplants were included, 31 in the BB group and 81 in the ST historical control group, with no differences in demographics between both groups. Median follow-up for the BB group was 18 (12-43) months compared to 46 (15-62) months for the ST group. There were 3 failures (9.6%) in the BB group v 2 (2.4%) in the ST group (n.s.) with a mean time to failure of 9 months in both groups. 9 patients (29%) required a re-operation (all cause) in the BB group v 24 patients (29.6%) in the ST group (n.s). There was no difference in complications between both groups. There was significant improvement (p < 0.0001) in all PROMs (Tegner, IKDC, KOOS and Lysholm) between baseline and 2-year follow-up for both groups but no between-group differences.

CONCLUSION

Lateral MAT has a high success rate for symptomatic meniscal deficiency with significant benefits irrespective of the fixation technique. There is no advantage in performing the more technically demanding BB technique over ST fixation.

LEVEL OF EVIDENCE

Level 2.

Graft Extrusion of 3 Millimeters Is Acceptable at a Minimum of 5-Year Outcomes for Lateral Meniscal Allograft Transplantation

PURPOSE

To determine the acceptable amount of graft extrusion based on long-term radiographic outcomes in lateral meniscal allograft transplantation (MAT).

METHODS

94 lateral MAT patients with a minimum 5-year follow-up period were reviewed. Graft extrusion was measured on MRI scans taken 1 year after surgery, and the study population was divided according to the amount of extrusion: group A, extrusion <3 mm; group B, 3 mm ≤ extrusion <5 mm; and group C, extrusion ≥5 mm. For radiographic evaluation, the bilateral lateral joint space widths (JSWs) were measured on a standing 45° flexion posteroanterior radiograph. To standardize the measurements, the affected JSW was divided by the contralateral JSW. The change in the standardized JSW (ΔJSWstd) between the preoperative and latest follow-up assessments was analyzed according to the three groups. Multiple regression analysis was performed to control other related factors, such as lower limb alignment and cartilage status at the time of MAT. The acceptable amount of graft extrusion was calculated using a receiver operating characteristic (ROC) curve for the third quartile of ΔJSWstd. Clinical outcomes were evaluated using the Lysholm score and were compared among the groups.

RESULTS

The mean follow-up duration was 8.3 ± 3.1 years. There were 54, 25, and 15 patients in group A, group B, and group C, respectively. In multiple regression analysis, both group B and group C had significant associations with ΔJSWstd and their beta coefficients were comparable (group B, P < .001, β = .642; group C, P < .001, β = 0.613). No significant difference in ΔJSWstd was found between group B and group C (P = .494). On the basis of the ROC curve, the acceptable amount of graft extrusion was 3.74 mm (sensitivity, 81.8%; specificity, 77.8%). There were no differences in the Lysholm scores among the three groups (P = .329).

CONCLUSIONS

ΔJSWstd differed between graft extrusion <3 mm (group A) and graft extrusion ≥3 mm (group B and group C). However, there was no significant difference in ΔJSWstd between group B and group C. No significant difference in clinical outcomes was found according to graft extrusion. This study gave supporting evidence for the currently recognized acceptable amount of graft extrusion (3 mm).

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Effect of High Body Mass Index on Survivorship After Lateral Meniscal Allograft Transplantation: A Propensity Score Matching Analysis

BACKGROUND

Preoperative body mass index (BMI) is one of the correctable factors before surgery. Few studies have investigated the effect of BMI on the survivorship of lateral meniscal allograft transplantation (MAT).

HYPOTHESIS

Patients with a high BMI have inferior survivorship after lateral MAT when compared with those with a normal BMI.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Overall, 306 consecutive patients who underwent lateral MAT were retrospectively reviewed. According to the classification criteria of the World Health Organization, patients were split into 2 groups: normal weight (BMI <25.0) and overweight (BMI ≥25.0). There were 104 patients (34.0%) allocated into the overweight group. Given the demographic heterogeneity between the groups, propensity score matching was performed. Before and after propensity score matching, the anatomic and clinical survival rates of the 2 groups were compared by Kaplan-Meier survival analysis. Anatomic failure was defined as a tear covering >50% of the allograft or unstable peripheral rim on follow-up magnetic resonance imaging and second-look arthroscopy. Clinical failure was defined as a Lysholm score <65 or need for additional surgery, such as revision MAT.

RESULTS

For all patients, the mean ± SD follow-up period was 6.9 ± 4.2 years. The mean BMI of the overweight and normal weight groups was 27.8 ± 2.6 and 22.0 ± 1.9, respectively. The mean Lysholm scores at the last follow-up were not significantly different between the groups. However, the anatomic survival rate in the overweight group (77.9%) was significantly lower than that in the normal weight group (90.1%) (P < .001). The clinical survival rate (82.7%) in the overweight group was significantly lower than that in the normal weight group (95.0%) (P < .001). After propensity score matching for patient characteristics, which left 87 patients per group, the anatomic and clinical survival rates were significantly lower in the overweight group.

CONCLUSION

Preoperative high BMI was associated with inferior anatomic and clinical survival rates. The results of the current study suggest that weight loss before lateral MAT may be required in overweight patients for the improvement of anatomic and clinical survival rates.

Survivorship After Lateral Meniscal Allograft Transplantation Plus Concurrent Cartilage Procedure in Patients With Poor Cartilage Status: A Comparative Study

BACKGROUND

The effect of a concurrent cartilage procedure in lateral meniscal allograft transplantation (MAT) in patients with bipolar cartilage lesions (high-grade lesions on both the femoral and the tibial side) is not well studied. An objective evaluation of graft status after MAT and a concurrent cartilage procedure has not been reported.

PURPOSE

To investigate the effect of concurrent cartilage procedures and lateral MAT on objective and clinical outcomes, including survival, in patients with bipolar cartilage lesions.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 149 patients with high-grade (International Cartilage Regeneration & Joint Preservation Society grade 3 or 4) cartilage lesions were enrolled and assigned to 1 of 3 groups based on the cartilage procedure and cartilage status at the time of MAT. Femoral cartilage procedures (microfracture, n = 18; osteochondral autograft transfer, n = 13) and lateral MAT were performed in 31 patients with bipolar cartilage lesions (cartilage procedure group). Another 70 patients with bipolar lesions underwent only lateral MAT without cartilage procedure (bipolar lesion group). The remaining 48 patients, who had high-grade lesions only on the tibial side and underwent lateral MAT without a cartilage procedure, were selected as a control group (unipolar lesion group). Anatomic survival was objectively assessed by follow-up magnetic resonance imaging and second-look arthroscopy. Clinical survivorship was determined with a Lysholm score <65 or need for additional surgery, such as revision MAT.

RESULTS

The mean Lysholm score improved from 67.2 ± 15.9 preoperatively to 86.7 ± 11.1 with a mean follow-up of 78.0 ± 51.2 months (P < .001). The postoperative scores were not significantly different between the 3 groups. The estimated 5-year anatomic survival rate in the cartilage procedure group (86.7%) was higher than that in the bipolar lesion group (65.0%; P = .043) but comparable with that in the unipolar lesion group (90.2%; P = .572). The estimated 5-year clinical survival rates were not significantly different between the groups (P = .187).

CONCLUSION

A concurrent femoral cartilage procedure improved the anatomic survival rate in patients with bipolar chondral lesions who underwent lateral MAT. This finding suggests that the cartilage procedure is an effective treatment choice and may improve the status of an allograft after lateral MAT for patients with bipolar cartilage lesions.

Nonextruded Grafts Result in Better Cartilage Quality After Lateral Meniscal Allograft Transplantation: Quantitative 3-T MRI T2 Mapping

BACKGROUND

Several studies have reported that graft extrusion after meniscal allograft transplantation (MAT) is associated with deterioration of surgical outcomes. However, no study has investigated the effect of graft extrusion on the articular cartilage using objective quantitative methods.

PURPOSE/HYPOTHESIS

This study aimed to investigate the influence of graft extrusion on the chondroprotective effect of lateral MAT on knee articular cartilage. We hypothesized that MAT without graft extrusion would result in better cartilage quality than MAT with graft extrusion.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Altogether, 105 patients who underwent isolated lateral MAT were divided into the extrusion and nonextrusion groups based on postoperative 3-month magnetic resonance imaging. Quantitative T2 mapping was performed on pre- and postoperative magnetic resonance imaging at midterm follow-up (mean ± SD, 3.2 ± 0.7 years). The weightbearing area of the femoral and tibial plateau articular cartilage was divided into 6 segments (F1, F2, F3, TP1, TP2, and TP3) from the anterior to posterior direction according to the meniscal coverage area. Each segment was further segmented into superficial and deep layers for zonal analysis. Longitudinal change in cartilage T2 value was compared between the groups. Lysholm scores were used to evaluate clinical function.

RESULTS

The mean T2 value of the nonextrusion group showed a significant improvement in 14 of 18 segments after lateral MAT, whereas the extrusion group demonstrated no statistically significant change. The biochemical properties of cartilage tissue as judged by quantitative T2 mapping indicated improvement in the nonextrusion group as compared with the extrusion group in the F2, TP2, and TP3 segments overall; the deep layers of the F1, F2, and TP2 segments; and the superficial layer of the TP3 segment (P < .05).

CONCLUSION

This study shows that the nonextruded graft results in better cartilage properties of the knee joint after lateral MAT as compared with the extruded graft at midterm follow-up.

Outcomes, Complications, and Reoperations After Meniscal Allograft Transplantation

Background:

Outcomes following meniscal allograft transplantation (MAT) are an evolving topic.

Purpose:

To review clinical outcomes in younger, previously active patients who underwent an isolated MAT or MAT plus any osteotomy. Concurrent surgeries, complications, and graft survivorship are presented.

Study Design:

Case series; Level of evidence, 4.

Methods:

Inclusion criteria included having undergone MAT with a minimum of 1 year of follow-up with at least 1 of the following patient-reported outcome (PRO) measures collected pre- and postoperatively: visual analog scale for pain, Knee injury and Osteoarthritis Outcome Score (KOOS), the Western Ontario and McMaster Universities Arthritis Index, the 36-Item Short Form Health Survey, and overall satisfaction. From patient records, we recorded descriptive data, side (medial/lateral), previous or concurrent procedures, perioperative complications, revisions, and conversion to arthroplasty. Two-factor analysis of variance (ANOVA) was used to test for differences in age and body mass index (BMI). A 2 × 2 chi-square test was used to determine if the spectrum of procedures performed on our study’s patient group was representative of the entire population. PRO results were analyzed using a multivariate ANOVA.

Results:

From a total of 91 eligible patients, 61 (63 knees) met our inclusion criteria. Mean presurgery age was 25.5 ± 9.2 years, and mean BMI was 26.7 (range, 18.5-38.4). At follow-up (mean, 4.8 years; range, 1.0-13.6 years) overall PROs were statistically and clinically improved at final follow-up ( P ≤ .003); effect sizes were moderate and large. KOOS Pain and KOOS Activities of Daily Living showed some main or interaction effects that were trivial or small. Patient satisfaction with the treatment was ≥7 out of 10 in 85% of patients. A minimum of 1 subsequent surgery for various concerns was necessary in 23% of the 93 knees. Graft survival in the included patients was 100%.

Conclusion:

Complications (conditions requiring at least 1 subsequent surgery) affected about one-quarter of the patients who underwent MAT. Nevertheless, MAT seemed to provide our patients with adequate pain relief and improved function.

