The Urgent Need for Evidence in Arthroscopic Meniscal Surgery

Addressing meniscal deficiency part 1: An umbrella review of systematic reviews and meta-analyses on meniscal allograft transplantation

Purpose

Meniscal injuries are common in the young and active population. There is increasing utilization of surgical interventions like meniscal allograft transplantation (MAT) to restore the protective function of menisci following injury leading to meniscal deficiency. Extensive research and publications exist on the management of meniscal injury and the sequalae of meniscal deficiency. However, a comprehensive synthesis of the existing evidence through an umbrella review is lacking. This study aims to fill this gap by providing a current examination of the literature on MAT.

Methods

A comprehensive search was conducted in the MEDLINE, Embase and Scopus databases to identify relevant systematic reviews and meta-analyses. Studies were screened based on predefined inclusion and exclusion criteria. The quality of the included studies was assessed using the AMSTAR-2 tool.

Results

A total of 41 studies were included in the review, with most published within the last decade. The majority of studies (56.1%) received a 'Critically Low' confidence rating, 26.8% were rated as 'Low', and only 14.6% were rated as 'High' confidence. From the included studies, 51.2% reported on PROMs, with the Lysholm score being the most common. Transplant failure and reoperation rate were reported in 34.1% and 19.5% of studies respectively. Studies on MAT reported favourable short-term outcomes in terms of patient-reported outcome measures (PROMs) but were limited by the lack of randomized control trials and consistent comparison groups.

Conclusions

This umbrella review highlights an increase in interest in MAT but underscores the need for higher-quality reviews with standardized reporting and rigorous methodologies. Future research should focus on long-term outcomes, optimal surgical techniques, patient selection criteria and risk factors for transplant failure. There is also a need for more studies focusing on MAT in pediatric populations. Overall, this review provides a comprehensive assessment of the current state of research in MAT and identifies areas for improvement in future studies.

Level of Evidence

Level IV.

Prevalence of Articular Surface Injuries in Patients Undergoing Meniscal Surgery: A Retrospective Analysis of 758 Cases

Background and aim Meniscal tears are often associated with articular surface damage, which could be an important factor in the clinical outcome. However, these concomitant lesions are usually reported as binary variables. Reports of the severity/extent of the concomitant lesions and stratification by meniscal tear are scarce in the literature; in addition, sample sizes of previous reports are limited. This study aimed to characterize meniscal lesions, determine the prevalence of articular surface lesions and their severity, and correlate these lesions with meniscal injury characteristics. Methods A cross-sectional study of patients undergoing meniscal surgery between 2017 and 2023 was conducted. Patient characteristics and arthroscopic findings on the location and type of meniscal injury as well as the degree of chondral lesion (sICRS score) were recorded by the surgeon. Statistical analysis included frequency reporting for patient characteristics and study variables, including the median and interquartile range of the sICRS classification of articular surface lesions. Meniscal tear types were categorized as degenerative or non-degenerative to explore associations with chondral injury. Chi-square test and univariate and multivariate logistic regression models were employed to analyze relationships between variables. Results A total of 758 surgeries were analyzed, with a mean age of 39.56 years (SD: 12.71) and 67.90% male participants. Medial meniscus injuries accounted for 57.52%, lateral meniscus 36.02%, and both menisci 6.64%. Significant differences were found in vascular area, topography, and lesion type between isolated medial and lateral meniscus lesions (p<0.01). Chondral lesions were present in 35.22% of cases, with significant differences among meniscal injury types (p<0.01). Degenerative tears showed higher rates of chondral damage compared to non-degenerative tears, particularly in lateral meniscus injuries (p<0.01). Regression analysis identified age, gender, meniscal injury characteristics, and meniscectomy percentage as risk factors for articular surface injuries. Conclusion Articular surface injuries frequently accompany meniscal lesions, with associations between affected menisci and articular damage extent. Femoral condyles show greater involvement corresponding to compartment-specific meniscal lesions, unlike tibial plateaus. Meniscal degeneration is present in about half of articular cartilage injury cases. Some meniscal tear types may relate to more severe articular lesions, but larger studies are needed to confirm these findings and explore other tear patterns.

Does Concomitant Meniscectomy or Meniscus Repair Affect Muscle Strength, Lower Extremity Balance, and Functional Tests after Anterior Cruciate Ligament Reconstruction?

Background/Objective: The effects of concomitant meniscal tears and their associated treatment on strength, lower extremity balance, and functional status after anterior cruciate ligament reconstruction (ACLR) have not been widely investigated. This study aimed to compare the functional outcomes in patients who underwent ACLR with concomitant treatment of the medial meniscus repair versus meniscectomy when returning to unrestricted physical activity. Methods: A total of 85 patients who underwent primary ACLR with combined meniscal repair (MREP; n = 39) or meniscectomy (MRES; n = 46) were assessed. The dataset included the Functional Movement ScreenTM (FMS) outcomes and single-leg balance test (SLBT) with anterior-posterior, medial-lateral, and overall stability indexes. Isokinetic knee extension and flexion strengths were tested at velocities of 60 deg·s-1 and 180 deg·s-1. The peak torque-to-body weight ratio (PT/BW) and limb symmetry index (LSI) were calculated. Results: In the functional assessment, there was no significant inter-group difference in the composite score of the FMS (MREP: 15.08 pts vs. MRES: 15.13 pts; p > 0.05). The SLBT outcomes in inter-group and inter-extremity comparisons were irrelevant (p > 0.05), too. Significant differences emerged in the inter-group comparison of the knee extension strength in the non-operated extremity at both 60 deg·s-1 and 180 deg·s-1 (p = 0.02). Inter-extremity differences were significant in both the MREP and MRES groups for knee extension and flexion at both angular velocities (all p values < 0.05). For knee extension, the LSI values ranged from 82% to 87%, and for flexion, from 77% to 84%, with no significant inter-group differences. Conclusions: Patients undergoing ACLR with concomitant meniscal repair or resection did not exhibit differences in isokinetic muscle strength, lower extremity balance, and functional tests upon returning to activity. However, participants in both groups demonstrated significant differences between the operated and non-operated extremities as far as the knee joint extensor and flexor strengths are concerned. Therefore, rehabilitation protocols should prioritize equalizing inter-extremity strength differences after the ACLR with additional treatment procedures addressing the menisci.

Reduced physiological extrusion of the medial meniscus in axial load-bearing condition in anterior cruciate ligament deficiency

PURPOSE

In this study, ultrasonography was used to measure medial meniscus (MM) extrusion under weight-bearing and nonweight-bearing conditions in both anterior cruciate ligament (ACL)-deficient and ACL-intact knee groups. This study aimed to determine the possible differences between these groups with an eventual impact on meniscal tears in ACL-deficient knees.

METHODS

A total of 107 patients who underwent ACL reconstructive surgery between June 2022 and April 2023 were enroled. After applying exclusion criteria, 37 patients met the conditions for inclusion in the study and formed the ACL deficiency group (Group D). Of the 141 patients presenting to an outpatient clinic who agreed to have ultrasonography conducted on their nondiscomforting contralateral knee, 37 patients matched for age, sex, hip-knee-ankle angle and body mass index with Group D patients were selected for the ACL intact group (Group I). Ultrasonography was used to measure MM extrusion in weight-bearing and nonweight-bearing conditions for all participants.

RESULTS

Seventy-four patients were included in the study (n = 37 per group). The supine position showed an MM extrusion of 1.2 ± 0.7 mm in Group I and 1.2 ± 0.7 mm in Group D (not significant). In the standing position, MM extrusion measured 2.0 ± 0.6 mm in Group I and 1.3 ± 0.8 mm in Group D. The difference in extrusion (Δextrusion) between the two positions was 0.8 ± 0.6 in Group I and 0.1 ± 0.2 in Group D, with statistical significance (p < 0.01). A consistent reduction in MM extrusion during weight-bearing was observed in patients with ACL deficiency, irrespective of the duration of ACL deficiency, age, sex and BMI.

CONCLUSION

ACL deficiency did not significantly impact MM extrusion during nonweight-bearing conditions; however, less MM extrusion was observed in response to axial loading conditions. These findings indicate altered MM biomechanics due to increased anterior-posterior meniscal motion and rotational instability after ACL injury.

LEVEL OF EVIDENCE

Level III.

Arthroscopic surgery or exercise therapy for degenerative meniscal lesions: a systematic review of systematic reviews

BACKGROUND

Arthroscopic partial meniscectomy (APM) is widely applied for the treatment of degenerative meniscal lesions in middle-aged patients; however, such injury is often associated with mild or moderate osteoarthritis and has been reported by MRI in asymptomatic knees. Previous studies suggested, in most patients, a lack of benefit of surgical approach over conservative treatment, yet many controversies remain in clinical practice. Our aims were to assess the functional and pain scores between exercise therapy and arthroscopic surgery for degenerative meniscal lesions and to evaluate the methodological quality of the most recent systematic reviews (SRs).

METHODS

Two authors independently searched PubMed and Google Scholar for SRs comparing the outcome (in knee pain and functionality) of arthroscopic treatment and exercise therapy or placebo for degenerative meniscal lesions. The timeframe set was from 2009 to 2019 included.

RESULTS

A total of 13 SRs were selected. Two reviewers independently assessed the methodological quality of each paper using the AMSTAR 2 tool: seven scored as "moderate," four obtained a "low" grade while the remaining two were evaluated as "critically low." SRs agreed that in middle-aged patients with degenerative meniscal lesions arthroscopic surgery appears to grant no long-term improvement in pain and function over exercise therapy or placebo.

