The effects of meniscus injury on the development of knee osteoarthritis: data from the osteoarthritis initiative

Influence of preoperative medial meniscus extrusion and subchondral bone marrow edema on outcomes after medial opening wedge high tibial osteotomy

OBJECTIVE

No studies have assessed the correlation between preoperative medial meniscus extrusion (MME) and subchondral bone marrow edema (BME) or which factor influences the outcomes after medial opening wedge high tibial osteotomy (MOWHTO). The present study aimed to determine the influence of preoperative MME and BME on outcomes after MOWHTO.

METHODS

This study included 151 patients between January 2019 and January 2022 with a mean follow-up of 3.2 years. MME was classified into 2 groups according to the presence of pathologic MME (≥ 3 mm). BME was graded into 4 groups according to the lesion volume based on the MRI Osteoarthritis Knee Score (MOAKS) criteria. Clinical outcomes were assessed with the Hospital for Special Surgery (HSS) score, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and Knee Society Score (KSS).

RESULTS

The mean ± standard deviation preoperative MME for all patients was 3.6 ± 1.9 mm. A total of 103 patients (68.2%) had pathologic MME. MME significantly increased with increasing BME grade. Those with pathologic MME showed significantly worse outcomes in terms of the WOMAC and KSS for pain and function and HSS score than those without pathologic MME at 1 and 2 years postoperatively (all p < 0.05). A total of 122 patients (80.8%) had BME. Among the 151 patients, 29 (19.2%), 61 (40.4%), 42 (27.8%), and 19 (12.6%) were classified as having an MOAKS of 0, 1, 2, and 3, respectively, with significant differences in the preoperative WOMAC and KSS for pain and function and HSS score among these 4 groups (all P < 0.001). However, there were no significant differences in these indices at 1 or 2 years postoperatively (all P > 0.05). Only MME correlated with worse clinical outcomes in univariate (p < 0.001) and multivariate (p < 0.001) analyses.

CONCLUSIONS

Short-term clinical outcomes were worse for patients with preoperative MME greater than 3 mm than for those with preoperative MME less than 3 mm. There were no correlations between preoperative subchondral BME severity and postoperative outcomes.

Survivorship and outcomes of intra- and perimeniscal corticosteroids injections with structured physiotherapy for degenerative medial meniscus tears

BACKGROUND

Degenerative medial meniscus tears are a common pathology in the general population. Recent randomized trials demonstrated non-superiority of arthroscopic partial meniscectomy over conservative management. However, there is a paucity of information regarding the outcomes of combined conservative treatments.

HYPOTHESIS

It was hypothesized that combined intra- and perimeniscal corticosteroid injections with structured physiotherapy, for degenerative medial meniscus tears, would result in high surgery-free and second injection-free survivorship.

METHODS

A retrospective review of 671 patients with symptomatic degenerative medial meniscus tears, who received intra- and perimeniscal corticosteroids injection combined with structured physiotherapy, was conducted. An ultrasound-guided injection of Triamcinolone Hexacetonide 20 mg/ml comprised; 1.5 ml intra-meniscal,1.5 ml in the meniscal wall, and 2 ml in the peri-meniscal space, was performed. Surgery free- and a second injection free-survivorship were analysed. Western Ontario and Macmaster University scores (WOMAC), Tegner activity scores, patient satisfaction, return-to-work status and average time to return to work were recorded.

RESULTS

A total of 481 patients who met the inclusion criteria were included. The mean age was 51.1 ± 7.9 years. At five years post-procedure, surgery-free, and second injection-free survivorship of the ipsilateral knee was 83%, and 52%, respectively. A multivariate analysis adjusting survival on parametric risk factors identified that only effusion before steroid injection was an independent risk factor of treatment failure. At a mean follow-up of 4 ± 2 years, there was an improvement in WOMAC scores by 5.2 ± 4.9 for pain, by 2 ± 2 for stiffness, by 7.3 ± 7.4 for function, and by 12.4 ± 12.7 for the global scores. Additionally, there was significant improvement in the Tegner activity scores (All p < 0.001). Knee effusion and advanced osteoarthritis (Kellgren-Lawrence > III) were significantly associated with poorer outcomes; p < 0.003 and p < 0.0004, respectively.