Increased MRI Signal Intensity of Allografts in the Midterm Period After Meniscal Allograft Transplant: An Evaluation of Clinical Significance According to Location and Morphology

Background:

Magnetic resonance imaging (MRI) is an effective tool for objective evaluation after meniscal allograft transplant (MAT). Little is known about the association between MRI features of allograft and clinical outcomes.

Purpose/Hypothesis:

To assess the degree and location of signal intensity (SI) as well as the morphology of allografts on MRI after MAT and evaluate the association between clinical outcomes and MRI features in the midterm period. It was hypothesized that a high SI accompanied by a deformed allograft in specific locations on MRI would be associated with inferior clinical outcomes.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

Included were patients who underwent MAT with fresh-frozen allografts and had >3 years of follow-up with 3.0-T MRI scans. Allograft status was assessed by SI on MRI as grade 0 (normal), grade 1 (globular increased SI not adjacent to the articular surface), grade 2 (linear SI within the meniscus), or grade 3 (increased SI extended to the articular surface). Allograft morphology was assessed by the presence of distorted contours. Clinical outcomes were evaluated using the Lysholm score. The association between clinical outcomes and MRI findings was assessed by multiple linear regression analysis.

Results:

A total of 138 patients (156 MAT procedures: 132 lateral, 24 medial) with a mean follow-up period of 55.4 ± 19.9 months (range, 36-110 months) were enrolled in this study. Grade 3 SI was observed in the posterior meniscus root and posterior third of the allograft in 39 (25%) and 62 (39.7%) MATs, respectively. Among the 62 MATs with grade 3 SI in the posterior third of the allograft, 34 (54.8%) were accompanied by distorted allograft contour. The presence of grade 3 SI with distorted contour in the posterior third of the allograft was significantly associated with inferior outcomes (β = –6.5 [95% CI, –12.5 to –0.5]; P < .035), as was the presence of grade 3 SI in the posterior meniscus root (β = –5.5 [95% CI, –10.5 to –0.4]; P < .034).

Conclusion:

On MRI evaluation in the midterm period after MAT, grade 3 SIs of the meniscal allograft were observed in about a third of the cases, and the association with clinical outcomes was dependent on the specific location and morphology of the allograft on MRI.

Extrusions do not affect degenerative morphologic changes in lateral meniscus allografts during midterm follow-ups

PURPOSE

To investigate degenerative morphological changes in meniscus allograft after lateral meniscus allograft transplantation (MAT) based on extrusions.

METHODS

Ninety-one patients who underwent lateral MAT were divided into extruded and non-extruded groups. Serial magnetic resonance imaging scans obtained 6 weeks, 1 year, and at the last follow-up (midterm, 3-7 years) post-surgery were evaluated retrospectively. Degenerative morphological changes at each time point in each group were compared using the postoperative meniscal width, thickness, and intrameniscal signal intensity (IMSI) at the anterior horn, mid-body, and posterior horn. The Lysholm scores and meniscal tears based on graft extrusion were also investigated.

RESULTS

The mean age was 33.7 ± 11.1 years (64 men and 27 women). Fifty-three (58%) and 38 knees (42%) were classified into the non-extruded and extruded groups, respectively. The overall meniscal width of the mid-body decreased from 9.6 ± 1.3 to 6.5 ± 1.2 mm (p < 0.01), and IMSI of mid-body was increased from 1.2 ± 0.1 to 1.7 ± 0.1 (p < 0.01) during midterm follow-ups. No significant differences were observed between the meniscal width, thickness, and IMSI at the anterior horn (n.s.), mid-body (n.s.), and posterior horn (n.s.) of the two groups during the midterm follow-ups. The incidence of meniscus tears and Lysholm scores did not differ significantly between the groups during midterm follow-ups.

CONCLUSION

The overall meniscus width of mid-body decreased while the relative IMSI of mid-body increased during midterm follow-ups after lateral MAT. Meniscal allograft extrusions did not influence postoperative changes in meniscus width, thickness, and relative intrameniscal signal intensity.

LEVEL OF EVIDENCE

Level III.

Does intermeniscal ligament tenodesis affect meniscal allograft extrusion? Retrospective comparative study at a minimum follow-up of 2 years

INTRODUCTION

Meniscal allograft transplantation (MAT) is indicated for the treatment of post-meniscectomy syndrome in young patients who do not have severe cartilage loss. While its clinical effectiveness is well established in the short- and mid-term, it does not appear to stop the progression of osteoarthritis. Meniscal extrusion often occurs early on and is irreversible. The aim of this study was to evaluate results of arthroscopic MAT combined with reconstruction of the intermeniscal ligament (IML).

HYPOTHESIS

Concurrent reconstruction of the IML decreases the incidence of early allograft extrusion when compared to conventional soft-tissue techniques.

MATERIALS AND METHODS

This was a retrospective single-centre comparative study of 55 patients operated between 2011 and 2018. The 34 patients who met the inclusion criteria were divided into two subgroups: the IML group (MAT with IML repair, n=14) and the non-IML group (MAT without IML repair, n=20). Clinical outcomes consisted of the KOOS at the last follow-up visit and the surgical revision rate. MRI was performed at a minimum of 12 months (mean 34±25 months) to determine absolute and relative meniscal extrusion, sagittal anterior and posterior extrusion, and cartilage coverage in the frontal and sagittal planes.

RESULTS

The KOOS score was not significantly different between the two groups. There were no reoperations in the IML group, but there were four in the non-IML group (13%) (p=0.13). Meniscal extrusion of the allograft occurred in 43% of patients (6/14) in the IML group versus 85% (17/20) in the non-IML group (p<0.03). Absolute meniscal extrusion was 2.9mm ([2.2-3.6] SD=1.2) in the ILM group versus 5.4 mm ([4.1-6.7] SD=2.9) (p=0.004) in the non-ILM group.

DISCUSSION

Adding ILM tenodesis or reconstruction can significantly limit early extrusion of the meniscal allograft. Clinical outcomes at a mean of 34 months are not different when compared to standard procedure. These patients should be re-evaluated in the long term to determine whether the incidence of osteoarthritis is lower with ILM tenodesis.

LEVEL OF EVIDENCE

III; case-control study.

Meniscal Deficiency Period and High Body Mass Index Are Preoperative Risk Factors for Joint Space Narrowing After Meniscal Allograft Transplantation

BACKGROUND

Several studies have reported further reduction in joint space width (JSW) after meniscal allograft transplantation; some contributing postoperative factors are known, although preoperative factors remain unclear. This study is the first to analyze the preoperative risk factors for reduced JSW in patients after lateral meniscal allograft transplantation (LMAT).

HYPOTHESIS

Poor cartilage status and high preoperative body mass index (BMI) influence the postoperative progression of joint space narrowing.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

We retrospectively studied 79 patients after LMAT who were observed for at least 5 years. JSWs on weightbearing flexion posteroanterior radiographs were measured preoperatively and at the 5-year mark. Differences in JSW were divided into more progression and less progression groups. The modified Outerbridge cartilage grades based on magnetic resonance imaging assessments were compared at subtotal/total meniscectomy and at LMAT to determine the difference between time points. Preoperative between-group differences in sex, age, surgical side, follow-up period, weight, height, BMI, and meniscal deficiency period were analyzed. Clinical outcomes were evaluated using the Lysholm score. Data were examined using univariate and multivariate logistic regressions.

RESULTS

Radiographically, the overall change in JSW from preoperative to follow-up was 0.58 mm (range, -0.23 to 1.83 mm). Reductions in JSW in the more progression and less progression groups were 0.94 ± 0.32 and 0.22 ± 0.21 mm (mean ± SD), respectively. There was no difference in cartilage status between the groups at meniscectomy or LMAT; however, changes between time points were significant on the lateral femoral condyle and lateral tibial plateau. Clinically, there were significant differences in weight, BMI, and meniscal deficiency period between the 2 groups. Postoperative Lysholm scores increased as compared with the preoperative scores, but there was no difference among the postoperative time points. In the univariate logistic regression risk analysis, weight, BMI, meniscal deficiency period, and the difference in cartilage status between time points for the lateral femoral condyle and lateral tibial plateau were identified as significant. In the subsequent multivariate logistic regression, BMI (odds ratio, 1.45; P = .016) and meniscal deficiency period (odds ratio, 1.21; P = .037) were the statistically significant factors.

CONCLUSION

BMI and meniscal deficiency period were preoperative risk factors for JSW narrowing after LMAT. This suggests that the meniscal deficiency period from meniscectomy to LMAT may be shortened and that proper weight management can lead to successful LMAT.

Progression of Allograft Extrusion in Both the Coronal and Sagittal Planes at Midterm Follow-up After Medial Meniscal Allograft Transplant

Background

Although many studies have examined allograft extrusion after medial meniscal allograft transplant (MMAT), it is unclear whether allograft extrusion progresses at midterm follow-up.

Hypothesis

After MMAT, allograft extrusion would not progress during the midterm follow-up period.

Study Design

Case series; Level of evidence, 4.

Methods

A total of 30 patients who underwent MMAT between December 1996 and March 2016 were enrolled. Allograft extrusion was measured on magnetic resonance imaging scans obtained at 6 weeks, 1 year, and 3 to 7 years postoperatively. In the coronal plane, the absolute allograft extrusion and relative percentage of extrusion were measured. In the sagittal plane, the absolute and relative anterior cartilage meniscal distance and posterior cartilage meniscal distance were measured. The joint-space width (JSW) on radiographic Rosenberg view was measured at 3 time points. The axial alignment was measured preoperatively and at the midterm follow-up.

Results

In the coronal plane, there were no significant differences in absolute and relative coronal extrusions between 6 weeks and 1 year postoperatively; however, the values were significantly increased at midterm follow-up compared with both of the earlier follow-up periods. Similarly, in the sagittal plane, the mean absolute and relative anterior and posterior cartilage meniscal distances were not significantly different between 6 weeks and 1 year postoperatively but showed significant increases at midterm follow-up compared with both of the earlier follow-up periods. The mean preoperative axial alignment showed a positive correlation with the delta value of relative percentage of extrusion in the coronal plane (r = 0.378; P = .036). The mean JSW was 4.42 ± 0.88 mm preoperatively, 4.30 ± 0.83 mm at 1-year follow-up, and 3.96 ± 1.06 mm at the midterm follow-up. No significant difference was found between the preoperative and postoperative 1-year values, but the mean JSW was significantly decreased at midterm follow-up compared with both of the other time points (P = .001 for both).

Conclusion

Allograft extrusion did not progress until 1 year after MMAT; however, by midterm follow-up, extrusion had progressed in both the coronal and the sagittal planes. Preoperative axial alignment showed a positive correlation with allograft extrusion in the coronal plane.

Large chondral defect not covered by meniscal allograft is associated with inferior graft survivorship after lateral meniscal allograft transplantation

PURPOSE

This study aimed to evaluate graft survivorship according to the size and location of chondral defects and its effect on clinical outcomes after meniscal allograft transplantation (MAT). It was hypothesized that large chondral defects would be associated with inferior outcomes.

