Medial meniscus extrusion correlates with disease duration of the sudden symptomatic medial meniscus posterior root tear

Subchondral insufficiency fractures of the medial tibial condyle are associated with medial meniscus extrusion: A retrospective observational study

BACKGROUND

To the best of our knowledge, no prior studies have identified any risk factors for subchondral insufficiency fractures of the medial tibial condyle. This study aimed to explain relationships between subchondral insufficiency fractures of the medial tibial condyle and the meniscus status, lower extremity alignment, or osteoporosis.

METHODS

This retrospective study included 325 consecutive patients whose chief complaint is knee joint pain and who had visited one institution between April 2016 and March 2021, of which 70 patients (8 men and 62 women) who had suspected subchondral insufficiency fractures of the medial tibial condyle had undergone magnetic resonance imaging and radiographic examination. These patients were divided into two groups based on the results of their magnetic resonance imaging: the insufficiency fracture group included 46 patients who had subchondral insufficiency fractures of the medial tibial condyle and the nonfracture group included 24 patients without fractures. The meniscus injury and medial meniscus extrusion (MME) were evaluated by using magnetic resonance imaging. The Kellgren-Lawrence grade, the femorotibial angle, and the percent mechanical axis (%MA) were evaluated with the use of knee radiographs. T-scores were also measured by using dual-energy X-ray absorptiometry with a bone densitometer.

RESULTS

MME were significantly larger and the %MA was significantly smaller in the insufficiency fracture group than that in the nonfracture group. The prevalence of medial meniscus injuries and pathological MME were higher in the insufficiency fracture group than those in the nonfracture group. The prevalence of varus knee and osteoporosis did not vary remarkably different between the two groups.

CONCLUSION

The patients who had insufficiency fractures of the medial tibial condyle tended to have medial meniscus extrusion.

Root Repair Has Superior Radiological and Clinical Outcomes Than Partial Meniscectomy and Nonoperative Treatment in the Management of Meniscus Root Tears: A Systematic Review

PURPOSE

To compile and analyze structural and clinical outcomes after meniscus root tear treatment as currently described in the literature.

METHODS

A review was conducted to identify studies published since 2011 on efficacy of repair, meniscectomy, and nonoperative management in the treatment of meniscus root tears. Patient cohorts were grouped into treatment categories, with medial and lateral root tears analyzed separately; data were collected on patient demographics, structural outcomes including joint space width, degree of medial meniscal extrusion, progression to total knee arthroplasty, and patient-reported outcome measures. Risk of bias was assessed using the MINORS (methodological index for non-randomized studies) criteria. Heterogeneity was measured using the I-statistic, and outcomes were summarized using forest plots without pooled means.

RESULTS

The 56 included studies comprised a total of 3,191 patients. Mean age among the included studies ranged from 24.6 to 65.6 years, whereas mean follow-up ranged from 12 to 125.9 months. Heterogeneity analysis identified significant differences between studies. Change in joint space width ranged from -2.4 to -0.6 mm (i.e., decreased space) after meniscectomy (n = 186) and -0.9 to -0.1 mm after root repair (n = 209); change in medial meniscal extrusion ranged from -0.6 to 6.5 mm after root repair (n = 521) and 0.2 to 4.2 mm after meniscectomy (n = 66); and event rate for total knee arthroplasty ranged from 0.00 to 0.22 after root repair (n = 205), 0.35 to 0.60 after meniscectomy (n = 53), and 0.27 to 0.35 after nonoperative treatment (n = 93). Root repair produced the greatest numerical increase in International Knee Documentation Committee and Lysholm scores of the 3 treatment arms. In addition, root repair improvements in Knee Injury and Osteoarthritis Outcome Score Pain (range: 22-32), Sports and Recreational Activities (range: 23-36), Quality of Life (range: 22-42), and Symptoms subscales (range: 10-19), in studies with low risk of bias.

CONCLUSIONS

The literature reporting on the treatment of meniscus root tears is heterogenous and largely limited to Level III and IV studies. Current evidence suggests root repair may be the most effective treatment strategy in lessening joint space narrowing of the knee and producing improvements in patient-reported outcomes.

LEVEL OF EVIDENCE

Level IV, systematic review of Level II-IV studies.

Modified Mason-Allen vs Two Simple Stitch Fixation for Medial Meniscus Posterior Root Tears: A Systematic Review and Meta-analysis

BACKGROUND

Various suture configurations are available for medial meniscus posterior root tear (MMPRT) repair. The modified Mason-Allen (MMA) technique has been proposed as a refixation technique for MMPRT instead of the conventional 2 simple stitches (TSS). This is in view of its superior biomechanical characteristics.

PURPOSE

To perform a systematic review and meta-analysis to compare MMA and TSS configuration techniques for MMPRT repair and identify any differences between the 2 techniques in terms of clinical outcomes, medial meniscal extrusion (MME), and postoperative healing.

STUDY DESIGN

Meta-analysis; Level of evidence, 4.

METHODS

The Cochrane Controlled Register of Trials, PubMed, Medline, and Embase databases were used to perform a systematic review and meta-analysis using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) criteria with the following search terms: ("meniscus" OR "meniscal injuries") AND ("Mason-Allen" OR "simple stitch" OR "suture techniques"). Data pertaining to all patient-reported outcome measures, postoperative complications, MME, postoperative healing, cartilage degeneration, and progression of knee osteoarthritis were extracted from each study. The pooled outcome data were analyzed using random- and fixed-effects models.

RESULTS

After abstract and full-text screening, 6 clinical studies were included. In total, there were 291 patients; 160 underwent MMA fixation, and 131 underwent the TSS technique. The majority of studies had similar surgical techniques regarding repair technique, suture material, tibial fixation, and number and position of tibial tunnels. There were no differences between the groups in terms of patient-reported outcome measures at 14.2 months. Both techniques were also similar in the degree of postoperative MME and meniscal healing.

CONCLUSION

Both suture configurations were equivalent in terms of clinical outcomes, the extent of meniscal extrusion, and postoperative healing. The TSS technique may offer advantages in terms of faster learning curve and shorter operative time. However, randomized controlled trials with large sample sizes, longer follow-up and assessment of chondral degeneration, and presence of knee osteoarthritis are required to assess whether a true difference exists, as the majority of included studies were limited by their retrospective design.

Ultrasonographic diagnosis of medial meniscus posterior root tear in early knee osteoarthritis: a comparative study

INTRODUCTION

This study aimed to detect medial meniscal posterior root tear (MMPRT) diagnostic methods with high sensitivity and specificity using dynamic ultrasonographic evaluation in patients with early knee osteoarthritis (OA) and demonstrate the usefulness of dynamic ultrasonographic medial meniscal extrusion (MME) evaluation in MMPRT diagnosis using a cutoff value.

MATERIALS AND METHODS

Between 2018 and 2020, a total of 120 patients were diagnosed with early knee OA using clinical and radiographic findings. Dynamic ultrasonographic evaluations and magnetic resonance imaging were performed in all patients, and 47 patients who had and 73 patients who did not have MMPRT were classified into the MMPRT and non-MMPRT groups, respectively. Age, sex, femorotibial angle, MME of knee extension and flexion, and MME at weight-bearing were compared between the two groups. Additionally, the sensitivity and specificity of significant ultrasonographic findings were calculated using a receiver operating characteristic (ROC) curve.

RESULTS

The MMEs under knee extension-flexion and weight-loading in the MMPRT group were significantly larger than those in the non-MMPRT group. ROC curve analysis for each ultrasonographic evaluation condition to diagnose MMPRT indicated that the sensitivity was 72-88% and the specificity was 66-85% when the cutoff values of MME under knee flexion at 0°, 90°, and weight-loading were set at 2.55 mm, 2.00 mm, and 3.55 mm, respectively. The highest sensitivity (88%) and specificity (85%) were exhibited upon > 2 mm MME at a knee flexion of 90° and were the most useful indicators for MME diagnosis.

CONCLUSIONS

Ultrasonographic MME evaluations for MMPRT diagnosis showed relatively high sensitivity and specificity in patients with early knee OA. Dynamic ultrasonographic MME evaluation may lead to appropriate additional examinations, early diagnosis, and intervention for MMPRT in patients with early knee OA.

Increased Medial Femoral Condyle Angle and Narrow Intercondylar Notch Are Associated With Medial Meniscus Posterior Root Tear

PURPOSE

To investigate the correlation between nontraumatic medial meniscus posterior root tear (MMPRT) and bone morphology of the knee with a particular emphasis on MMPR impingement.