CONCLUSION

A combination of intra- and perimeniscal corticosteroid injections and structured physiotherapy for degenerative medial meniscus tears, results in high surgery-free (83%) and second injection-free (52%) survivorship, as well as, effective clinical outcomes and satisfaction at 5 years.

LEVEL OF EVIDENCE

IV; Retrospective Case Series.

Commercial Insurance Payer Coverage Criteria for Meniscal Allograft Transplantation Poorly Reflect Modern Indications for the Procedure

ObjectiveTo investigate whether insurance coverage criteria for meniscal allograft transplantation (MAT) are sufficiently supported in the policy documentation and whether these criteria represent current research and expert consensus on indications for the procedure.DesignThe top 11 United States (US)-based national commercial health insurance payers for MAT were identified. A Google search was performed to identify payer coverage policies. Cited references within policy documents were classified by type of reference and reviewed for level of evidence (LOE). Specific coverage criteria for each individual payer were then extracted and compared to assess for similarities among commercial payers. Finally, all references cited were examined to determine whether they supported the coverage criteria stated by policies for each specific payer.ResultsSeven of the 11 payers had accessible coverage policies. This study found that the majority of cited references were primary journal articles (20, 57.1%) and that the vast majority of references cited (27, 77.1%) were level IV evidence. Of the seven payers, only two (Cigna = 8, HCSC = 19) cited more than six sources. There was a high degree of homogeneity in coverage criteria among payers. The sources cited did not consistently support specific payer coverage criteria. Payer criteria also tended to be arbitrary and poorly supported by current evidence on MAT.ConclusionThis study demonstrates that insurance coverage policies for MAT frequently use outdated references or cite references inappropriately. In addition, these policies fail to reflect current research and consensus on indications for the procedure.

Development and Characterization of a Polycaprolactone/Graphene Oxide Scaffold for Meniscus Cartilage Regeneration Using 3D Bioprinting

Background/Objectives: Meniscus injuries represent a critical challenge in orthopedic medicine due to the limited self-healing capacity of the tissue. This study presents the development and characterization of polycaprolactone/graphene oxide (PCL/GO) scaffolds fabricated using 3D bioprinting technology for meniscus cartilage regeneration. Methods: GO was incorporated at varying concentrations (1%, 3%, 5% w/w) to enhance the bioactivity, mechanical, thermal, and rheological properties of PCL scaffolds. Results: Rheological analyses revealed that GO significantly improved the storage modulus (G') from 36.1 Pa to 97.1 Pa and the yield shear stress from 97.2 Pa to 507.1 Pa, demonstrating enhanced elasticity and flow resistance. Mechanical testing showed that scaffolds with 1% GO achieved an optimal balance, with an elastic modulus of 614 MPa and ultimate tensile strength of 46.3 MPa, closely mimicking the native meniscus's mechanical behavior. FTIR analysis confirmed the successful integration of GO into the PCL matrix without disrupting its chemical integrity, while DSC analysis indicated improved thermal stability, with increases in melting temperatures. SEM analysis demonstrated a roughened surface morphology conducive to cellular adhesion and proliferation. Fluorescence microscopy using DAPI staining revealed enhanced cell attachment and regular nuclear distribution on PCL/GO scaffolds, particularly at lower GO concentrations. Antibacterial assays exhibited larger inhibition zones against E. coli and S. aureus, while cytotoxicity tests confirmed the biocompatibility of the PCL/GO scaffolds with fibroblast cells. Conclusions: This study highlights the potential of PCL/GO 3D-printed scaffolds as biofunctional platforms for meniscus tissue engineering, combining favorable mechanical, rheological, biological, and antibacterial properties.