METHODS

Patients who underwent lateral MAT with fresh-frozen allografts between 2007 and 2016 were retrospectively reviewed. The inclusion criteria were patients with femoral or tibial chondral defects (International Cartilage Repair Society grade 4) who were followed up more than 2 years with 3.0-T magnetic resonance imaging (MRI) scans. Maximal lesion diameter and location were assessed on MRI. The patients were divided into two groups, with chondral defects of < 3 and ≥ 3 cm² on the tibial side. Graft survivorship was compared between the two groups. Graft failure was defined as revisional MAT, meniscal tear or meniscectomy greater than one-third of the allograft on MRI. Clinical outcomes were evaluated using the modified Lysholm score.

RESULTS

Twenty-eight knees in 26 patients (mean age 37.4 ± 10.3 years) with a mean follow-up of 3.6 ± 1.0 (range 2.0-5.4) years were identified. Nineteen knees in 17 patients had both femoral and tibial chondral defects, 7 knees in 7 patients had only femoral chondral defects, and 2 knees in 2 patients had only tibial chondral defects. The mean preoperative femoral and tibial chondral defect sizes were 1.7 ± 1.2 and 3.0 ± 1.4 cm², respectively. Among the seven graft failures, no graft failure occurred in the cases with tibial chondral defects of < 3 cm². Tibial chondral defects of ≥ 3 cm² were significantly associated with graft failure (P = 0.004; odds ratio 28.3; 95% confidence interval 2.5-4006.7). Defects of < 3 cm² were located primarily in the posterior aspect of the lateral tibial plateau, and most lesions were covered by allograft (7/9, 77.8%). The modified Lysholm scores significantly improved irrespective of chondral defects size (P < 0.001).

CONCLUSIONS

Larger chondral defects, more than 3 cm² on the tibial side, were associated with inferior graft survivorship but did not influence the clinical outcomes after MAT at the 3.6-year follow-up. Chondral defect location was associated with defect size.

LEVEL OF EVIDENCE

IV.

Medial and Lateral Meniscus Allograft Transplantation Showed No Difference With Respect to Graft Survivorship and Clinical Outcomes: A Comparative Analysis With a Minimum 2-Year Follow-Up

PURPOSE

To compare the differences with respect to clinical and graft survivorship and patient-reported outcomes (PROs) between lateral (LMAT) and medial (MMAT) meniscus allograft transplantation.

METHODS

Patients having a primary MAT between 1998 and 2016 were enrolled. The inclusion criteria were (1) patients who had a minimum 2-year follow-up and (2) patients who had magnetic resonance imaging (MRI) >2 years after surgery. Knees with localized grade 4 articular cartilage lesions >3 cm² at the time of MAT were excluded. Clinical failure was defined as follows: modified Lysholm score <65, meniscectomy >50% of the graft, meniscectomy to the meniscocapsular junction zone, conversion to revision MAT, or realignment osteotomy or arthroplasty. Graft failure was defined as follows: tears involving >50% of the graft or unhealed peripheral rim observed on MRI. Kaplan-Meier survival analysis with log-rank test was used to compare survivorship between LMAT and MMAT. Patient-reported outcomes were compared based on the Hospital for Special Surgery, modified Lysholm, and International Knee Documentation Committee subjective scores collected preoperatively and at the final follow-up.

RESULTS

A total of 299 knees (249 LMAT, 50 MMAT, mean age 33.0 ± 9.8 years) were included. Twenty clinical [2 MMAT (4.0%), 18 LMAT (7.2%)] and 24 graft [2 MMAT (4.0%), 22 LMAT (8.8%)] failures were identified. The mean clinical follow-up period was 63.1 ± 43.1 months (range 2 to 248), and MRI follow-up period was 62.6 ± 43.8 months (range 2 to 248). No significant differences in clinical and graft survivorship were found between the LMAT and MMAT groups (P = .481, P = .271, respectively). PROs preoperatively and at last follow-up also showed no significant difference between the groups.

CONCLUSION

No significant differences in clinical survivorship, graft survivorship, and PROs were found between the LMAT and MMAT groups.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Postoperative Subchondral Bone Marrow Lesion Is Associated With Graft Extrusion After Lateral Meniscal Allograft Transplantation

BACKGROUND

Adverse effects of graft extrusion after meniscal allograft transplantation (MAT) are difficult to assess and can be determined only in the long term using a simple radiograph. Recently, subchondral bone marrow lesions (BMLs) detected on magnetic resonance imaging (MRI) scans have been used to evaluate the outcomes or prognoses of various knee surgeries. However, whether subchondral BMLs on MRI scans reflect the effects of allograft extrusion remains unclear.

HYPOTHESIS

Subchondral BML in the lateral compartment of the knee joint on postoperative MRI scans would be associated with graft extrusion after lateral MAT.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Overall, 170 patients with lateral MAT between 2008 and 2013 were classified into extrusion (≥3 mm) and nonextrusion (<3 mm) groups based on findings on MRI scans obtained 3 to 6 months postoperatively. Subchondral BMLs in the lateral compartment were evaluated on the latest MRI scans. To exclude any bone marrow signal changes other than those caused by allograft extrusion, the latest MRI scans were compared with those obtained 3 to 6 months postoperatively. Only subchondral BMLs that occurred after that time point were counted. The association between allograft extrusion and subchondral BML was assessed using chi-square analysis. Logistic regression analysis was performed to control other related factors, including age, sex, body mass index, time from previous meniscectomy, alignment, and cartilage status at the time of MAT. Clinical outcomes according to subchondral BML were evaluated using the Lysholm score.

RESULTS

Of the 170 patients, 20 (11.8%) had subchondral BML on the latest MRI scans at a mean 53.6 ± 31.2 months postoperatively, with 14 and 6 patients in the extrusion and nonextrusion groups, respectively. Chi-square analysis showed a significant association between allograft extrusion and subchondral BMLs (P = .025). Logistic regression analysis showed that extrusion and age were significant factors associated with subchondral BML (P = .011 and .004, respectively). However, no differences were observed in the Lysholm scores in accordance with the subchondral BML (P = .248).

CONCLUSION

Subchondral BMLs on postoperative MRI scans were associated with graft extrusion after lateral MAT. However, there was no difference in clinical outcomes according to subchondral BML.

Meniscus transplantation-prospective assessment of clinical results in two, five and ten year follow-up

PURPOSE

The authors present clinical results in patients following transplantation of deep-frozen menisci within ten years following the surgery.

METHODS

A cohort of 46 patients who were transplanted altogether 49 menisci was subject to prospective study following six months, two, five and ten years after meniscus transplantation. For subjective assessment, we used KOOS, IKDC and Lysholm scores; objective assessment was based on load X-ray examination of the operated knee at two, five and ten years after the surgery, MRI examination of 34 patients in the interval of two and ten years after the operation, control arthroscopy was performed in 23 patients eight of whom suffered a new injury.

RESULTS

All 38 patients who have completed ten year follow-up without any new injury of the operated joint demonstrated statistically significant improvement of mobility in the period of six months and two, five and ten years following the meniscal transplantation. Further follow-up demonstrated different results in patients with a new injury and without a new injury of the operated knee joint. In eight patients (17.3%), the follow-up was disturbed by a new injury of the operated joint within three to eight years after the meniscal transplantation. In three patients with the damaged meniscal transplant, a cartilage deterioration from degree II to degree IIIa was found. In second-look arthroscopy, the patients with no injury showed signs of the improved condition of cartilage by one degree according to ICRS classification on average. The MRI imaging showed relatively frequent (47%) extrusion of the anterior and medial part of meniscus (2.5-3.8 mms) without the followed-up dynamics of changes at two and ten years after the surgery.

CONCLUSION

All patients in the selected cohort proved the positive benefit of meniscus transplant when it comes to the improvement of clinical symptoms and improvement of mobility of the operated knee joint. The higher mobility following the transplantation compared to the activity prior to the surgery could have contributed to a new injury of the operated joint in 17% of the patients in the cohort.

Does Age Itself Have an Adverse Effect on Survivorship of Meniscal Allograft Transplantation? A Cartilage Status and Time From Previous Meniscectomy-Matched Cohort Study

BACKGROUND

The aging process is accompanied by several conditions that could affect the outcome of meniscal allograft transplantation (MAT). These conditions have made it difficult for clinicians to determine the effect of chronologic age on survivorship after MAT.

HYPOTHESIS

Advanced age does not have an adverse effect on survivorship of MAT when controlling for age-related factors, such as cartilage status and time from previous meniscectomy.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

The records of 264 consecutive patients who underwent primary medial or lateral MAT were reviewed. To check whether there was a difference in MAT survivorship according to age, a cutoff value was calculated from a time-dependent receiver operating characteristic curve. Survival rates, as well as clinical improvement as determined using the Lysholm score, were compared between groups divided by the cutoff value. Patients were matched for cartilage status and elapsed time from previous meniscectomy. Differences in survivorship and clinical outcomes were assessed between the matched groups.

RESULTS

A time-dependent receiver operating characteristic curve showed that the difference in MAT survivorship was maximized with a cutoff age of 43 years. Kaplan-Meier analysis showed a significant difference in MAT survivorship between the older and younger groups (log-rank test, P = .01). However, after matching for cartilage status and time from previous meniscectomy, which left 56 patients per group, there was no significant difference in MAT survivorship (log-rank test, P = .10) between the groups. Regarding clinical outcomes, the mean Lysholm scores were not significantly different between the older and younger groups (P = .19, before matching; P = .39, after matching).

CONCLUSION

MAT survivorship was more affected by age-related prognostic factors, such as cartilage status and time from previous meniscectomy, than age itself. Clinical outcomes did not show differences according to age, either.

Influence of Varus Alignment on Survivorship After Lateral Meniscal Allograft Transplantation

BACKGROUND

Factors associated with graft survival after lateral meniscal allograft transplantation (MAT) have not been fully determined, and survival analysis focused on effect of varus alignment has not been performed.

HYPOTHESIS

Varus alignment of the knee leads to better graft survival and clinical outcomes after lateral MAT than normal alignment.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

The records of 204 consecutive patients who underwent lateral MAT were reviewed. After exclusion of cases undergoing revision MAT, cases without hip-knee-ankle standing radiographs, and cases with valgus alignment, the patients were categorized into 2 groups, those with normal alignment within -3° to 3° of the mechanical axis and those with varus alignment >3°. Cumulative graft survival rates were compared in the 2 groups before and after controlling for other covariates, including sex, age, body mass index (BMI), time from meniscectomy, the number of accompanying procedures, and cartilage status. Failure was defined as (1) a graft tear involving >50% or unstable peripheral rim of the allograft; (2) a Lysholm score <65 that was not improved afterward; (3) meniscectomy >50% or to the zone of meniscocapsular junction; or (4) conversion to revision MAT, realignment osteotomy, or arthroplasty. Clinical outcomes were compared between the 2 groups by Lysholm score.

RESULTS

Of the 190 patients, 149 showed normal alignment of 0.3° ± 1.3° (range, -3° to 3°) and 41 showed varus alignment of 4.8° ± 0.6° (range, 4°-8°). A total of 22 patients (11.6%) experienced MAT failure: 21 patients with normal alignment and 1 with varus alignment. Kaplan-Meier survival analysis showed a significant difference in the cumulative graft survival rates between the 2 groups (log-rank test, P = .001). After controlling for age, sex, BMI, time from meniscectomy, the number of accompanying procedures, and cartilage status, varus alignment was found to be a significant protective factor (P = .004). On the other hand, there was no difference in clinical improvement measured by the Lysholm score between the 2 groups (P = .651).