CONCLUSIONS

Conservative treatment based on physical therapy should be the first-line management. However, most SRs revealed subgroups of patients that fail to improve after conservative treatment and find relief when undergoing surgery. In the future, randomized controlled trials, evidence should be looked for that APM can be successful in case of the unsatisfactory results after physical therapy.

Failure rates and clinical outcomes of synthetic meniscal implants following partial meniscectomy: a systematic review

Background

Meniscal injury is one of the most common indications for knee surgery. The advent of meniscal repair techniques has facilitated meniscal preservation in suitable cases. Meniscal substitution with scaffolds may be advantageous following partial meniscal resection. There are three main scaffolds in current clinical use; Collagen Meniscal Implant (CMI Stryker Corporation, Kalamazoo, MI, USA), Actifit (Actifit, Orteq Ltd, London, UK) and NUsurface (Active Implants, LLC). The purpose of this systematic review was to compare clinical outcomes and failure rates of patients who have had implantation with these meniscal scaffolds.

Methods

MEDLINE and EMBASE databases were searched for studies that included patients who had surgical implantation with Actifit or CMI. Eligibility criteria included papers that described both clinical outcomes and failure rates of these implants, a mean follow up of 5 years and studies published in English. A Google search was also performed to identify any grey literature.

Results

Five Level IV studies were found for Actifit. One Level II, one Level III and four Level IV studies were found for the CMI implant. One Level II study was identified for the NUsurface scaffold with a follow-up 12 months and was included for completeness. Overall, 262 patients were treated with Actifit, 109 with CMI and 65 with NUsurface. Failure rates for Actifit were 18% (range 6.3–31.8%) with a mean follow up of 66.8 months, and for CMI 6.5% (range 0–11.8%) with a mean follow up of 97.1 months. The NUsurface failure rate was 16.9% at 12 months. Clinical outcomes such as VAS, Tegner and Lysholm scores improved significantly post-operatively. However, there was a high volume of concurrent procedures, such as anterior cruciate ligament reconstructions and high tibial osteotomies in each study group; 118 (45%) for Actifit and 53 (45%) for CMI.

Conclusion

The evidence for meniscal scaffold use is insufficient to suggest that they could potentially improve clinical outcomes in patients post-meniscal resection. This is largely due to the high proportion of concurrent procedures performed at index procedure for both CMI and Actifit. On the basis of current evidence, the use of meniscal scaffolds as a sole treatment for partial meniscal defects cannot be recommended, owing to the relatively high failure rate and paucity of clinical data.

All-Inside Meniscus Repair

PURPOSE OF REVIEW

The indications for partial meniscectomy are becoming increasingly limited, and recent evidence suggests that the meniscus should be preserved whenever possible. Because of its many proposed advantages, all-inside meniscus repairs are becoming increasingly common. This review discusses the indications, advantages, disadvantages, and biomechanical and clinical outcomes of all-inside meniscus repair.

RECENT FINDINGS

All-inside meniscus repair demonstrates equal functional outcomes, healing rates, and complications compared to inside-out repair of vertical longitudinal and bucket-handle tears with the advantages of decreased surgical time and faster post-operative recovery. In addition, return-to-sport and activity levels are high following all-inside repair regardless of whether concomitant anterior cruciate ligament reconstruction is performed. Biomechanical studies have demonstrated advantages of all-inside meniscal based repairs on radial and horizontal tears. All-inside meniscus repair compares favorably to inside-out repair of vertical longitudinal and bucket-handle tears and continues to increase in popularity. Both capsular based and meniscal based repairs can be used to repair a variety of tear patterns. While biomechanical results are encouraging, further research on the clinical outcomes of meniscal based repairs is needed to elucidate the role of these techniques in the future.

Inside-Out Approach to Meniscus Repair: Still the Gold Standard?

PURPOSE OF REVIEW

The purpose of this review is to provide an up-to-date summary on the current literature and trends regarding use of the inside-out approach to meniscus repair. Additionally, the paper describes the authors preferred techniques for inside-out meniscus repair utilizing posteromedial and posterolateral exposures.

RECENT FINDINGS

There has been a substantial increase in recent publications regarding meniscus repair. However, comparisons regarding the optimal repair technique have not been conclusive. Despite the recent increase in use of all-inside devices, multiple investigations with short-to-mid-term follow-up have demonstrated similar rates of meniscus healing between inside-out and all-inside repair techniques. Similarly, current literature describes comparable failure rates of around 20%. There are variations in the profile of complications, with all-inside devices having more implant-related complications and inside-out techniques with higher neurovascular injuries. Inside-out meniscus repair is a versatile, cost-effective technique that remains the gold standard for management of most meniscus tear patterns. Through a thoughtful approach, efficient suture retrieval and repair can be performed while protecting critical neurovascular structures. All-inside meniscus repair devices have increased in popularity and surgeon access, but this technique is not without limitations and comparisons to inside-out meniscus repair demonstrates equivocal outcomes.

Arthroscopic surgery for degenerative knee disease (osteoarthritis including degenerative meniscal tears)

BACKGROUND

Arthroscopic knee surgery remains a common treatment for symptomatic knee osteoarthritis, including for degenerative meniscal tears, despite guidelines strongly recommending against its use. This Cochrane Review is an update of a non-Cochrane systematic review published in 2017.

OBJECTIVES

To assess the benefits and harms of arthroscopic surgery, including debridement, partial menisectomy or both, compared with placebo surgery or non-surgical treatment in people with degenerative knee disease (osteoarthritis, degenerative meniscal tears, or both).

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, and two trials registers up to 16 April 2021, unrestricted by language.

SELECTION CRITERIA

We included randomised controlled trials (RCTs), or trials using quasi-randomised methods of participant allocation, comparing arthroscopic surgery with placebo surgery or non-surgical interventions (e.g. exercise, injections, non-arthroscopic lavage/irrigation, drug therapy, and supplements and complementary therapies) in people with symptomatic degenerative knee disease (osteoarthritis or degenerative meniscal tears or both). Major outcomes were pain, function, participant-reported treatment success, knee-specific quality of life, serious adverse events, total adverse events and knee surgery (replacement or osteotomy).

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies for inclusion, extracted data, and assessed risk of bias and the certainty of evidence using GRADE. The primary comparison was arthroscopic surgery compared to placebo surgery for outcomes that measured benefits of surgery, but we combined data from all control groups to assess harms and knee surgery (replacement or osteotomy).

MAIN RESULTS

Sixteen trials (2105 participants) met our inclusion criteria. The average age of participants ranged from 46 to 65 years, and 56% of participants were women. Four trials (380 participants) compared arthroscopic surgery to placebo surgery. For the remaining trials, arthroscopic surgery was compared to exercise (eight trials, 1371 participants), a single intra-articular glucocorticoid injection (one trial, 120 participants), non-arthroscopic lavage (one trial, 34 participants), non-steroidal anti-inflammatory drugs (one trial, 80 participants) and weekly hyaluronic acid injections for five weeks (one trial, 120 participants). The majority of trials without a placebo control were susceptible to bias: in particular, selection (56%), performance (75%), detection (75%), attrition (44%) and selective reporting (75%) biases. The placebo-controlled trials were less susceptible to bias and none were at risk of performance or detection bias. Here we limit reporting to the main comparison, arthroscopic surgery versus placebo surgery. High-certainty evidence indicates arthroscopic surgery leads to little or no difference in pain or function at three months after surgery, moderate-certainty evidence indicates there is probably little or no improvement in knee-specific quality of life three months after surgery, and low-certainty evidence indicates arthroscopic surgery may lead to little or no difference in participant-reported success at up to five years, compared with placebo surgery. Mean post-operative pain in the placebo group was 40.1 points on a 0 to 100 scale (where lower score indicates less pain) compared to 35.5 points in the arthroscopic surgery group, a difference of 4.6 points better (95% confidence interval (CI) 0.02 better to 9 better; I² = 0%; 4 trials, 309 participants). Mean post-operative function in the placebo group was 75.9 points on a 0 to 100 rating scale (where higher score indicates better function) compared to 76 points in the arthroscopic surgery group, a difference of 0.1 points better (95% CI 3.2 worse to 3.4 better; I² = 0%; 3 trials, 302 participants). Mean post-operative knee-specific health-related quality of life in the placebo group was 69.7 points on a 0 to 100 rating scale (where higher score indicates better quality of life) compared with 75.3 points in the arthroscopic surgery group, a difference of 5.6 points better (95% CI 0.36 better to 10.68 better; I² = 0%; 2 trials, 188 participants). We downgraded this evidence to moderate certainty as the 95% confidence interval does not rule in or rule out a clinically important change. After surgery, 74 out of 100 people reported treatment success with placebo and 82 out of 100 people reported treatment success with arthroscopic surgery at up to five years (risk ratio (RR) 1.11, 95% CI 0.66 to 1.86; I² = 53%; 3 trials, 189 participants). We downgraded this evidence to low certainty due to serious indirectness (diversity in definition and timing of outcome measurement) and serious imprecision (small number of events). We are less certain if the risk of serious or total adverse events increased with arthroscopic surgery compared to placebo or non-surgical interventions. Serious adverse events were reported in 6 out of 100 people in the control groups and 8 out of 100 people in the arthroscopy groups from eight trials (RR 1.35, 95% CI 0.64 to 2.83; I² = 47%; 8 trials, 1206 participants). Fifteen out of 100 people reported adverse events with control interventions, and 17 out of 100 people with surgery at up to five years (RR 1.15, 95% CI 0.78 to 1.70; I² = 48%; 9 trials, 1326 participants). The certainty of the evidence was low, downgraded twice due to serious imprecision (small number of events) and possible reporting bias (incomplete reporting of outcome across studies). Serious adverse events included death, pulmonary embolism, acute myocardial infarction, deep vein thrombosis and deep infection. Subsequent knee surgery (replacement or high tibial osteotomy) was reported in 2 out of 100 people in the control groups and 4 out of 100 people in the arthroscopy surgery groups at up to five years in four trials (RR 2.63, 95% CI 0.94 to 7.34; I² = 11%; 4 trials, 864 participants). The certainty of the evidence was low, downgraded twice due to the small number of events.