METHODS

Magnetic resonance imaging (MRI) findings were examined between January 2018 and December 2020. MRI findings of patients with traumatic MMPRT, Kellgren Lawrence stage 3-4 arthropathy on radiographs, single- or multiple-ligament injuries and/or those who underwent treatment for these diseases, and surgery in and around the knee were excluded from the study. MRI measurements included medial femoral condylar angle (MFCA), intercondylar distance (ICD), and intercondylar notch width (ICNW), distal/posterior medial femoral condylar offset ratio, notch shape, medial tibial slope (MTS) angle, and medial proximal tibial angle (MPTA) measurements and spur presence and were compared between groups. All measurements were performed by two board-certified orthopedic surgeons on a best agreement basis.

RESULTS

MRI examinations of patients aged 40-60 were analyzed. MRI findings were divided into two groups: the study group of MRI findings of patients with MMPRT (n = 100) and the control group of MRI findings of patients without MMPRT (n = 100). MFCA was found to be significantly higher in the study group (mean: 46.5 ± 3.58) than in the control group (mean: 40.04 ± 4.61) (P < .001). In the study group, the ICD (study group mean: 76.26 ± 4.89; control group mean: 78.18 ± 6.1) was significantly narrower (P = .018), and the ICNW (study group mean: 17.19 ± 2.23; control group mean: 20.48 ± 2.13) was significantly shorter (P < .001). The ICNW/ICD ratio was significantly lower in patients in the study group (0.22 ± 0.02) than in the control group (0.25 ± 0.02) (P < .001). Bone spurs were present in 84% of the study group and only in 28% of those in the control group. In the study group, the most common notch type was A-type with 78%, while the least common was the U-type notch with 10%. However, in the control group, the most common notch type was A-type with 43%, and the least common was the W-type notch with 22%. The distal/posterior medial femoral condylar offset ratio was statistically lower in the study group (0.72 ± 0.07) than in the control group 0.78 ± 0.07) (P < .001). No significant intergroup differences were found in MTS (study group mean: 7.51 ±2.59; control group mean: 7.83 ± 2.57) (P = .390) and MPTA (study group mean: 86.92 ±2.15; control group mean: 87.48 ±1.8) measurements (P = .67).

CONCLUSIONS

Increased medial femoral condylar angle, low distal/posterior femoral offset ratio, narrow intercondylar distance and intercondylar notch width, A-type notch shape, and spur presence are associated with MMPRT.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Meniscal Extrusion Measurements After Posterior Medial Meniscus Root Tears: A Systematic Review and Meta-analysis

BACKGROUND

Meniscal extrusion has become increasingly utilized when evaluating meniscus root abnormalities. However, no consensus definition or approach exists on how to measure extrusion.

PURPOSE/HYPOTHESIS

The purpose of this study was to evaluate the extent of heterogeneity in meniscal extrusion measurement techniques and reported extrusion values in knees with posterior medial meniscus root tears (PMMRTs). We hypothesized that meniscal extrusion measurement techniques would vary considerably throughout reported studies, with resultant wide-ranging published extrusion values.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

A systematic review was conducted according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement. The inclusion criteria consisted of all clinical and cadaveric studies reporting on meniscal extrusion after PMMRTs, excluding studies lacking data in full extension, those presenting only semiquantitative analyses, articles reporting only differences in meniscal extrusion, and review articles.

RESULTS

A total of 45 studies were included. Imaging modality types included magnetic resonance imaging (89%), 3-dimensional reconstruction with computed tomography (7%), linear displacement transducers (2%), and a combination of magnetic resonance imaging and ultrasound (2%). The 3 most commonly used landmarks to acquire coronal images for meniscal extrusion measurements were the medial collateral ligament (38%), the midpoint of the anterior-posterior length of the medial meniscus (23%), and the middle of the medial femoral condyle (19%). The pooled mean extrusion values according to the measurement location were 3.5 ± 0.7 mm, 3.9 ± 0.8 mm, and 4.5 ± 2.1 mm, respectively, with no significant differences noted between the modality types (P = .23). The pooled mean meniscal extrusion from all included studies was 3.2 ± 2.0 mm.

CONCLUSION

Substantial variation exists in measurement techniques for meniscal extrusion, particularly as it relates to the coronal cross-sectional reference location. Further studies should aim to provide clear descriptions of the measurement method and have uniform measurement methodology to allow comparisons and pooling between studies.

Unique patterns of medial meniscus extrusion during walking and its association with limb kinematics in patients with knee osteoarthritis

Medial meniscus extrusion (MME) is exacerbated by repeated mechanical stress. Various factors would affect MME; however, there is limited information about the behaviour of the medial meniscus during walking in patients with knee osteoarthritis (KOA). This study aimed to investigate the pattern of MME during walking and its association with limb biomechanics in patients with KOA. Fifty-five patients with KOA and ten older adult volunteers as a control group were involved in this study. The MME and limb biomechanics during walking were evaluated simultaneously by ultrasound and a motion analysis system, respectively. The waveform was constructed from the values of MME, and the point showing the highest value of MME was identified during the gait cycle. According to the peak timing of MME in the waveform, the pattern of the waveform was evaluated and compared to the control group. Lateral thrust, knee adduction moment (KAM), and flexion moment were obtained from motion analysis, and their association with the MME was evaluated. The patients with KOA demonstrated unique peak timing during walking. Compared to the control group, there were three groups of MME waveforms, early (< 59%), normal (60-83%), and late (> 84%) from the peak timing in the gait cycle. The pattern of MME waveform in early, normal, and late groups was correlated with the first KAM and lateral thrust, second KAM, and knee flexion moment, respectively. A unique MME pattern during walking was demonstrated, and these patterns were associated with limb biomechanics in patients with KOA.

Meniscal extrusion: risk factors and diagnostic tools to predict early osteoarthritis

Meniscal extrusion (ME) is strongly correlated with cartilage wear and osteoarthritis (OA), be-cause of the altered kinematic and the decreased contact area between the tibia and femur. The aim of this narrative review is to analyze the process of ME, focusing on the possible causes, and to evaluate the correlation between ME and knee OA, in order to provide early diagnosis and treatments. Studies written in English that analyzed the causes of ME, provided indications re-garding diagnosis and treatment, and evaluated the relation between ME and early OA were in-cluded. Injuries, degeneration of the meniscal substance and meniscus root tears are associated with significantly increased ME. An extruded meniscus could be a manifestation of other pa-thologies such as disruption of coronary ligaments, cartilage loss, knee malalignment, ligament injuries, or OA. ME is strongly associated with osteoarthritis features, particularly with bone marrow lesion and cartilage damage. Magnetic resonance imaging represents the gold standard for the detection of ME. The severity of the medial meniscus extrusion may also affect healing af-ter repair, and meniscus extrusion is not completely reduced by meniscus posterior root tear re-pair. In this study, we proved that ME represents an important risk factor for early knee OA. We provided alternative theories of ME, such as meniscal fibers injury first and "dynamic extrusion of the menisci". The phenomenon of aging has been described as a new concept in the etiology of ME. Finally, we stated all the main techniques and characteristics of the diagnostic process, as well as the current knowledge in the therapeutic field.

Meniscus extrusion is a predisposing factor for determining arthroscopic treatments in partial medial meniscus posterior root tears

BACKGROUND

Patients with partial medial meniscus posterior root tears (MMPRTs) sometimes require arthroscopic pullout repair because of their intolerable/repeated knee pains and continuous disturbance in gait during activities of daily living. However, the predisposing factors for future knee surgery in patients with partial MMPRTs remain unclear. We compared the findings of magnetic resonance imaging (MRI) between patients who underwent pullout repair and nonoperative management following partial MMPRTs.

METHODS

Twenty-five patients who required arthroscopic repair for partial MMPRTs and 23 patients who were managed nonoperatively were evaluated during a mean follow-up period of 27.1 months. Sex, age, height, body weight, body mass index, duration from onset to initial MRI, MRI findings, and medial meniscus (MM) extrusion were compared between the two groups. Linear regression analysis was used to assess the correlation between MM extrusion and duration from onset to MRI examination.