CONCLUSION

Varus alignment was associated with better graft survival after lateral MAT than normal alignment. However, no significant differences in clinical outcomes were observed.

Absolute Meniscal Extrusion After Lateral Meniscal Allograft Transplantation Does Not Progress During Long-term Follow-up: Average of 10.3 Years' Follow-up Longitudinal Magnetic Resonance Imaging Study

BACKGROUND

Long-term outcomes after lateral meniscal allograft transplantation (MAT) are not completely understood.

PURPOSE/HYPOTHESIS

We investigated changes in meniscal extrusion in the coronal and sagittal planes using magnetic resonance imaging (MRI) after lateral MAT through long-term follow-up. We hypothesized that meniscal extrusion would progress during follow-up.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Patients subjected to lateral MAT were followed up by MRI evaluation in both planes at 1, 4 to 6, and >8 years after MAT. Meniscal extrusion and entire meniscal widths in the coronal plane and anterior (ACMD) and posterior (PCMD) cartilage meniscal distances in the sagittal plane were measured, and values were compared at each time point. Clinical outcomes were evaluated using the Lysholm score.

RESULTS

A total of 27 lateral MATs were included with a mean MRI follow-up period of 10.3 years (range, 8.1-15.3 years). The mean absolute meniscal extrusion (coronal plane) was not significantly different at each time point. However, the relative value differed (0.27 ± 0.04 at 1 year; 0.33 ± 0.06 at >8 years after MAT) owing to entire meniscal width reduction. There was no difference in the mean absolute value of the ACMD in the sagittal plane. However, relative values differed (0.21 ± 0.01 at 1 year; 0.27 ± 0.06 at >8 years) owing to entire meniscal width reduction. Absolute and relative values of the PCMD remained unaffected at each time point. The Lysholm score increased after surgery but did not differ postoperatively.

CONCLUSION

During the long-term follow-up of extrusion after lateral MAT using MRI, absolute extrusion remained unchanged across all planes. Relative extrusion in the coronal plane and of the ACMD in the sagittal plane significantly increased, with no differences in the PCMD on follow-up. Clinical outcomes after surgery improved compared with those before surgery and were maintained throughout the long-term follow-up period.

Meniscal Allograft Transplantation With Soft-Tissue Fixation Including the Anterior Intermeniscal Ligament

Meniscal allograft transplantation has been introduced as a treatment for symptomatic meniscus-deficient patients to improve clinical outcomes. We describe an arthroscopic technique for meniscal allograft with soft-tissue fixation including the anterior intermeniscal ligament (AIML): arthroscopic double soft-tissue fixation technique. The AIML and anterior and posterior roots are detached and sutured using running locked Krackow stitches. After preparation of the meniscal bed, the meniscus is passed into the knee and the posterior meniscal horn is fixed with sutures through bone tunnels. The body of the meniscus is fixed with all-inside sutures. Then, the anterior meniscal suture is fixed on the anatomic point of the anterior root with an anchor. The AIML suture is fixed with an anchor to the bare area of the proximal tibia, anterior to the anterior cruciate ligament insertion. This reliable and reproducible technique is less complex than bone plug methods; it is less invasive but still provides stable and secure graft fixation. It will help surgeons to improve clinical results and to limit early secondary extrusion of the graft.

Is Lateral Posterior Tibial Slope Correlated With Clinical Outcomes of Lateral Meniscus Allograft Transplantation?

PURPOSE

To investigate (1) the correlation between lateral posterior tibial slope (PTS) and clinical outcomes of lateral meniscus allograft transplantation (MAT) and (2) the difference of lateral PTS between the extrusion and nonextrusion groups or between the failure and nonfailure groups in lateral MAT.

METHODS

Between January 2001 and February 2016, we retrospectively evaluated 61 patients (mean age, 29.1 ± 12.2 years) who underwent postoperative magnetic resonance imaging (MRI) and were followed for a minimum of 2 years after primary lateral MAT. The lateral PTS and graft extrusion in the coronal and sagittal planes were assessed by using MRI performed at 1 year postoperatively. Clinical scores and graft failure were evaluated at the last follow-up visit. The correlation between lateral PTS and clinical outcomes (clinical scores, graft extrusion) was analyzed. Lateral PTS was compared between the extrusion and nonextrusion groups and between the failure and nonfailure groups.

RESULTS

Mean lateral PTS on MRI was 6.6° ± 3.1° (range, 0.8° to 15.7°). A significant correlation was not identified between lateral PTS and clinical outcomes (clinical scores, graft extrusion in the coronal and sagittal planes). A significant difference in lateral PTS was not identified between the extrusion and nonextrusion groups in the coronal (6.2° ± 2.5° vs 7.0° ± 3.4°, P = .400) and sagittal (anterior horn, 6.5° ± 2.3° vs 6.7° ± 3.7°, P = .988; posterior horn, 6.8° ± 3.5° vs 6.5° ± 2.7°, P = .771) planes. Moreover, a significant difference was not identified between the failure and nonfailure groups (7.5° ± 3.3° vs 6.4° ± 3.0°, P = .388).

CONCLUSIONS

A significant correlation between lateral PTS and clinical or radiologic outcomes of lateral MAT was not identified.

LEVEL OF EVIDENCE

Level IV, therapeutic case series with subgroup analysis.

Morphometric measurements to predict meniscal size in skeletally mature dogs for meniscal transplantation

OBJECTIVE

To determine a relationship between morphometric measurements (MM) and meniscal dimensions (MD) in the dog.

STUDY DESIGN

Cadaveric study.

ANIMALS

Eighteen mixed-breed canine cadavers (22.35 ± 4.06 kg); 36 each of medial and lateral menisci.

METHODS

The following MM were obtained in duplicate: height at scapula, withers, pelvis, rump, and greater trochanter; chest circumference; pelvic circumference; length from occiput to the base of the tail; hock to stifle length (HS); body weight; body condition score; and body fat percentage (BF%). Stifles were disarticulated, and digital photographs of in situ menisci were used to obtain meniscal measurements in duplicate. Morphometric parameters were compared with MD via Pearson correlation (r). A correlation of r ≥ 0.65 was considered strong.

RESULTS

The strongest correlation was noted between HS and MD, with r = 0.85 for lateral meniscal width, r = 0.77 for medial meniscal length, and r = 0.76 for medial meniscal width. Lateral meniscal length had the strongest correlation with height at rump (HRu) (r = 0.73). Body weight correlated strongly with meniscal width and fairly with meniscal length. Body condition score and BF% correlated weakly with MD.

CONCLUSION

Hock to stifle length was an easily obtainable variable and was proportional to MD.

CLINICAL SIGNIFICANCE

Hock to stifle length may be considered by tissue banks and veterinary surgeons as a quick and cost effective screening tool for appropriate meniscal sizing in dogs.

Biomechanical considerations are crucial for the success of tendon and meniscus allograft integration-a systematic review

PURPOSE

This systematic review intends to give an overview of the current knowledge on how allografts used for the reconstruction of cruciate ligaments and menisci are integrated and specifically perform regarding their biomechanical function.

METHODS

Two reviewers reviewed the PubMed and Central Cochrane library with focus on the biomechanical integration of tendon ligament and meniscus allografts. The literature search was conducted in accordance with the PRISMA statement for reporting systematic reviews and meta-analyses.

RESULTS

The analysed literature on tendon allografts shows that they are more vulnerable to overstretching in the phase of degradation compared to autografts as the revascularization process starts later and takes longer. Therefore, to avoid excessive graft loads, allografts for cruciate ligament replacement should be selected that exhibit much higher failure loads than the native ligaments to counteract the detrimental effect of degradation. Further, placement techniques should be considered that result in a minimum of strain differences during knee joint motion, which is best achieved by near-isometric placement. The most important biomechanical parameters for meniscus allograft transplantation are secure fixation and proper graft sizing. Allograft attachment by bone plugs or by a bone block is superior to circumferential suturing and enables the allograft to restore the chondroprotective biomechanical function. Graft sizing is also of major relevance, because too small grafts are not able to compensate the knee joint incongruity and too large grafts may fail due to extrusion. Only adequate sizing and fixation together can lead to a biomechanically functioning allograft. The objective assessment of the biomechanical quality of allografts in a clinical setting is challenging, but would be highly desirable for monitoring the remodelling and incorporation process.

CONCLUSIONS

Currently, indicators like ap-stability after ACL reconstruction or meniscal extrusion represent only indirect measures for biomechanical graft integration. These parameters are at best clinical indicators of allograft function, but the overall integration properties comprising e.g. fixation and graft stiffness remain unknown. Therefore, future research should e.g. focus on advanced imaging techniques or other non-invasive methods allowing for in vivo assessment of biomechanical allograft properties.

Open Meniscal Allograft Transplantation With Transosseous Suture Fixation of the Meniscal Body Significantly Decreases Meniscal Extrusion Rate Compared With Arthroscopic Technique

PURPOSE

To assess and compare meniscal extrusion rates after lateral "bridge-in-slot" meniscal allograft transplantation (MAT) with arthroscopic versus open insertion.

METHODS

In this review of prospectively collected data, we analyzed data from patients who underwent arthroscopic or open lateral MAT. Patients who underwent concomitant distal femoral osteotomy, for whom 1-year postoperative magnetic resonance imaging was unavailable, or who underwent open lateral MAT without the use of transosseous sutures were excluded. Meniscal extrusion in the included patients was assessed by 2 independent examiners by measuring the absolute value and the relative percentage of extrusion on 1.5-T magnetic resonance images at 1-year follow-up. The number of MATs with radial displacement larger or smaller than 3 mm was determined.

RESULTS

A total of 20 patients met the inclusion criteria, of whom 10 underwent arthroscopic and 10 underwent open lateral MAT. No statistically significant differences were found in baseline demographic data. Absolute meniscal extrusion was similar between the groups (P = .091). A significantly larger relative percentage of extrusion (arthroscopic MAT, 31 ± 27 mm; open MAT, 10 ± 29 mm; 95% confidence interval, -0.4 to -0.02 mm; P = .03) and a significantly higher extrusion rate were found in patients treated with arthroscopic MAT than in those treated with open MAT (>3 mm in 5 patients [50%] with arthroscopic MAT and 0 patients with open MAT, P = .01).

CONCLUSIONS

This study identified similar absolute extrusion and significantly lower postoperative lateral meniscal extrusion rates after open MAT compared with arthroscopic MAT. Transosseous fixation of the meniscal body appears protective against meniscal extrusion after MAT.

LEVEL OF EVIDENCE

Level III, case-control study.

The International Knee Documentation Committee Score Indicates Midterm Patient Satisfaction with Outcomes after Meniscal Allograft Transplantation

BACKGROUND

This study aimed to identify the factors associated with patient satisfaction with the outcome of meniscal allograft transplantation (MAT).

MATERIALS AND METHODS

Patients treated with MAT from March 2006 to May 2009 were asked to complete a five-point Likert scale regarding satisfaction with the outcome of MAT, in addition to the following subjective outcome evaluation forms: the International Knee Documentation Committee (IKDC) subjective forms, Knee Society Score knee and function forms, and Lysholm Knee Scoring Scale. We collected radiologic data using X-ray and magnetic resonance imaging and assessed isokinetic muscle strength test using the Biodex System 3. We investigated whether these parameters were significantly associated with patient satisfaction. Statistical analysis was computed using univariate and multivariable logistic regression.