AUTHORS' CONCLUSIONS

Arthroscopic surgery provides little or no clinically important benefit in pain or function, probably does not provide clinically important benefits in knee-specific quality of life, and may not improve treatment success compared with a placebo procedure. It may lead to little or no difference, or a slight increase, in serious and total adverse events compared to control, but the evidence is of low certainty. Whether or not arthroscopic surgery results in slightly more subsequent knee surgery (replacement or osteotomy) compared to control remains unresolved.

Histologic and molecular features in pathologic human menisci from knees with and without osteoarthritis

The objective of this study was to evaluate histologic and molecular features of meniscus degeneration in cohorts of patients with and without osteoarthritis (OA) of the knee. Menisci were obtained from patients undergoing total knee arthroplasty for OA (TKA) or arthroscopic partial meniscectomy (APM) for a torn knee meniscus. Degenerative meniscal tears were among the most common tear type in the APM group based on the pattern. Using an integrative workflow for molecular evaluation of formalin-fixed and paraffin-embedded tissues, human menisci underwent blinded histologic evaluation and NanoString gene expression analyses. Histology revealed increased proteoglycan content in TKA menisci compared to APM menisci, but otherwise no significant differences in the total pathology score or sub-scores between patients based on age or cohort. NanoString analyses revealed differential expression of genes primarily associated with the PI3K-AKT signaling pathway, cell cycle, and apoptosis. These data provide new insights into histological and molecular features of meniscus degeneration in patients with and without knee OA. Histologic assessment of menisci showed similar severity of overall degeneration between cohorts, but there were differences at the molecular level. The dysregulated pathways identified in this study could contribute to early-onset meniscus degeneration, or to a predisposition to meniscus tears and subsequent knee OA. Further studies that validate genes and pathways uncovered in this study will allow us to evaluate novel approaches to assess and treat meniscal degeneration.

Mechanical symptoms and meniscal tear: a reappraisal

OBJECTIVE

To identify and summarize literature related to the association between mechanical symptoms (catching and locking of the knee), the presence of meniscal tear, and outcomes after arthroscopic surgery.

DESIGN

We searched PubMed and hand-searched reference lists for relevant articles and selected 38 for analysis.

RESULTS

Mechanical symptoms appear to have modest sensitivity (ranging 0.32-0.69), specificity (ranging 0.45-0.74) and positive predictive value (ranging 0.75-0.81) for meniscal tear. There is also very little evidence to suggest that those with mechanical symptoms experience better outcomes after arthroscopic surgery.

CONCLUSION

Our examination of the literature does not support the hypothesis that mechanical symptoms are related to the presence of meniscal tear or portend better outcomes after arthroscopic surgery.

The Epidemiology of Meniscus Injury

Meniscus surgery is one of the most commonly performed orthopedic procedures worldwide. Modifiable risk factors for meniscus injury include body mass index, participation in athletics and occupation. Nonmodifiable risk factors include age, sex, lower extremity alignment, discoid meniscus, ligamentous laxity, and biconcave tibial plateau. Conditions commonly associated with meniscal injury are osteoarthritis, anterior cruciate ligament injury, and tibial plateau fractures. Tear type and location vary by patient age and functional status. Surgical management of meniscus injury is typically cost-effective in terms of quality-adjusted life years. The purpose of this review is to provide an overview of meniscal injury epidemiology by summarizing tear types and locations, associated conditions, and factors that increase the risk for meniscal injury. The economic burden of meniscus injury and strategies to prevent injury to the meniscus are also reviewed.

Meniscal Regenerative Scaffolds Based on Biopolymers and Polymers: Recent Status and Applications

Knee menisci are structurally complex components that preserve appropriate biomechanics of the knee. Meniscal tissue is susceptible to injury and cannot heal spontaneously from most pathologies, especially considering the limited regenerative capacity of the inner avascular region. Conventional clinical treatments span from conservative therapy to meniscus implantation, all with limitations. There have been advances in meniscal tissue engineering and regenerative medicine in terms of potential combinations of polymeric biomaterials, endogenous cells and stimuli, resulting in innovative strategies. Recently, polymeric scaffolds have provided researchers with a powerful instrument to rationally support the requirements for meniscal tissue regeneration, ranging from an ideal architecture to biocompatibility and bioactivity. However, multiple challenges involving the anisotropic structure, sophisticated regenerative process, and challenging healing environment of the meniscus still create barriers to clinical application. Advances in scaffold manufacturing technology, temporal regulation of molecular signaling and investigation of host immunoresponses to scaffolds in tissue engineering provide alternative strategies, and studies have shed light on this field. Accordingly, this review aims to summarize the current polymers used to fabricate meniscal scaffolds and their applications in vivo and in vitro to evaluate their potential utility in meniscal tissue engineering. Recent progress on combinations of two or more types of polymers is described, with a focus on advanced strategies associated with technologies and immune compatibility and tunability. Finally, we discuss the current challenges and future prospects for regenerating injured meniscal tissues.

Editorial Commentary: Arthroscopic Partial Meniscectomy Is Not a First-Line Treatment for Degenerative Meniscus Tear: To Meniscectomize or Not to Meniscectomize?

A painful knee with a degenerative meniscal tear is a quite common problem in the middle-aged patient. Arthroscopic partial meniscectomy is too often used to alleviate pain and seems to work in the short-term. However, arthroscopic partial meniscectomy does not guarantee success, particularly in the long run, particularly in patients with greater grades of osteoarthritis, patients who are older than 60 years, female patients, patients with malalignment, and patients having lateral meniscectomy. There is a need for better science to recommend arthroscopic meniscectomy in those cases.

Outcomes at 20 Years After Meniscectomy in Patients Aged 50 to 70 Years

PURPOSE

To report the outcomes of arthroscopic meniscectomy (AM) at 20 years of follow-up through timing/rate of conversion to total knee replacement (TKR) and Knee Injury and Osteoarthritis Outcome Score (KOOS), focusing on detection of specific predictor variables for these outcomes, in patients 50 to 70 years old.

METHODS

We performed a retrospective study of 289 patients, ages at surgery 50 to 70 years, with diagnosis of degenerative meniscal tear who underwent arthroscopic meniscectomy. We collected the following baseline data: age, sex, injured meniscus (medial, lateral, or both), knee alignment, osteoarthritis (OA), associated lesion identified during arthroscopy, and associated procedure performed during arthroscopy. At 20 years of follow-up, we collected rate and timing of TKR conversion, and we evaluated clinical outcomes with KOOS.

RESULTS

Female sex (P < .01), older age (P < .01), lateral meniscectomy (P = .02), malalignment (P = .03), and advanced chondral lesion (P < .01) were found to be significantly related to subsequent TKR. No significant correlation was found between amount of resection and subsequent TKR (P = .26). Negative predictor factors to obtain equal or superior to age- and sex-adjusted KOOS scores were age 60 to 70 years at time of AM (P = .03) and lateral meniscectomy (P = .02).

CONCLUSIONS

We report a 15.7% conversion rate at 20 years from AM to TKR and a mean time between surgeries of 7 years. Subsequent TKR in the 20 years after AM for degenerative meniscus tears were significantly associated with preoperative OA and chondral lesion (Kellgren Lawrence 2; Outerbridge >2), lateral meniscectomy, age at surgery, female sex, and malalignment. Furthermore, age >60 years, lateral meniscectomy, and concurrent anterior cruciate ligament reconstruction were negative predictors for poor clinical outcomes at 20 years. Therefore, if patients present with negative predictor factors, the AM should not be proposed as second-line treatment, and nonoperative management should be continued until TKR is unavoidable.

LEVEL OF EVIDENCE

IV, case series.

Time to Achievement of Clinically Significant Outcomes After Isolated Arthroscopic Partial Meniscectomy: A Multivariate Analysis

Purpose

To define the time required to achieve the minimally clinically important difference (MCID), substantial clinical benefit (SCB) and patient acceptable symptomatic state (PASS) for isolated arthroscopic partial meniscectomy (APM), and define preoperative and intraoperative factors that predict both early and late achievement of the stated metrics.

Methods

Patients who underwent isolated APM between 2014 and 2017 were retrospectively included. Patients without preoperative and 6-month patient-reported outcome measure scores, revision procedures, and significant concomitant procedures were excluded. The MCID, SCB, and PASS were calculated for knee-based patient-reported outcome measure scores using receiver operating curve analysis. Kaplan-Meier survival analysis established the time required to achieve MCID, SCB and PASS. Hazard ratios from multivariate Cox regression allowed for the isolation of demographic and intraoperative factors predictive of the delayed time required to achieve MCID, SCB and PASS.