Medial Meniscus Allograft Transplantation: Bone Plug Technique With Anatomic Anterior and Posterior Horn Fixation

Meniscus preservation is crucial for avoiding cartilage degeneration after symptomatic meniscal tears. Despite efforts, meniscal repair procedures may fail, which requires a partial or total meniscectomy. Meniscus allograft transplantation (MAT) presents a viable solution, offering symptom alleviation, enhanced knee function, and potential osteoarthritis progression delay. Although MAT can address both lateral and medial compartments, medial MAT poses greater challenges as the result of its intricate attachments and limited mobility. The medial meniscus's unique anatomy, including attachments to the intermeniscal ligament, deep medial collateral ligament, capsule, and the anterior cruciate ligament, demands meticulous transplantation techniques. Refinements in surgical techniques are ongoing, emphasizing the importance of anatomical precision, particularly in positioning the anterior and posterior horns of the medial meniscus. Here, we present a bone plug technique for medial MAT, prioritizing the accurate anatomical attachment of the anterior horns of the allograft to improve surgical outcomes.

Biomechanical Comparison of Inside-Out and All-Inside Meniscal Repair in Controlling the Peripheral Gap and Extrusion of the Lateral Meniscus With a Complete Radial Tear: A Cadaveric Study Using a Robotic Simulator

Background

Although both the classical inside-out and all-inside techniques are performed for the repair of complete radial tears, which should be the standard technique is, to the authors' knowledge, controversial considering the clinical outcomes and biomechanical studies. There are no biomechanical studies of repairs of the lateral meniscus (LM) evaluating the peripheral side gap (peripheral gap) of the radial tear site and extrusion of the LM, which seems to be important in the treatment of radial tears.

Purpose

To compare the inside-out and all-inside meniscal repair techniques by evaluating the peripheral gap and extrusion of the LM with complete radial tear using a 6 degrees of freedom robotic system and fresh-frozen cadavers.

Study Design

Controlled laboratory study.

Methods

This study was performed using 6 fresh-frozen cadaveric knee specimens, a robotic testing system, and ultrasound evaluation. Ultrasound evaluations were performed to measure peripheral gaps and extrusions. The first ultrasound evaluation under 5 N·m of valgus load was performed on the knee at 30° and 90° of flexion. After a complete radial tear at the midsegment of the LM was created, a second ultrasound evaluation under valgus load was performed. Finally, all-inside and inside-out meniscal repairs done with 1 horizontal suture were performed on the same knee in a randomized order. Subsequently, the third and fourth ultrasound evaluations under valgus load were performed.

Results

The peripheral gap of the inside-out meniscal repair technique was significantly smaller than that of all-inside meniscal repairs at knee flexion angles of 30° and 90° (6.0 vs 11.5 mm and 5.6 vs 10.9 mm [both P < .0167], respectively). The extrusion of inside-out meniscal repair was significantly smaller than that of all-inside meniscal repair at a knee flexion angle of 90° (2.6 vs 3.2 mm; P < .0083).

Conclusion

The inside-out meniscal repair technique showed less peripheral gap and extrusion of the LM in a complete radial tear than the all-inside meniscal repair. Inside-out repair may be advantageous for radial tears over all-inside repair because only inside-out repair can tighten the peripheral side of the radial tear.

Clinical Relevance

The LM with a complete radial tear should be repaired using the inside-out technique.

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.

Current advances in animal model of meniscal injury: From meniscal injury to osteoarthritis

Meniscal injury is a prevalent orthopedic practice that causes articular cartilage wear and degeneration due to tissue damage or loss, and may eventually result in the occurrence of knee osteoarthritis (KOA). Hence, investigating the structural regeneration and mechanical function restoration of the meniscus after injury is pivotal research topic for preventing KOA. Animal models are essential for investigating therapeutic strategies for meniscal injuries and their clinical translation, yet no current model can fully recapitulate the complexity of human meniscal injuries. This review aims to categorize the prevalent animal models of meniscal injury by their establishment methods, elucidate their principles and procedures, and discuss the suitability and limitations of each model. We delineate the pros and cons of different models in simulating the pathology and biomechanics of human meniscal injury. We also analyze different animal species regarding their meniscal structure, function, and repair potential, and their implications for model selection. We conclude that selecting an appropriate animal model requires a comprehensive consideration of various factors, such as research aims, anticipated outcomes, and feasibility. Furthermore, to translate novel therapeutic approaches to clinical applications more safely and effectively, future model development should emphasize aspects such as choosing animals of suitable age. The Translational Potential of this Article: This review aims to categorize and discuss current animal models of meniscal injury by establishment methods and provides a comprehensive overview of the routinely employed experimental animals in each model to facilitate the clinical translation of OA-related research.