RESULTS

Among the 130 patients who underwent MAT, 49 participated in the interview and were included in this study. The mean followup period was 50.4 months. Mean patient age was 40 (±9) years; 33 were male and 16 were female (33%). The lateral meniscus was transplanted in 13 (27%) patients, while the medial meniscus was involved in 36 (73%) patients. On univariate analysis, sex and isokinetic extension strength deficit at 60° and 180° as well as the IKDC, Knee Society, and Lysholm scores showed significant association with patient satisfaction regarding the outcome. On multivariable logistic regression, only the IKDC score showed a significant association, with P = 0.04.

CONCLUSIONS

The study results support the importance of patient-reported subjective outcomes in terms of patient satisfaction following a surgical procedure. Regarding MAT, the IKDC outcome score reflects patient satisfaction.

LEVEL OF EVIDENCE

Level III.

Early and Delayed Meniscal Shrinkage After Fresh-Frozen Lateral Meniscal Allograft Transplantation: Magnetic Resonance Imaging Study With a Midterm Follow-up

PURPOSE

To evaluate whether fresh-frozen meniscal allograft shrinkage occurs only during the first year of the early remodeling period or progresses over the delayed period of midterm years and to determine whether these changes were associated with certain clinical and radiologic outcomes.

METHODS

We retrospectively reviewed meniscal allograft transplantations (MATs) performed by 1 senior surgeon (S-I.B.) using fresh-frozen allograft from 2008 to 2013. The inclusion criteria were the patients who had midterm follow-up magnetic resonance imaging (MRI) scans between 3 and 6 years after isolated lateral MATs. We excluded the graft tears found on the 1-year or midterm MRI scans. MATs were indicated for the treatment persistent compartmental pain in young to middle-aged, physically active patients who had well-aligned nonarthritic joint without ligament insufficiency. The meniscal width of the transplants at the midbody and posterior horn was measured on day 2 (as a reference), at 1 year (after early remodeling period), and after 3 to 6 years (delayed period) postoperatively. Joint space width changes during each interval were measured on 45° flexion posteroanterior views. The Lysholm score and Tegner activity scale were used to evaluate clinical outcomes.

RESULTS

Eighty-four isolated lateral MATs with the midterm MRI scans were identified. Of these, 17 graft tears were found; therefore, we analyzed 67 patients (32 male and 35 female patients) with a mean age of 30.9 years (range, 15-52 years). The mean relative meniscal width at the midbody decreased to 93.7% (95% confidence interval [CI], 91.8%-95.6%; P < .001) at 1 year postoperatively and to 88.0% (95% CI, 85.6%-90.3%; P < .001) at the midterm follow-up of 4.0 ± 1.0 years. The posterior horn shrank less than the midbody during the same period (96.0%; 95% CI, 94.8%-97.1%) at 1 year (P < .001) and 92.5% (95% CI, 91.0%-94.1%) at the last follow-up (P < .001). Although there was no severe shrinkage (>50% of the initial size), the incidence of moderate (25%-50%) changes at the midbody increased from 1 (1.5%) at 1 year to 5 (7.5%) at the last follow-up, respectively. We could not find any significant positive correlations between the relative meniscal width and patient-reported outcomes or joint space width changes after 1 year or at the last follow-up.

CONCLUSIONS

Shrinkage of fresh-frozen meniscal transplants occurred during both the early remodeling and delayed midterm periods. Although the changes were greater in the midbody than in the posterior horn, the overall changes were less than those of the previous studies using cryopreserved grafts. We could not find that the meniscal shrinkage over the midterm period were significantly associated with inferior outcomes in this series.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Clinical Outcomes of Meniscal Allograft Transplantation With or Without Other Procedures: A Systematic Review and Meta-analysis

BACKGROUND

While additional procedures correcting accompanying pathological conditions can improve the clinical outcomes of meniscal allograft transplantation (MAT), whether those outcomes are comparable or poorer than those of isolated MAT has yet to be clarified.

PURPOSE

To evaluate whether there is a difference in clinical outcomes between isolated MAT and MAT combined with other procedures (combined MAT).

STUDY DESIGN

Meta-analysis and systematic review.

METHODS

For the comparison of clinical outcomes between isolated MAT and combined MAT, the authors searched MEDLINE, Embase, and the Cochrane Library. Studies that separately reported the clinical outcomes of isolated MAT and combined MAT were included. Clinical outcomes were evaluated in terms of patient-reported outcomes (PROs) and complication, reoperation, survivorship, and failure rates. We conducted a meta-analysis of the PROs that were used in more than 3 studies.

RESULTS

A total of 24 studies were included in this study. In the meta-analysis, no significant differences in Lysholm scores (95% CI, -5.92 to 1.55; P = .25), Tegner activity scores (95% CI, -0.54 to 0.22; P = .41), International Knee Documentation Committee subjective scores (95% CI, -5.67 to 3.37; P = .62), and visual analog scale scores (95% CI, -0.15 to 0.94; P = .16) were observed between isolated MAT and combined MAT. For PROs that were not included in the meta-analysis, most studies reported no significant difference between the 2 groups. As for the survivorship and failure rates, studies showed varying outcomes. Four studies reported that additional procedures did not affect MAT failure or survivorship. However, 3 studies reported that ligament surgery, realignment osteotomy, and osteochondral autograft transfer were risk factors of failure. One study reported that the medial MAT group in which high tibial osteotomy was performed showed a higher survival rate than the isolated medial MAT group.

CONCLUSION

Overall, there seems to be no significant difference between the postoperative PROs in terms of isolated MAT and combined MAT. However, more data are required to verify the effects of osteotomy and cartilage procedures on the clinical outcomes of MAT. We could not draw conclusions about the differences in complication, reoperation, survivorship, and failure rates between the 2 groups because we did not obtain sufficient data.

Low-impact sports activities are feasible after meniscus transplantation: a systematic review

PURPOSE

To determine sports activities achieved after meniscus transplantation and if associations exist between sports activity levels and transplant failure or progression of tibiofemoral osteoarthritis (OA).

METHODS

A systematic search was performed using PubMed and Cochrane online databases. Inclusionary criteria were English language, clinical trials published from 1996 through May 2017, minimum 2 years of follow-up, and sports activity data reported.

RESULTS

Twenty-eight studies were included in which 1521 menisci were implanted into 1497 patients. The mean age was 34.3 ± 6.7 years, and the mean follow-up was 5.0 ± 3.7 years. Details on sports activities were provided in 7 studies (285 patients) that reported 70-92% of patients returned to a wide variety of sports activities. Mean Tegner activity scores were reported in 24 investigations. The mean score was <5 in 58% of these studies, indicating many patients were participating in light recreational activities. There was no association between mean Tegner scores and transplant failure rates. A moderate correlation was found between failure rates and mean follow-up time (R = 0.63). The effect of sports activity levels on progression of tibiofemoral OA could not be determined because of limited data. Only two studies determined whether symptoms occurred during sports activities; these reported 1/38 (3%) and 5/69 (7%) patients had knee-related problems.

CONCLUSIONS

It appeared that the majority of individuals returned to low-impact athletic activities after meniscus transplantation. The short-term follow-up did not allow for an analysis on the effect of return to high-impact activities on transplant failure rates or progression of OA.

LEVEL OF EVIDENCE

IV.

Graft extrusion after medial and lateral MAT differs according to surgical technique: a meta-analysis

INTRODUCTION

It is unclear whether the incidence and amount of graft extrusion differ between knees undergoing medial and lateral meniscus allograft transplantation (MAT). This meta-analysis, therefore, compared the incidence and amount of transplanted meniscus allograft extrusion following medial and lateral MAT.

MATERIALS AND METHODS

All studies comparing absolute or relative extrusions, or proportion of major extrusions (> 3 mm), on magnetic resonance imaging between medial and lateral MATs were included.

RESULTS

Eight studies were included in the meta-analysis. Using the arthroscopic-assisted technique, medial MAT had significantly greater absolute (0.99 mm, p = 0.002) and relative (19.4%, p = 0.001) extrusions than lateral MAT. Using the complete arthroscopic technique, lateral MAT had 1.45 mm greater absolute extrusion than medial MAT (p < 0.001), but there was no difference in relative extrusion. Using the arthroscopic-assisted technique, the proportion of knees with major extrusion was greater for medial than lateral MAT (OR 5.32, p < 0.001), but, using the complete arthroscopic procedure, there was no difference in proportions of major extrusions between medial and lateral MAT (OR 0.28, p = 0.08).

CONCLUSION

Graft extrusions after medial and lateral MAT differed according to surgical technique. Graft extrusion was greater after medial than lateral MAT using the arthroscopic-assisted technique, but was greater after lateral than medial MAT using the complete arthroscopic procedure.

LEVEL OF EVIDENCE

Meta-analysis (Level II).

Editorial Commentary: Meniscal Allograft Transplantation: Still Effective With Poor Cartilage, But Much Better With Good Cartilage-Better Done Earlier

Meniscal allograft transplantation (MAT) is an established treatment for a symptomatic, meniscus-deficient knee. It is well known that MAT is effective in patients with good cartilage even in the early era of this procedure. The role of MAT in arthritic knees is getting more and more clear with increasing evidence over the last decade. Now we are able to expand our surgical indication to arthritic patients and provide them with individualized explanation for outcome and survival.

Incidence and Extent of Graft Extrusion following Meniscus Allograft Transplantation

Background

The incidence and extent of graft extrusion after meniscus allograft transplantation (MAT) may differ in patients undergoing medial and lateral meniscus transplantation due to the use of different surgical techniques. This meta-analysis was therefore designed to quantify the extent and incidence of graft extrusion after meniscus allograft transplantation.

Methods

Following preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines, all studies reporting absolute extrusion, relative percentage of extrusion (RPE), or frequency of major extrusions (>3 mm) on magnetic resonance imaging in patients undergoing medial or lateral MAT were included.

Results

The pooled mean absolute extrusion following all MATs was 3.15 mm but was significantly greater following medial than lateral MAT (3.26 versus 3.01 mm; p = 0.001). The pooled mean RPE following all MATs was 32.79% and was significantly greater after medial than lateral MAT (32.69% versus 28.81%; p < 0.001). The pooled mean proportion of knees with major (>3 mm) extrusion was 53% (95% CI: 49% to 58%) and was significantly greater after medial than lateral MAT (61% versus 39%; p < 0.001).

Conclusion

Mean graft extrusion after arthroscopic assisted MAT using bony fixation was 3.2 mm, with major graft extrusion > 3 mm occurring in about 50% of transplanted menisci. Graft extrusion was significantly greater after medial than lateral MAT.

Lateral Meniscal Allograft Transplant via a Medial Approach Leads to Less Extrusion

BACKGROUND

Accurate positioning of the bony bridge is crucial to prevent extrusion of meniscal allografts after transplant. However, oblique or lateralized placement of the bony bridge of the lateral meniscal allograft may occur due to technical error or a limited visual field. The patellar tendon may be an obstacle to approaching the anterior horn of the lateral meniscus, resulting in a laterally placed allograft. Therefore, lateral meniscal transplant through a medial arthrotomy would be an alternative approach. However, no report exists regarding allograft extrusion when comparing medial and lateral arthrotomy techniques in lateral meniscal transplants.