RESULTS

No significant differences were observed between the pullout repair and nonoperative management groups in terms of patient demographics and the positive ratio of MRI-based root tear signs. However, absolute MM extrusion in the pullout repair group (3.49 ± 0.82 mm) was larger than that in the nonoperative management group (2.48 ± 0.60 mm, P < 0.001). Extrusion of the MM (> 3 mm) was detected more frequently in the pullout repair group than in the nonoperative management group (P < 0.001). The odds ratio in the pullout repair and MM extrusion > 3 mm cases was 9.662. Linear regression analysis revealed a fair correlation between the duration from onset to MRI and MM extrusion only in the pullout repair group (0.462 mm/month increase in MM extrusion).

CONCLUSIONS

This study demonstrated that more severe MM extrusions were observed in the pullout repair group than in the nonoperative management group. Major extrusion (> 3 mm) was also observed more in the pullout repair group than in the nonoperative group. Assessing MM extrusion and its severity can help determine a valid treatment for patients with partial MMPRTs.

LEVEL OF EVIDENCE

IV, Retrospective comparative study.

Increased cleft width during knee flexion is useful for the diagnosis of medial meniscus posterior root tears

PURPOSE

This study aimed to evaluate changes in the cleft width, defined as the distance between the lateral edge of the medial tibial plateau and that of the medial meniscus (MM) posterior root, using open magnetic resonance imaging (MRI) in patients with MM posterior root tear (MMPRT).

METHODS

This study included 25 patients (20 women and 5 men; mean age: 65.2 years) who were diagnosed with MMPRT and underwent pullout repair. Upon coronal imaging, the cleft width was evaluated at the 10° and 90° flexed knee positions. The difference in the cleft width (defined as the cleft width at 90° minus the cleft width at 10°) was also calculated. Upon sagittal imaging, the MM posterior extrusion (MMPE) at 90° was also evaluated. Separate univariate linear regression models were used to determine the association between the time from injury to MRI and radiographic measurements.

RESULTS

The mean cleft width at 10° and 90° was 4.9 ± 2.6 mm and 7.4 ± 3.7 mm, respectively; the mean difference in cleft width was 2.5 ± 1.5 mm, and the mean MMPE at 90° was 3.7 ± 1.3 mm. There was a significant difference in cleft width at 10° and 90° (p < 0.001). The time from injury to MRI was significantly associated with the cleft width at 10° (R = 0.42; p = 0.023), cleft width at 90° (R = 0.59; p = 0.002), the difference in the cleft width (R = 0.62; p = 0.008), and MMPE at 90° (R = 0.53; p = 0.008).

CONCLUSION

This study demonstrates that the cleft width is significantly larger during knee flexion than during knee extension. Increased cleft width during knee flexion ("graben" sign) may help diagnose MMPRT, especially in cases where the cleft sign is unclear during knee extension.

LEVEL OF EVIDENCE

III.

Clinical outcomes of medial meniscus posterior root repair: A midterm follow-up study

BACKGROUND

Transtibial pullout repair of medial meniscus posterior root tears (MMPRTs) cannot prevent the progression of knee osteoarthritis. Conversions of knee arthroplasties are occasionally required following MMPRT repair. However, other knee-related surgical treatments following MMPRT repair are unclear. This study was aimed at investigating the midterm clinical outcomes and knee-related surgical events following MMPRT repair.

METHODS

Patients with MMPRT underwent pullout repair using FasT-Fix modified Mason-Allen (F-MMA) suturing with an all-inside meniscal repair device. Thirty-two patients with follow-up duration >2 years were enrolled. We assessed the clinical outcomes and postoperative surgical treatment of both knees.

RESULTS

F-MMA pullout repair improved all clinical evaluation scores in patients with MMPRT at a mean follow-up of 36.1 months. Postoperative arthroscopic debridement was required for one patient. An additional MMPRT repair was performed in one patient on second-look arthroscopy. None of the patients required ipsilateral knee arthroplasty. In the contralateral knees, one pullout repair of a newly developed MMPRT and two knee arthroplasties were performed.

CONCLUSIONS

This study demonstrated that F-MMA pullout repair yielded satisfactory clinical outcomes. However, subsequent knee-related surgeries were observed in 6.3% of the pullout-repaired knees and 9.4% of the contralateral knees. Our results suggest that surgeons should be aware of the worsening and/or occurrence of contralateral knee joint disease, even when the postoperative clinical outcomes are satisfactory following MMPRT repair.

LEVEL OF EVIDENCE

IV.

Trans-Posterior Cruciate Ligament All-Inside Root Repair Versus Partial Meniscectomy for Medial Meniscus Posterior Root Tears: Comparison of Semiquantitative and Quantitative MRI Outcomes in Cartilage Degeneration and Osteoarthritic Progression

OBJECTIVE

To perform conventional, morphological, and T2 mapping compositional MRI imaging to assess the cartilage degeneration and osteoarthritic progression in patients with medial meniscus posterior root tears (MMPRTs) who underwent trans-posterior cruciate ligament (PCL) all-inside repair or partial meniscectomy.

DESIGN

Patients with MMPRTs after trans-PCL all-inside repair (group AR) or partial meniscectomy (group PM) between 2015 and 2018 were retrospectively identified. Preoperative and postoperative conventional MRI were collected to assess medial meniscus extrusion (MME) and the whole-organ magnetic resonance imaging score (WORMS). Postoperative morphological MRI and T2 mapping compositional MRI were collected to evaluate the quantitative cartilage thickness/volume and cartilage composition.

RESULTS

The final cohort consisted of 21 patients in group AR and 22 patients in group PM, with no differences in demographic data and baseline patient characteristics between the 2 groups. Group AR demonstrated less progression of articular cartilage wear (P < 0.05) and decreased meniscal extrusion (P = 0.008) than group PM at the final follow-up. In addition, group AR demonstrated less extracellular matrix degeneration in the cartilage subregion of the medial compartment (P < 0.05) than group PM with lower T2 relaxation times in the superficial layer of the articular cartilage.

CONCLUSION

Trans-PCL all-inside repair of MMPRTs could delay the initial cartilage deterioration and morphological cartilage degeneration compared with partial meniscectomy. However, the amount of residual meniscal extrusion is clinically important, and an improved root repair fixation method should be investigated.

Medial meniscus posterior root repairs: A comparison among three surgical techniques in short-term clinical outcomes and arthroscopic meniscal healing scores

BACKGROUND

Medial meniscus (MM) posterior root repairs lead to favorable clinical outcomes in patients with MM posterior root tears (MMPRTs). However, there are few comparative studies in evaluating the superiority among several pullout repair techniques such as modified Mason-Allen suture, simple stitch, and concomitant posteromedial pullout repair. We hypothesized that an additional pullout suture at the MM posteromedial part would have clinical advantages in transtibial pullout repairs of the MMPRTs. The aim of this study was to compare the clinical usefulness among several types of pullout repair techniques in patients with MMPRTs.

METHODS

Eighty-three patients who underwent arthroscopic pullout repairs of the MMPRTs were investigated. Patients were divided into three groups using different pullout repair techniques: a modified Mason-Allen suture using FasT-Fix all-inside meniscal repair device (F-MMA, n = 28), two simple stitches (TSS, n = 30), and TSS concomitant with posteromedial pullout repair using all-inside meniscal repair device (TSS-PM, n = 25). Postoperative clinical outcomes and semi-quantitative arthroscopic meniscal healing scores (0-10 points) were evaluated at second-look arthroscopies.

RESULTS

No significant differences among the three groups were observed in patient demographics and preoperative clinical scores, except for preoperative Lysholm scores. At second-look arthroscopies, there were no significant differences among the three techniques in postoperative clinical outcomes and meniscal healing scores.

CONCLUSIONS

This study demonstrated that the TSS-PM pullout repair technique did not show better scores in postoperative clinical outcomes and meniscal healings compared with the F-MMA and TSS techniques. Our results suggest that the concomitant posteromedial pullout suture may have no clinical advantage in the conventional pullout repairs for the patients with MMPRTs.

Medial meniscus posterior root repair prevents the progression of subchondral insufficiency fracture of the knee

BACKGROUND

Medial meniscus posterior root tear (MMPRT) causes medial meniscus extrusion (MME) and leads to subchondral insufficiency fracture of the knee (SIFK). However, the progression of SIFK after MMPRT pullout repair remains unknown. This study aimed to investigate the progression of SIFK and compare clinical outcomes in patients with SIFK to those without SIFK after MMPRT pullout repair. We hypothesized that the progression of SIFK would be prevented by MMPRT pullout repair, and clinical outcomes would improve in all patients.