Healthy but not osteoarthritic human meniscus-derived matrix scaffolds promote meniscus repair

Meniscus tissue is commonly injured due to sports-related injuries and age-related degeneration and approximately 50% of individuals with a meniscus tear will develop post-traumatic osteoarthritis (PTOA). Given that the meniscus has limited healing potential, new therapeutic strategies are required to enhance meniscus repair. Porcine meniscus-derived matrix (MDM) scaffolds improve meniscus integrative repair, but sources of human meniscus tissue have not been investigated. Therefore, the objectives of this study were to generate healthy and osteoarthritic (OA) MDM scaffolds and to compare meniscus cellular responses and integrative repair. Meniscus cells showed high viability on both healthy and OA scaffolds. While DNA content was higher in cell-seeded OA scaffolds than cell-seeded healthy scaffolds, CCK-8, and both sGAG and collagen content were similar between scaffold types. After 28 days in an ex vivo meniscus defect model, healthy and OA scaffolds had similar DNA, sGAG, and collagen content. However, the shear strength of repair was reduced in defects containing OA scaffolds compared to healthy scaffolds. In conclusion, healthy human allograft tissue is a useful source for generating MDM scaffolds that can support cellular growth, ECM production, and ex vivo integrative repair of the meniscus, highlighting the potential suitability for tissue engineering approaches to improve meniscus repair.

Artificial intelligence applied to magnetic resonance imaging reliably detects the presence, but not the location, of meniscus tears: a systematic review and meta-analysis

OBJECTIVES

To review and compare the accuracy of convolutional neural networks (CNN) for the diagnosis of meniscal tears in the current literature and analyze the decision-making processes utilized by these CNN algorithms.

MATERIALS AND METHODS

PubMed, MEDLINE, EMBASE, and Cochrane databases up to December 2022 were searched in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) statement. Risk of analysis was used for all identified articles. Predictive performance values, including sensitivity and specificity, were extracted for quantitative analysis. The meta-analysis was divided between AI prediction models identifying the presence of meniscus tears and the location of meniscus tears.

RESULTS

Eleven articles were included in the final review, with a total of 13,467 patients and 57,551 images. Heterogeneity was statistically significantly large for the sensitivity of the tear identification analysis (I2 = 79%). A higher level of accuracy was observed in identifying the presence of a meniscal tear over locating tears in specific regions of the meniscus (AUC, 0.939 vs 0.905). Pooled sensitivity and specificity were 0.87 (95% confidence interval (CI) 0.80-0.91) and 0.89 (95% CI 0.83-0.93) for meniscus tear identification and 0.88 (95% CI 0.82-0.91) and 0.84 (95% CI 0.81-0.85) for locating the tears.

CONCLUSIONS

AI prediction models achieved favorable performance in the diagnosis, but not location, of meniscus tears. Further studies on the clinical utilities of deep learning should include standardized reporting, external validation, and full reports of the predictive performances of these models, with a view to localizing tears more accurately.

CLINICAL RELEVANCE STATEMENT

Meniscus tears are hard to diagnose in the knee magnetic resonance images. AI prediction models may play an important role in improving the diagnostic accuracy of clinicians and radiologists.

KEY POINTS

• Artificial intelligence (AI) provides great potential in improving the diagnosis of meniscus tears. • The pooled diagnostic performance for artificial intelligence (AI) in identifying meniscus tears was better (sensitivity 87%, specificity 89%) than locating the tears (sensitivity 88%, specificity 84%). • AI is good at confirming the diagnosis of meniscus tears, but future work is required to guide the management of the disease.