Results

A total of 126 patients (42.86% female, age: 48.9 ± 12.4 years) were included. Overall achievement rates ranged between 73.0% and 89.7% for MCID, 43.7% and 68.2% for SCB, and 50.8% and 68.3% for PASS. Median achievement time for MCID was 5.68-5.78 months, 5.73-6.05 months for SCB and 6.54-7.72 months for PASS. Multivariate Cox regression identified older age, workers' compensation status, diabetes, and various tear types (i.e., longitudinal, transverse, bucket handle, complex) as predictors of early clinically significant outcome achievement (hazard ratio: 1.02-24.72), whereas subsequent steroid injection, higher preoperative scores and root and flap tears predicted delays in clinically significant outcome achievement (hazard ratio: 0.12-0.99).

Conclusions

The majority of patients undergoing APM achieve benefit within 6 months of surgery, with diminishing proportions at later timepoints. Important factors for consideration of the the timeline of achieving clinically significant outcome include age, diabetes, workers' compensation, preoperative score, and tear type. The timeline for achieving improvement that was established by this study may aid in setting patient expectations and designing future outcome studies involving APM.

Study design

Level IV, Therapeutic Case Series.

Tissue optical properties combined with machine learning enables estimation of articular cartilage composition and functional integrity

Absorption and reduced scattering coefficients ( μ a , μ s ' ) of biological tissues have shown significant potential in biomedical applications. Thus, they are effective parameters for the characterization of tissue integrity and provide vital information on the health of biological tissues. This study investigates the potential of optical properties ( μ a , μ s ' ) for estimating articular cartilage composition and biomechanical properties using multivariate and machine learning techniques. The results suggest that μ_a could optimally estimate cartilage proteoglycan content in the superficial zone, in addition to its equilibrium modulus. While μ s ' could effectively estimate the proteoglycan content of the middle and deep zones in addition to the instantaneous and dynamic moduli of articular cartilage.

Delayed or neglected meniscus tear repair and meniscectomy in addition to ACL reconstruction have similar clinical outcome

PURPOSE

To compare the clinical outcomes of meniscus repair and meniscus resection with concurrent anterior cruciate ligament (ACL) reconstruction in patients with ACL rupture and neglected or delayed medial meniscus tears.

METHODS

Thirty patients with ACL ruptures and unstable vertical longitudinal medial meniscus tears were included. Patients were divided into two groups. Group I included 15 patients who underwent meniscal repair and Group II included 15 patients who underwent meniscectomy. The knee range of motion, McMurray test, Lachman test, pivot shift test, Lysholm Knee Scoring Scale, International Knee Documentation Committee (IKDC) Questionnaire, Hospital for Special Surgery (HSS) Knee score, and Tegner activity (TA) scale were used to assess all patients.

RESULTS

The median follow-up time was 3.6 (0.5-6.5) years. Median age was 28 (16-36) years. Fourteen patients (93.3%) in Group I and six patients (40%) in Group II returned to their preinjury sport activity level (P = .007). Median maximum knee flexion was 132° (121°-140°) in Group I and 134° (121°-139°) in Group II (n.s.). All patients had full knee extension and negative McMurray test results. Lachman and pivot shift test results were similar between groups. The median IKDC Questionnaire score was 99 (86-100) in Group I and 93 (70-100) in Group II (P = .016). The difference in Lysholm Knee Scoring Scale, HSS knee, and TA scale score between groups were not significant.

CONCLUSION

Clinical outcomes of patients that underwent meniscus repair were better than those that underwent meniscus resection with concurrent ACL reconstruction. The technically complicated and costly meniscus repair may achieve better clinical outcomes than meniscectomy when treating a neglected or delayed meniscal tear with a concurrent ACL tear.

LEVEL OF EVIDENCE

III.

An Up-to-Date Review of the Meniscus Literature: A Systematic Summary of Systematic Reviews and Meta-analyses

Background:

A large number of systematic reviews and meta-analyses regarding the meniscus have been published.

Purpose:

To provide a qualitative summary of the published systematic reviews and meta-analyses regarding the meniscus.

Study Design:

Systematic review; Level of evidence, 4.

Methods:

A systematic search of all meta-analyses and systematic reviews regarding the meniscus and published between July 2009 and July 2019 was performed with PubMed, CINAHL, EMBASE, and the Cochrane database. Published abstracts, narrative reviews, articles not written in English, commentaries, study protocols, and topics that were not focused on the meniscus were excluded. The most pertinent results were extracted and summarized from each study.

Results:

A total of 332 articles were found, of which 142 were included. Included articles were summarized and divided into 16 topics: epidemiology, diagnosis, histology, biomechanics, comorbid pathology, animal models, arthroscopic partial meniscectomy (APM), meniscal repair, meniscal root repairs, meniscal allograft transplantation (MAT), meniscal implants and scaffolds, mesenchymal stem cells and growth factors, postoperative rehabilitation, postoperative imaging assessment, patient-reported outcome measures, and cost-effectiveness. The majority of articles focused on APM (20%), MAT (18%), and meniscal repair (17%).

Conclusion:

This summary of systematic reviews and meta-analyses delivers surgeons a single source of the current evidence regarding the meniscus.

Comparison of Clinical and Semiquantitative Cartilage Grading Systems in Predicting Outcomes After Arthroscopic Partial Meniscectomy

OBJECTIVE. Cartilage loss on preoperative knee MRI is a predictor of poor outcomes after arthroscopic partial meniscectomy. The purpose of this study was to compare the ability to predict outcomes after arthroscopic partial meniscectomy with a clinically used modified Outerbridge system versus a semiquantitative MRI Osteoarthritis Knee Score system for grading cartilage loss. MATERIALS AND METHODS. Patients who underwent preoperative knee MRI within 6 months of arthroscopic partial meniscectomy and who had outcomes available from the time of surgery and 1 year later were eligible for inclusion. Cases were evaluated by two radiologists and one radiology fellow with the use of both grading systems. The accuracy of each system in discriminating between surgical success and failure was estimated using the ROC curve (AUC) with 95% CIs. A Wald test was used to assess noninferiority of the clinical grading system. Interreader agreement regarding the accuracy of the grading systems in predicting outcomes was also compared. RESULTS. A total of 78 patients (38 women and 40 men; mean age, 56.6 years) were included in the study. A prediction model using clinical grading (AUC = 0.695; 95% CI, 0.566-0.824) was noninferior (p = 0.047) to a model using MRI Osteoarthritis Knee Score grading (AUC = 0.683; 95% CI, 0.539-0.827). Both MRI prediction models performed better than a model using demographic characteristics only (AUC = 0.667; 95% CI, 0.522-0.812). Inter-reader agreement with clinical grading (80.8%) was higher than that with MRI Osteoarthritis Knee Score grading (65.0%; p = 0.012). CONCLUSION. A clinically used system to grade cartilage loss on MRI is as effective as a semiquantitative system for predicting outcomes after arthroscopic partial meniscectomy, while also offering improved interreader agreement.

Reliability of meniscus tear description: a study using MRI from the Osteoarthritis Initiative

Despite being one of the most common indications for surgery, data on the types of meniscus tear that should be treated surgically are limited. Improving patient selection requires agreement on meniscus tear description. This study evaluates a simple MRI tear classification system for inter-observer agreement. Knee MRI examinations from 57 subjects from the Osteoarthritis Initiative cohort were reviewed by two sub-specialty trained, musculoskeletal radiologists. Based on two pulse sequences, each meniscus was classified by: tear or no tear; location of tear in anterior, middle or posterior third or multiple thirds; and displaced or non-displaced radial, horizontal, longitudinal or complex tear pattern. A tear was defined as signal abnormality extending to the surface on at least two images and displacement as more than 2 mm of extrusion or separation measured orthogonal to the tear plane. Kappa, weighted Kappa and percentage agreement were calculated. For the medial meniscus, Kappa and percentage agreement estimates were, respectively: the presence of tear, 0.79 and 89.5%; tear with displacement, 0.70 (weighted Kappa) and 66.0%; tear description, 0.47 and 61.4%; tear location, 0.64 and 79.0%. For the lateral meniscus, estimates were: the presence of tear, 0.75 and 89.5%; tear with displacement, 0.81 (weighted Kappa) and 86.0%; tear description, 0.56 and 78.9%; tear location, 0.74 and 87.7%. The strength of agreement between readers was moderate to substantial underscoring the challenge of meniscus tear classification.

Complex Tears, Extrusion, and Larger Excision Are Prognostic Factors for Worse Outcomes 1 and 2 Years After Arthroscopic Partial Meniscectomy for Degenerative Meniscal Tears: A Secondary Explorative Study of the Surgically Treated Group From the Odense-Oslo Meniscectomy Versus Exercise (OMEX) Trial

BACKGROUND

Few studies have examined morphological findings from preoperative magnetic resonance imaging (MRI) and arthroscopic findings as prognostic factors for outcomes 1 and 2 years after arthroscopic partial meniscectomy (APM).

PURPOSE/HYPOTHESIS

The purpose was to evaluate prognostic factors of preoperative findings from MRI and arthroscopic evaluation on lower extremity performance at 1 year and patient-reported outcomes at 1 to 2 years after APM. The hypothesis was that medial compartment abnormalities would be prognostic for 1- and 2-year functional outcomes.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

This secondary analysis from the OMEX (Odense-Oslo Meniscectomy Versus Exercise) trial included 40 patients treated surgically. Regression analyses with adjustments for age, sex, and body mass index explored associations between MRI findings (tear complexity and extrusion), arthroscopic findings (tear length, cartilage injury, and amount of excised meniscal tissue), and the following: lower extremity performance tests and thigh muscle strength at 1 year and the 5 Knee injury and Osteoarthritis Outcome Score (KOOS) subscales at 1 and 2 years.

