Effects of medial meniscal posterior horn avulsion and repair on meniscal displacement

Biomechanical impact of meniscal ramp lesions on knee joint contact characteristics in ACL deficient knees: a cadaveric analysis

PURPOSE

To evaluate the changes in contact characteristics of the tibiofemoral joint resulting from a meniscal ramp lesion in the medial meniscus.

METHODS

Twelve cadaveric knees (six matched pairs) were subjected to a 600 N axial load using a custom testing jig, which allowed for knee positioning at 0°, 45°, and 90° of flexion without other constraints. The knees were randomly assigned to either a ramp lesion group (n = 6) or a posterior root lesion group (n = 6). Four testing conditions were examined: (1) intact, (2) isolated ramp lesion, (3) isolated posterior root tear of the medial meniscus, and (4) combined ramp lesion and posterior root tear of the medial meniscus. Contact characteristics were evaluated using a flexible pressure sensor, the I-Scan System.

RESULTS

Peak contact pressure in isolated ramp lesions (4.15 ± 0.98 MPa, P = 0.206) showed non-significant increases compared to the intact condition (3.86 ± 1.32 MPa). Peak contact pressure in isolated posterior root tears (4.58 ± 1.70 MPa, P = 0.040) and, combined ramp and posterior root lesions (4.67 ± 1.47 MPa, P = 0.003) were significantly higher than that in the intact condition. The knee flexion position significantly affected the medial tibiofemoral joint's contact area, contact pressure, and peak contact pressure (P < 0.001 for all).

CONCLUSION

Isolated ramp lesions did not significantly impact force transmission, contact area, or contact pressure. In contrast, isolated root lesions and combined ramp and posterior root tears of the medial meniscus significantly intensified the changes in contact characteristics in the medial tibiofemoral joint compared to the intact condition.

LEVEL OF EVIDENCE

Level III.

Extrusion and meniscal mobility evaluation in case of ramp lesion injury: a biomechanical feasibility study by 7T magnetic resonance imaging and digital volume correlation

Introduction: The existing body of literature on the biomechanical implications of ramp lesions is limited, leaving a significant gap in our understanding of how these lesions impact joint kinematics and loading in the medial compartment. This cadaveric biomechanical study aims to address this gap by employing an innovative Digital Volume Correlation (DVC) method, utilizing 7 Tesla Magnetic Resonance Imaging (MRI) images under various loading conditions. The primary objective is to conduct a comprehensive comparison of medial meniscal mobility between native knees and knees affected by grade 4 ramp lesions. By focusing on the intricate dynamics of meniscal mobility and extrusion, this work seeks to contribute valuable insights into the biomechanical consequences of medial meniscus ramp lesions. Materials and methods: An initial set of 7T MRI imaging sessions was conducted on two intact native knees, applying load values up to 1500N. Subsequently, a second series of images was captured on these identical knees, with the same loads applied, following the creation through arthroscopy of medial meniscus ramp lesions. The application of DVC enabled the precise determination of the three components of displacement and spatial variations in the medial menisci, both with and without ramp lesions. Results: The measured directional displacements between native knees and injured knees indicate that, following the application of axial compression load, menisci exhibit increased extrusion and posterior mobility as observed through DVC. Discussion: Injuries associated with Subtype 4 medial meniscus ramp lesions appear to elevate meniscal extrusion and posterior mobility during axial compression in the anterior cruciate ligament of intact knees. Following these preliminary results, we plan to expand our experimental approach to encompass individuals undergoing weight-bearing MRI. This expansion aims to identify meniscocapsular and/or meniscotibial insufficiency or rupture in patients, enabling us to proactively reduce the risk of osteoarthritic progression.

Medial Meniscus Posterior Root Tears Lead to Changes in Joint Contact Mechanics at Low Flexion Angles During Simulated Gait

BACKGROUND

Previous biomechanical studies evaluating medial meniscus posterior root tears (MMPRTs) are limited to low loads applied at specified loading angles, which cannot capture the effects of MMPRTs during the multidirectional forces and moments placed across the knee during physiological activities.

PURPOSE

To quantify the effects of MMPRTs on knee joint contact mechanics during simulated gait.

STUDY DESIGN

Controlled laboratory study.

METHODS

Six human cadaveric knees were mounted on a robotic simulator programmed to apply dynamic forces, moments, and flexion angles to mimic level walking. Twelve cycles of multidirectional and dynamic standard gait input waveforms, normalized to specimen-specific body weight, were applied to the following conditions: (1) native, intact meniscus and (2) MMPRT. Peak contact stress, contact area, and the position of the weighted center of contact across the medial tibial plateau throughout the stance phase of gait were quantified using an electronic sensor placed across the medial tibial plateau. The difference between the intact state and MMPRT condition was calculated for each metric, and then the means and 95% CIs were computed.

RESULTS

Despite heterogeneity in knee contact forces, MMPRTs significantly increased peak contact stress by a mean of 2 MPa across 20% to 37% of the simulated gait cycle and significantly decreased the contact area by a mean of 200 mm2 across 16% to 60% of the simulated gait cycle in comparison with the native state. There was no significant difference in the position of the weighted center of contact, in either the anterior-posterior or medial-lateral directions, after MMPRT.

CONCLUSION

MMPRTs led to both a significant increase in peak contact stress and decreased contact areas for a portion of the simulated gait cycle ranging from 20% to 37% of gait, during which time the femur was flexed <15°.

CLINICAL RELEVANCE

Contact mechanics are significantly affected after MMPRTs during early to midstance and at knee flexion angles lower than demonstrated previously. These data provide further biomechanical justification for treating MMPRTs.

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.

An Improved Transosseous Pullout Suture Technique for Arthroscopic Repair of a Meniscus Root Tear

OBJECTIVE

This study aimed to explore the clinical efficiency of an improved transosseous pullout suture technique for arthroscopic repair of a meniscus root tear.

METHODS

From January 2017 to January 2021, 53 patients with posterior meniscus root tears combined with anterior cruciate ligament (ACL) and/or posterior cruciate ligament (PCL) tears were collected. Totally, in 29 patients (group A), the 2.0 mm modified pullout tunnel method was used to suture the posterior meniscus root, while 24 patients (group B) were treated with the traditional 4.5 mm pullout tunnel method. In group A, 20 patients had lateral meniscus posterior root (LMPR) combined with ACL tears, 5 patients had LMPR combined with ACL and PCL tears, and 4 patients had medial meniscus posterior root (MMPR) combined with ACL tears. In group B, 19 patients had LMPR combined with ACL tears, 3 patients had LMPR combined with ACL and PCL tears, and 2 patients had MMPR combined with ACL tears. The improvement of the Lysholm and VAS scores and the incidence of complications in group A and group B before the operation, 1 month and 3 months after the operation, and after the final follow-up were compared.

RESULTS

Preoperative Lysholm score was 26.0±5.6 in group A and 26.7±5.8 in group B (P>0.05). One-month postoperative Lysholm score was 66.5±5.7 in group A and 54.3±2.4 in group B (P<0.001). Three-month postoperative Lysholm score was 81.1±7.2 in group A and 73.2±9.7 in group B (P<0.05). Lysholm scores after the final follow-up was 90.3±5.6 in group A and 90.0±5.0 in group B (P>0.05). Preoperative VAS score was 6.3±1.4 in group A and 6.3±1.2 in group B (P>0.05). One-month postoperative VAS score was 1.8±0.7 in group A and 2.4±0.9 in group B (P<0.05). Three-month postoperative VAS score was 0.7±0.6 in group A and 0.8±0.6 in group B (P>0.05). VAS score after the final follow-up was 0.2±0.4 in group A and 0.3±0.5 in group B (P>0.05).

CONCLUSION

The improved transosseous pullout suture technique using a smaller 2.0 mm bone tunnel can virtually eliminate the risk of conflict with other bone tunnels and facilitate the management of bone tunnels in multiple ligament injuries, while also diminishing suture abrasion caused by the windshield wiper effect. The technique achieves good clinical efficacy.

A Biomechanical Comparison of All-Inside Versus Transtibial Meniscus Root Repair Techniques

BACKGROUND

Meniscus root tears are associated with chondral injury, early degenerative change, and a high conversion rate to total knee arthroplasty. It is well-established that meniscus root tears lead to decreased femorotibial contact area, increased peak contact pressures, and increased stress on the articular cartilage.

PURPOSE

To evaluate the biomechanical characteristics of the all-inside meniscus root repair procedure and compare it with the previously described transtibial technique.

STUDY DESIGN

Controlled laboratory study.

METHODS

Nine paired cadaveric knees were prepared by removing skin, subcutaneous tissues, quadriceps muscles, patella, and patellar tendon, while leaving the capsule in place. Pressure-mapping sensors were inserted, and specimens underwent compressive loading to obtain peak pressures, mean pressures, and femorotibial contact area in the medial and lateral compartments. Tests were performed as static compression tests with the knee locked at 0° of flexion. Compression testing was performed in 3 states: meniscus intact, meniscus root cut, and after meniscus root repair with an all-inside repair technique. Additionally, testing was completed on 9 pairs of cadaveric knees to compare stiffness and maximal load to failure between the all-inside and transtibial meniscus root repair techniques.

RESULTS

In the medial compartment, there were significant increases in median peak pressures and median mean pressures in the root cut state as compared with the intact state (+636 kPA [95% CI, 246 to 1026] and +190 kPA [95% CI, 49 to 330], respectively). All-inside meniscus root repair restored median peak pressures and median mean pressures to approach those of the intact meniscus (+311 kPA [95% CI, -79 to 701] and +137 kPA [95% CI, -3 to 277]). In the lateral compartment, there were also significant increases in median peak pressures and median mean pressures in the root cut state as compared with the intact state (+718 kPA [95% CI, 246 to 1191] and +203 kPA [95% CI, 51 to 355]). All-inside meniscus root repair restored median peak pressures and median mean pressures such that they were not significantly different from the intact state (+322 kPA [95% CI, -150 to 795] and +18 kPA [95% CI, -134 to 171]). There was no difference between repair techniques regarding load to failure (P = .896). Transtibial meniscus root repair had significantly more stiffness (mean ± SD, 24.8 ± 9.3 N/mm) as compared with the all-inside meniscus root repair technique (13.6 ± 3.8 N/mm, P = .015).