METHODS

The SIFK grade (1-4) was evaluated using T2-fat suppression magnetic resonance imaging. Thirty-eight patients without SIFK (n = 22) and with low-grade SIFK (1 and 2; n = 16) who underwent MMPRT pullout repair were included. Preoperative factors, such as the duration from injury to the time of magnetic resonance imaging/surgery (weeks), femorotibial angle (degree), MME (mm), and clinical outcomes were evaluated, as well as the progression of SIFK.

RESULTS

SIFK was identified in only 9 patients (grade 1) postoperatively. Significantly improved clinical outcomes were observed in all patients. Preoperative femorotibial angle, MME, and duration from injury to the time of magnetic resonance imaging/surgery were 177.1 ± 1.5°, 3.2 ± 1.6 mm, and 6.4 ± 7.0/10.1 ± 7.5 weeks, respectively. No significant difference in preoperative factors and clinical outcomes was observed between patients with SIFK and those without SIFK.

CONCLUSIONS

MMPRT pullout repair prevented the progression of low-grade SIFK and improved clinical outcomes in all patients, although bone contusions (grade 1 SIFK) were not completely healed within 1 year. MMPRT pullout repair could be a good treatment option for optimizing clinical outcomes in patients with low-grade SIFK.

A characteristic MRI finding to diagnose a partial tear of the medial meniscus posterior root: an ocarina sign

BACKGROUND

Diagnosing partial tears of the medial meniscus (MM) posterior root is difficult. The aim of this study was to evaluate diagnostic values involved in conventional magnetic resonance imaging (MRI) features of MM posterior root tears (MMPRTs) and find other MRI-based findings in patients with partial MMPRTs.

METHODS

Eighteen patients who had arthroscopically confirmed partial MMPRTs were included. As a control, 18 patients who underwent partial meniscectomy for other types of MM tears were evaluated. Isolated partial MMPRTs were classified into the following three types: type A, accurate partial stable tear (cleavage < 1/2 of root width); type B, bridged unstable root tear (cleavage ≥ 1/2 of root width); type C, complex horn tear expanded to the root. Conventional MRI-based findings of MMPRTs were evaluated between two groups (n = 23). Posterior root irregularity, bone marrow spot, and ocarina-like appearance showing several condensed circles in triangular meniscal horn (ocarina sign) were also evaluated.

RESULTS

Posterior root irregularity and bone marrow spot were frequently observed in the partial MMPRTs (47.8%), compared with the other MM tears (P = 0.007 and 0.023, respectively). The ocarina sign was detected in 69.6% of patients with partial MMPRTs. A significant difference between two groups was observed in a positive ratio of ocarina sign (P < 0.001). Types A, B, and C of the partial tear/damage were observed in three, eight, and seven patients, respectively. The ocarina sign was the most common MRI finding in each type of partial MMPRT.

CONCLUSIONS

This study demonstrated that a characteristic MRI finding, "ocarina sign," was frequently observed in patients with partial tear/damage of the MM posterior root. The ocarina sign was the most common MRI finding in several types of partial MMPRTs. Our results suggest that the ocarina sign may be useful to diagnose unnoticed partial MMPRTs.

LEVEL OF EVIDENCE

IV, retrospective comparative study.

Transtibial pullout repair of medial meniscus posterior root tears: effects on the meniscus healing score and ICRS grade among patients with mild osteoarthritis of the knee

PURPOSE

To assess the effects of transtibial pullout repair for medial meniscus posterior root tears (MMPRTs) among patients with early osteoarthritis of the knee as measured by the meniscus healing score and to determine whether the meniscus healing score correlates with the International Cartilage Repair Society (ICRS) grade progression.

METHODS

Forty-seven patients with mild osteoarthritic knees (Kellgren-Lawrence grade ≤ 2 and varus alignment < 5°) who underwent transtibial pullout repair less than 3 months after MMPRT onset were assessed. The association between meniscus healing scores at 1 year postoperatively and cartilage damage of the medial compartment (medial femoral condyle [MFC] and medial tibial plateau [MTP]) were evaluated. The MFC was divided into six zones (A to F) and the MTP into two zones (G and H). The mean ICRS grade for each zone was compared between the primary surgery and second-look arthroscopy. The correlation between cartilage damage and meniscus healing status at the time of second-look arthroscopy in each zone was analysed.

RESULTS

The mean time interval from injury to surgery was 63 days, and all clinical scores showed significant improvement. There were no significant differences in the extent of cartilage damage in areas B, C, E, or F (n.s.) for MFC or in areas G and H (n.s.) for MTP. The meniscus healing score and cartilage damage were correlated in the loading areas (B, C, E, and H; - 0.53, - 0.45, - 0.33, and - 0.38, respectively; p < 0.05).

CONCLUSION

Transtibial pullout repair of MMPRTs among patients with mild osteoarthritic knees improved the clinical outcomes and showed a negative correlation between high meniscus healing scores and ICRS grades in the medial compartment loading area. This study suggests that early surgery should be undertaken for patients with mild osteoarthritic knee who develop MMPRTs.

LEVEL OF EVIDENCE

Level IV.

Comparison of the Predicting Performance for Fate of Medial Meniscus Posterior Root Tear Based on Treatment Strategies: A Comparison between Logistic Regression, Gradient Boosting, and CNN Algorithms

This study aimed to validate the accuracy and prediction performance of machine learning (ML), deep learning (DL), and logistic regression methods in the treatment of medial meniscus posterior root tears (MMPRT). From July 2003 to May 2018, 640 patients diagnosed with MMPRT were included. First, the affecting factors for the surgery were evaluated using statistical analysis. Second, AI technology was introduced using X-ray and MRI. Finally, the accuracy and prediction performance were compared between ML&DL and logistic regression methods. Affecting factors of the logistic regression method corresponded well with the feature importance of the six top-ranked factors in the ML&DL method. There was no significant difference when comparing the accuracy, F1-score, and error rate between ML&DL and logistic regression methods (accuracy = 0.89 and 0.91, F1 score = 0.89 and 0.90, error rate = 0.11 and 0.09; p = 0.114, 0.422, and 0.119, respectively). The area under the curve (AUC) values showed excellent test quality for both ML&DL and logistic regression methods (AUC = 0.97 and 0.94, respectively) in the evaluation of prediction performance (p = 0.289). The affecting factors of the logistic regression method and the influence of the ML&DL method were not significantly different. The accuracy and performance of the ML&DL method in predicting the fate of MMPRT were comparable to those of the logistic regression method. Therefore, this ML&DL algorithm could potentially predict the outcome of the MMRPT in various fields and situations. Furthermore, our method could be efficiently implemented in current clinical practice.

Steep medial tibial slope and prolonged delay to surgery are associated with bilateral medial meniscus posterior root tear

PURPOSE

Contralateral medial meniscus posterior root tear (MMPRT) can sometimes occur after primary surgeries for MMPRT and lead to unsatisfactory outcomes. The incidence rate and risk factors for contralateral MMPRT have not been well investigated, despite their clinical importance. Therefore, the incidence and predictors of bilateral MMPRT were aimed to be evaluated.

METHODS

Fourteen patients with bilateral MMPRT (group B) and 169 patients with unilateral MMPRT (group U) were enrolled in this study. Sex, age, body mass index, time between injury and surgery, and medial tibial slope angle (MTSA) were compared between the groups. MTSA was measured using lateral radiographs.

RESULTS

The incidence rate of bilateral MMPRT was 6.2% among all patients with MMPRTs. Multivariate logistic regression analysis showed that a prolonged time between injury and surgery (odds ratio [OR], 1.0; 95% confidence interval [CI] 1.00-1.01; P < 0.05) and steeper MTSA (OR, 1.85; 95% CI 1.21-2.64; P < 0.01) were significantly associated with the development of bilateral MMPRT. Receiver operating characteristic curve analysis showed that MTSA > 10.0° was associated with bilateral MMPRT, with a sensitivity of 93% and specificity of 69%.

CONCLUSION

A longer time between injury and surgery and steeper MTSA were risk factors for the development of bilateral MMPRT. Surgeons need to pay close attention to the contralateral knee in addition to the primary injured knees when treating knees with steep MTSA. Besides, early meniscal repair of primary MMPRT would be important to prevent the events of contralateral MMPRT.

LEVEL OF EVIDENCE

III.