RESULTS

A complex meniscal tear was a significant and clinically relevant prognostic factor for worse KOOS Symptoms subscores at 2 years (mean, 14.1 points [95% CI, 6.1-22.2]). Meniscal extrusion of at least 11%, 25%, and 20% were significant and clinically relevant prognostic factors for worse KOOS Activities of Daily Living (ADL) subscores at 1 year and worse KOOS Sports and Recreation (Sports/Rec) subscores at 1 and 2 years, respectively. Tear lengths of at least 7.0 mm, 6.7 mm, and 6.5 mm were significant and clinically relevant prognostic factors for better KOOS Symptoms subscores at 1 year and better KOOS Sports/Rec subscores at 1 and 2 years, respectively. A cartilage injury in the medial compartment was a significant and clinically relevant prognostic factor for worse KOOS ADL and Quality of Life (QoL) subscores at 2 years (mean, 10.4 and 19.4 points, respectively [95% CI, 3.4-17.4 and 7.7-31.1, respectively]). More than 20% meniscal tissue excised was a significant and clinically relevant prognostic factor for worse KOOS Pain, Symptoms, ADL, and Sports/Rec subscores at 1 and 2 years (mean, 8.9-41.5 points [95% CI, 2.2-15.5 to 21.0-62.0]) and worse KOOS QoL subscores at 2 years (mean, 25.3 points [95% CI, 13.6-37.0]).

CONCLUSION

Complex meniscal tears, larger extrusion, cartilage injuries, and larger meniscal excision were significant and clinically relevant prognostic factors for worse outcomes 1 and 2 years after APM.

REGISTRATION

NCT01002794 (ClinicalTrials.gov identifier).

Nonoperative Management Prior to Hip Arthroscopy for Femoroacetabular Impingement Syndrome: An Investigation Into the Utilization and Content of Physical Therapy

BACKGROUND

There has been a significant increase in surgeries for femoroacetabular impingement syndrome in recent years, but little is known about the use of physical therapy prior to surgery.

OBJECTIVES

To investigate the use of physical therapy prior to hip arthroscopy for femoroacetabular impingement syndrome, by assessing the number of visits and use of exercise. A secondary objective was to evaluate whether comorbidities prior to surgery were associated with the use of physical therapy.

METHODS

In this retrospective observational cohort study, eligible participants between the ages of 18 and 50 years undergoing hip arthroscopy between 2004 and 2013 in the Military Health System were included. Patients were categorized based on whether they saw a physical therapist for their hip in the year prior to surgery. For physical therapy patients, dosing variables were identified, including total number of visits and visits that included an exercise therapy procedure code.

RESULTS

Of 1870 participants, 1106 (59.1%) did not see a physical therapist for their hip prior to surgery. For those who did, the median number of visits was 2. Only 220 (11.8%) had 6 or more unique visits with an exercise therapy procedure code. Exercise was coded in 43.4% to 63.0% of the total visits in each individual course of care (mean, 52.3%). There was an association between substance abuse and exercise utilization. No other comorbidities were associated with physical therapy or exercise therapy utilization.

CONCLUSION

Physical therapy was not commonly used before undergoing arthroscopic hip surgery by patients seeking care in the Military Health System. Further research is needed to understand the reasons for poor utilization and better define failed nonoperative management.

LEVEL OF EVIDENCE

Therapy, level 2b. J Orthop Sports Phys Ther 2019;49(8):593-600. Epub 15 May 2019. doi:10.2519/jospt.2019.8581.

A comprehensive review of randomized clinical trials in three medical journals reveals 396 medical reversals

The ability to identify medical reversals and other low-value medical practices is an essential prerequisite for efforts to reduce spending on such practices. Through an analysis of more than 3000 randomized controlled trials (RCTs) published in three leading medical journals (the Journal of the American Medical Association, the Lancet, and the New England Journal of Medicine), we have identified 396 medical reversals. Most of the studies (92%) were conducted on populations in high-income counties, cardiovascular disease was the most common medical category (20%), and medication was the most common type of intervention (33%).

Arthroscopic meniscal surgery: a national society treatment guideline and consensus statement

AIMS

The aim of the British Association for Surgery of the Knee (BASK) Meniscal Consensus Project was to develop an evidence-based treatment guideline for patients with meniscal lesions of the knee.

MATERIALS AND METHODS

A formal consensus process was undertaken applying nominal group, Delphi, and appropriateness methods. Consensus was first reached on the terminology relating to the definition, investigation, and classification of meniscal lesions. A series of simulated clinical scenarios was then created and the appropriateness of arthroscopic meniscal surgery or nonoperative treatment in each scenario was rated by the group. The process was informed throughout by the latest published, and previously unpublished, clinical and epidemiological evidence. Scenarios were then grouped together based upon the similarity of clinical features and ratings to form the guideline for treatment. Feedback on the draft guideline was sought from the entire membership of BASK before final revisions and approval by the consensus group.

RESULTS

A total of 45 simulated clinical scenarios were refined to five common clinical presentations and six corresponding treatment recommendations. The final guideline stratifies patients based upon a new, standardized classification of symptoms, signs, radiological findings, duration of symptoms, and previous treatment.

CONCLUSION

The 2018 BASK Arthroscopic Meniscal Surgery Treatment Guidance will facilitate the consistent identification and treatment of patients with meniscal lesions. It is hoped that this guidance will be adopted nationally by surgeons and help inform healthcare commissioning guidance. Validation in clinical practice is now required and several areas of uncertainty in relation to treatment should be a priority for future high-quality prospective studies. Cite this article: Bone Joint J 2019;101-B:652-659.

[Meniscal lesion. A pre-osteoarthritic condition of the knee joint]

BACKGROUND

A close relationship between meniscal damage and articular cartilage exist. Likewise, (partial) meniscectomy may lead to the development of osteoarthritis (OA).

OBJECTIVES

With a special emphasis on therapeutic consequences for orthopaedic surgeons, the structural and functional relationship between meniscal tears/extrusion and cartilage loss, and/or the effect of meniscectomy or meniscal repair on the development of OA, are emphasized.

MATERIALS AND METHODS

A selective literature review with implementation of own research findings.

RESULTS

The close topographical and functional interplay between the menisci and the tibiofemoral cartilage is the basis for the clinically important relationship between meniscal damage and cartilage degeneration. In particular, due to its close connection to tibiofemoral OA, a degenerative meniscal lesion represents a pre-osteoarthritic condition. Meniscus extrusion is also often associated with tibiofemoral OA. Even large cartilage defects can cause meniscus lesions. Partial meniscectomy is strongly associated with the incidence and risk of progression of OA. Clinical results are particularly problematic after partial resection of the lateral meniscus. Although the use of arthroscopic partial resection for degenerative meniscal lesions has been controversially discussed, no long-term studies are available. A large number of studies emphasize the medium-term value of meniscus reconstruction compared to partial meniscus resection. Combined meniscus and cartilage damage are complex cases, and the value of a simultaneous therapy remains unclear.

CONCLUSIONS

Preserving the meniscus is the first step towards cartilage repair. Randomized and controlled studies will provide better information on the long-term outcomes of meniscal resection and repair with regard to OA development.

Predictive Factors and Duration to Return to Sport After Isolated Meniscectomy

Background:

Return to sport (RTS) after meniscectomy is an important metric for young, active patients. However, the impact of the duration from surgery to RTS on clinical outcomes is not fully understood and is not reflected in outcome scores.

Purpose:

To establish when patients RTS after meniscectomy and to determine predictive measures for the ability to return to their preinjury activity.

Study Design:

Case-control study; Level of evidence, 3.

Methods:

All patients undergoing meniscectomy between 2016 and 2017 from a single institution were assessed for inclusion. RTS, type of activity, and level of function upon returning were obtained. The minimal clinically important difference (MCID), substantial clinical benefit, and patient acceptable symptom state (PASS) were calculated for the Knee injury and Osteoarthritis Outcome Score (KOOS) and International Knee Documentation Committee (IKDC) questionnaire using anchor-based and distribution-based approaches. Preoperative knee-specific and generic quality-of-life scores were analyzed to determine their predictive power of RTS. A multivariate logistical analysis was also performed to determine which demographic variables corresponded to RTS.

Results:

Overall, 94 patients (mean age, 51.0 ± 11.1 years) who underwent meniscectomy participated in sports within 6 months of surgery. Of these patients, 76.6% returned to sport without permanent restrictions at a mean of 8.6 ± 6.9 weeks postoperatively. RTS rates for low-, medium-, and high-intensity activities were 75.0%, 70.0%, and 82.5%, respectively. RTS was associated with achieving the PASS for the KOOS–Physical Function short form (PS), KOOS-Pain, and KOOS-Sports (P = .004, P = .007, and P = .006, respectively) but not for the IKDC questionnaire (P = .3). Achieving the MCID was associated with RTS for the KOOS-Sports, KOOS-Pain, and IKDC questionnaire (P < .001, P = .03, and P = .001, respectively). There was no preoperative or intraoperative variable that was predictive of RTS. Preoperative KOOS-PS scores ≥37.8 (area under the curve = 76.3%) and KOOS-Pain scores ≥51.4 (area under the curve = 72.5%) were predictive of RTS.