Predicting incident radiographic knee osteoarthritis through quantitative meniscal lesion parameters: data from the osteoarthritis initiative

BACKGROUND

This study investigates the potential of novel meniscal parameters as predictive factors for incident radiographic knee osteoarthritis (ROA) over a span of four years, as part of the Osteoarthritis Initiative (OAI) study.

OBJECTIVES

Quantitative measurements of meniscal parameters alteration could serve as predictors of OA's occurrence and progression.

METHODS AND MATERIALS

A nested matched case-control study design was used to select participants from OAI study. Case knees (n = 178) were defined as those with incident ROA (Kellgren Lawrence Grade (KLG) 0 or 1 at baseline (BL), evolving into KLG 2 or above by year 4). Control knees were matched one-to-one by sex, age and radiographic status with case knees. The mean distance from medial-to-lateral meniscal lesions [Mean(MLD)], mean value of tibial plateau width [Mean(TPW)] and the mean of the relative percentage of the medial-to-lateral meniscal lesions distance [Mean(RMLD)] were evaluated through coronal T2-weighted turbo spin echo (TSE) MRI at P-0 (visit when incident ROA was found on radiograph), P-1(one year prior to P-0) and baseline, respectively. Using the imaging data of one patient, the mechanism was investigated by finite element analysis.

RESULTS

Participants were on average 60.22 years old, predominantly female (66.7%) and overweight (mean BMI: 28.15). Mean(MLD) and Mean(RMLD) were significantly greater for incident knees compared to no incident knees at baseline, P-1 and P-0. [Mean(MLD), Mean(RMLD); (42.56-49.73) mean ± (7.70-9.52) mm SD vs. (38.14-40.78) mean ± (5.51-7.05)mm SD; (58.61-68.95) mean ± (8.52-11.40) mm SD vs. (52.52-56.35) mean ± (6.53-7.85)mm SD, respectively]. Baseline Mean(MLD) and Mean(RMLD), [Adjusted OR, 95%CI: 1.11(1.07 to 1.16) and 1.13(1.09 to 1.17), respectively], were associated with incident ROA during 4 years, However, Mean(TPW) [Adjusted OR, 95%CI: 0.98(0.94 to 1.02)] was not associated with incident ROA during 4 years. While Mean(TPW) at P-1 and P-0 was not associated with the risk of incident ROA, Mean(MLD) and Mean(RMLD) at P-1 and P-0 were significantly positively associated with the risk of incident ROA.

CONCLUSIONS

The meniscal parameters alteration could be an important imaging biomarker to predict the occurrence of ROA.

In vivo movement interrelationships among the medial meniscus, joint capsule, and semimembranosus during tibial rotation

The meniscal position within the knee is critical to maintain normal knee function. The joint capsule might dynamically coordinate the medial meniscus (MM) by transmitting a semimembranosus action. However, their interrelationships in vivo are unclear. We aimed to determine relationships among the MM, joint capsule, and semimembranosus during passive tibial external-internal and isometric tibial internal rotation at the medial and posteromedial knees of 10 healthy individuals in vivo using ultrasound. We analyzed images of the MM and joint capsule locations at the medial and posteromedial knee and the velocity waveform similarity of each structure during rotational tasks. Both isometric internal rotation with semimembranosus action and passive tibial external rotation displaced the MM inward at the medial knee. The MM and joint capsule during these MM displacements coordinately moved with more than moderate cross-correlation coefficients (passive external and isometric internal rotations, ≥ 0.54 and ≥ 0.90, respectively). The movements of the MM and joint capsule to the semimembranosus during isometric internal rotation also coordinated with moderate cross-correlation coefficients (≥ 0.62). Therefore, the joint capsule might dynamically coordinate the MM by transmitting semimembranosus action. Whether increased tibial internal rotation or semimembranosus shortening causes MM extrusion awaits further investigation.