CONCLUSION

All-inside meniscus root repair reduced median peak and mean pressures to those of the native intact meniscus with the knee in extension in the cadaveric model. When compared with a transtibial meniscus root repair technique, all-inside repair demonstrated decreased stiffness and a similar load to failure.

CLINICAL RELEVANCE

All-inside meniscus root repair restored mean and peak femorotibial pressures to those of the intact meniscus. Additionally, it offers a technically easier technique for management of meniscus root tears.

Medial Meniscal Extrusion in Patients With Medial Meniscus Root Tears: A Systematic Review and Meta-analysis

Background

Medial meniscal extrusion (MME) has received significant interest because of its correlation with medial meniscus root tears (MMRTs), its potential as a diagnostic tool, and its significance in the progression of knee osteoarthritis (OA).

Purpose

To (1) evaluate if MMRTs significantly increase MME compared with nonroot tears (NRTs) and no tears and (2) determine the clinical outcomes of increased MME.

Study Design

Systematic review; Level of evidence, 4.

Methods

Electronic database searches of PubMed, Embase, Scopus, Web of Science, and Cochrane Central Register of Controlled Trials were conducted on June 6, 2022, in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 checklist criteria. The searches were conducted using the keywords "meniscus tear" and "extrusion." No restrictions were placed on the date of publication. Quality and sensitivity assessments were conducted on included studies. Major MME was defined as an extrusion ≥3 mm.

Results

Twenty-two studies involving 7882 knees were included. Compared with patients with NRTs, those with MMRTs had a 1.12-mm greater mean absolute meniscal extrusion (AME) and were 3.45 times more likely to have major MME (P < .001 for both). Compared with patients with no tears, those with MMRTs had a 2.13-mm greater AME (P < .001). Within patients with MMRT, those with widely displaced MMRT had a 1.01-mm greater AME compared with nondisplaced MMRT (P < .001). Patients with OA had a 0.73-mm greater AME and were 3.86 times more likely to have major MME compared with patients without OA (P < .001 for both). Within patients who were not stratified according to MMRT, NRT, or no tears, those who eventually developed OA had a 0.79-mm greater AME than those who did not have OA (P = .02).

Conclusion

Patients with MMRTs had higher MME values compared with those with other types of meniscal tears and those without any meniscal tears. Patients with knee OA were more likely to have higher MME compared with those without OA.

Short-Term Outcomes after High Tibial Osteotomy Aimed at Neutral Alignment Combined with Arthroscopic Centralization of Medial Meniscus in Osteoarthritis Patients

The study aimed to improve the long-term outcomes of open-wedge high tibial osteotomy (OWHTO); procedures combining OWHTO aimed at neutral alignment and arthroscopic centralization for meniscal extrusion have been introduced. The present study evaluated short-term patient-reported outcome measures; namely, the patient subjective satisfaction scores and Numeric Rating Scale (NRS) for walking pain after OWHTO aimed at neutral alignment with and without arthroscopic centralization for an extruded medial meniscus. A retrospective review of 50 primary OWHTO patients was conducted. Thirty-nine patients were included in the analysis after applying the exclusion criteria. The centralization group included 21 patients with knee osteoarthritis patients who underwent the OWHTO with arthroscopic meniscal centralization, while the control group included 18 patients who underwent OWHTO alone. The patient subjective satisfaction scores and NRS for walking pain were recorded at outpatient visits from before surgery to 3 years after surgery. In terms of the Lysholm knee scale, International Knee Documentation Committee subjective score, and Knee Osteoarthritis Outcome Score, the latest data (at least 2 years after surgery) were reviewed. Radiographic changes in joint space width and joint line congruence angle were measured 2 years postoperatively. Patient demographic data were also reviewed. One patient in the centralization group experienced a superficial surgical site infection. The patient subjective satisfaction and NRS scores for walking pain gradually improved by 1 year after surgery and were sustained until 3 years after surgery in both groups, with no significant difference between the groups. The course of patient-reported outcome measures from before surgery to 3 years after surgery for solely OWHTO aimed at neutral alignment and OWHTO aimed at neutral alignment with arthroscopic centralization showed the similar trends.

Comparative Efficacy of Root Repair versus Partial Meniscectomy and Observation for Patients with Meniscus Root Tears

The purpose of this study was to (1) compare the efficacy of root repair versus partial meniscectomy and observation for patients with meniscus root tears; (2) compare osteoarthritis (OA) progression and functional outcomes in patients with isolated repair and with adjuvant surgery; and (3) evaluate OA progression and functional outcomes after pullout repair or all-inside repair of meniscus root tears. We performed a systematic literature search in PubMed, Embase, Scopus, and the Cochrane Library up to September 1, 2020, to identify studies that evaluated the efficacy of root repair versus partial meniscectomy and observation in patients with meniscus root tears. Random-effects meta-analysis was used to pool data. A total of nine studies were included in the meta-analysis, with 485 patients comprising 238 in the root repair group, 113 in the partial meniscectomy group, and 134 in the observation group. The mean age of the patients ranged from 46.1 to 64.8 years. Compared with partial meniscectomy, root repair was associated with significantly lower postoperative Kellgren-Lawrence (K-L) grade (mean difference [MD]: -0.62, 95% confidence interval [CI]: -1.00 to -0.23) and progression to arthroplasty rate (odds ratio [OR]: 0.15, 95% CI: 0.04-0.60) at final follow-up. Compared with observation, root repair was associated with significantly lower arthroplasty rate (OR: 0.07, 95% CI: 0.01-0.44) and better International Knee Documentation Committee (IKDC) score (MD: 8.07, 95% CI: 0.72-15.41) at final follow-up. Moreover, significantly lower postoperative K-L grade and progression to arthroplasty rate, as well as higher IKDC and Lysholm scores were seen in favor of root repair in patients with isolated meniscus root tears. Additionally, significantly lower OA progression and higher function scores were found in favor of root repair when the tears were repaired with pullout technique. Current evidence indicates that root repair with pullout technique may be a better choice than partial meniscectomy and observation for patients with isolated meniscus root tears as measured by OA progression, progression to arthroplasty, as well as functional outcomes.

Varus stress MRI in diagnosis of medial meniscal posterior root tear

Background

Early and accurate diagnosis of medial meniscal posterior root tear (MMPRT) via magnetic resonance imaging (MRI) is crucial to prevent the development of medial meniscus extrusion (MME) and subsequent osteoarthritic changes. The study aims to assess the role of MRI in diagnosing the medial meniscal posterior root tear (MMPRT) as well as to investigate the additive value of a new MRI technique (varus stress position technique) in measuring the accurate degree of a truly extruded meniscus, during normal daily activities like standing or walking. This prospective study included 70 patients who had an episode of posteromedial knee pain. All patients underwent conventional MRI, whereas only 35 of them underwent MRI with varus stress loading position.

Results

The study included 70 patients, of which 56 were female (80.0%), with a mean age of 49.1 ± 8.5 years. According to duration onset of MMPRT, 39 patients were in the chronic stage (4–12 months), 16 patients were in the acute stage (early < 1 month), and 15 patients were in the subacute stage (1–3 months). It was found that varus stress position could detect 100% of the patients (35/35) with positive medial meniscus extrusion (MME) (≥ 3 mm), whereas the MRI with the traditional position could detect only 62.9% of the cases (22/35) (P < 0.000). Regarding the chronicity of MMPRT, a significant increase was observed in the amount of MME in post-varus MRI compared with that in pre-varus MRI for each stage (acute, subacute, and chronic) (P < 0.000).

Conclusion

MRI is considered a superior imaging modality in diagnosing MMPRT through several characteristic MRI findings. The varus stress position showed a valuable role in assessing the presence and degree of severity of true extruded meniscus using positional varus stress load.

Semi-quantitative arthroscopic scoring system is related to clinical outcomes in patients after medial meniscus posterior root repair

BACKGROUND

Different methods are available to assess the healing status of repaired root for medial meniscus posterior root tears (MMPRT) using second-look arthroscopy. However, few studies are comparing them or validating their usefulness. Therefore, it was hypothesized that the semi-quantitative arthroscopic score might correlate more with 1-year clinical outcomes in patients with MMPRT than the qualitative evaluation.

METHODS

Data of 61 patients who underwent MMPRT pullout repair and second-look arthroscopy were retrospectively evaluated. The semi-quantitative arthroscopic scoring system was divided into three evaluation criteria: scores from 0 to 10 points include the width of the bridging tissue, stability of the repaired root, and synovial coverage. The qualitative evaluation was classified into 4 status; complete healing, lax healing, scar tissue healing, and failed healing according to the stability and mobility of the repaired root. Multivariate linear regression analyses were used to identify predictors of 1-year postoperative clinical outcomes, including Knee Injury and Osteoarthritis Outcome, Lysholm, or International Knee Documentation Committee scores. Spearman's correlation analysis was used to analyze the correlation between second-look arthroscopic score/qualitative evaluation and 1-year postoperative clinical outcomes. In addition, the optimal cutoff point of semi-quantitative arthroscopic score was determined by receiver operating characteristic (ROC) curve. The Mann-Whitney U test was used to compare clinical outcomes between patients with semi-quantitative arthroscopic scores ≥8 and scores <8.

RESULTS

All clinical scores significantly improved at 1 year postoperatively. A good correlation was observed between the semi-quantitative score and clinical scores, but none between qualitative evaluation and clinical scores. The optimal cutoff point of semi-quantitative second-look arthroscopic score was 8 points. Significantly, better clinical outcomes were observed in patients with semi-quantitative scores ≥8 points.

CONCLUSIONS

All 1-year postoperative clinical scores were significantly improved. The semi-quantitative arthroscopic scores correlate more with 1-year clinical outcomes in patients with MMPRT than the qualitative evaluation.

LEVEL OF EVIDENCE

IV case series study.