An MRI-based suspension bridge sign can predict an arthroscopically favorable meniscal healing following the medial meniscus posterior root repair

BACKGROUND

Medial meniscus (MM) posterior root repairs show favorable clinical outcomes in patients with MM posterior root tears (MMPRTs). However, there is no useful magnetic resonance imaging (MRI) finding to determine a functionally good meniscal healing following MM posterior root repairs. We hypothesized that a characteristic postoperative MRI finding can predict a good meniscal healing following pullout repairs. The aim of this study was to investigate a clinical usefulness of several MRI findings for estimating an actual meniscal healing following MMPRT repairs.

METHODS

Fifty eight patients who had a posteromedial painful popping of the injured knee and underwent an arthroscopic pullout repair for the MMPRT were included. Arthroscopic meniscal healing was assessed according to the Furumatsu scoring system at 1 year postoperatively. We evaluated postoperative MRI-based meniscal healing using signal intensity, continuity, suspension bridge-like sign of the MM posterior root, and MM medial extrusion on coronal images. Postoperative clinical outcome evaluations were performed at second-look arthroscopy.

RESULTS

Twenty three patients showed good arthroscopic healing scores (≥7 points). Thirty five patients had moderate/poor arthroscopic healing scores (<7 points). At 1-year follow-up period, clinical outcome scores were significantly higher in the good healing group than in the moderate/poor healing group. A characteristic meniscal shape, termed "suspension bridge sign", was highly observed in the good meniscal healing group (83%) compared with in the moderate/poor healing group (26%, P < 0.001). High signal intensity and continuity of the MM posterior root and MM medial extrusion showed no differences between both groups.

CONCLUSIONS

Our study demonstrated that the MRI-based suspension bridge sign can predict an arthroscopically favorable meniscal healing following the MM posterior root repair. The suspension bridge-like MRI finding of the MM would be a useful indicator to evaluate the actual meniscal healing in patients who underwent pullout repairs for MMPRTs.

The role of MRI in evaluation of arthroscopic transtibial pullout repair for medial meniscus posterior root tears

Medial meniscus posterior root tears (MMPRT) can lead to meniscal extrusion, loss of hoop tension, loss of load-sharing ability and increased contact pressure. Currently, the most commonly used technique for root repair is arthroscopic transtibial pullout repair (ATPR). This article aims to illustrate both normal and abnormal postoperative imaging findings of the MMPRT repair performed with ATPR, with emphasis on MRI. The radiologist must highlight the tunnel position, the reduction of the medial meniscus posterior root to its anatomical attachment, the signs of root healing (continuity and lower signal intensity), and eventual meniscal extrusion or signs of osteoarthritis.

Analysis of Affecting Factors of the Fate of Medial Meniscus Posterior Root Tear Based on Treatment Strategies

Meniscal tear is a common reason for patients to undergo knee operation, and the medial meniscus posterior root tear (MMPRT) is one of the most frequent kinds of meniscal tears. The purpose of this study was to analyze participants’ factors (anthropometric and medical) to the fate of the MMPRT based on the treatment strategy. The hypothesis of this study was that treatment modalities from conservative treatment to final arthroplasty would be affected by participants’ affecting factors. From July 2003 to May 2018, 640 participants were included. Groups were categorized according to the treatment strategies such as conservative treatment, arthroscopic surgery, high tibial osteotomy (HTO) and arthroplasty surgery. Participants’ affecting factors were analyzed by one-way analysis of variance according to the four different treatment strategies and a correlation between affecting factors was also analyzed. Participants with K-L (Kellgren–Lawrence) Grade 4 and high BMI > 28.17 were appropriate candidates for arthroplasty, with K-L Grade 4 being a greater determining factor than high BMI. Participants with alignment factors such as low initial weight bearing line (WBL) (26.5%) and high delta WBL ratio (5.9%) were appropriate candidates for HTO, with the delta WBL ratio being a greater determining factor than initial WBL. Longer MRI-event times (1.44 year) and a lesser extent of meniscal extrusion (2.98 mm) were significantly associated with conservative treatment. Understanding the correlation of each affecting factor to the treatment strategy will help clinicians decide on the appropriate treatment for patients with MMPRT.

The correlation between osteoarthritis stage and the effect of the lateral wedge insole for 3 months on medial meniscus extrusion in the knee joint

BACKGROUND

Medial meniscus extrusion (MME) leads to symptomatic knee osteoarthritis (OA) due to increased mechanical stress. MME increases with weight-bearing, and the difference in MME between non-weight-bearing and weight-bearing status (ΔMME) is a factor that causes greater MME. The lateral wedge insole (LWI) is an ideal approach for decreasing the amount of ΔMME associated with the reduction of medial loading stress in the early stage of knee OA. However, the effect of the LWI for 3 months on the ΔMME and its response to OA stage have not been elucidated.

OBJECTIVE

To investigate the effects of the LWI for 3 months on MME and the ΔMME in each stage of OA.

METHODS

Participants were divided into three groups: no intervention with the LWI (control group; n = 9) and intervention with the LWI in early OA (early OA group: Kellgren-Lawrence (K/L) stage = 2, n = 17) and late OA (late OA group: K/L stage > 2, n = 13). MME was evaluated using ultrasound, and the ΔMME was obtained as the difference in MME from non-weight-bearing and weight-bearing conditions. These measurements were performed at two time points: the initial office visit as a baseline and post-3 months.

RESULTS

The weight-bearing MME and ΔMME values post-3 months were significantly decreased compared with those at baseline in the early OA group but not in the control or late OA groups.

CONCLUSIONS

The use of the LWI for 3 months decreased weight-bearing MME and ΔMME values, and its effectiveness was more pronounced in the early stage of knee OA.

Investigating the Chronology of Meniscus Root Tears: Do Medial Meniscus Posterior Root Tears Cause Extrusion or the Other Way Around?

Background

Meniscus root tears are increasingly being recognized. Meniscal extrusion has previously been associated with medial root tears; however, the relationship between secondary meniscal restraints, such as the meniscotibial (MT) ligament, extrusion, and root tears has yet to be formally evaluated.

Purpose

To better understand the association between MT ligament competence, medial meniscal extrusion, and medial meniscus posterior root tears (MMPRTs) as well as to determine the progression of meniscal extrusion over time.

Study Design

Case series; Level of evidence, 4.

Methods

Serial magnetic resonance imaging (MRI) scans were reviewed for patients who showed evidence of medial meniscal extrusion and MMPRTs on at least 1 of ≥2 available MRI scans. All patients were symptomatic at the time of diagnosis. All MRI scans were analyzed independently by 2 board-certified musculoskeletal radiologists. MT ligament disruption, medial meniscal extrusion, and MMPRTs were recorded for each MRI scan. The time between MRI scans, presence of insufficiency fractures, and Outerbridge classification for the medial femur and tibia were also evaluated.

Results

Overall, 27 knees in 26 patients were included in this study, with a total of 63 MRI scans analyzed (21 knees with 2 MRI scans, 3 with 3 MRI scans, and 3 with 4 MRI scans). All patients demonstrated clear medial meniscal extrusion and MT ligament disruption before the subsequent development of MMPRTs (P < .001). Mean extrusion at the time of initial MRI was 3.3 ± 1.1 mm and increased significantly to 5.5 ± 1.8 mm at the time of first imaging with an identified MMPRT (P < .001). The mean time between initial MRI and the first identification of an MMPRT on later MRI was 1.7 ± 1.6 years.

Conclusion

In a sample of 27 symptomatic knees with serial MRI scans both before and after an MMPRT diagnosis, all patients demonstrated MT ligament disruption and associated meniscal extrusion before the development of subsequent medial meniscus root tears. These findings suggest that MT ligament disruption and medial meniscal extrusion represent early and predisposing events contributing to MMPRTs. Therefore, this provides a possible explanation of why meniscal extrusion is not corrected with medial meniscus root repair.

Medial meniscus posterior root repair restores the intra-articular volume of the medial meniscus by decreasing posteromedial extrusion at knee flexion

PURPOSE

Transtibial repair of a medial meniscus posterior root tear (MMPRT) can improve clinical outcomes, although meniscal extrusion remains. However, few studies have investigated the volume of meniscal extrusion. This study aimed to evaluate the effect of transtibial repair in reducing the volume using three-dimensional (3D) magnetic resonance imaging, at 10° and 90° knee flexion.