Conclusion:

Approximately 77% of patients returned to sport after meniscectomy at a mean of 2 months postoperatively. The level of activity intensity did not significantly alter the rate of RTS. Higher preoperative scores on the KOOS-PS and KOOS-Pain were predictive of RTS. Identifying these factors allows physicians to counsel patients on expected outcomes after meniscectomy.

Arthroscopic partial meniscectomy for meniscal tears of the knee: a systematic review and meta-analysis

OBJECTIVE

To assess the benefit of arthroscopic partial meniscectomy (APM) in adults with a meniscal tear and knee pain in three defined populations (taking account of the comparison intervention): (A) all patients (any type of meniscal tear with or without radiographic osteoarthritis); (B) patients with any type of meniscal tear in a non-osteoarthritic knee; and (C) patients with an unstable meniscal tear in a non-osteoarthritic knee.

DESIGN

Systematic review and meta-analysis.

DATASOURCES

A search of MEDLINE, Embase, CENTRAL, Scopus, Web of Science, Clinicaltrials.gov and ISRCTN was performed, unlimited by language or publication date (inception to 18 October 2018).

ELIGIBILITYCRITERIA

Randomised controlled trials performed in adults with meniscal tears, comparing APM versus (1) non-surgical intervention; (2) pharmacological intervention; (3) surgical intervention; and (4) no intervention.

RESULTS

Ten trials were identified: seven compared with non-surgery, one pharmacological and two surgical. Findings were limited by small sample size, small number of trials and cross-over of participants to APM from comparator interventions. In group A (all patients) receiving APM versus non-surgical intervention (physiotherapy), at 6-12 months, there was a small mean improvement in knee pain (standardised mean difference [SMD] 0.22 [95% CI 0.03 to 0.40]; five trials, 943 patients; I² 48%; Grading of Recommendations Assessment, Development and Evaluation [GRADE]: low), knee-specific quality of life (SMD 0.43 [95% CI 0.10 to 0.75]; three trials, 350 patients; I² 56%; GRADE: low) and knee function (SMD 0.18 [95% CI 0.04 to 0.33]; six trials, 1050 patients; I² 27%; GRADE: low). When the analysis was restricted to people without osteoarthritis (group B), there was a small to moderate improvement in knee pain (SMD 0.35 [95% CI 0.04 to 0.66]; three trials, 402 patients; I² 58%; GRADE: very low), knee-specific quality of life (SMD 0.59 [95% CI 0.11 to 1.07]; two trials, 244 patients; I² 71%; GRADE: low) and knee function (SMD 0.30 [95% CI 0.06 to 0.53]; four trials, 507 patients; I² 44%; GRADE: very low). There was no improvement in knee pain, function or quality of life in patients receiving APM compared with placebo surgery at 6-12 months in group A or B (pain: SMD 0.08 [95% CI -0.24 to 0.41]; one trial, 146 patients; GRADE: low; function: SMD -0.08 [95% CI -0.41 to 0.24]; one trial, 146 patients; GRADE: high; quality of life: SMD 0.05 [95% CI -0.27 to 0.38]; one trial; 146 patients; GRADE: high). No trials were identified for people in group C.

CONCLUSION

Performing APM in all patients with knee pain and a meniscal tear is not appropriate, and surgical treatment should not be considered the first-line intervention. There may, however, be a small-to-moderate benefit from APM compared with physiotherapy for patients without osteoarthritis. No trial has been limited to patients failing non-operative treatment or patients with an unstable meniscal tear in a non-arthritic joint; research is needed to establish the value of APM in this population.

PROTOCOL REGISTRATION NUMBER

PROSPERO CRD42017056844.

Anterior cruciate ligament (ACL) reconstruction and meniscal repair rates have both increased in the past 20 years in England: hospital statistics from 1997 to 2017

Objectives

We investigated the temporal trend and the geographical variation in the rate of an anterior cruciate ligament (ACL) reconstruction and meniscal repair (MR) performed in England during a 20-year window.

Methods

All hospital episodes for patients undergoing ACL reconstruction or MR between 1 April 1997 and 31 March 2017 were extracted by procedure code from the national hospital episode statistics. Age-standardised and sex-standardised rates of surgery were calculated using Office for National Statistics population data as the denominator and analysed over time both nationally and regionally by National Health Service clinical commissioning group (CCG).

Results

Between 1997–1998 and 2016–2017, there were 133 270 cases of ACL reconstruction (124 489 patients) and 42 651 cases of MR (41 120 patients) (isolated or simultaneous). Nationally, the rate of ACL reconstruction increased 12-fold from 2.0/100K population (95% CI 1.9 to 2.1) in 1997–1998 to 24.2/100K (95% CI 23.8 to 24.6) in 2016–2017. The rate of MR increased more than twofold from 3.0/100K (95% CI 2.8 to 3.1) in 1997–1998 to 7.3/100K (95% CI 7.1 to 7.5) in 2016–2017. Of these cases, the rate of simultaneous ACL reconstruction and MR was 2.6/100K (95% CI 2.5 to 2.8) in 2016/2017. In 2016–2017, for patients aged 20–29, the sex-standardised rate of ACL reconstruction was 76.9/100K (95% CI 74.9 to 78.9) and for MR was 19.8/100K (95% CI 18.8 to 20.9). Practice varied by region—in 2016–2017, 14.5% (30/207) of the CCGs performed more than twice the national average rate of ACL reconstruction and 15.0% (31/207) performed more than twice the national average rate of MR.

Conclusions

The rate of ACL reconstruction (12-fold) and MR (2.4-fold) has increased in England over the last two decades. There is variation in these rates across geographical regions and further work is required to deliver standardised treatment guidance for appropriate use.

Arthroscopic meniscal surgery versus conservative management in patients aged 40 years and older: a meta-analysis

INTRODUCTION

The efficacy of arthroscopic meniscus surgery in old aged patients remains controversial. The purpose of the present study was to review published studies comparing arthroscopic meniscal surgery with conservative management to treat meniscal injuries in patients 40 years of age and older.

MATERIALS AND METHODS

Several electronic databases were queried for articles published until July 2017 that evaluated outcomes of arthroscopic meniscal surgery in patients aged 40 years and older. Data searches, extraction, analysis, and quality assessment were performed according to the Cochrane Collaboration guidelines, and the clinical outcomes were evaluated using various outcome values. The results are presented as the standard mean difference (SMD) for continuous outcomes with 95% confidence intervals (CIs).

RESULTS

Nine randomized controlled trials (RCTs) were included. There were no significant differences in clinical outcomes such as relief in knee pain (SMD = 0.01, 95% CIs = - 0.15 to 0.18, I² = 38%) and improved knee function (SMD = 0.01, 95% CIs = - 0.19 to 0.21, I² = 57%) between arthroscopic meniscal surgery and conservative management for degenerative meniscal tears.

CONCLUSIONS

The efficacy of arthroscopic surgery was not superior to conservative management in this type of patients. Therefore, arthroscopic meniscal surgery should not be recommended as a first choice of treatment for degenerative meniscal tears. In patients over 40 years of age, arthroscopic surgery should be cautiously considered for degenerative meniscal tears and only when there has not been a satisfactory response to conservative management.

Arthroscopic repair of the meniscus: Surgical management and clinical outcomes

From the biomechanical and biological points of view, an arthroscopic meniscal repair (AMR) should always be considered as an option. However, AMR has a higher reoperation rate compared with arthroscopic partial meniscectomy, so it should be carefully indicated.

Compared with meniscectomy, AMR outcomes are better and the incidence of osteoarthritis is lower when it is well indicated.

Factors influencing healing and satisfactory results must be carefully evaluated before indicating an AMR.

Tears in the peripheral third are more likely to heal than those in the inner thirds.

Vertical peripheral longitudinal tears are the best scenario in terms of success when facing an AMR.

‘Inside-out’ techniques were considered as the gold standard for large repairs on mid-body and posterior parts of the meniscus. However, recent studies do not demonstrate differences regarding failure rate, functional outcomes and complications, when compared with the ‘all-inside’ techniques.

Some biological therapies try to enhance meniscal repair success but their efficacy needs further research. These are: mechanical stimulation, supplemental bone marrow stimulation, platelet rich plasma, stem cell therapy, and scaffolds and membranes.

Meniscal root tear/avulsion dramatically compromises meniscal stability, accelerating cartilage degeneration. Several options for reattachment have been proposed, but no differences between them have been established. However, repair of these lesions is actually the reference of the treatment.

Meniscal ramp lesions consist of disruption of the peripheral attachment of the meniscus. In contrast, with meniscal root tears, the treatment of reference has not yet been well established.

Cite this article: EFORT Open Rev 2018;3:584-594. DOI: 10.1302/2058-5241.3.170059

Temporal trends and regional variation in the rate of arthroscopic knee surgery in England: analysis of over 1.7 million procedures between 1997 and 2017. Has practice changed in response to new evidence?

OBJECTIVES

We investigated trends and regional variation in the rate of arthroscopic knee surgery performed in England from 1997-1998 to 2016-2017.

DESIGN

Cross-sectional study of the national hospital episode statistics (HES) for England.

METHODS

All hospital episodes for patients undergoing a knee arthroscopy between 1 April 1997 and 31 March 2017 were extracted from HES by procedure code. Age and sex-standardised rates of surgery were calculated using Office for National Statistic population data as the denominator. Trends in the rate of surgery were analysed by procedure both nationally and by Clinical Commissioning Group (CCG).