Clinical evaluation of suture materials for transtibial pullout repair of medial meniscus posterior root tear

BACKGROUND

There are no recommendations for specific suture materials in transtibial pullout repair of medial meniscus posterior root tears. This study aimed to evaluate the clinical outcomes of transtibial pullout repair of medial meniscus posterior root tears using ultrahigh-molecular-weight polyethylene sutures and suture tape.

METHODS

We retrospectively reviewed the data of 36 patients (27 women and 9 men, mean age 64.1 years) who had undergone transtibial pullout repair of medial meniscus posterior root tears between November 2018 and December 2019. Two groups of 18 patients each received either two different cord-like sutures or suture tape. Clinical parameters were assessed preoperatively and on second-look arthroscopy (mean postoperative period 12 months). The meniscal healing status was assessed using a previously published scoring system (ranging from 0 to 10), and the incidence rate of suture cut-out was assessed on second-look arthroscopy.

RESULTS

All clinical scores significantly improved in both groups, with no significant between-group differences on second-look arthroscopy. The arthroscopic meniscal healing scores significantly differed between sutures (mean 6.7 points) and suture tape (mean 7.4 points; p = 0.044). No significant between-group difference in the suture cut-out rate was observed.

CONCLUSIONS

This study found no significant differences in the clinical outcomes between ultrahigh-molecular-weight polyethylene sutures and suture tape. Favorable clinical outcomes were obtained using both types of suture; however, the usefulness of suture tape appears to be limited.

Global research status and hotspot analysis of meniscal root tears based on the WOS database

Background

Meniscal root tears are one of the common diseases in the field of orthopedics and sports medicine today and are the subject of many current investigative efforts.

Purpose

This study aims to identify and evaluate the global trends, hotspots and frontiers in meniscal root tear research using bibliometric analysis.

Methods

A bibliometric analysis of research findings related to meniscal root tears over the past three decades was performed. CiteSpace was used to conduct document co-citation and cluster analyses on the collected data. The research was conducted based on the following factors: country and institution distribution, chronological distribution, source journal analysis, keyword co-occurrence analysis, and reference co-citation analysis.

Results

A total of 626 research articles on meniscal root tears in English published from 1989 to 2021 were obtained. There was a significant upward trend in the total number of scientific publications over the past decades, especially in 2015–2020. The most productive countries, institutions, journals and authors are the USA, STEADMAN PHILIPPON, KNEE SURGERY SPORTS TRAUMATOLOGY ARTHROSCOPY, and LAPRADE RF. North America and East Asia made outstanding contributions to the research on meniscal root tears, but cooperation and exchanges between countries and institutions were not close enough. A total of 9 clusters were obtained from the citation analysis, and 8 clusters were obtained from the keyword analysis. The main keywords that ranked first were posterior root tear, medial meniscus, menisci tibial, and ACL reconstruction, and these clusters combined with the corresponding emergence reflected the current status of research at different times.

Conclusion

Research in this field over the past 32 years has gone through a phase of exploration in the understanding of the anatomy of the meniscal root and the diagnosis of this disease and a phase of development with in-depth biomechanical studies and improved and innovative surgical techniques. The current research focuses on the innovation of meniscal root tear repair techniques, the long-term efficacy of surgery, the variability in the efficacy of different surgical techniques, and surgical strategies for combined injuries. There will be more breakthroughs in surgical techniques, surgical equipment and surgical materials to resolve meniscal root tears.

Meniscal extrusion under increasing varus in stress patients with a medial meniscus posterior root-tear

Posterior root-tear of the medial meniscus and accompanied meniscal extrusion can lead to functional loss of the meniscus. The aim of this study is to assess medial meniscus extrusion at increasing varus forces utilizing magnetic resonance imaging (MRI), in order to evaluate the contribution of the adduction moment of the knee during gait. We prospectively enrolled 19 patients (38 knees). Patients underwent gait analysis testing to calculate adduction moment, followed by an MRI at rest and with increasing varus forces according to the patient's specific adduction moment. Meniscal extrusion and root gap at increasing varus forces were measured and compared. Functional outcomes and their association to meniscal extrusion was analyzed. We found the average meniscal extrusion at rest, 100% and 150% applied varus force for the control group to be 1.7mm, 1.7mm and 1.9mm, respectively; and for the index group average meniscal extrusion was 5.3mm, 6.4mm and 6.8mm, respectively. Meniscal extrusion increase from rest to 100% varus force was significantly higher in the index group (p=0.0002). Further meniscal extrusion and root gap increase from 100% varus force to 150% varus force did not show a statistically significant difference (p=0.39). The association between greater increase of meniscal extrusion with varus force and WOMAC scores was not statistically significant. In conclusion this study defines the contribution of the varus force component of the adduction moment to meniscal extrusion, in patients with a medial meniscus posterior root-tear.

Correlation of factors affecting correction of meniscal extrusion and outcome after medial meniscus root repair

INTRODUCTION

Meniscus extrusion in medial meniscus posterior root tears (MMPRT) is a consistent MRI finding and correction of extrusion is a primary objective of the meniscal root repair. The purpose of the study is to evaluate feasibility of correction of extrusion and correlation of various factors affecting the postoperative extrusion correction and outcomes in all degenerative medial meniscus posterior roots (MMPRTs).

METHODS

A retrospective study of patients who presented with degenerative MMPRTs following trivial incident (Jun 2014 and Aug 2018) and included isolated Laprade type 2 root tear with extrusion in MRI. Patients with ligament injuries, tricompartmental arthritis, malalignment (> 5⁰) and irreparable meniscal tears excluded. All patients underwent arthroscopic trans-tibial tunnel suture pull-out repair. A screening MRI was taken at a 6-month follow-up and functional scores (IKDC and Lysholm's) at final follow-up. The effects of age, gender, duration of symptoms, hip-knee-ankle angle on weight-bearing X-rays, ICRS grading of cartilage status, and MRI data (extrusion distance, tunnel location and healing status of meniscus) on outcomes were analysed.

RESULTS

MMPRT (n = 54) with a mean follow-up of 34.6 months (24-48). Mean functional outcomes improved postoperatively IKDC (43.40 ± 5.16-78.65 ± 5.11, p < 0.001) and Lysholm's (65.27 ± 4.28-83.16 ± 4.83, p < 0.001) scores at final follow-up. 57.4% (31) had good correction of extrusion, 3.7% (2) no correction and 38.8% (21) showed increase in extrusion postoperatively. Of all the factors we explored, age, ICRS (low grade) and knee varus (less 2.5 degree) affected extrusion correction. Patients with healed (41 patients), partially healed (9 patients) and anatomic tunnel placement (46 patients) had better extrusion correction than those with non-healing (4 patients) and non-anatomical tunnel (8 patients).

CONCLUSION

Patients younger than 50 years, with low grade cartilage damage (ICRS 1, 2), lower KL grade and varus alignment (< 2.5⁰) had good correction of extrusion. Correction of extrusion/progression of extrusion did not influence the clinical outcome at the short-term. The progression of meniscal extrusion is inevitable even after successful repair in elderly and high-risk patients.

STUDY DESIGN

Retrospective Case series, level of evidence IV.

Examining the Efficacy of Medial Meniscus Posterior Root Repair: A Meta-analysis and Systematic Review of Biomechanical and Clinical Outcomes

BACKGROUND

Medial meniscus posterior root (MMPR) injuries accelerate the progression of osteoarthritis. While partial meniscectomy was once considered the gold standard for treatment, meniscus root repair has become increasingly utilized with reported improvements in clinical and biomechanical outcomes.

PURPOSE

To perform a systematic review of biomechanical outcomes and a meta-analysis of clinical and radiographic outcomes after MMPR repair.

STUDY DESIGN

Meta-analysis and systematic review; Level of evidence, 4.

METHODS

The PubMed, Embase, and Cochrane databases were queried in August 2021 for studies reporting biomechanical, clinical, and radiographic outcomes after MMPR repair. Biomechanical studies were assessed for main results and conclusions. Data including study characteristics, cohort demographics, and outcomes were extracted. Included clinical studies were analyzed with a random-effects meta-analysis of proportions for binary outcomes or continuous outcomes for mean differences between preoperative and postoperative time points. Subgroup analysis for studies reporting repair outcomes with concomitant high tibial osteotomy (HTO) was performed where appropriate.

RESULTS

A total of 13 biomechanical studies were identified and reported an overall improvement in mean and peak contact pressures after MMPR repair. There were 24 clinical studies, consisting of 876 patients (877 knees), identified, with 3 studies (106 knees) reporting outcomes with concomitant HTO. The mean patient age was 57.1 years (range, 23-74 years), with a mean follow-up of 27.7 months (range, 2-64 months). Overall, clinical outcomes (Lysholm, Hospital for Special Surgery, International Knee Documentation Committee, visual analog scale for pain, Tegner, and Knee injury and Osteoarthritis Outcome Score scores) were noted to improve postoperatively compared with preoperatively, with improved Lysholm scores in patients undergoing concomitant HTO versus MMPR repair alone. Meniscal extrusion was not significantly improved after MMPR repair compared with preoperative measurements. The progression in Kellgren-Lawrence grades from grade 0 to grades 1 to 3 occurred in 5.9% (21/354) of patients after repair, with no patients progressing from grades 1 to 3 to grade 4.

CONCLUSION

MMPR repair generally improved biomechanical outcomes and led to improved patient-reported outcomes with greater improvements noted in patients undergoing concomitant HTO. Repair did not significantly improve meniscal extrusion, while only 5.9% of patients were noted to progress to low-grade osteoarthritis. The high level of heterogeneity in the included biomechanical and clinical investigations emphasizes the need for more well-designed studies that evaluate outcomes after MMPR repair.

Improvement of clinical and radiological outcomes of root repair patients with advanced articular cartilage degeneration and osteoarthritis

PURPOSE

The main purpose of this study was to investigate clinical and radiological outcomes of medial meniscus posterior root tear (MMPRT) repair in knees with advanced articular cartilage degeneration and osteoarthritis compared to those with minimal degenerative change.