METHODS

Twenty patients with MMPRTs and 16 volunteers with normal knees participated. The 3D models of meniscus were constructed using SYNAPSE VINCENT^®. The meniscal extrusion and its volume were measured at 10° and 90° knee flexion. Differences between the pre- and postoperative examinations were assessed using the Wilcoxon signed-rank test. The postoperative parameters were compared to those in patients with normal knees.

RESULTS

There were no significant pre- and postoperative differences in any parameter at 10° knee flexion. At 90° knee flexion, the posterior extrusion and its meniscal volume were decreased significantly after transtibial repair (p < 0.05), even though these parameters were larger than in the normal knees. On the other hand, intra-articular meniscal volume calculated by the extrusion volume was increased to the level of the normal knee.

CONCLUSIONS

This study demonstrated that transtibial repairs improved the intra-articular/intra-tibial surface volume of the medial meniscus by reducing the posteromedial extrusion during knee flexion. This 3D analysis is clinically relevant in evaluating that, while transtibial root repair has a limited ability to reduce meniscal extrusion, it can restore the functional volume of the medial meniscus which contributes to the shock absorber postoperatively.

LEVEL OF EVIDENCE

IV.

A histological study of the medial meniscus posterior root tibial insertion

Purpose/Aim of the study: Posterior root injury of the medial meniscus often leads to articular cartilage degeneration due to altered biomechanics. To avoid dysfunction, the attachment must be repaired using the transtibial pullout technique. To guide appropriate placement of the tibial tunnel, additional details on the normal anatomy of the meniscus insertion are needed. Therefore, we performed a histological analysis of a tibial bone slice with the medial meniscus posterior insertion obtained during total knee arthroplasty surgery. Materials and methods: Horizontal slices of the proximal tibia were obtained from 7 patients with osteoarthritis who underwent total knee arthroplasty. After decalcification, the region of the posterior horn was cut out and segmented into four pieces (2.0 mm thickness; medial to lateral). Sagittal sections were evaluated by safranin O staining or immunohistochemistry with anti-type collagen antibody. Results: Safranin O staining showed that the insertion of the posterior root consisted primarily of fibrocartilaginous layers in segment 2. Anatomically, segment 2 corresponded to the sagittal plane passing through the peak of the medial intercondylar tubercle. In this section, safranin O staining and immunohistochemistry revealed that the anterior one-third of the posterior root insertion was richer in proteoglycans and type II collagen than the central and posterior one-third. Conclusions: Anatomical insertion of the posterior root of the medial meniscus was located at the sagittal plane passing through the peak of the medial intercondylar tubercle. The structure of the medial meniscus posterior insertion was mainly localized in the anterior one-third.

Medial meniscus posterior root repair decreases posteromedial extrusion of the medial meniscus during knee flexion

BACKGROUND

Medial meniscus (MM) medial extrusion in the coronal plane does not always improve, even after repair. This study aimed to determine the extent of posteromedial extrusion of the MM during knee flexion before and after MM pullout repair using three-dimensional magnetic resonance imaging (MRI).

METHODS

Data from 14 patients (mean age, 63.4 years; 86% female) who had undergone MM pullout repair at the current institution between August 2017 and October 2018 were retrospectively reviewed. The MRIs were performed pre-operatively and ≥3 months postoperatively. Three-dimensional MRIs of the tibial surface and MM were evaluated using Tsukada's measurement method before and after pullout repair. The expected center of MM posterior root attachment (point A), the point on the extruded edge of the MM farthest away from point A (point E), and the point of intersection of a line through the posteromedial corner of the medial tibial plateau and a line connecting points A and E (point I) were identified. Subsequently, the pre-operative and postoperative AE and IE distances were calculated and compared.

RESULTS

Point E was laterally shifted by the pullout repair, whereas point I showed no significant change. The postoperative IE distance (6.7 mm) was significantly shorter than the pre-operative one (9.1 mm, P < 0.01). The postoperative AE distance (29.3 mm) was significantly shorter than the pre-operative one (31.5 mm, P < 0.01).

CONCLUSIONS

The AE and IE distances significantly decreased after MM posterior root repair, suggesting that transtibial pullout repair may be useful in reducing posteromedial extrusion of the MM.

Correlation between meniscal extrusion and symptom duration, alignment, and arthritic changes in medial meniscus posterior root tear: research article

Background

Medial meniscus posterior root tear can result in medial meniscus extrusion. However, the severity of medial meniscus extrusion is different in each root tear patient. The purpose of this study was to identify the factors that contribute to the severity of medial meniscus extrusion with medial meniscus posterior root tear, such as duration of disease, the degree of arthritis—chondral wear, subchondral edema, osteophyte size, and Kellgren–Lawrence (K/L) grade—and mechanical alignment for appropriate treatment method.

Methods

From January 2009 to August 2014, we retrospectively analyzed magnetic resonance imaging (MRI) and simple x-ray of 99 patients with medial meniscus posterior root tear. The duration of the disease was identified through retrospective chart review. The severity of medial meniscus extrusion, the presence of subchondral edema, the degree of chondral wear, and the size of the osteophyte were measured on MRI. K/L grade was confirmed on simple x-ray, and the mechanical axis was measured on whole extremity radiographs. Statistical analysis was performed by using bivariate correlation analysis and one-way analysis of variance.

Results

The mean medial meniscus extrusion was 4.61 mm, and the mean duration of the disease was 15.52 months. The mean degree of chondral wear was 25.8%, and 63 out of 99 cases showed subchondral edema. The average alignment was 4.30 degrees, and the average size of the osteophyte was 1.48 mm. There were 40 cases (40.4%) with K/L grade I, 48 cases (48.5%) with grade II, 11 cases (11.1%) with grade III, and no cases with grade IV. In the group mean analysis between the K/L grade and the severity of medial meniscus extrusion, the average medial meniscus extrusions were 3.97 mm in grade I, 4.93 mm in grade II, and 5.59 mm in grade III. There was a statistical significance between the size of the osteophyte and the severity of medial meniscus extrusion (P = 0.000), K/L grade, and the severity of medial meniscus extrusion (P = 0.001).

Conclusions

The severity of medial meniscus extrusion with medial meniscus posterior horn root tear is associated with the size of the osteophyte and K/L grade.

The accuracy of a newly developed guide system in medial meniscus posterior root repair: a comparison between two aiming guides

Purpose

Posterior root repair of the medial meniscus (MM) can prevent rapid progression of knee osteoarthritis in patients with a MM posterior root tear (MMPRT). The anatomic reattachment of the MM posterior root is considered to be critical in a transtibial pullout repair. However, tibial tunnel creation at the anatomic attachment is technically difficult. We hypothesized that a newly developed point-contact aiming guide [Unicorn Meniscal Root (UMR) guide] can create the tibial tunnel at a better position rather than a previously designed MMPRT guide. The aim of this study was to compare the position of the created tibial tunnel between the two meniscal root repair guides.

Materials and methods

Thirty-eight patients underwent transtibial pullout repairs. Tibial tunnel creation was performed using the UMR guide (19 cases) or MMPRT guide (19 cases). Three-dimensional computed tomography images of the tibial surface were evaluated using the Tsukada’s measurement method postoperatively. The expected anatomic center of the MM posterior root attachment was defined as the center of three tangential lines referring to three anatomic bony landmarks (anterior border of the posterior cruciate ligament, lateral margin of the medial tibial plateau, and retro-eminence ridge). The expected anatomic center and tibial tunnel center were evaluated using the percentage-based posterolateral location on the tibial surface. The distance between the anatomic center and tunnel center was calculated.

Results

The anatomic center of the MM posterior root footprint was located at a position of 79.2% posterior and 39.5% lateral. The mean of the tunnel center in the UMR guide was similar to that in the MMPRT guide (posterior direction, P = 0.096; lateral direction, P = 0.280). The mean distances between the tunnel center and the anatomic center were 4.06 and 3.99 mm in the UMR and MMPRT guide group, respectively (P = 0.455).

Conclusions

The UMR guide, as well as the MMPRT guide, is a useful device to create favorable tibial tunnels at the MM posterior root attachment for pullout repairs in patients with MMPRTs.

Level of evidence

IV

Alignment factors affecting the medial meniscus extrusion increases the risk of osteoarthritis development

PURPOSE

Varus alignment is known as one of the major causes of medial compartment osteoarthritis (OA). Medial meniscus extrusion also plays a critical role in the in the development of OA. However, studies on the exact relationship between alignment parameters and medial meniscus extrusion are limited. Therefore, this study aimed to investigate this relationship in patients with knee OA.