Structure-Mechanics Principles and Mechanobiology of Fibrocartilage Pericellular Matrix: A Pivotal Role of Type V Collagen

The pericellular matrix (PCM) is the immediate microniche surrounding resident cells in various tissue types, regulating matrix turnover, cell-matrix cross-talk and disease initiation. This study elucidated the structure-mechanical properties and mechanobiological functions of the PCM in fibrocartilage, a family of connective tissues that sustain complex tensile and compressive loads in vivo. Studying the murine meniscus as the model tissue, we showed that fibrocartilage PCM contains thinner, random collagen fibrillar networks that entrap proteoglycans, a structure distinct from the densely packed, highly aligned collagen fibers in the bulk extracellular matrix (ECM). In comparison to the ECM, the PCM has a lower modulus and greater isotropy, but similar relative viscoelastic properties. In Col5a1 +/- menisci, the reduction of collagen V, a minor collagen localized in the PCM, resulted in aberrant fibril thickening with increased heterogeneity. Consequently, the PCM exhibited a reduced modulus, loss of isotropy and faster viscoelastic relaxation. This disrupted PCM contributes to perturbed mechanotransduction of resident meniscal cells, as illustrated by reduced intracellular calcium signaling, as well as upregulated biosynthesis of lysyl oxidase and tenascin C. When cultured in vitro, Col5a1 +/- meniscal cells synthesized a weakened nascent PCM, which had inferior properties towards protecting resident cells against applied tensile stretch. These findings underscore the PCM as a distinctive microstructure that governs fibrocartilage mechanobiology, and highlight the pivotal role of collagen V in PCM function. Targeting the PCM or its molecular constituents holds promise for enhancing not only meniscus regeneration and osteoarthritis intervention, but also addressing diseases across various fibrocartilaginous tissues.

Clinical and imaging findings associated with preservation of knee joint health over 8 years in individuals aged 65 and over: data from the OAI

OBJECTIVE

While risk factors for osteoarthritis (OA) are well known, it is not well understood why certain individuals maintain high mobility and joint health throughout their life while others demonstrate OA at older ages. The purpose of this study was to assess which demographic, clinical and MRI quantitative and semi-quantitative factors are associated with preserving healthy knees in older individuals.

METHODS

This study analyzed data from the OA Initiative (OAI) cohort of individuals at the age of 65 years or above. Participants without OA at baseline (BL) (Kellgren-Lawrence (KL) ≤ 1) were followed and classified as incident cases (KL ≥ 2 during follow-up; n = 115) and as non-incident (KL ≤ 1 over 96-month; n = 391). Associations between the predictor-variables sex, age, BMI, race, clinical scoring systems, T2 relaxation times and Whole-Organ Magnetic Resonance Imaging-Score (WORMS) readings at BL and the preservation of healthy knees (KL ≤ 1) during a 96-month follow-up period were assessed using logistic regression models.

RESULTS

Obesity and presence of pain showed a significant inverse association with maintaining radiographically normal joints in patients aged 65 and above. T2 relaxation times of the lateral femur and tibia as well as the medial femur were also significantly associated with maintaining radiographically normal knee joints. Additionally, absence of lesions of the lateral meniscus and absence of cartilage lesions in the medial and patellofemoral compartments were significantly associated with maintaining healthy knee joints.

CONCLUSION

Overall, this study provides protective clinical parameters as well as quantitative and semi-quantitative MR-imaging parameters associated with maintaining radiographically normal knee joints in an older population over 8 years.

Approaches to optimize analyses of multidimensional ordinal MRI data in osteoarthritis research: A perspective

Objective

Knee osteoarthritis (OA) is a disease of the whole joint involving multiple tissue types. MRI-based semi-quantitative (SQ) scoring of knee OA is a method to perform multi-tissue joint assessment and has been shown to be a valid and reliable way to measure structural multi-tissue involvement and progression of the disease. While recent work has described how SQ scoring may be used for clinical trial enrichment and disease phenotyping in OA, less guidance is available for how these parameters may be used to assess study outcomes.

Design

Here we present recommendations for summarizing disease progression within specific tissue types. We illustrate how various methods may be used to quantify longitudinal change using SQ scoring and review examples from the literature.

Results

Approaches to quantify longitudinal change across subregions include the count of number of subregions, delta-subregion, delta-sum, and maximum grade changes. Careful attention should be paid to features that may fluctuate, such as bone marrow lesions, or with certain interventions, for example pharmacologic interventions with anticipated cartilage anabolic effects. The statistical approach must align with the nature of the outcome.