METHODS

Thirty-three knees underwent MMPRT repair using an arthroscopic pullout repair tibial tunnel technique. Clinical scores including Lysholm Score, International Knee Documentation Committee (IKDC) Score and Knee injury and Osteoarthritis Outcome (KOOS) Score were collected preoperatively and sequentially at 6 months, 12 months and mean final follow-up of 39.4 months. Kellgren-Lawrence (K-L) osteoarthritis grade, Outerbridge classification of cartilage degeneration and the presence of bone marrow oedema on MRI were also evaluated.

RESULTS

All clinical scores improved at final follow-up for knees with K-L grade ≥ 2 osteoarthritis (p < 0.001), with no significant difference compared to K-L 0/1. Patients with Outerbridge class 3/4 cartilage degeneration also reported improvements in clinical scores, albeit lower than those with class 2 degeneration (p < 0.05). During recovery, the majority of patients reported clinical improvements by 6 months, and six patients further improved by at least 15 points in IKDC score between 6 and 12 months. Osteoarthritis progressed in 10 of 31 knees (32%), with an overall mean pre-operative K-L grade of 1.6 ± 0.9 compared to 2.0 ± 0.9 at final follow-up (n.s.). No knees progressed to K-L 4 or underwent re-operation. Pre-operative bone marrow oedema was present in 17 knees (52%), all of which had signal localised to the medial tibia or femur. Oedema had resolved in all but 5 knees post-operatively (p < 0.01).

CONCLUSION

Arthroscopic repair of medial meniscus posterior root tears is associated with improved outcomes in knees with advanced cartilage degeneration and osteoarthritis. Meaningful improvements in clinical outcomes can be achieved beyond 6 months, thus success of the operation is best determined at the 12-month mark. Oedema signal significantly improved post-operatively, however a relatively high proportion of knees had K-L progression.

LEVEL OF EVIDENCE

IV - Case Series.

Medial meniscal extrusion greater than 4 mm reduces medial tibiofemoral compartment contact area: a biomechanical analysis of tibiofemoral contact area and pressures with varying amounts of meniscal extrusion

PURPOSE

The primary objective of this study is to evaluate the contact areas, contact pressures, and peak pressures in the medial compartment of the knee in six sequential testing conditions. The secondary objective is to establish how much the medial meniscus is able to extrude, secondary to soft tissue injury while keeping its roots intact.

METHODS

Ten cadaveric knees were dissected and tested in six conditions: (1) intact meniscus, (2) 2 mm extrusion, (3) 3 mm extrusion, (4) 4 mm extrusion, (5) maximum extrusion, (6) capsular based meniscal repair. Knees were loaded with a 1000-N axial compressive force at 0°, 30°, 60°, and 90° for each condition. Medial compartment contact area, average contact pressure, and peak contact pressure data were recorded.

RESULTS

When compared to the intact state, there was no statistically significant difference in medial compartment contact area at 2 mm of extrusion or 3 mm of extrusion (n.s.). There was a statistically significant decrease in contact area compared to the intact state at 4 mm (p = 0.015) and maximum extrusion (p < 0.001). The repair state was able to improve medial compartment contact area, and there was no statistically significant difference between the repair and the intact states (n.s.). No significant differences were found in the average contact pressure between the repair, intact, or maximum extrusion conditions at any flexion angle (n.s.). No significant differences were found in the peak contact pressure between the repair, intact, or maximum extrusion conditions at any flexion angle (n.s.).

CONCLUSION

In this in vitro model, medial meniscus extrusion greater than 4 mm reduced medial compartment contact area, but meniscal extrusion did not significantly increase pressure in the medial compartment. Additionally, meniscal centralization was effective in restoring the medial tibiofemoral contact area to intact state when the meniscal extrusion was secondary to meniscotibial ligament injury. The diagnosis of meniscal extrusion may not necessarily involve meniscal root injury. Since it is known that meniscal extrusion greater than 3 or 4 mm has a biomechanical impact on tibiofemoral compartment contact area and pressures, specific treatments can be established. Centralization restored medial compartment contact area to the intact state.

Association Between Transtibial Meniscus Root Repair and Rate of Meniscal Healing and Extrusion on Postoperative Magnetic Resonance Imaging: A Prospective Multicenter Study

Background:

Prospective studies evaluating second-look imaging of meniscus root repair using a transtibial pull-out technique are limited; therefore, optimal surgical indications and the technique for meniscus root repair remain uncertain.

Hypothesis:

It was hypothesized that there would be a high rate of healing, improvement in meniscal extrusion, and prevention of articular cartilage degeneration and subchondral bone abnormalities after meniscus root repair.

Study Design:

Case series; Level of evidence, 4.

Methods:

Consecutive patients undergoing transtibial root repair were prospectively enrolled at 2 orthopaedic centers between March 2017 and January 2019. Pre- and postoperative magnetic resonance imaging (MRI) scans were reviewed by a musculoskeletal radiologist in a blinded fashion for meniscal healing, quantification of extrusion, articular cartilage grade, subchondral bone changes, and coronary/meniscotibial ligament abnormalities. Given persistent extrusion observed on postoperative MRI scans, an additional 10 patients gave consent and were enrolled for immediate (before weightbearing) postoperative MRI scans.

Results:

A total of 45 patients (16 male, 29 female; mean ± standard deviation age, 42.3 ± 12.9 years; body mass index, 31.6) were prospectively enrolled in the study; there were 47 meniscus root repairs: 29 medial and 18 lateral (2 with both). Postoperative MRI was obtained at an average of 6.3 months (range, 5.1-8 months); 98% of meniscal repairs had evidence of healing. Mean extrusion increased significantly, from 1.9 ± 1.5 mm preoperatively to 2.6 ± 1.4 mm postoperatively (P = .03). There was no significant progression of chondromalacia grade, subchondral edema, insufficiency fracture, subchondral cysts, or subchondral collapse. In the additional 10-patient cohort, the mean preoperative extrusion (1.6 ± 1.2 mm) was not significantly different from that immediately postoperatively (2.0 ± 1.0 mm; P = .23).

Conclusion:

Prospective MRI analysis of transtibial meniscus root repair confirmed a high rate of meniscal healing and no observable progression of cartilage degeneration or subchondral bone abnormalities at the short-term follow-up. However, meniscal extrusion worsened in the first 6 months after surgery.

Registration:

NCT03037242 (ClinicalTrials.gov identifier).

Meniscal Ramp Lesions and Root Tears: A Review of the Current Literature

The importance of the menisci in providing joint stability and their role in load transmission within the knee are well understood. A growing body of literature has emerged on 2 distinct injury patterns to these crucial anatomic structures, ramp lesions and root tears. Ramp lesions may be characterized as tears at the posterior meniscocapsular junction, while root tears involve bony or soft tissue avulsion of the meniscal insertions at the anterior or posterior intercondylar regions. In this 2-part review, we present an overview of the current available literature on ramp lesions and meniscal root tears, summarizing the unique anatomic considerations, etiology, biomechanics, management decisions, clinical outcomes pertinent to these very distinct injuries.

A New Clinical Sign for Diagnosing Medial Meniscus Posterior Root Tear

Background

In the presence of medial meniscus posterior root tear (MMPRT), there is a possibility of reduced compression of meniscal tissue in hyperflexion as the intra-articular mobility of the meniscus increases. This phenomenon can be mimicked during clinical examination.

Purpose

To describe, evaluate, and validate the diagnostic performance of a new clinical indicator, the Akmese sign, for the diagnosis of an MMPRT.

Study Design

Cohort study (diagnosis); Level of evidence, 2.

Methods

In this study, we prospectively enrolled patients aged 18 to 55 years who were scheduled for arthroscopic surgery after a diagnosis of medial meniscal lesion at a single institution between January 2016 and January 2018. All of the patients underwent preoperative examination for the Akmese sign. All surgeries were performed by a single surgeon with more than 5 years of experience in sports injury surgery, who was blinded to the Akmese sign results.

Results

A total of 273 patients with a mean age of 42.4 ± 5.3 years met the study criteria. The Akmese sign was identified as positive in 33 patients, and MMPRT was confirmed during arthroscopy in 36 cases. The performance parameters of the Akmese sign were a sensitivity of 86.1%, specificity of 99.1%, Youden index of 0.85, and kappa index of 0.88.

Conclusion

This study showed that the Akmese sign is a useful new physical examination test that can help clinicians distinguish MMPRTs from other meniscal medial meniscal pathology.

Factors Related to Meniscal Extrusion and Cartilage Lesions in Medial Meniscus Root Tears

The purpose of this study was to identify factors affecting medial meniscus extrusion and cartilage degeneration in medial meniscus root tears (MMRT) and to determine the optimal cut-off values for the factors that predict disease severity. We retrospectively evaluated 86 consecutive patients diagnosed with an isolated MMRT by magnetic resonance imaging (MRI) examinations and arthroscopic procedures for 2 years. Patient-specific factors such as age, sex, the time between injury and MRI (mTIME), the time between injury and surgery (sTIME), the time between MRI and surgery (dTIME), Kellgren-Lawrence (KL) grades, and the mechanical tibiofemoral axis angle (mTFA) were documented. Regression analyses and receiver operating characteristic (ROC) curve analyses were performed. The mTIME was only positively correlated with meniscal extrusion (r = 0.425, p < 0.001). The patients who had grades 3 and 4 cartilage lesions had only significantly higher KL grades and longer sTIME than the patients who had lower grades of cartilage lesion (6.5 months [interquartile range (IQ): 3.0-12.0) vs. 2.5 months [IQ: 0.9-3.9]; p < 0.001). The cut-off value of mTIME and sTIME were 2.5 and 6 months. Relapse times greater than 2.5 months and 6 months after a specific event were associated with a 7.8-fold increased risk for meniscus extrusion and an 18.2-fold increased risk for cartilage lesions, respectively. The risk of medial extrusion of the meniscus and the severity of articular cartilage lesions increased with time after an injury. The period of time from 2.5 to 6 months after traumatic event might be a critical window for intervention in the patients with MMRT to perform the repair in the status which the meniscus did not extrude more than 3 mm and the cartilage lesion did not progress more than grade 3. This study is a retrospective and uncontrolled case series and reflects level IV of evidence.