METHODS

Based on a retrospective analysis of the outpatient magnetic resonance imaging (MRI) database, 190 knees were identified to be examined using weight-bearing, whole-leg radiographs and MRIs within 3 months from the first consultation. Subsequently, various parameters of lower leg alignment were measured, which affected the knee varus in radiographs. Finally, a statistical analysis was performed to assess the relationships between the OA grade, distance of medial meniscus extrusion (MME), and alignment parameters; hip-knee-ankle angle (HKAA), percentage of mechanical axis (% MA), medial proximal tibial angle (MPTA), and joint line convergence angle (JLCA). The subjects were divided according to the presence or absence of MME (Group A: MME distance below 3 mm, Group B: MME distance 3 mm and above) to assess the differences in each alignment parameter correlated with MME distance between the groups.

RESULTS

MME distance significantly increased with OA grade progression. HKAA, % MA, MPTA, and JLCA significantly correlated with medial meniscus extrusion distance (r = - 0.21, - 0.23, - 0.16, 0.3, respectively). Multiple regression analysis of each significant alignment combined with age, sex, and body mass index revealed that HKAA, % MA, MPTA, and JLCA were significant independent factors of MME distance (P = 0.008, 0.0026, 0.011, 0.0001, respectively). These significant findings were reinforced in group B. In contrast, the correlation between alignment parameters and medial meniscus extrusion distance was not significant in group A.

CONCLUSION

Varus alignment factors are related to MME distance especially in extruded meniscus knees, as the OA grade progressed. Therefore, the coexistence of varus alignment and MME can be the risk factors for OA progression. As the low MPTA was an independent alignment factor for generating varus alignment, patients with osteoarthritis of the knee with both, low MPTA and MME could be the appropriate candidates for early intervention by high tibial osteotomy.

LEVEL OF EVIDENCE

III.

Pullout repair using modified Mason-Allen suture induces better meniscal healing and superior clinical outcomes: A comparison between two surgical methods

BACKGROUND

Pullout repairs of medial meniscus posterior root tears (MMPRTs) have many surgical options. However, there has been no reliable clinical study conducted to compare the superiority of each pullout repair technique. The current study hypothesized that pullout repairs using a modified Mason-Allen suture with FasT-Fix (F-MMA) would have several advantages in postoperative clinical outcomes and meniscal healing compared with single FasT-Fix. The aim of this study was to investigate the clinical usefulness of these two techniques in treating MMPRTs.

METHODS

Thirty-eight patients who had complete MMPRTs were included. All patients underwent transtibial pullout repairs. To compare the clinical usefulness between pullout repairs using single FasT-Fix and F-MMA techniques, patients were divided into two groups. Second-look arthroscopic evaluations of meniscal healing were performed at one year postoperatively. Clinical outcomes were assessed using: Lysholm and visual analogue scale (VAS) pain scores, and Knee Injury and Osteoarthritis Outcome Score (KOOS).

RESULTS

Single FasT-Fix and F-MMA pullout repairs improved clinical outcomes in patients with MMPRTs. At second-look arthroscopy, VAS pain, KOOS pain, and arthroscopic meniscal healing scores following F-MMA pullout repairs were superior to those after single FasT-Fix pullout repairs.

CONCLUSIONS

This study demonstrated that F-MMA suture configuration obtained better meniscal healing and superior clinical outcomes compared with single FasT-Fix repairs in patients with MMPRTs. These results suggest that the F-MMA pullout repair may possibly reduce knee pain in arthroscopic treatments of MMPRTs.

A Novel Arthroscopic Classification of Degenerative Medial Meniscus Posterior Root Tears Based on the Tear Gap

Background:

Degenerative medial meniscus posterior root tears (MMPRTs) are reportedly associated with medial compartment osteoarthritis and meniscal extrusion with a displaced gap from the root insertion. However, degenerative MMPRTs have not yet been clearly classified according to arthroscopic findings.

Purpose:

To classify degenerative MMPRTs according to the tear gap and to investigate how the classification could reflect the joint condition properly.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

Patients who underwent arthroscopic surgery, performed by a single orthopaedic surgeon, for degenerative MMPRTs between August 2006 and February 2017 were included. MMPRTs were classified according to tear patterns observed during arthroscopic surgery (type 1, incomplete root tear; types 2-5, complete root tears), with each type further divided by the size of the tear gap, defined as the degree of tear displacement from the root (type 2, no gap or overlapped; type 3, gap of 1-3 mm; type 4, gap of 4-6 mm; type 5, gap of ≥7 mm). We compared preoperative factors, including the Kellgren-Lawrence (K-L) grade, absolute extrusion, relative percentage of extrusion (RPE), tear gap on magnetic resonance imaging (MRI), and mechanical alignment, as well as intraoperative factors, including chondral wear at surgery, between each MMPRT type.

Results:

A total of 116 root tears were categorized according to this classification: type 1, 16.4% (19 knees); type 2, 9.5% (11 knees); type 3, 40.5% (47 knees); type 4, 25.0% (29 knees); and type 5, 8.6% (10 knees). Chondral wear of the medial femoral condyle (MFC) (P = .001), K-L grade (P = .001), meniscal extrusion (P = .001), and tear gap on MRI (P = .001) showed a tendency to increase with a higher tear type. Chondral wear (ρ for MFC = 0.388; ρ for MTP = 0.311), K-L grade (ρ = 0.390), and meniscal extrusion (ρ for absolute extrusion = 0.500; ρ for RPE = 0.451) showed a moderate correlation with tear type, whereas tear gap on MRI (ρ = 0.907) showed a strong correlation with tear type.

Conclusion:

Our study introduces a new classification based on the tear gap that can concisely describe a degenerative MMPRT. The classification system demonstrated that a higher tear type (increasing displacement of the tear gap in arthroscopic surgery) is associated with higher meniscal extrusion, severe chondral wear, and greater severity of arthritis.

Injury patterns of medial meniscus posterior root tears

INTRODUCTION

Medial meniscus posterior root tear (MMPRT) can occur in middle-aged patients who have a posteromedial painful popping during light activities. MMPRTs are more common in patients with increased age, female gender, sedentary lifestyle, obesity, and varus knee alignment. However, injury mechanisms of minor traumatic MMPRTs are still unclear. We hypothesized that high flexion activities are the major cause of MMPRTs. The aim of this study was to clarify injury patterns of MMPRTs.

MATERIALS AND METHODS

One hundred patients were diagnosed having MMPRTs after posteromedial painful popping episodes. Details of posteromedial painful popping episode, situation of injury, and position of injured leg were obtained from the patients by careful interviews. Injury patterns were divided into 8 groups: descending knee motion, walking, squatting, standing up action, falling down, twisting, light exercise, and minor automobile accident.

RESULTS

A descending knee motion was the most common cause of MMPRTs (38%) followed by a walking injury pattern (18%) and a squatting action related to high flexion activities of the knee (13%). The other injury patterns were less than 10%.

DISCUSSION

Descending knee motions associated with descending stairs, step, and downhill slope are the most common injury pattern of MMPRTs. High flexion activities of the knee are not the greatest cause of MMPRTs. Our results suggest that the descending action with a low knee flexion angle may trigger minor traumatic MMPRTs.

LEVEL OF EVIDENCE

IV, retrospective cohort study.

Transtibial pullout repair of medial meniscus posterior root tear restores physiological rotation of the tibia in the knee-flexed position

BACKGROUND

Medial meniscus posterior root tear (MMPRT) results in joint overloading and degenerative changes in the knee. Favorable clinical outcomes have been reported after transtibial pullout repair of MMPRT. To date, however, in vivo tibial rotational changes before and after root repair remain poorly understood. The purpose of this study was to investigate postoperative changes in tibial rotation following MMPRT pullout repair.

HYPOTHESIS

Pathological external rotation of the tibia in the knee-flexed position is caused by MMPRT and is reduced after transtibial pullout repair.

PATIENTS AND METHODS

Fifteen patients who underwent MMPRT pullout repair and 7 healthy volunteers were included. Magnetic resonance imaging examinations were performed in the 10° and 90° knee-flexed positions. The angles between the surgical epicondylar axis and a line between the medial border of the patellar tendon and the apex of the medial tibial spine were measured. Baseline was defined as a line lying at a right angle to the other, and a value was positive and negative when the tibia rotated internally and externally, respectively.