Conclusions

SQ scoring presents a way to understand disease progression across the whole joint. As OA is increasingly recognized as a heterogeneous disease with different phenotypes a better understanding of longitudinal progression across tissue types may present an opportunity to match study outcome to patient phenotype or to treatment mechanism of action.

Cyclic compressive loading induces a mature meniscal cell phenotype in mesenchymal stem cells with an atelocollagen-based scaffold

Introduction: Biomechanical stimulation is reportedly pivotal in meniscal regeneration, although its effect on mesenchymal stem cell (MSC) meniscal differentiation remains elusive. In this study, we investigated how cyclic compressive loading (CCL) could impact MSCs using three-dimensional cultures in atelocollagen-based meniscal substitute (ACMS). Methods: We extracted MSCs from the meniscus, synovium, and articular cartilage, cultured them in three-dimensional cultures, and exposed them to CCL for 7 days. We then compared the transcriptomes of MSCs treated with and without CCL. Results: Our RNA-seq analysis revealed that CCL induced significant transcriptome changes, significantly affecting chondrocyte-related genes, including SOX9, TGFB1, and PRG4 upregulation. CCL induced transcriptional differentiation of meniscus progenitors toward mature meniscal cells. Conclusion: This study unveils the potential of mechanical stress in promoting MSC meniscal differentiation within ACMS. Our investigations provide new insights for mechanisms underlying meniscal regeneration with ACMS.

The Impact of Bone Marrow Venting Augmentation on Knee Functions in the Repair of Vertical/Longitudinal Meniscus Tears: A Triple Comparison

Objective

Preserving and restoring meniscus function is crucial for maintaining knee biomechanics and overall functionality. To enhance the healing process after meniscus repair, various biological techniques have been introduced. In this study, three treatment approaches examined were bone marrow venting with stem cells (BMVP), anterior cruciate ligament reconstruction (ACLR) with meniscus repair, and isolated meniscus repair.

Materials and Methods

From 2015 to 2019, we retrospectively analyzed data from 83 patients who presented with complaints of knee pain or pain in addition to instability, were diagnosed with vertical/longitudinal meniscus tears, and underwent arthroscopic repair (30 with isolated repair, 28 with ACLR repair, and 25 with BMVP) at our University Hospital. Among the 28 patients with anterior cruciate ligament rupture, pain and instability were the predominant complaints, whereas 55 patients with meniscus tear primarily complained pain. Clinical and functional conditions were assessed using Lysholm, WOMAC, IKDC, and VAS scores before and 18 months after surgery. Surgical success was evaluated based on Barrett's criteria. Causes of failure were analyzed considering demographic data, smoking status, injury time, tear location, shape, zone, and suture type and number.

Results

Of the participants, 58 were male, 25 were female, 61 had medial meniscus lesions, and 22 had lateral meniscus lesions. The tear types included 51 simple longitudinal tears, 18 bucket handle tears, and 14 complex tears. A significant improvement was observed in the postoperative 18 month Lysholm, WOMAC, and IKDC values in all three groups (p: 0.001). At the 18 month mark, clinical and functional outcomes were comparable between BMVP and ACLR repair groups (Lysholm p: 0.951, WOMAC p: 0.241, IKDC p: 0.984). Both of these procedures yielded better results compared to isolated meniscus repair (Lysholm p: 0.001, WOMAC p: 0.027, IKDC p: 0.001).

Conclusion

The superior clinical and functional outcomes observed after meniscus repair with BMVP and ACLR, compared to isolated meniscus repair, indicate positive effects of bone marrow stem cells, blood components, and tissue healing factors on meniscus repair and knee function.