HYPOTHESIS

Extrusion of the midbody of the allograft is less severe and the rotation of the bony bridge is less oblique in lateral meniscal allograft transplants through the medial parapatellar approach than those through the lateral approach.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A bony bridge was used to perform 55 lateral meniscal transplants through either a medial or a lateral arthrotomy. Thirty-two allografts were transplanted through a medial arthrotomy and 23 were transplanted through a lateral arthrotomy, not randomly. Because correct positioning of the bony trough through the medial arthrotomy was easier than that through the lateral arthrotomy, the method of the arthrotomy was changed for the latter. The procedure for both groups was identical except for the arthrotomy technique, and rehabilitation was identical for both groups. Follow-up magnetic resonance imaging was conducted for all patients to measure the postoperative extrusion and obliquity of the bony bridge of the allograft. On the coronal view, extrusion was measured as the distance between the outer edge of the articular cartilage of the lateral tibial plateau and the outer edge of the meniscal allograft. On the axial view, a line (line B) was drawn along the longitudinal axis of the bony bridge. The posterior tibial condylar tangential line was drawn between the medial and lateral posterior tibial condylar cortices. A line (line T) was drawn perpendicular to the posterior tibial condylar tangential line. The angle (trough angle) between lines B and T was measured. Postoperative extrusion and the trough angle were compared between the medial and lateral arthrotomy groups.

RESULTS

The median extrusion of the midbody of the allograft was 2.2 mm (interquartile range [IQR], 2.4 mm; range, 0-4.6 mm) in the medial arthrotomy group and 3.1 mm (IQR, 1.5 mm; range, 0-5.3 mm) in the lateral arthrotomy group ( P = .001). Seven (21.9%) patients demonstrated extrusion in the medial arthrotomy group, and 15 (65.2%) patients had extrusion in the lateral group ( P = .002). The median trough angle was 0.9° (IQR, 9.3°; range, -8.8-15.8°) in the medial arthrotomy group and 11.6° (IQR, 2.8°; range, 3-19.8°) in the lateral arthrotomy group ( P < .001).

CONCLUSION

Based on this experience, lateral meniscal allograft transplant through a medial arthrotomy is preferred to decrease postoperative extrusion of the allograft.

Comparison of medial versus lateral meniscus allograft transplantation. Literature review and meta-analysis

Objectives:

To perform a literature review and meta-analysis evaluating the effectiveness of medial and lateral meniscus allograft transplantation (MAT).

Methods:

The literature review and meta-analysis were conducted between August and October 2015 in the People’s Hospital of China Three Gorges University, Yi Chang, China. A systematic search was performed in the Medline and EMBASE databases, and the Cochrane Library for relevant literature published through October 2015. The outcomes of the included studies were analyzed in terms of the Lysholm Score, International Knee Documentation Committee (IKDC) Score, Knee Injury And Osteoarthritis Outcome Score (KOOS), Visual Analog Scale (VAS), Tegner Activity Score, MRI results, and failure rates. An adapted version of the Newcastle-Ottawa Scale was used for the methodological quality assessment in the meta-analyses.

Results:

The literature review identified 12 observational studies, including 7 retrospective studies, 4 prospective studies, and the nature of one study was not reported. Significant differences in the outcomes of the lateral MAT group and the medial MAT group were observed in the IKDC scores, KOOS pain values, KOOS activities of daily living (ADL) values, and the absolute and relative extrusions observed on MRI, which suggested that the lateral MAT patients experienced superior clinical benefits compared with the medial MAT patients. However, significant differences between the lateral MAT group and the medial MAT group were not observed with regards to the Lysholm Scores, KOOS symptom values, KOOS sports and recreations values, KOOS quality of life (QOL) values, Tegner Activity Scores, VAS for pain values, and failure rates.

Conclusion:

The analysis results indicated that lateral MAT provides superior clinical outcomes compared with medial MAT according to the KOOS and IKDC scores. In addition, greater graft extrusion was observed in the medial group on MRI. Although significant differences were not detected between the 2 groups, the medial MAT patients were more prone to failure compared with the lateral MAT patients.

Survivorship After Meniscal Allograft Transplantation According to Articular Cartilage Status

BACKGROUND

Clinical outcomes after meniscal allograft transplantation (MAT) in arthritic knees are unclear, and objective estimates of graft survival according to the articular cartilage status have not been performed.

HYPOTHESIS

MAT should provide clinical benefits in knees with high-grade cartilage damage, but their graft survivorship should be inferior to that in knees with low-grade chondral degeneration after MAT.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

The records of 222 consecutive patients who underwent primary MAT were reviewed to compare clinical outcomes and graft survivorship. The patients were grouped according to the degree and location of articular cartilage degeneration: low-grade chondral lesions (International Cartilage Repair Society [ICRS] grade ≤2) on both the femoral and tibial sides (ideal indication), high-grade lesions (ICRS grade 3 or 4) on either the femoral or tibial side (relative indication), and high-grade lesions on both sides (salvage indication). Kaplan-Meier survival analysis with the log-rank test was performed to compare the clinical survival rates and graft survival rates between the groups. A Lysholm score of <65 was considered a clinical failure, and graft failure was defined as a meniscal tear or meniscectomy of greater than one-third of the allograft, objectively evaluated by magnetic resonance imaging (MRI) and second-look arthroscopic surgery.

RESULTS

The mean (±SD) Lysholm score significantly improved from 63.1 ± 15.1 preoperatively to 85.1 ± 14.3 at the latest follow-up of a mean 44.6 ± 19.7 months ( P < .001). However, the postoperative scores were not significantly different between the 3 groups (85.7 ± 14.2 for ideal indication, 84.7 ± 17.0 for relative indication, and 84.7 ± 14.2 for salvage indication; P = .877). On MRI at the latest follow-up of a mean 23.0 ± 19.9 months and second-look arthroscopic surgery of a mean 19.3 ± 20.7 months, there were 25 (11.3%) failed MAT procedures (4 medial, 21 lateral); of these, 5 lateral MAT procedures (2.3%) went on to allograft removal. Clinical survival rates were not significantly different between the groups ( P = .256). However, on objective evaluation, the estimated cumulative graft survival rate at 5 years in the salvage indication group (62.2% [95% CI, 41.6-82.8]) was significantly lower than that in the other 2 groups (ideal indication: 93.8% [95% CI, 88.5-99.1]; relative indication: 90.9% [95% CI, 81.1-100.0]) ( P = .006).

CONCLUSION

Our findings showed that MAT was an effective symptomatic treatment in knees with advanced bipolar chondral lesions. However, better graft survival can be expected when articular cartilage is intact or if chondral damage is limited to a unipolar lesion. MAT should be considered before the progression of chondral damage to a bipolar lesion for better graft survivorship and should be performed cautiously in arthritic knees.

Meniscal Extrusion Does Not Progress During the Midterm Follow-up Period After Lateral Meniscal Transplantation

BACKGROUND

Meniscal extrusion is related to degeneration of the native knee joint. However, the clinical effect of the phenomenon after meniscal allograft transplantation (MAT) has not been clearly identified. Purpose/Hypothesis: The purpose of this study was to evaluate the change in meniscal extrusion in both the coronal and sagittal planes after lateral MAT through the midterm follow-up period. We hypothesized that meniscal extrusion does not progress during the midterm follow-up period.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 46 patients with a mean follow-up of 51.1 ± 7.1 months were included in the study. The patients underwent lateral MAT using the keyhole technique. Postoperative magnetic resonance imaging (MRI) was performed at 6-week, 1-year, and midterm (3- to 5-year) follow-up. In the coronal plane, the absolute value of meniscal subluxation and the relative percentage of extrusion (RPE) were measured. In the sagittal plane, meniscal subluxation was measured as the absolute and relative anterior cartilage meniscal distance (ACMD) and posterior cartilage meniscal distance (PCMD). The joint-space width (JSW) on weightbearing radiographs with 2 different knee positions was measured preoperatively and at 1-year and midterm follow-up. The Lysholm score was assessed at the same time points.

RESULTS

In the coronal plane, the mean absolute meniscal extrusion at 6-week, 1-year, and final follow-up was 2.90 ± 0.94, 2.85 ± 0.97, and 2.83 ± 0.89 mm, respectively, and the mean RPE was 27.0% ± 9.4%, 27.1% ± 10.1%, and 27.8% ± 9.7%, respectively. There were no statistically significant differences in absolute and relative coronal extrusion among the 3 time periods ( P > .05). The percentage of patients with meniscal extrusion (≥3 mm) was 37.0% at 6-week follow-up and 34.8% at 1-year and final follow-up. In the sagittal plane, the mean absolute ACMD was 2.59 ± 1.75, 2.58 ± 1.85, and 2.37 ± 1.60 mm, respectively, and the mean relative ACMD was 20.7% ± 13.1%, 20.6% ± 13.8%, and 19.0% ± 12.2%, respectively, at the 3 follow-up time points. The mean absolute PCMD was -1.23 ± 3.34, -1.28 ± 3.08, and -1.42 ± 2.77 mm, respectively, and the mean relative PCMD was -10.3% ± 25.9%, -11.0% ± 24.6%, and -12.2% ± 23.2%, respectively, at the same time points. Sagittal extrusion was not significantly different between the time points ( P > .05). The mean JSW at 2 days preoperatively, 1 year postoperatively, and midterm follow-up was 5.40 ± 1.07, 5.44 ± 1.04, and 5.43 ± 0.98 mm, respectively, on anterior-posterior radiographs with full extension, and it was 4.90 ± 0.94, 4.94 ± 0.98, and 4.89 ± 0.96 mm, respectively, on posterior-anterior radiographs with 45° of flexion. The mean JSW values were not significantly different between the 3 different time points ( P > .05). The mean preoperative Lysholm score was 58. 9 ± 8.3; the score increased to 90.4 ± 9.7 at 1 year postoperatively and 90.5 ± 10.1 at final follow-up, which is a significant improvement compared with the preoperative status ( P < .05). There was no statistically significant difference between the scores at the 2 postoperative time points ( P > .05).

CONCLUSION

This study demonstrated that extrusion of the meniscal allograft did not significantly progress either in the coronal or sagittal plane after lateral MAT during the midterm follow-up period.

Long-term Survival Analysis of Meniscus Allograft Transplantation With Bone Fixation

PURPOSE

To investigate the long-term clinical results and clinical survival rate of meniscus allograft transplantation (MAT) with bone fixation.

METHODS

The inclusion criteria of this study were previous MAT with bone fixation technique in our institution and minimum follow-up duration of 8 years. Potential subjects were identified using the medical records and database that was prospectively collected from December 1996 to December 2005. The exclusion criteria were diffuse International Cartilage Repair Society grade IV articular cartilage degeneration that was not treated with a concomitant or staged cartilage repair procedure. Surgical indication for MAT was previous total or subtotal meniscectomy followed by persistent swelling and pain in involved compartment. Recommendations to return to contact sports or strenuous activities were not made. Clinical outcomes were evaluated using the modified Lysholm score, and comparison between preoperative and final Lysholm score was done using Student t-test. During the follow-up period, failure was defined as (1) subtotal resection of the allograft, (2) conversion to total knee arthroplasty, or (3) a modified Lysholm score less than 65 or that of the preoperative status. Survival analysis was performed using the Kaplan-Meier method.