Arthroscopic Centralization of the Extruded Medial Meniscus

Tears of the posterior medial meniscus root commonly result in extrusion of the meniscus and disruption of tibiofemoral contact mechanics. Transtibial pull-through repair of the root often results in healing of the tear, but postoperative extrusion may persist. In this scenario, the meniscus is unlikely to be chondroprotective. Therefore, an additional centralization procedure is necessary to improve the extrusion. Biomechanical studies have demonstrated that centralization can improve meniscus mechanics and potentially reduce the risk of osteoarthritis. This Technical Note describes an arthroscopic technique for medial meniscus posterior root repair that combines transtibial pullout and centralization sutures.

Traumatic avulsion of the anterior medial meniscus root combined with PCL injury: a case report

Background

Avulsion of the anterior medial meniscus root (AMMR) has a low incidence rate, especially when it is combined with posterior cruciate ligament (PCL) injury, which hasn’t been reported in any literature to date. The aim of this study was to share our experience in the diagnosis and treatment of a patient with traumatic avulsion of AMMR combined with PCL injury.

Case presentation

This article reports a 26-year-old male patient diagnosed with traumatic avulsion of the AMMR with PCL injury. After arthroscopic surgery, he achieved remission of symptoms and recovery of functions.

Conclusions

Anterior meniscus root injuries are relatively rare. Its diagnosis can be made preliminarily based on clinical manifestations, physical examinations, and magnetic resonance imaging (MRI), and then confirmed by arthroscopic exploration. Arthroscopic suture anchor fixation of the injured anterior meniscus horn shows a good therapeutic effect.

Meniscal Root Injuries

Meniscal root tears are an increasingly recognized injury leading to notable functional limitations, potential rapid cartilage deterioration of the affected compartment, and subsequent risk of total knee arthroplasty if left untreated. Repair of these tears is advised when articular cartilage remains intact because both medial and lateral meniscus root repairs have demonstrated favorable results. Recent literature demonstrates decreased rates of osteoarthritis and arthroplasty after medial meniscus root repair compared with partial meniscectomy and nonsurgical management. The transtibial pull-out repair technique is most commonly used and provides a biomechanically strong suture construct with standard and familiar knee arthroscopy portals. Furthermore, repair has recently been shown to be economically effective by decreasing overall societal healthcare costs when compared with more conservative management strategies. This review outlines the evaluation, treatment, and documented outcomes of meniscal root repair, which is imperative to the preservation of knee function and maintaining quality of life.

Magnetic resonance imaging of the meniscal roots

The meniscal roots and supporting structures anchor the menisci to the tibial plateau and resist hoop stress, thereby preventing radial displacement of the menisci and secondary degenerative tibiofemoral compartment changes that may occur if this is compromised. The anatomy of the four meniscal roots and their supporting structures on magnetic resonance imaging (MRI) will be outlined in this review article, as well as the imaging appearances of meniscal root-related pathology, namely meniscal root degeneration and tears, meniscal extrusion and tibial plateau cystic lesions.

Knotless Anchor Fixation for Transosseous Meniscal Root Repair Using Suture Tape Is Inferior Compared With Button or Screw Fixation: A Biomechanical Study

Background

A 2 mm-wide ultrahigh-molecular-weight polyethylene (UHMWPE) tape improves the contact pressure at root repair sites compared with high-strength suture and provides a stronger repair construct. UHMWPE tape is commonly used in rotator cuff repair, and fixation is often achieved with knotless suture anchors. The optimal method for tape fixation for meniscal root repair has not been established.

Hypothesis

The use of suture anchors for the tibial fixation of 2-mm UHMWPE tape transosseous root repairs will lead to better biomechanical performance compared with other fixation methods.

Methods

The medial meniscal posterior root attachment in 25 porcine knees was divided, and a standardized transtibial root repair was performed using 2-mm UHMWPE tape. The testing was performed by cyclic loading followed by load to failure. Tibial fixation was randomized to 5 tibial fixation types: (1) cortical fixation button, (2) pound-in suture anchor with screw-down interference suture locking, (3) tap-in suture anchor with inner locking plug, (4) postscrew, and (5) postscrew and washer.

Results

There was no difference in displacement during cyclic loading between tibial fixation groups except for a highly significant difference in the maximum load at failure. Repairs in both suture anchor fixation groups all failed by tape slippage at relatively low loads (median, 145 and 116 N, respectively). Repairs tied over a cortical button, postscrew, or screw and washer failed by tape breakage at loads of 431, 405, and 528 N.

Conclusion

For meniscal root repairs with 2-mm UHMWPE tape, use of suture anchors offers weaker fixation compared with tying over a button or postscrew/washer. While suture anchor fixation may be adequate for nonweightbearing postoperative protocols, it may not allow for more accelerated weightbearing.

Medial Versus Lateral Meniscus Root Tears: Is There a Difference in Injury Presentation, Treatment Decisions, and Surgical Repair Outcomes?

PURPOSE

To determine (1) the demographic characteristics as well as radiographic findings of medial versus lateral meniscal root tears at time of presentation, (2) treatment decisions and clinical outcomes of patients undergoing medial versus lateral root repair, and (3) risk factors for worse clinical and radiographic outcomes.

METHODS

A retrospective review was performed to identify patients with symptomatic, medial, or lateral meniscus posterior root tears with a minimum 2-year follow-up. Radiographs were graded using Kellgren-Lawrence scores. Subanalysis was performed on 62 patients who underwent root repair. Tegner, Lysholm, International Knee Documentation Committee scores, and progression to arthroplasty were analyzed in the repair groups. Patient demographics, radiographic findings, and clinical outcomes were compared between medial meniscus posterior horn root tear (MMRT) and lateral meniscus root repair (LMRT).

RESULTS

Of the 141 root tears, 109 were MMRTs, 30 were LMRTs, and 2 patients had both. At the time of injury, patients with MMRTs had a significantly higher age (MMRT = 51.4 vs LMRT=24.6, P < .0001), body mass index (MMRT = 32.1 vs LMRT 25.8, P < .0001), Kellgren-Lawrence score (MMRT = 1.3 vs LMRT=0.6, P < .0001), and higher rate of major meniscal extrusion (MMRT = 72% vs LMRT = 20%, P < .0001). Of the 30 LMRT, 30/30 (100.0%) were treated with meniscal repair. With MMRT, 52/109 (48%) were treated nonoperatively, 27/109 (25%) with partial meniscectomy, and 30/109 (27%) with meniscal repair. Sixty-two patients underwent meniscus root repair with an average 41-month follow-up. LMRT had significantly increased International Knee Documentation Committee (LMRT = 89.5, MMRT = 80.4, P = .02) and Tegner scores (LMRT = 6.5, MMRT = 5.1, P < .05) compared with MMRT.

CONCLUSIONS

Compared with MMRTs, LMRTs occur in younger male patients with lower body mass index, less cartilage degeneration, less extrusion on magnetic resonance imaging, and more commonly with a ligament injury. Although good to excellent clinical outcomes were attained in select patients for both medial and lateral meniscus root repair, LMRTs may have better results after repair, suggesting that differences in injury and patient characteristics may contribute to differences in these outcomes.

LEVEL OF EVIDENCE

Retrospective comparative study, Level III.

Outcomes of Arthroscopic All-Inside Repair Versus Observation in Older Patients With Meniscus Root Tears

BACKGROUND

Meniscus root tears lead to de-tensioning of the meniscus, increased contact forces, and cartilage damage. Management of older patients with root tears is controversial and the efficacy of different treatment options is unclear.

PURPOSE

To compare the clinical outcomes of patients with moderate knee osteoarthritis who underwent an all-inside meniscus root repair technique versus nonoperative management for either medial or lateral meniscus root tears.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Patients with a diagnosed posterior meniscus root tear who underwent arthroscopic repair (AR: 30 knees) or nonoperative treatment with observation (O: 18 knees) were followed for a minimum of 2 years (mean follow-up, 4.4 years). The arthroscopic repair included all-inside sutures to reduce the root back to its remnant (reduction sutures), thereby re-tensioning the meniscus, and 1 mattress suture to strengthen the repair by reapproximating the construct to the posterior capsule. The data collected included the Knee injury and Osteoarthritis Outcome Score (KOOS), Lysholm, Tegner, and Veterans RAND 12-Item Health Survey (VR-12) Physical Component Summary (PCS) and Mental Component Summary (MCS) scores and conversion to total knee arthroplasty (TKA).

RESULTS

Medial meniscus root tears comprised 80.0% of the AR group and 77.8% of the O group. The average Kellgren-Lawrence grade was 2 in both groups. The baseline scores for the KOOS Symptoms subscale were lower for AR (50.2 ± 19.3) than for O (66.5 ± 16.1) (P = .003), as were the KOOS Knee-Related Quality of Life scores (AR, 26.7 ± 16.1; O, 39.6 ± 22.1) (P = .046). No differences were found between groups for the absolute values at follow-up except that follow-up Tegner scores were lower in the O group than in the AR group (P = .004). Significant improvements were seen in the AR group from baseline to ultimate follow-up in average KOOS subscale scores (P < .001), Lysholm scores (P < .001), Tegner scores (P = .0002), and VR-12 PCS scores (P < .001), whereas the O group had a significant improvement only in average KOOS Pain (P = .003), KOOS Function in Daily Living (P = .006), and VR-12 PCS (P = .038) scores. Compared with the O group, the AR group had a significantly larger improvement from baseline to follow-up in average KOOS Pain (P = .009), KOOS Symptoms (P = .029), and Lysholm scores (P = .016). During follow-up, 3.3% of the AR group underwent a TKA compared with 33.3% of the O group (P = .008). The hazard ratio of TKA conversion was 93.2% lower for the AR group compared with the O group (P = .013).

CONCLUSION

All-inside medial or lateral meniscus root repair showed improved functional outcomes and decreased TKA conversion rates compared with nonoperative treatment and may be considered as a treatment option for the management of meniscus root tears in older patients with moderate osteoarthritis.