RESULTS

A total of 1 088 872 arthroscopic partial meniscectomies (APMs), 326 600 diagnostic arthroscopies, 308 618 knee washouts and 252 885 chondroplasties were identified (1 759 467 hospital admissions; 1 447 142 patients). The rate of APM increased from a low of 51/100 000 population (95% CI 51 to 52) in 1997-1998 to a peak at 149/100 000 (95% CI 148 to 150) in 2013-2014; then, after 2014-2015, rates declined to 120/100 000 (95% CI 119 to 121) in 2016-2017. Rates of arthroscopic knee washout and diagnostic arthroscopy declined steadily from 50/100 000 (95% CI 49 to 50) and 47/100 000 (95% CI 46 to 47) respectively in 1997-1998, to 4.8/100 000 (95% CI 4.6 to 5.0) and 8.1/100 000 (95% CI 7.9 to 8.3) in 2016-2017. Rates of chondroplasty have increased from a low of 3.2/100 000 (95% CI 3.0 to 3.3) in 1997-1998 to 51/100 000 (95% CI 50.6 to 51.7) in 2016-2017. Substantial regional and age-group variation in practice was detected. In 2016-2017, between 11% (22/207) and 16% (34/207) of CCGs performed at least double the national average rate of each procedure.

CONCLUSIONS

Over the last 20 years, and likely in response to new evidence, rates of arthroscopic knee washout and diagnostic arthroscopy have declined by up to 90%. APM rates increased about 130% overall but have declined recently. Rates of chondroplasty increased about 15-fold. There is significant variation in practice, but the appropriate population intervention rate for these procedures remains unknown.

National consensus on the definition, investigation, and classification of meniscal lesions of the knee

BACKGROUND

The aim of this study was to deliver standardised terminology for the identification and stratification of patients with meniscal lesions of the knee.

METHODS

A national group of expert surgeons was convened by the British Association for Surgery of the Knee (BASK) and a formal consensus process was undertaken following a validated methodology. A combination of nominal group techniques and an iterative Delphi process was used to develop and refine relevant definitions. Where appropriate, definitions were placed into categories to facilitate use in clinical practice and guideline development.

RESULTS

A degenerative meniscus develops progressively with degradation of meniscal tissue and this may be revealed by intra-meniscal high signal on magnetic resonance imaging (MRI). A meniscal tear was defined as a defect or split in the meniscocapsular complex, which can occur in a degenerative or non-degenerative meniscus. Degenerative meniscal lesions (high signal or tear) are frequent in the general population and are often incidental findings on knee MRI. Symptoms were defined and classified into three groups: (1) strongly suggestive of a treatable meniscal lesion, (2) potentially suggestive of a treatable meniscal lesion, (3) osteoarthritic. A strategy for radiological imaging (radiograph ± MRI) was agreed for the investigation of the patients with a possible meniscal tear. Meniscal lesions and tear patterns on MRI imaging were defined and classified with reference to potential treatability: (1) target, (2) possible target, (3) no target.

CONCLUSIONS

The agreed terminology will enable patients with meniscal lesions to be identified and stratified consistently in clinical practice, research and guideline development.

Pure intervention effect or effect in routine health care - blinded or non-blinded randomized controlled trial

BACKGROUND

Randomized trials provide the most valid evidence of effectiveness of interventions. The study aims to determine the primary study question for randomized controlled trials; to evaluate the study questions in trials on effectiveness of arthroscopic meniscectomy for meniscal rupture of the knee; and to explore the clinical and research implications.

METHODS

Previous studies on benchmarking controlled trials were utilized. A literature search was undertaken to find the trials on arthroscopic surgery for meniscal rupture of the knee, data was extracted, and checked for accuracy twice.

RESULTS

The first question in RCTs is whether to assess the pure intervention effect, or intervention effect in routine health care circumstances. The former necessitates a double blinded design and the latter a non-blind design. The trials on arthroscopic meniscectomy of the knee showed considerable differences in study characteristics.

CONCLUSIONS

The study question in RCTs on pure intervention effect dictates use of blinded design, while question of intervention effect in routine health care dictates use of non-blinded design. Blinding should not be considered a validity criterion when study question is on effectiveness in routine health care. When informing patients, the potential for other effects besides the pure intervention effect should be considered.

Meniscal repair results in inferior short-term outcomes compared with meniscal resection: a cohort study of 6398 patients with primary anterior cruciate ligament reconstruction

PURPOSE

To compare patient reported outcome measures (PROMs) during the first postoperative year between isolated anterior cruciate ligament (ACL) reconstruction and ACL reconstruction with concomitant meniscal intervention.

METHODS

Patients who underwent primary ACL reconstruction at Capio Artro Clinic, Stockholm, Sweden, between 1st Jan 2001 and 31st Dec 2014 without concomitant injuries others than meniscal and/or cartilage lesions were included. Five groups of meniscal treatment simultaneously to ACL reconstruction were established; medial meniscal (MM) resection, MM repair, lateral meniscal (LM) resection, LM repair, and MM + LM resection. Patients treated with isolated ACL reconstruction formed a separate group. Preoperative, 6-month and 1-year Knee Injury and Osteoarthritis Outcome Score (KOOS), and Lysholm knee score and Tegner Activity scale were collected. Differences in the change over time were analyzed with an ANOVA for repeated measurements with age at surgery, gender, and cartilage injury as covariates. A univariate ANOVA was applied to analyze PROMs between groups at the final follow-up.

RESULTS

A total of 6398 patients were included (56.8% males, mean age 28.5 ± 10.2 years). The KOOS improved across all subscales for all treatment groups. The mean change over time differed significantly between groups for the subscales symptoms (p = 0.017) and activities in daily living (ADL) (p < 0.001). Symptoms was least improved in the MM repair group, while the MM + LM resection group showed the largest improvement. For the ADL subscale, the isolated ACL reconstruction group showed the least improvement and the MM + LM resection group showed the major improvement. At 1-year follow-up, a significant difference between the groups was found for the subscale symptoms (p = 0.019), where the MM repair group reported the lowest score [mean 78.4 (95% CI 76.3-80.5)]. No significant differences were found between groups in change of the Lysholm score over time; however, at 6 months, the difference between groups was significant (p = 0.006) with the meniscal repair groups reporting the lowest scores.

CONCLUSION

Patients with concomitant meniscal resection are able to reach the same subjective knee function as isolated ACL reconstructions as early as 6 months postoperatively. However, patients with meniscal repair may have slightly worse subjective knee function at both 6- and 12-month follow-up. These findings could help clinicians to set realistic short-term expectations for patients undergoing ACL reconstruction with simultaneous meniscal intervention.

LEVEL OF EVIDENCE

3.

Meniscus repair with simultaneous ACL reconstruction demonstrated similar clinical outcomes as isolated ACL repair: a result not seen with meniscus resection

PURPOSE

To compare Knee Injury and Osteoarthritis Outcome Score (KOOS) and EuroQol-5D (EQ-5D) subscale scores at 2-year follow-up for patients with primary isolated ACL reconstruction with patients undergoing ACL reconstruction and simultaneous meniscal treatment in terms of either resection or repair in the Swedish National Knee Ligament Register (SNKLR).

METHODS

All ACL reconstruction patients within the SNKLR at 2-year follow-up were reviewed. The KOOS and EQ-5D subscales were assessed in four distinct patient groups: isolated ACL reconstruction, ACL reconstruction + medial meniscus resection, ACL reconstruction + lateral meniscus resection, ACL reconstruction + medial meniscus repair, and ACL reconstruction + lateral meniscus repair. The primary analysis was conducted using linear regression with isolated ACL reconstruction designated as the reference group, and was adjusted for patient age, gender, and time from injury to surgery.

RESULTS

The included patients consisted of 10,001 (65.0%) individuals with an isolated ACL injury, 588 (3.8%) with ACL injury plus treated with medial meniscus repair, 2307 (15.0%) with ACL injury plus treated with medial meniscus resection, 323 (2.1%) with ACL injury plus treated with lateral meniscus repair, and 2173 (14.1%) with ACL injury plus treated with lateral meniscus resection. Meniscus resection demonstrated significantly worse results with respect to the KOOS Symptoms subscale for both the medial and lateral meniscus resection groups. Medial meniscus resection also demonstrated worse results for the KOOS quality of life (QoL) subscale, while lateral meniscus resection only approached significance. Outcomes were not different between the isolated ACL reconstruction group and the meniscus repair groups.

CONCLUSION

Meniscus resection in addition to ACL reconstruction resulted in worse clinical outcomes than isolated ACL reconstruction patients; a result not seen within the meniscus repair group. This suggests that, when possible, meniscus repair may provide greater clinical outcomes over resection when treating a reparable meniscal tear that presents along with an ACL tear. Clinicians should consider and implement these findings for the management of future meniscus tear patients within their clinical practice.

LEVEL OF EVIDENCE

Level III.

Does MRI add value in general practice for patients with traumatic knee complaints? A 1-year randomised controlled trial

OBJECTIVE

To determine whether referral to MRI by the general practitioner (GP) is non-inferior to usual care (no access to MRI by GPs) in patients with traumatic knee complaints regarding knee-related daily function.

METHODS

This was a multicentre, non-inferiority randomised controlled trial with 1-year follow-up. GPs invited eligible patients during or after their consultation. Eligible patients (18-45 years) consulted a GP with knee complaints due to a trauma during the previous 6 months. Patients allocated to the MRI group received an MRI at (median) 7 (IQR 1-33) days after the baseline questionnaire. Patients in the usual care group received information on the course of knee complaints, and a referral to a physiotherapist or orthopaedic surgeon when indicated. The primary outcome measure was knee-related daily function measured with the Lysholm scale (0 to 100; 100=excellent function) over 1 year, with a non-inferiority margin of 6 points.