RESULTS

During the study period, 52 knees underwent MAT in our institution and 49 knees were eligible for this study. Three knees were excluded because they had diffuse grade IV cartilage degeneration in the respective compartment. Among the 49 knees enrolled, 34 underwent lateral and 15 underwent medial MAT. Two patients had bilateral lateral MAT. Of those 47 patients, 37 were male and 10 were female. Mean patient age at the time of the MAT was 30.4 ± 8.6 years. The median follow-up period was 11.5 years (8 to 17 years). The preoperative mean modified Lysholm score was 73.2 ± 10.6, which significantly increased to 89.4 ± 13.2 at the time of the final follow-up (P < .001). There were 2 failures noted at 6 months and 11.3 years, respectively, after MAT. All of the other allografts were surviving at the time of the latest follow-up. The 10-year survival rate was 98.0% (95% confidence interval [CI], 94.1%-100%), and the 15-year survival rate was 93.3% (95% CI, 83.7%-100%) according to the Kaplan-Meier analysis.

CONCLUSIONS

MAT using the bone fixation techniques demonstrated a high clinical survival rate according to the long-term observation.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Meniscal allograft subluxations are not associated with preoperative native meniscal subluxations

PURPOSE

To determine the relationship between preoperative subluxation of the original menisci and postoperative graft subluxation after lateral meniscal allograft transplantation (MAT).

METHODS

Forty patients who underwent isolated lateral MATs in meniscus-deficient knees with a low-grade chondral lesion (≤ICRS grade 2) were assessed. Lateral subluxation of the native meniscus before meniscectomy and those of remaining meniscal tissue before MAT were measured on mid-coronal MRI scans taken at each time point. Postoperative meniscal subluxation was assessed using MRI at 6 months postoperatively, when the full rehabilitation protocols were completed. Correlation analyses were conducted to determine the associations between each of two preoperative lateral displacements and the postoperative graft subluxation.

RESULTS

The mean lateral subluxations before primary meniscectomy and before MAT were 0.3 ± 1.0 mm and 0.2 ± 0.8 mm, respectively. At 6 months postoperatively, it was 2.3 ± 1.9 mm. There were no significant correlations between the preoperative subluxation at the two preoperative time points and the postoperative extrusion (Spearman rho 2-sided test: ρ = - 0.058, (n.s.) for the native meniscus; Pearson r 2-sided test, r = 0.309, (n.s.) for the remaining meniscal rim). Between the postoperative nonextruded and extruded groups, there were no significant differences for the preoperative subluxations.

CONCLUSIONS

There are no associations between preoperative lateral subluxation of the native menisci and postoperative subluxation of meniscal transplants in patients who undergo MAT on the lateral compartment with low-grade arthritic changes. The extrusion phenomenon may be a distinct feature of transplanted menisci rather than an individual characteristic of meniscal displacement. Surgeons need to keep in mind that graft extrusion in nonarthritic knees might occur during transplantation.

LEVEL OF EVIDENCE

IV.

Risk Factors for Radiographic Progression of Osteoarthritis After Meniscus Allograft Transplantation

PURPOSE

To identify risk factors that predict radiographic progression of osteoarthritis after meniscus allograft transplantation (MAT) using multivariate logistic regression.

METHODS

Inclusion criteria were consecutive patients who underwent medial or lateral MATs from January 2005 to September 2012 by one surgeon. Exclusion criteria were lack of postoperative magnetic resonance image, loss to follow-up for a minimum of 3 years, and simultaneous surgery on articular cartilage or the anterior cruciate ligament. According to the change of Kellgren-Lawrence (KL) grade at the mean final follow-up of 56.2 months, the enrolled MATs were sorted into the no progression of osteoarthritis (NOA) and progression of osteoarthritis (POA) groups. Multivariate logistic regression was used to analyze risk factors, including age, sex, body mass index, time from previous meniscectomy to MAT, extent of previous meniscectomy, previous anterior cruciate ligament reconstruction, knee alignment angle, KL grade, side of transplanted meniscus, Outerbridge grade, posterior repair technique, and relative percentage of extrusion.

RESULTS

In comparison between the NOA (n = 38) and the POA (n = 31) groups, a significant risk factor for radiographic progression of osteoarthritis after MAT was medial MAT compared with lateral MAT. Medial MAT compared with lateral MAT was also a significant risk factor (adjusted odds ratio, 3.763; 95% confidence interval, 1.212-11.683).

CONCLUSIONS

Patients need to be counseled about the increased risk of osteoarthritis progression after MAT over time, particularly for medial MAT.

LEVEL OF EVIDENCE

Level III, retrospective case control study.

Revision Meniscal Allograft Transplantation in the Lateral Compartment: Disparate MRI and Clinical Outcomes During the Early Postoperative Period

BACKGROUND

Little is known about clinical outcomes after revision meniscal allograft transplantation (RMAT), and there are no studies on magnetic resonance imaging (MRI) evaluations during the early remodeling period.

HYPOTHESIS

The objective imaging results, as determined by MRI evaluation, would be inferior to those of published data on primary meniscal allograft transplantations (MATs), although short-term clinical improvement would be achieved after RMAT.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

We retrospectively reviewed 9 consecutive patients (6 male and 3 female) who underwent RMAT from 2010 to 2014. The mean patient age was 33 years (range, 28-45 years). All patients had prior failed MATs in the lateral compartment. None of the patients had malalignment or ligament instability, and 7 patients had grade 3 or higher chondral degeneration. We assessed the RMAT with routine MRI evaluations during the remodeling period of the first postoperative year to determine graft healing and the mode of refailures, if any. We also investigated the problems specific for revision operations, as well as clinical outcomes.

RESULTS

Four of the 9 RMAT patients had significant intra-articular fibrosis with or without motion limitations at the time of RMAT. MRI evaluations demonstrated that the overall early refailure rate was 33.3% (3/9) during the first year; bucket-handle displacement with no meniscocapsular healing was the mode of all failures. Insufficient meniscal healing was also found in 2 other RMATs without premature failure. After a mean follow-up of 29.2 months (range, 21-45 months) in the 6 patients with preserved RMATs, Lysholm and International Knee Documentation Committee subjective scores showed significant improvements over preoperative scores (from 53.3 ± 6.0 to 87.7 ± 2.9 [P = .028] and from 53.4 ± 9.0 to 69.9 ± 4.8 [P = .043], respectively; Wilcoxon signed rank test).

CONCLUSION

The MRI findings showed that poor or insufficient meniscal healing to the host joint capsule was the major drawback of RMAT. Although more than half of our patients experienced clinical improvement after RMAT, the short-term graft survival was inferior to that of primary MATs in the literature. Our findings suggest that this challenging revision procedure requires great caution, especially with regard to the effects of poor host tissue quality on meniscal healing. Although RMAT can be an effective treatment, close observation with routine MRI evaluation is necessary during the early remodeling period to assess the status of the revised meniscal allograft.

Changes in the T2 value of cartilage after meniscus transplantation over 1 year

OBJECTIVES

To evaluate the changes in the mean T2 values of articular cartilage on serial follow-up images up to 1 year in patients who underwent lateral meniscus allograft transplantation (MAT).

METHODS

Fifty-two patients who underwent lateral MAT surgery at our hospital were evaluated preoperatively and at 2 days, 6 weeks, 3 months, 6 months, and 1 year after MAT using 3.0-T magnetic resonance imaging (MRI) that included T2 mapping. T2 value changes according to the arthroscopic grading of chondromalacia were evaluated in the lateral and medial compartment. Lysholm scores were obtained pre- and postoperatively.

RESULTS

The T2 values of cartilage were significantly increased 2 days after operation, and then gradually reduced to the baseline level after 1 year in both compartments. In morphologic assessment performed after 1 year, most areas (92.9 %) showed no interval change of chondromalacia grade. Lyshom knee scores increased significantly from the mean preoperative value of 62.5 (range, 23-95) to 89.7 (range, 64-100) at 1 year (p < 0.001).

CONCLUSION

Mean T2 values of cartilage following MAT exhibited a return to baseline level after 1 year. T2 measurement can be a useful tool for quantitative evaluation of postoperative cartilage changes compared to conventional MRI.

KEY POINTS

• T2 mapping provides objective data for longitudinal monitoring following surgery. • Increased cartilage T2 values post-MAT returned to baseline in one year. • Further studies are required to predict the chondroprotective effect of MAT.

Does Lateral Meniscal Allograft Transplantation Using the Keyhole Technique Restore the Anatomic Location of the Native Lateral Meniscus?

BACKGROUND

It is important to restore the normal anatomy of the native meniscus in meniscal allograft transplantation (MAT) for successful surgical results.

PURPOSE/HYPOTHESIS

The purpose of this study was to compare the anatomic positions of the anterior horn (AH) and posterior horn (PH) between the preoperative lateral meniscus and postoperative meniscal allograft after lateral MAT using the keyhole technique. We hypothesized that the keyhole technique could restore the preoperative anatomy of the native lateral meniscus.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Between December 2012 and December 2014, a total of 70 patients underwent lateral MAT using the keyhole technique. The anatomic positions of both horns of the native lateral meniscus and the meniscal allograft were measured on magnetic resonance imaging (MRI). Preoperative MRI was performed 1 day before lateral MAT, while postoperative MRI was performed 2 days after lateral MAT. A percentage reference method was used to measure the location of both horns.

RESULTS

For the AH, the mean delta value of the absolute position was 0.7 ± 1.8 mm (95% CI, 0.3-1.1 mm) in the coronal plane and 0.5 ± 1.6 mm (95% CI, 0.2-0.9 mm) in the sagittal plane, and the mean delta value of the relative position was 1.0% ± 2.3% (95% CI, 0.5%-1.6%) in the coronal plane and 1.1% ± 3.3% (95% CI, 0.2%-1.8%) in the sagittal plane. For the PH, the mean delta value of the absolute position was 2.4 ± 2.6 mm (95% CI, 1.8 to 3.1 mm) in the coronal plane and -0.1 ± 2.1 mm (95% CI, -0.6 to 0.4 mm) in the sagittal plane, and the mean delta value of the relative position was 3.3% ± 3.5% (95% CI, 2.5% to 4.2%) in the coronal plane and -0.3% ± 4.4% (95% CI, -1.3% to 0.8%) in the sagittal plane. Therefore, the AH moved by a mean of 0.7 mm laterally and 0.5 mm anteriorly (absolute values) and 1.0% laterally and 1.1% anteriorly (relative values) compared with the preoperative position. The PH moved by a mean of 2.4 mm laterally and 0.1 mm posteriorly (absolute values) and 3.3% laterally and 0.3% posteriorly (relative values) compared with the preoperative position. For the AH, the proportion of patients with an absolute delta value of ≥5 mm was 4.3% in the coronal plane and 2.9% in the sagittal plane. For the PH, the proportion of patients with an absolute delta value of ≥5 mm was 18.6% in the coronal plane and 4.3% in the sagittal plane.

CONCLUSION

When comparing the position of the horns preoperatively and postoperatively, both horns showed mean relative postoperative positional changes of <5% of relative values and <5 mm of absolute values in both the coronal and sagittal planes. The keyhole technique in lateral MAT can reconstruct the lateral meniscus close to its native anatomic position by avoiding displacement of >5 mm in both the coronal and sagittal planes.

Proper Cartilage Status for Meniscal Allograft Transplantation Cannot Be Accurately Determined by Patient Symptoms

BACKGROUND

Candidates for meniscal allograft transplantation (MAT) often already have a significant cartilage lesion when they present with a symptomatic knee. However, the level of symptoms required for MAT to be performed is poorly defined, leading to difficulties in selecting patients and the potential for further cartilage loss.