US detection of medial meniscus extrusion can predict the risk of developing radiographic knee osteoarthritis: a 5-year cohort study

OBJECTIVES

To clarify the relationship between the baseline value of medial meniscus extrusion (MME) and the radiographic change of knee osteoarthritis (KOA) through a 5-year follow-up.

METHODS

Overall, 472 participants and 944 knees were eligible. MME (mm) was measured at the baseline, and KOA was radiographically evaluated at both baseline and 5-year follow-up by Kellgren-Lawrence grade (KLG). Radiographic KOA (ROA) was defined as the knee showing KLG ≥ 2. Incident ROA (iROA) was defined if the baseline KLG of 0-1 increased to KLG ≥ 2 in 5 years. Progressive ROA (pROA) was defined if the baseline KLG of 2-3 worsened to a higher grade in 5 years. Receiver operating characteristic (ROC) curve and generalized estimating equations were used for analysis.

RESULTS

Of 574 non-ROA knees at the baseline, 43 knees (7.5%) developed iROA; of 370 ROA knees, 47 knees (12.7%) developed pROA. Based on the ROC curves, 4 mm was the optimal cutoff to detect the risk of iROA (area under curve [AUC] 0.639 [right knee]; AUC 0.641 [left knee]) and that of pROA (AUC 0.750 [right knee]; AUC 0.863 [left knee]). Multiple regression analysis showed that the 4-mm cutoff of MME was significantly associated with both the prevalence of iROA (regression coefficient [B] 1.909; p ≤ 0.001; adjusted odds ratio [aOR] 6.746) and that of pROA (B 1.791; p ≤ 0.001; aOR 5.993).

CONCLUSIONS

On ultrasonography, the participants with more extruded medial meniscus showed a higher prevalence of both iROA and pROA. Ultrasonography could identify patients who had a risk of developing KOA.

KEY POINTS

• Through a 5-year follow-up, the current cohort study was conducted to clarify the relationship between the baseline value of medial meniscus extrusion (MME) and the radiographic change of knee osteoarthritis (KOA). • More extruded medial meniscus evaluated by ultrasonography was associated with the development of radiographic KOA. • Ultrasonography could identify the patients who had a risk of developing KOA, and the 4-mm cutoff of MME was optimal to detect this risk.

Injury of the Meniscus Root

Meniscus root tears biomechanically disrupt normal joint loading and lead to joint overload with the possible development of spontaneous osteonecrosis of the knee and early-onset osteoarthritis. Proper identification and treatment of meniscal root tears has been proven to restore joint loading and improve patient outcomes.

The effect of a longitudinal tear of the medial meniscus on medial meniscal extrusion in anterior cruciate ligament injury patients

PURPOSE

The purpose of this study was to investigate the effect of a longitudinal tear of the medial meniscus (MM) and its meniscal repair on MM extrusion in anterior cruciate ligament (ACL)-injured patients. The hypothesis underlying this study was that a longitudinal tear of the MM is correlated with MM extrusion, and that the extrusion would persist after ACL reconstruction with concomitant MM repair.

METHODS

Forty-three ACL-injured patients with a concomitant MM longitudinal tear were included in the MM tear group. Thirty-four solely ACL-injured patients without any meniscal injuries were included in the Control group. Medial meniscus extrusion width (MEW) was measured pre-operatively and three months after surgery on magnetic resonance imaging.

RESULTS

Pre-operative MEW in the MM tear group was significantly larger than that in the Control group (MM tear group: 1.5 mm, Control: 0.3 mm, P < 0.001). The MEW change in the MM tear group was significantly greater than that in the Control group three months after operation (MM tear group: 0.8 mm, Control: -0.2 mm, P < 0.001). The number of sutures required for repair was correlated with MEW both pre-operatively and postoperatively in the MM tear group (pre-operative: P = 0.005, R = 0.42, postoperative: P < 0.001, R = 0.54).

CONCLUSION

Longitudinal tear of the MM was correlated with MM extrusion and the MM extrusion persisted after ACL reconstruction with concomitant MM repair in the MM tear group. The initial meniscal tear size was directly correlated with the pre-operative MEW. Therefore, meniscal extrusion after longitudinal tears of the medial meniscus should be taken into careful consideration.

Tear gap and severity of osteoarthritis are associated with meniscal extrusion in degenerative medial meniscus posterior root tears

INTRODUCTION

Meniscal extrusion is a typical finding of medial meniscus posterior root tear, and it causes loss of the chondroprotective function of the meniscus as well as progression of osteoarthritis; it is therefore associated with poor clinical outcomes. The purpose of this study was to investigate factors associated with meniscal extrusion in degenerative medial meniscus posterior root tear. It was hypothesized that larger displacement from the posterior root insertion was associated with larger meniscal extrusion.

MATERIALS AND METHODS

One hundred and nine knees with degenerative medial meniscus posterior root tears were retrospectively reviewed. Multiple regression analysis was used to determine whether factors such as age, weight, body mass index, chondral wear at surgery, Kellgren-Lawrence (KL) grade, alignment, tibial slope, and tear gap on performing magnetic resonance imaging (MRI) were associated with meniscal extrusion. Subjects were divided based on the amount of displacement (displaced group: tear gap≥1mm, non-displaced group: tear gap<1mm) to compare meniscal extrusion, chondral wear, and severity of arthritis.

RESULTS

The mean age of the patients was 58.14±9.64years, the mean absolute extrusion was 4.02±1.22mm, the mean relative percentage of extrusion was 44.53±13.09%, and the mean tear gap was 2.39±2.42mm. Multiple regression analysis showed that absolute extrusion was only associated with tear gap on MRI (B=0.242, p=0.001) and that the relative percentage of extrusion was associated with tear gap (B=1.894, p=0.001) and the K-L grade (B=4.492, p=0.024). Absolute extrusion was significantly higher in the displaced group than in the non-displaced group (4.29±1.04mm vs. 3.01±1.35mm, p=0.001). Relative percentage of extrusion was also significantly higher in the displaced group than in the non-displaced group (47.70±11.44% vs. 36.17±13.65%, p=0.001). The proportion of chondral wear (Outerbridge grade III and IV) on the medial femoral condyle and K-L grade III and IV were significantly greater in the displaced group than in the non-displaced group (76% vs. 53.3%, p=0.023 and 13.9% vs. 0%, p=0.001, respectively).

DISCUSSION

Greater tear gap is significantly associated with increasing meniscal extrusion in medial meniscus posterior root tear. Additionally, severity of arthritis is significantly associated with increasing relative percentage of extrusion. Chondral wear and severity of arthritis tended to be significantly worse in the displaced group than in the non-displaced group.

LEVEL OF EVIDENCE

III, comparative retrospective study.

Different Suture Materials for Arthroscopic Transtibial Pull-out Repair of Medial Meniscal Posterior Root Tears: A Human Biomechanical Study

Background

Transtibial pull-out repair of the medial meniscal posterior root (MMPR) has been largely assessed through biomechanical studies. Biomechanically comparing different suture types would further optimize MMPR fixation and affect clinical care.

Purpose/Hypothesis

The purpose of this study was to determine the optimal suture material for MMPR fixation. It was hypothesized that ultra high-molecular weight polyethylene (UHMWPE) suture tape would be biomechanically superior to UHMWPE suture and standard suture.

Study Design

Controlled laboratory study.

Methods

The MMPR attachment was divided in 24 human cadaveric knees and randomly assigned to 3 repair groups: UHMWPE suture tape, UHMWPE suture, and standard suture. Specimens were dissected down to the medial meniscus, and the posterior root attachments were sectioned off the tibia. Two-tunnel transtibial pull-out repair with 2 sutures, as determined by the testing group, was performed. The repair constructs were cyclically loaded between 10 and 30 N at 0.5 Hz for 1000 cycles to mimic the forces experienced on the medial meniscus during postoperative rehabilitation. Displacement was recorded at 1, 50, 100, 500, and 1000 cycles. Ultimate failure load, displacement at failure, and load at 3 mm of displacement (clinical failure) were also recorded.

Results

UHMWPE suture tape had significantly less displacement of the medial meniscus when compared with standard suture at 1 (-0.22 mm [95% CI, -0.41 to -0.02]; P = .025) and 50 (-0.35 mm [95% CI, -0.67 to -0.03]; P = .029) cycles. There were no other significant differences observed in displacement between groups at any number of cycles. UHMWPE suture tape had significantly less displacement at the time of failure than standard suture (-3.71 mm [95% CI, -7.17 to -0.24]; P = .034). UHMWPE suture tape had a significantly higher load to reach the clinical failure displacement of 3 mm than UHMWPE suture (15.64 N [95% CI, 0.02 to 31.26]; P = .05). There were no significant differences in ultimate failure load between groups.

Conclusion

The meniscal root repair construct with UHMWPE suture tape may be stronger and less prone to displacement than that with standard suture or UHMWPE suture.

Clinical Relevance

UHMWPE suture tape may provide better clinical results compared with UHMWPE suture and standard suture.

The role of radiography and MRI for eligibility assessment in DMOAD trials of knee OA

Currently, no disease-modifying osteoarthritis drugs (DMOADs) have been approved. Past clinical trials have failed for several reasons, including the commonly applied definition of eligibility based on radiographic assessment of joint structure. In the context of precision medicine, finding the appropriate patient for a specific treatment approach will be of increasing relevance. Phenotypic stratification by use of imaging at the time of determining eligibility for clinical trials will be paramount and cannot be achieved using radiography alone. Furthermore, identification of joints at high risk of rapid progression of osteoarthritis is needed in order to enable a more efficient DMOAD trial design. In addition, joints at high risk of collapse need to be excluded at screening. The use of MRI might offer advantages over radiography in this context. Technological advances and simplified image assessment address many of the commonly perceived barriers to the application of MRI to assessment of eligibility for DMOAD clinical trials.

Biomechanical Properties of Posterior Meniscal Root Repairs: A Systematic Review

PURPOSE

To systematically review the literature regarding the biomechanical properties of various meniscal root repair techniques.