RESULTS

A total of 356 patients were included and randomised to MRI (n=179) or usual care (n=177) from November 2012 to December 2015. MRI was non-inferior to usual care concerning knee-related daily function during 1-year follow-up, for the intention-to-treat (overall adjusted estimate: 0.33; 95% CI -1.73 to 2.39) and per-protocol (overall adjusted estimate: 0.06; 95% CI -2.08 to 2.19) analysis. There were no differences between both groups in the amount of patients visiting other healthcare providers.

CONCLUSION

MRI in general practice in patients with traumatic knee complaints was non-inferior to usual care regarding knee-related daily function during 1-year follow-up.

TRIAL REGISTRATION NUMBER

NTR3689.

Randomized Controlled Trials for Arthroscopy in Degenerative Knee Disease: Was Conservative Therapy Appropriately Tried Prior to Arthroscopy?

PURPOSE

We aimed to determine if the randomized controlled trials (RCTs) evaluated in the most recent meta-analysis on arthroscopic surgery for degenerative knee arthritis included documented trials of appropriate conservative treatment prior to randomization.

METHODS

We selected all RCTs of the most recent meta-analysis by Brignardello-Petersen and recorded for each RCT, if physiotherapy prior to randomization was mandatory. We compared the treatment effect of arthroscopy in studies in which physiotherapy prior to randomization was mandatory versus studies in which it was not. This review was registered in the PROSPERO database (CRD42017070091).

RESULTS

Of the 13 RCTs in the meta-analysis, there were 2 in which physiotherapy prior to randomization was mandatory. In 1 additional multicenter RCT, prior conservative treatment was mentioned as mandatory in the publication, but not in the protocol. The treatment effects attributed to arthroscopy in terms of short-term pain (P = .0037), short-term function (P = .0309), and long-term function (P = .0012) were larger in studies in which prior physiotherapy was mandatory.

CONCLUSIONS

Although the most recent meta-analysis claims that it is based "on patients who do not respond to conservative treatment," physiotherapy was mandatory prior to randomization only in 2 of the 13 studies. As several orthopaedic guidelines recommend that the first line of treatment in patients with degenerative arthritis of the knee should be conservative, for instance with physiotherapy, and the question of performing arthroscopy arises once conservative treatment fails, 11 of the 13 RCTs failed to adhere to these accepted guidelines. Therefore, patient selection in these 11 studies may not represent the typical indications for arthroscopy, where patients have tried conservative management prior to being offered surgery. When comparing studies where prior physiotherapy was mandatory to studies in which it was not mandatory, there were statistically significant effects favoring arthroscopy in terms of pain in the short term, and for function both in the short and the long term. These findings suggest that the treatment effects attributed to arthroscopy were higher when prior physiotherapy was mandatory. Given these findings, the external validity of most of these RCTs, and the resulting "strong recommendation against the use of arthroscopy in nearly all patients with degenerative knee disease," is called into question.

LEVEL OF EVIDENCE

Level II, systematic review of Level I and II studies.

Better outcome from arthroscopic partial meniscectomy than skin incisions only? A sham-controlled randomised trial in patients aged 35-55 years with knee pain and an MRI-verified meniscal tear

OBJECTIVE

Compare arthroscopic partial meniscectomy to a true sham intervention.

METHODS

Sham-controlled superiority trial performed in three county hospitals in Denmark comparing arthroscopic partial meniscectomy to skin incisions only in patients aged 35-55 years with persistent knee pain and an MRI-confirmed medial meniscus lesion. A computer-generated table of random numbers generated two comparison groups. Participants and outcome assessors were blinded to group allocation. Exclusions were locking knees, high-energy trauma or severe osteoarthritis. Outcomes were collected at baseline, 3 and 24 months. We hypothesised no difference between groups. The primary outcome was the between-group difference in change from baseline to 2 years in the mean score across all five normalised Knee injury and Osteoarthritis Outcome Score (KOOS) subscales (KOOS5).

RESULTS

Forty-four patients (of the estimated 72) underwent randomisation; 22 in each group. Sixteen participants (36%) were non-blinded and eight participants (36%) from the sham group crossed over to the surgery group prior to the 2-year follow-up. At 2 years, both groups reported clinically relevant improvements (surgery 21.8, skin incisions only 13.6), the mean difference between groups was 8.2 in favour of surgery, which is slightly less than the cut-off of 10 prespecified to represent a clinically relevant difference; judged by the 95% CI (-3.4 to 19.8), a possibility of clinically relevant difference could not be excluded. In total, nine participants experienced 11 adverse events; six in the surgery group and three in the skin-incisions-only group.

CONCLUSION

We found greater improvement from arthroscopic partial meniscectomy compared with skin incisions only at 2 years, with the statistical uncertainty of the between-group difference including what could be considered clinically relevant. Because of the study being underpowered, nearly half in the sham group being non-blinded and one-third crossing over to surgery, the results cannot be generalised to the greater patient population.

TRIAL REGISTRATION NUMBER

NCT01264991.

Arthroscopic partial meniscectomy versus placebo surgery for a degenerative meniscus tear: a 2-year follow-up of the randomised controlled trial

OBJECTIVE

To assess if arthroscopic partial meniscectomy (APM) is superior to placebo surgery in the treatment of patients with degenerative tear of the medial meniscus.

METHODS

In this multicentre, randomised, participant-blinded and outcome assessor-blinded, placebo-surgery controlled trial, 146 adults, aged 35-65 years, with knee symptoms consistent with degenerative medial meniscus tear and no knee osteoarthritis were randomised to APM or placebo surgery. The primary outcome was the between-group difference in the change from baseline in the Western Ontario Meniscal Evaluation Tool (WOMET) and Lysholm knee scores and knee pain after exercise at 24 months after surgery. Secondary outcomes included the frequency of unblinding of the treatment-group allocation, participants' satisfaction, impression of change, return to normal activities, the incidence of serious adverse events and the presence of meniscal symptoms in clinical examination. Two subgroup analyses, assessing the outcome on those with mechanical symptoms and those with unstable meniscus tears, were also carried out.

RESULTS

In the intention-to-treat analysis, there were no significant between-group differences in the mean changes from baseline to 24 months in WOMET score: 27.3 in the APM group as compared with 31.6 in the placebo-surgery group (between-group difference, -4.3; 95% CI, -11.3 to 2.6); Lysholm knee score: 23.1 and 26.3, respectively (-3.2; -8.9 to 2.4) or knee pain after exercise, 3.5 and 3.9, respectively (-0.4; -1.3 to 0.5). There were no statistically significant differences between the two groups in any of the secondary outcomes or within the analysed subgroups.

CONCLUSIONS

In this 2-year follow-up of patients without knee osteoarthritis but with symptoms of a degenerative medial meniscus tear, the outcomes after APM were no better than those after placebo surgery. No evidence could be found to support the prevailing ideas that patients with presence of mechanical symptoms or certain meniscus tear characteristics or those who have failed initial conservative treatment are more likely to benefit from APM.

Efficacy of dexmedetomidine for pain management in knee arthroscopy: A systematic review and meta-analysis

BACKGROUND

Dexmedetomidine showed some potential in pain control in patients undergoing knee arthroscopy. We conducted a systematic review and meta-analysis to explore the efficacy of dexmedetomidine in patients undergoing knee arthroscopy.

METHODS

We searched the randomized controlled trials (RCTs) assessing the effect of dexmedetomidine on knee arthroscopy in PubMed, EMbase, Web of science, EBSCO, and Cochrane library databases. The primary outcome was pain scores. Meta-analysis was performed using the random-effect model.

RESULTS

Five RCTs were included. Overall, compared with control intervention in patients with knee arthroscopy, dexmedetomidine intervention could significantly reduce the pain scores [Std. mean difference = -0.84; 95% confidence interval (95% CI) = -1.24 to -0.44; P < .0001] and postoperative diclofenac sodium consumption (Std. mean difference = -1.76; 95% CI = -3.32 to -0.21; P = .03), improve duration of analgesic effect (Std. mean difference = 1.78; 95% CI = 0.56-3.00; P = .004), but showed no influence on hypotension [risk ratio (RR) = 0.93; 95% CI = 0.14-5.92; P = .94], bradycardia (RR = 4.93; 95% CI = 0.91-26.58; P = .06), nausea, and vomiting (RR = 1.96; 95% CI = 0.31-12.58; P = .48).

CONCLUSION

Dexmedetomidine intervention was able to significantly reduce the pain scores and postoperative diclofenac sodium consumption, and improve duration of analgesic effect in patients undergoing knee arthroscopy, but had no influence on hypotension, bradycardia, nausea, and vomiting.

The biology of meniscal pathology in osteoarthritis and its contribution to joint disease: beyond simple mechanics

The meniscal cartilages in the knee function to improve congruity of the medial and lateral femoro-tibial joints and play critical roles in load distribution and joint stability. Meniscal tears of various configurations are one of the most common conditions of the knee and are associated with an increased risk of developing osteoarthritis (OA). While this risk has been largely attributed to loss of the biomechanical functions of the menisci, there is accumulating evidence suggesting that other aspects of meniscal biology may play a role in determining the long-term consequences of meniscal damage for joint health. In this narrative review, we examine the existing literature and present some new data implicating synthesis and secretion of enzymes and other pro-catabolic mediators by injured and degenerate menisci, contributing to the pathological change in other knee joint tissues in OA.