RESULTS

In the volunteer's normal knees, tibial internal rotation was +1.00°±3.27° at 10° flexion and +4.14°±3.46° at 90° flexion. In the MMPRT preoperative knees, tibial internal rotation was +1.07°±3.01° at 10° flexion and +1.27°±2.96° at 90° flexion. In the postoperative knees, tibial internal rotation was +1.60°±2.85° at 10° flexion and +4.33°±2.89° at 90° flexion.

DISCUSSION

This study demonstrates discontinuity of the MM posterior root may induce a pathological external rotation of the tibia during knee flexion and that MMPRT pullout repair reduces the pathological external rotation of the tibia in the knee-flexed position.

LEVEL OF EVIDENCE

III, comparative retrospective study.

Medial knee osteoarthritis precedes medial meniscal posterior root tear with an event of painful popping

BACKGROUND

An event of painful popping is a highly predictive clinical sign of medial meniscal posterior root tears (MMPRTs) in middle-aged to older patients. There are lacks of studies about the prevalence of a painful popping event and the condition of the medial compartment at the time of popping event in MMPRTs.

HYPOTHESIS

We hypothesized that most of MMPRTs with a single painful popping event would show pre-existed pathologic medial meniscal extrusion (MME) and articular cartilage degeneration, and larger contact area of medial femoral condyle to medial tibial plateau could affect the MME. In addition, MME would be correlated with knee osteoarthritis.

PATIENTS AND METHODS

Thirty-eight patients (mean age 58.5±10.5) who had painful popping within 3 weeks were included. On MRIs, absolute MME, relative percentage of extrusion (RPE), MME-medial femoral condyle (MFC)/medial tibial condyle (MTC) at 0° ratio, and medial compartments' Modified Outerbridge Scale (MOS) were evaluated. Kellgren-Lawrence (K-L) grade was also assessed.

RESULTS

The MME parameters including absolute MME, RPE, and the ratio between MME and MFC/MTC at 0° were 2.9±1.2mm, 22.0±10.3%, and 3.2±1.3. Patients who with MOS and K-L grade≥2 were 33 (86.8%) and 32 (84.2%). Patients were divided into MME≥3mm (group G, n=20) and MME<3mm (groupL, n=18). The MME parameters were significantly greater in group G than group L (all, p<0.001). The group G had worse osteoarthritis progression in terms of MOS and K-L grade than the group L (p=0.035 and 0.077, respectively) MME≥3mm showed significantly association with MOS≥3 (p=0.045).

DISCUSSION

More than 80% of MMPRT patients with an event of painful popping within 3 weeks showed that medial compartment degeneration preceded the event of popping. Therefore, identification of MME and articular cartilage degeneration at the time of painful popping in MMPRTs could be helpful when the surgeon determines the most appropriate treatment.

LEVEL OF EVIDENCE

IV, Case-series.

Arthroscopic scoring system of meniscal healing following medial meniscus posterior root repair

PURPOSE

Medial meniscus posterior root tear (MMPRT) leads to a rapid degradation of articular cartilage. In the treatment of MMPRT, transtibial pullout repair demonstrates a high clinical survival rate. However, there is no reliable method to evaluate the meniscal healing after surgery. We propose an arthroscopic scoring system for evaluating the meniscal healing status. The aim of this study was to investigate the correlations between second-look arthroscopic scores and clinical outcomes after transtibial pullout repair.

METHODS

Twenty patients who had MMPRTs underwent transtibial pullout repairs. Clinical outcomes were assessed using the Japanese Knee Injury and Osteoarthritis Outcome Score (KOOS) and pain score evaluated by visual analogue scale at preoperatively and 1 year postoperatively. The healing status of repaired MM was assessed at one year post-operatively using a semi-quantitative arthroscopic scoring system (total, 10 points) composed of three evaluation criteria: (i) anteroposterior width of bridging tissues, (ii) stability of the MM posterior root, and (iii) synovial coverage of the sutures. Linear regression analysis was used to assess the correlation between second-look arthroscopic scores and clinical outcomes.

RESULTS

Transtibial pullout repairs of MMPRTs significantly improved clinical evaluation scores at one year post-operatively. A median of second-look arthroscopic scores was 6.5 (5.75-8). A good correlation was observed between the arthroscopic score and KOOS quality of life (QOL) subscale. A moderate negative correlation between the arthroscopic score and pain score was observed.

CONCLUSIONS

This study demonstrated that our semi-quantitative scoring system of meniscal healing correlated with the KOOS QOL subscale following MMPRT transtibial pullout repair. Our results suggest that the second-look arthroscopic score using this system may be a useful scale to determine and compare the healing status of the MM posterior root.

Medial meniscus posterior root tear induces pathological posterior extrusion of the meniscus in the knee-flexed position: An open magnetic resonance imaging analysis

BACKGROUND

A medial meniscus posterior root tear (MMPRT) is defined as an injury to the posterior meniscal insertion on the tibia. In MMPRT, the medial meniscus (MM) hoop function is damaged, and the MM undergoes a medial extrusion into the interior from the superior articular surface of the tibia. However, the details of MM position and movement during knee joint movement are unclear in MMPRT cases. The present study aims to evaluate MM position and movement via magnetic resonance imaging (MRI) examination of the MM posterior extrusion (MMPE) at knee flexion angles of 10° and 90°. We hypothesized that, during knee flexion, the MM will shift to the posterior and the posterior extrusion will increase compared to that when the knee is extended.

MATERIALS AND METHODS

Twenty-four patients were diagnosed with symptomatic MMPRT on open MRI examination. Preoperative MMPE, anteroposterior interval (API) of the MM, and MM medial extrusion (MMME) at knee flexion angles of 10° and 90° were measured.

RESULTS

For patients with MMPRT, the MMPE increased from -4.77±1.43mm to 3.79±1.17mm (p<0.001) when the knee flexion angle increased from 10° to 90°. Further, flexing the knee from 10° to 90° decreased the API of the MM from 20.19±4.22mm to 16.41±5.14mm (p<0.001). MMME showed no significant change between knee flexion angles of 10° and 90°.

DISCUSSION

This study demonstrated that, in cases of MMPRT, the MMPE clearly increases when the knee is flexed to 90°, while MMME does not change. Our results suggest that open MRI examination can be used to evaluate the dynamic position of the posterior MM by scanning the knee as it flexes to 90°.

LEVEL OF EVIDENCE

IV: retrospective cohort study.

Modern treatment of meniscal tears

The complex ultrastructure of the meniscus determines its vital functions for the knee, the lower extremity, and the body.

The most recent concise, reliable, and valid classification system for meniscal tears is the International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine (ISAKOS) Classification, which takes into account the subsequent parameters: tear depth, tear pattern, tear length, tear location/rim width, radial location, location according to the popliteal hiatus, and quality of the meniscal tissue.

It is the orthopaedic surgeon’s responsibility to combine clinical information, radiological images, and clinical experience in an effort to individualize management of meniscal tears, taking into account factors related to the patient and lesion.

Surgeons should strive not to operate in most cases, but to protect, repair or reconstruct, in order to prevent early development of osteoarthritis by restoring the native structure, function, and biomechanics of the meniscus.

Currently, there are three main methods of modern surgical management of meniscus tears: arthroscopic partial meniscectomy; meniscal repair with or without augmentation techniques; and meniscal reconstruction. Meniscus surgery has come a long way from the old slogan, “If it is torn, take it out!” to the currently accepted slogan, “Save the meniscus!” which has guided evolving modern treatment methods for meniscal tears. This last slogan will probably constitute the basis for newer alternative biological treatment methods in the future.

Cite this article: EFORT Open Rev 2018;3 DOI: 10.1302/2058-5241.3.170067.

Knotless Medial Meniscus Posterior Root Repair

Medial meniscus posterior root tears are common injuries, especially in the Asian world. This injury must be repaired where indicated to restore knee biomechanics and prevent arthritis. Suturing the meniscus using suture tapes provides good hold of the tissue. The use of a 70° arthroscope and creation of a transseptal portal improve visualization of the posterior compartment. Creation of a high posteromedial portal achieves the correct trajectory for the suture anchor insertion. A knotless suture anchor can be used to fix the posterior root at its anatomic attachment site. This obliterates the need for transtibial drilling for a suture pull-out repair or for knot tying and suture shuttling as for a conventional suture anchor.