METHODS

A systematic review of multiple databases was performed. The inclusion criteria included English language, studies relevant to meniscal root repairs, studies comparing 2 or more different discrete techniques, posterior root repairs, controlled laboratory studies, and human cadaveric or animal studies. Abstracts, case reports, cohort studies, case-control studies, systematic reviews and meta-analyses, and studies of meniscal body repairs were excluded.

RESULTS

Seventeen controlled laboratory studies were included for final analysis. There is no consensus on biomechanical superiority between transtibial pullout repair (TPR) and suture anchor repair. For TPR, there is no significant difference between 1 and 2 tibial tunnels. Nonanatomic repairs result in significantly lower joint surface contact areas and higher contact pressures, but suture placement farther from the root results in higher maximum load to failure. Two-suture repair has a greater maximum load to failure than 1-suture repair. Use of more than 2 sutures has diminishing returns. The modified Mason-Allen suture configuration is superior to a simple suture configuration, but there is no consensus regarding the superiority or feasibility of more complex sutures. There is no consensus on the superiority of a single suture material or shape.

CONCLUSIONS

Anatomic meniscal root repairs with either TPR or suture anchor repair have better joint surface contact pressures and contact surface areas than nonanatomic repairs. The use of 2 sutures results in better fixation than 1 suture. There is evidence that the modified Mason-Allen suture configuration is superior to a simple suture configuration in a TPR, although the benefits of more complicated configurations are unclear.

CLINICAL RELEVANCE

This study suggests that, in general, more complex sutures exhibit higher maximum loads. Increasing the number of sutures to up to 2 of the same configuration also increases the maximum load.

Characteristic location and rapid progression of medial femoral condylar chondral lesions accompanying medial meniscus posterior root tear

BACKGROUND

This study aimed to demonstrate the characteristics of the chondral lesion at the medial femoral condyle (MFC) in patients with medial meniscal posterior root tear (MMPRT), and to compare the progression rate of accompanying chondral disease in MMPRT with that in degenerative non-radial tear.

METHODS

Thirty-one patients who underwent arthroscopic surgery for MMPRT and 31 controls who underwent arthroscopic surgery for degenerative medial meniscus posterior horn horizontal tear (MMPHT) were included. Accompanying chondral lesions in the MFC were evaluated by magnetic resonance imaging (MRI) at initial diagnosis and from video taken at arthroscopic surgery using the International Cartilage Repair Society (ICRS) classification system. The difference in severity and extent of the chondral lesion between initial diagnosis and surgery was measured.

RESULTS

Twenty-five patients with MMPRT (80.6%) and 29 patients (93.5%) with MMPHT had ICRS grade ≥2 chondral injuries at MFC. In the MMPRT and MMPHT groups, the most severely injured areas of the MFC were the far medial compartment (52%) and central compartment (51%), respectively. Comparing MRI and arthroscopy, 12 patients (39%) in the MMPRT group showed progression of chondral disease after a mean of 3.5 months, whereas only three patients (10%) in the MMPHT group showed progression after a mean of 3.1 months.

CONCLUSIONS

MFC lesions accompanying MMPRT were located more medially and progressed faster than those with non-root horizontal tear. Earlier intervention such as repair of MMPRT or high tibial osteotomy, if malalignment is present, may be considered in order to prevent the progression of chondral lesion.

Utilization of Transtibial Centralization Suture Best Minimizes Extrusion and Restores Tibiofemoral Contact Mechanics for Anatomic Medial Meniscal Root Repairs in a Cadaveric Model

BACKGROUND

Although posterior medial meniscal root (PMMR) repairs are often successful, postoperative meniscal extrusion after a root repair has been identified as a potential clinical problem.

PURPOSE/HYPOTHESIS

The purpose was to quantitatively evaluate the tibiofemoral contact mechanics and extent of meniscal extrusion after a PMMR repair. It was hypothesized that the addition of a centralization suture (into the posterior medial tibial plateau) would help restore normal joint load-bearing characteristics and restore the native amount of meniscal extrusion after a root tear. Furthermore, we hypothesized that the amount of meniscal extrusion would be greatest in loaded and flexed knees when measured at the posterior border of the medial collateral ligament (MCL).

STUDY DESIGN

Controlled laboratory study.

METHODS

Meniscal extrusion and tibiofemoral contact mechanics were measured using 3-dimensional digitization and pressure sensors in 10 nonpaired, human cadaveric knees. The PMMR of each knee was tested under 6 states: (1) intact; (2) type 2A PMMR tear; (3) anatomic transtibial pull-out root repair; (4) anatomic transtibial pull-out repair with centralization; (5) nonanatomic transtibial pull-out repair; and (6) nonanatomic transtibial pull-out repair with centralization, with randomization of the order of conditions 3 and 4, and 5 and 6. The testing protocol loaded knees with a 1000-N axial compressive force at 4 flexion angles (0°, 30°, 60°, 90°) in each state. Meniscal extrusion was measured with a 3-dimensional coordinate digitizer at 0° and 90° in both the loaded and unloaded states and calculated from the difference from the articular margin of the tibia to the periphery of the meniscus. Peak contact pressure, contact area, and total contact pressure were also recorded for all states at all flexion angles. Statistical analysis investigated the independent effects of flexion, state, and loading using 3 distinct 2-factor models.

RESULTS

Differences in the contact mechanics between repair techniques were most notable at higher flexion angles, demonstrating significantly higher average and peak contact pressures for nonanatomic repair states when compared with anatomic repairs with and without centralization (all P < .05). In unloaded knees at full extension, the magnitude of medial meniscal extrusion was significantly higher at the posterior border of the MCL compared with the posterior medial tibia ( P < .001) and adjacent to the root attachment on the tibia locations ( P < .001). Both anatomic repair states had no significant difference in the degree of extrusion when compared with the intact state.

CONCLUSION

The anatomic transtibial pull-out root repair and the anatomic transtibial pull-out root repair with centralization techniques best restored contact mechanics of the knee and meniscal extrusion when compared with root tear and nonanatomic repair states at time zero. There were no significant differences in contact pressure or magnitude of extrusion between the anatomic repair state and the anatomic repair with centralization state. We found that extrusion is best measured in the coronal plane at the posterior border of the MCL for unloaded knees. However, the degree of extrusion increased as the knee was loaded and flexed to 90°.

CLINICAL RELEVANCE

When there are concerns about meniscal extrusion with a medial meniscal root repair, the addition of a centralization suture may be beneficial for patients in reducing pathologic meniscal extrusion and restoring joint contact mechanics.

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.

Clinical factors associated with successful meniscal root repairs: A systematic review

PURPOSE

To systematically review the literature to determine what clinical factors influence patient outcomes after meniscal root repairs.

METHODS

A systematic review of multiple databases was performed. The inclusion criteria included English language, studies evaluating clinical and/or radiographic factors related to meniscal root repair outcomes, medial or lateral posterior root repairs, and human studies. The exclusion criteria included meniscectomy studies, meniscal body studies, technique descriptions, studies reporting only failure rate of meniscal repairs, multiligament repairs, abstracts, controlled laboratory studies, meta-analyses, and systematic reviews.

RESULTS

Five studies were included for final analysis including four case series and one retrospective cohort study. A total of 178 patients in the five studies underwent posterior meniscal root repair (179 knees total). The mean age was 51.4 years. The mean duration of follow-up was 34.5 months. The mean Moga quality rating for case series studies was 15 points (83.3%) and NOS score for the retrospective comparative study was 8. Body mass index (BMI) was not associated with outcomes in 3/3 studies assessing BMI. Increased age was associated with worse outcome in 1/5 studies and had no association in 4/5 studies. Knee varus >5° was associated with worse outcomes in 3/3 studies.

CONCLUSIONS

Risk factors for poor clinical outcomes after posterior meniscal root repair include pre-existing high-grade (Outerbridge grade ≥ 3) chondral lesions and severe varus knee alignment (>5°) for medial root repairs.

LEVEL OF EVIDENCE

IV, systematic review.

Large meniscus extrusion ratio is a poor prognostic factor of conservative treatment for medial meniscus posterior root tear

PURPOSE

The purpose of this study was to find a prognostic factor of medial meniscus posterior root tear (MMPRT) for surgical decision making.

METHODS

Eighty-eight patients who were diagnosed as acute or subacute MMPRT without severe degeneration of the meniscus were treated conservatively for 3 months. Fifty-seven patients with MMPRT showed good response to conservative treatment (group 1), while the remaining 31 patients who failed to conservative treatment (group 2) received arthroscopic meniscus repair. Their demographic characteristics and radiographic features including hip-knee-ankle angle, joint line convergence angle, Kellgren-Lawrence grade in plain radiographs, meniscus extrusion (ME) ratio (ME-medial femoral condyle ratio, ME-medial tibial plateau ratio, ME-meniscus width ratio), the location of bony edema, and cartilage lesions in MRI were compared. Receiver operating characteristic (ROC) curve analysis was also performed to determine the cut-off values of risk factors.

RESULTS

The degree of ME-medial femoral condyle and medial tibia plateau ratio of group 2 was significantly higher than group 1 (0.08 and 0.07 vs. 0.1 and 0.09, respectively, both p < 0.001). No significant (n.s.) difference in other variables was found between the two groups. On ROC curve analysis, ME-medial femoral condyle ratio was confirmed as the most reliable prognostic factor of conservative treatment for MMPRT (area under ROC = 0.8).

CONCLUSION

The large meniscus extrusion ratio was the most reliable poor prognostic factor of conservative treatment for MMPRT. Therefore, for MMPRT patients with large meniscus extrusion, early surgical repair could be considered as the primary treatment option.

LEVEL OF EVIDENCE

III.

Rotational Laxity Control by the Anterolateral Ligament and the Lateral Meniscus Is Dependent on Knee Flexion Angle: A Cadaveric Biomechanical Study

BACKGROUND

Injury to the anterolateral ligament (ALL) has been reported to contribute to high-grade anterolateral laxity after anterior cruciate ligament (ACL) injury. Failure to address ALL injury has been suggested as a cause of persistent rotational laxity after ACL reconstruction. Lateral meniscus posterior root (LMPR) tears have also been shown to cause increased internal rotation of the knee.