PURPOSE

To evaluate if various clinical evaluation scores reflect the articular cartilage status of the lateral compartment preoperatively in symptomatic, lateral meniscus-deficient knees.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 113 consecutive patients who underwent lateral MAT were reviewed. All patients were preoperatively assessed by the most common patient-reported outcome measures (PROMs), including the visual analog scale (VAS) for pain, Lysholm knee scale, International Knee Documentation Committee (IKDC) subjective form, and Tegner activity scale. The maximum grade from the International Cartilage Repair Society (ICRS) scale on either femoral or tibial articular cartilage was used for a correlation analysis between PROMs and ICRS grades and a comparison of PROMs between patients with low-grade (ICRS grade ≤2) and high-grade (ICRS grade 3 or 4) cartilage degeneration.

RESULTS

More than half of the patients had high-grade cartilage degeneration, even though their mean VAS pain score was low (3.1 ± 1.3). There were no significant relationships between ICRS grades and PROMs, except for the IKDC subjective score, which was weakly associated with the ICRS grade (Spearman ρ test, 2-sided, ρ = -.200, P = .034). When comparing patients with low-grade versus high-grade cartilage degeneration, there were no differences in PROMs except for the Lysholm score (67.8 ± 14.7 vs 62.3 ± 13.9, respectively; P = .044). Notably, 37 of 58 patients (63.8%) with high-grade chondral lesions only felt pain during severe exertion.

CONCLUSION

Mild or tolerable symptoms did not necessarily mean that articular cartilage was well preserved in patients undergoing MAT. The study findings suggest a need for close observation and greater caution concerning possible chondral damage in the treatment of meniscus-deficient knees.

Repair of the Posterior Third of the Meniscus During Meniscus Allograft Transplantation: Conventional Inside-Out Repair Versus FasT-Fix All-Inside Repair

PURPOSE

To compare conventional inside-out (IO) repair and all-inside (AI) repair for the posterior third of the meniscus during meniscus allograft transplantation (MAT).

METHODS

Among the 64 enrolled patients, 31 patients underwent MAT with conventional IO repair, and 33 patients underwent MAT with AI repair using the FasT-Fix instrument for the posterior third of the meniscus allograft. All of the patients were retrospectively evaluated through clinical assessment at the last follow-up (54.3 months in the IO group and 55.4 months in the AI group) and through magnetic resonance imaging assessment for meniscal extrusion at 1 year postoperatively. Thirty patients (15 in each group) were evaluated through second-look arthroscopy at 1 year postoperatively.

RESULTS

There was no significant difference in the mean Lysholm score (91.3 in the IO group and 92.3 in the AI group; P = .358) or the mean Tegner activity scale (7.1 in each group; P = .885) between the 2 groups. There was no significant difference in the mean meniscal extrusion (2.6 mm in the IO group and 2.8 mm in the AI group; P = .454), relative percentage of extrusion value (25.6% in the IO group and 24.7% in the AI group; P = .721), or meniscal healing on second-look arthroscopy (P = .796) between the 2 groups. The difference in operative time between the 2 groups was found to be statistically significant (169.9 minutes in the IO group and 123.3 minutes in the AI group; P < .001).

CONCLUSIONS

Our comparative study on the different techniques for posterior repair of meniscus allograft suggested that AI posterior repair using FasT-Fix could be an alternative method to conventional IO repair as it gives a similar postoperative result and requires a shorter operative time.

Articular Cartilage Degenerates After Subtotal/Total Lateral Meniscectomy but Radiographic Arthrosis Progression Is Reduced After Meniscal Transplantation

BACKGROUND

Little is known about the degree of articular cartilage degeneration after subtotal/total lateral meniscectomy in patients who later undergo isolated lateral meniscal allograft transplantation (LMAT). It has not yet been studied whether arthritic changes as shown on radiographs were lower during the posttransplantation period than during the meniscus-deficient period.

HYPOTHESIS

Articular cartilage will significantly degenerate during the meniscus-deficient period, but the progression in radiographic arthrosis is reduced after LMAT.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

This study retrospectively reviewed 49 patients who underwent subtotal/total lateral meniscectomy before isolated LMAT performed over 1 year later by the same surgeon. International Cartilage Repair Society (ICRS) grades of the femorotibial joint at the time of subtotal/total meniscectomy and at LMAT were compared. Radiographic evaluation was performed at the time of initial meniscectomy, LMAT, and the latest follow-up in 38 patients (after 11 patients whose radiographs showed incomplete ossification at the time of meniscectomy were excluded). Arthrosis, based on Kellgren-Lawrence (K-L) grades, was determined on standing anteroposterior views. Joint space width (JSW) was measured on weightbearing flexion posteroanterior views.

RESULTS

Over a mean meniscus-deficient period of 4.5 years (range, 1-13 years), articular cartilage significantly degenerated on the femoral and tibial sides (P < .001). Grade ≥3 degeneration on the lateral tibial plateau was observed in 13 patients (27%) at the time of initial meniscectomy; this incidence doubled to 28 patients (57%) by the time of LMAT. The K-L grades worsened (P < .001) and JSWs narrowed significantly (-0.65 ± 1.09 mm; P = .001) during the mean meniscus-deficient period of 3.1 years. At radiographic assessment, however, the K-L grades (P = .097) and JSWs (4.06 ± 1.19 vs 3.92 ± 1.21 mm; mean difference, -0.14 ± 0.68 mm; P = .213) did not significantly change during the mean posttransplantation period of 3.8 years. The changes in ICRS grade and JSW during the meniscus-deficient period were not associated with age, body mass index, mechanical axis deviation, or Tegner activity level (P > .05 for all relationships).

CONCLUSION

Patients who underwent isolated LMAT showed substantial articular cartilage degeneration at the time of initial subtotal/total lateral meniscectomy, and this degeneration progressed thereafter. Further progression of radiographic arthrosis was delayed after LMAT.

Does Medial Meniscal Allograft Transplantation With the Bone-Plug Technique Restore the Anatomic Location of the Native Medial Meniscus?

BACKGROUND

Previous work has shown the importance of restoring the normal structure of the native meniscus with meniscal allograft transplantation.

PURPOSE/HYPOTHESIS

The purpose of this study was to compare the anatomic positions of the anterior horn and posterior horn between the preoperative medial meniscus and the postoperative meniscal allograft after medial meniscal allograft transplantation with the bone-plug technique. The hypothesis was that the bone-plug technique could restore the preoperative structure of the native medial meniscus.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Between December 1999 and December 2013, a total of 59 patients (49 male, 10 female) underwent medial meniscal allograft transplantation by use of the bone-plug technique. The anatomic positions of both horns in the native medial meniscus and in the meniscal allograft were measured via MRI. The percentage reference method was used to measure the locations of both horns.

RESULTS

On coronal MRI, the mean absolute distance of the posterior horn from the lateral border of the tibial plateau changed from 45.2 ± 3.3 to 48.1 ± 4.2 mm (P < .05), and the percentage distance of the posterior horn changed from 59.6% to 63.0% (P < .05). On sagittal MRI, the mean absolute distance of the posterior horn from the anterior reference point changed from 40.3 ± 3.0 to 42.0 ± 3.5 mm (P < .05), and the mean percentage distance of the posterior horn changed from 76.5% to 79.4% (P <.05). On coronal MRI, the mean absolute distance of the anterior horn from the lateral border of the tibial plateau changed from 41.3 ± 4.2 to 48.5 ± 5.6 mm (P < .05), and the mean percentage distance of the anterior horn changed from 54.5% to 63.8% (P < .05). On sagittal MRI, the mean absolute distance of the anterior horn from the anterior reference point changed from 5.5 ± 1.0 to 9.9 ± 2.9 mm (P < .05), and the mean percentage distance of the anterior horn changed from 10.6% to 19.0% (P < .05).

CONCLUSION

Despite attempts to place the meniscal allograft in the same position as the native meniscus, the anatomic locations of both horns were shifted posteromedially compared with those of the native medial meniscus. There were significant differences, attributed to several limitations in the bone-plug technique, between the preoperative and postoperative values of both horns. However, the posterior horn showed a location change of <5 mm, on average, in both the coronal and sagittal planes, whereas the anterior horn showed a location change of ≥ 5 mm in the coronal plane but <5 mm in the sagittal plane.

The quantitative evaluation of the impact of viable medial meniscus graft type on the biochemical and biomechanical properties of the rabbit tibial cartilage

BACKGROUND

Knowledge of the impact of viable medial meniscus allograft and autograft transplantation on biochemical and mechanical properties of cartilage is needed to understand the development of joint osteoarthritis. The purpose of this study was to evaluate this relationship 6 months after viable medial meniscal autograft and allograft transplantation.

METHODS

Twenty rabbits were chosen for the study. The medial menisci were excised from 14 animals and stored under tissue culture conditions for 2 weeks. Seven menisci were implanted as autografts (group A) and seven as allografts (group B). The control group consisted of six animals which underwent arthrotomy. The tibial cartilage was used for mechanical and biochemical evaluation.

RESULTS

The respective decreases of glycosaminoglycans (GAGs) and elasticity were 13.4 and 14.8% for group A and 30.4 and 32.6% for group B. The differences between group A and B and between each group and the control were statistically significant. The total collagen content was significantly lower in group B.

CONCLUSIONS

The type of viable meniscal graft has an influence on the biochemical composition of the extracellular matrix (ECM) and biomechanical properties of the underlying tibial cartilage. A 1% decrease of glycosaminoglycan content is associated with a 1.1% decrease of cartilage elasticity. The average ratio of decrease of cartilage elasticity to that of the meniscus was 0.77 regardless of the type of meniscus graft. The viable allograft causes irreversible ECM disorder of the cartilage. Knowledge of the biochemical composition of the ECM meniscal grafts may serve as a predictor of their chondroprotective properties.

Current status of second-look arthroscopy after meniscal allograft transplantation: review of the literature

INTRODUCTION

Clinical assessments do not accurately reflect the status of meniscal transplants and cannot evaluate the graft condition itself and joint preservation effects of meniscal allograft transplantation correctly. The purpose of this review was to assess the need and to ascertain the indication and the role of second-look arthroscopy for objective evaluation after MAT.

MATERIALS AND METHODS

We performed a literature search to identify all published clinical studies on MAT with the following medical subject heading (MeSH) terms: "meniscus," "meniscal transplant," "transplantation and allograft," "meniscal and transplant." Include in the review are studies with at least 6 months clinical, radiological, and/or histological follow-up in human subjects. Evaluation method of MAT was reviewed with an aim to describe the frequency of second-look arthroscopy, its feasibility, patient compliance, purposes, and results.

RESULTS

We identified 15 clinical studies that satisfied our inclusion and exclusion criteria. Only two studies always performed second-look arthroscopies. Most of the second-look arthroscopy was conducted mainly for the objective evaluation of meniscal allograft transplantation but, in several studies, arthroscopy was performed to treatment of other knee problem.

CONCLUSIONS

Although second-look arthroscopy has inevitably ethical issues, especially for asymptomatic and well-functioning knees, in this review, it could be a more dependable method available to detect meniscal healing if performed for certain indications such as a symptomatic patient with a magnetic resonance image indicating abnormalities.