QUESTIONS/PURPOSES

The purpose of this study was to determine the functional relationship between the ALL and LMPR in the control of internal rotation of the ACL-deficient knee. Specifically: (1) We asked if there was a difference in internal rotation among: the intact knee; the ACL-deficient knee; the ACL/ALL-deficient knee; the ACL/LMPR-deficient knee; and the ACL/ALL/LMPR-deficient knee. (2) We also asked if there was a difference in anterior translation among these conditions.

METHODS

Sixteen fresh frozen cadaveric knee specimens (eight men, mean age 79 years) were potted into a hip simulator (femur) and a 6 degree-of-freedom load cell (tibia). Rigid optical trackers were inserted into the proximal femur and distal tibia, allowing for the motion of the tibia with respect to the femur to be tracked during biomechanical tests. A series of points on the femur and tibia were digitized to create bone coordinate systems that were used to calculate internal rotation and anterior translation. Biomechanical testing involved applying a 5-Nm internal rotation moment to the tibia from full extension to 90° of flexion. Anterior translation was performed by applying a 90-N anterior load using a tensiometer. Both tests were performed in 15° increments tested sequentially in the following conditions: (1) intact; and (2) ACL injury (ACL-). The specimens were then randomized to either have the ALL sectioned (3) first (M+/ALL-); or (4) the LMPR sectioned first (M-/ALL+) followed by the other structure (M-/ALL-). A one-way analysis of variance was performed for each sectioning condition at each angle of knee flexion (α = 0.05).

RESULTS

At 0° of flexion there was an effect of tissue sectioning such that internal rotation of the M-/ALL- condition was greater than ACL- by 1.24° (p = 0.03; 95% confidence interval [CI], 0.16-2.70) and the intact condition by 2.5° (p = 0.01; 95% CI, 0.69-3.91). In addition, the mean (SD) internal rotations for the M+/ALL- (9.99° [5.39°]) and M-/ALL+ (12.05° [5.34°]) were greater by 0.87° (p = 0.04; 95% CI, 0.13-3.83) and by 2.15°, respectively, compared with the intact knee. At 45° the internal rotation for the ACL- (19.15° [9.49°]), M+/ALL- (23.70° [7.00°]), and M-/ALL- (18.80° [8.27°]) conditions was different than the intact (12.78° [9.23°]) condition by 6.37° (p = 0.02; 95% CI, 1.37-11.41), 8.47° (p < 0.01; 95% CI, 3.94-13.00), and 6.02° (p = 0.01; 95% CI, 1.73-10.31), respectively. At 75° there was a 10.11° difference (p < 0.01; 95% CI, 5.20-15.01) in internal rotation between the intact (13.96° [5.34°]) and the M+/ALL- (23.22° [4.46°]) conditions. There was also a 4.08° difference (p = 0.01; 95% CI, 1.14-7.01) between the intact and M-/ALL- (18.05° [7.31°]) conditions. Internal rotation differences of 6.17° and 5.43° were observed between ACL- (16.28° [6.44°]) and M+/ALL- (p < 0.01; 95% CI, 2.45-9.89) as well as between M+/ALL- and M-/ALL- (p = 0.01; 95% CI, -8.17 to -1.63). Throughout the range of flexion, there was no difference in anterior translation with progressive section of the ACL, meniscus, or ALL.

CONCLUSIONS

The ALL and LMPR both play a role in aiding the ACL in controlling internal rotation laxity in vitro; however, these effects seem to be dependent on flexion angle. The ALL has a greater role in controlling internal rotation at flexion angles > 30^o. The LMPR appears to have more of an effect on controlling rotation closer to extension.

CLINICAL RELEVANCE

Injury to the ALL and/or LMPR may contribute to high-grade anterolateral laxity after ACL injury. The LMPR and the ALL, along with the iliotibial tract, appear to act in concert as secondary stabilizers of anterolateral rotation and could be considered as the "anterolateral corner" of the knee.

Associations among meniscal damage, meniscal symptoms and knee pain severity

OBJECTIVE

Meniscal tears occur frequently in patients with knee osteoarthritis (OA). The aim of our study was to determine whether meniscal damage identified on magnetic resonance imaging (MRI) is associated with the severity of knee pain or the frequency of meniscal symptoms in patients with knee OA.

METHODS

We performed a cross-sectional study using data from the Meniscal Tear in Osteoarthritis Research (MeTeOR) trial. We characterized meniscal damage hierarchically as: root tear; maceration; long and short complex or horizontal tears; and simple tears. Subjects completed the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Pain Scale and a survey of frequency of meniscal symptoms. We used multivariable general linear models to assess the relationships between meniscal damage and 1) pain severity; and 2) meniscal symptoms, after adjusting for demographic and radiographic features. In further analysis root tear was considered as a binary variable.

RESULTS

Analysis included 227 knees. Root tears were present in 19%, maceration in 14%, long complex or horizontal tears in 22%, short complex or horizontal tears in 30%, and simple tears in 14%. Root tears were associated with higher WOMAC pain scores. The adjusted mean WOMAC pain score was 45.2 (standard error (SE) 2.7) for those with root tear and 38.7 (SE 1.2) for subjects without root tear (P = 0.03). We did not find statistically significant associations between meniscal morphology and frequency of meniscal symptoms.

CONCLUSION

Root tears were associated with greater pain than meniscal tears or maceration. We did not find a relationship between meniscal damage and meniscal symptoms.

Understanding posterior meniscal roots lesions: from basic science to treatment

The variability of symptoms and the fact that they are not easily recognized in imaging studies make the diagnosis and treatment of posterior meniscal roots lesions a challenging task to the orthopedist. In recent years, a more precise understanding of the anatomy and biomechanical impair of the knee joint in these cases has enabled great advances in therapeutic approaches. Well-documented studies have shown that the repair of these lesions presents superior functional and clinical improvement when compared with meniscectomy. However, the progression of degenerative joint changes in the long-term still exhibits conflicting results.

Non-operative management of medial meniscus posterior horn root tears is associated with worsening arthritis and poor clinical outcome at 5-year follow-up

PURPOSE

Medial meniscus posterior root tears (MMPRTs) are a significant source of pain and dysfunction, but little is known about the natural history and outcome and for non-operative management of these lesions. The purpose of this study was to evaluate (1) the mid-term clinical and radiographic outcomes of non-operative treatment of MMPRTs and (2) risk factors for worse outcomes.

METHODS

A retrospective review was performed for patients with symptomatic, unrepaired MMPRTs and a minimum 2-year follow-up for IKDC and Tegner outcome scores. Baseline and final radiographs were reviewed and graded according to Kellgren-Lawrence scores. Baseline MRIs were reviewed for the presence of meniscal extrusion, subchondral oedema, and insufficiency fractures. Failure was defined as conversion to arthroplasty or severely abnormal patient subjective IKDC score.

RESULTS

Fifty-two patients (21M:31F) with a mean age of 58 ± 10 years were diagnosed with symptomatic MMPRTs clinically and confirmed by MRI and followed for a mean of 62 ± 30 months. Sixteen patients (31 %) underwent total knee arthroplasty at a mean of 30 ± 32 months after diagnosis with higher Kellgren-Lawrence grades associated with increased rates of arthroplasty (p = 0.01). Mean IKDC scores for the remaining patients were 61.2 ± 21 with significantly lower scores in females compared to males (75 ± 12 vs. 49 ± 20; p = 0.03). Mean Kellgren-Lawrence grades and rates of arthritis progressed over time on radiographs (1.5 ± 0.7 vs. 2.4 ± 1.0; p < 0.001 and 78 % vs. 51 %; p = 0.01). Overall, 87 % of patients failed non-operative treatment.

CONCLUSIONS

Non-operative treatment of medial meniscus posterior horn root tears is associated with poor clinical outcome, worsening arthritis, and a relatively high rate of arthroplasty at 5-year follow-up. Female gender was associated with lower subjective scores and higher rate of arthroplasty. The current study provides a natural history benchmark for clinical outcomes that can be expected in patients with medial meniscus posterior horn root tears undergoing non-operative treatment and helps in counselling patients with these types of injuries.

LEVEL OF EVIDENCE

IV.

Larger medial femoral to tibial condylar dimension may trigger posterior root tear of medial meniscus

PURPOSE

The major meniscal functions are load bearing, load distribution, and shock absorption by increasing the tibiofemoral joint (TFJ) contact area and dissipating axial loads by conversion into hoop stresses. The increased hoop strain stretches the meniscus in outward direction towards radius, causing extrusion, which is associated with the root tear and resultant degenerative osteoarthritis. Since the larger contact area of medial TFJ may increase the hoop stresses, we hypothesized that the larger medial femoral to tibial condylar dimension would contribute to the development of medial meniscus posterior root tear (MMPRT). Thus, the purpose of the study was to assess the relationship between MMPRT and medial femoral to tibial condylar dimension.

METHODS

A case-control study was conducted to compare medial femoral to tibial condylar dimensions of patients with complete MMPRT (n = 59) with those of demography-matched controls (n = 59) during the period from 2010 to 2013. In each patient, MRIs were reviewed and several parameters were measured including articulation width of medial femoral condyle (MFC) at 0°, 30°, 60°, and 90°, medial tibial condyle (MTC) width, degree of meniscal extrusion, and medial femoral to tibial condylar width ratio (MFC/MTC) at 0°, 30°, 60°, and 90°, respectively. Demographic and radiographic data were assessed.

RESULTS

A larger medial femoral to tibial condylar dimension was associated with MMPRT at 0° and 30° knee angles. Patients with MFC/MTC greater than 0.9 at 0° also showed about 2.5-fold increase in the chance of MMPRT. Those with meniscal extrusion greater than 3 mm also had about 17.1 times greater chance for the presence of MMPRT accordingly.

CONCLUSIONS

A larger medial femoral to tibial condylar dimension may be considered as one of the regional contributors to the outbreak of MMPRT, and medial femoral to tibial condylar width ratio greater than 0.9 at 0° knee angle may be considered as a significant risk factor for MMPRT.

LEVEL OF EVIDENCE

III.