Usefulness of Probing Sensor Device for Evaluating Meniscal Suture and Scaffold Implantation

Appropriate suture tension is a key factor in successful meniscal repair. This study aimed to clarify the appropriate value of meniscal stabilization with suture repair based on a probing procedure for healthy porcine menisci and a novel meniscal scaffold. After evaluating the reliability of the probing sensor, meniscal vertical tear and partial meniscectomy models were developed, in which suture repair and meniscal scaffold implantation were performed at suture intervals ranging between 20 and 2.5 mm. The residence forces at each interval were evaluated using a probing sensor. Moreover, a tensile test was conducted to evaluate the displacement and presence or absence of gaps. We found that normal and meniscal scaffolds should be fixed within 5 mm of suture interval. The probing residence forces required were at least 1.0 N for vertical tears and 3.0 N for meniscal scaffolds. These findings may be taken into consideration to reduce suture failure following meniscal tear repair and stabilizing meniscal scaffold fixation.

Meniscal Radial Tears: A Classification System Based on Tear Morphology

Appropriate management of radial meniscal tears is complex, with continued efforts focused on optimizing diagnostic methods for identification to help dictate treatment, especially as surgical indications for repair have expanded, coupled with improvements in surgical techniques and instrumentation. Currently, no standardized classification system for radial meniscal tears exists, limiting the ability to accurately characterize injury patterns and guide surgical decision-making.

Biomechanical Comparison of All-Suture, All-Inside Meniscus Repair Devices in a Human Cadaveric Meniscus Model

OBJECTIVE

Newer all-suture, all-inside meniscus repair devices utilize soft suture anchors. The purpose of this study was to compare the biomechanical performance of 4 meniscus repair devices in human cadaver menisci: the JuggerStitch (all-suture, all-inside), the FiberStitch (all-suture, all-inside), a polyether ether ketone (PEEK) all-inside, and an inside-out device.

DESIGN

Forty human cadaver menisci were tested after creating 20 mm longitudinal tears in the posterior meniscus. Each knee was randomized to 1 of 4 meniscus repair groups: JuggerStitch (all-suture, all-inside), FiberStitch (all-suture, all-inside), FAST-FIX 360 (PEEK-based anchor all-inside), and inside-out (with BroadbandTM tape meniscus needles). For each meniscus, 2 devices were used to prepare vertical mattress repair construct. The specimens were tested by pre-conditioning 20 cycles between 5 N and 30 N and then the tear diastasis was measured, followed by distraction to failure phase after imposing a displacement at a rate of 0.5 mm/s.

RESULTS

Ten menisci were tested in each of the 4 groups. After pre-conditioning, there was no significant difference in the gap formation among groups (P = 0.212). The average failure load for the JuggerStitch, FiberStitch, PEEK all-inside, and inside-out was 384 N, 311 N, 207 N, and 261 N, respectively, with a significant difference between groups (P = 0.034). Post hoc analysis showed the JuggerStitch failure load was higher than the PEEK all-inside and inside-out (P = 0.005, and P = 0.045, respectively). There was no significant difference between the failure load of the JuggerStitch and FiberStitch (P = 0.225).

CONCLUSION

The JuggerStitch all-suture device, FiberStitch all-suture device, PEEK all-inside, and inside-out devices have similar biomechanical properties for gapping and stiffness. The JuggerStitch all-suture, all-inside device has superior failure load compared with the PEEK all-inside and inside-out repair for longitudinal meniscus tear repair.

Knee Offloading by Patients During Walking and Running After Meniscectomy

Background

Changes in knee loading have been reported after meniscectomy. Knee loading has previously been assessed during jogging and treadmill running rather than overground running, which could give altered results.

Purpose/Hypothesis

The purpose of this study was to evaluate knee function during overground running and walking after meniscectomy. It was hypothesized that the affected limb would demonstrate higher external knee adduction moment, lower knee flexion moment (KFM), and lower knee rotation moment (KRM) compared with the contralateral limb and with healthy individuals.

Study Design

Controlled laboratory study.

Methods

Kinematic and kinetic data were collected during running and walking in individuals after a meniscectomy and healthy individuals. Total knee joint moments (TKJM) were calculated from the sagittal, frontal, and transverse knee moments. Isometric quadriceps strength, perceived knee function, and kinesiophobia were also assessed. A mixed linear model compared differences between the affected leg, the contralateral leg, and the healthy leg.

Results

Data were collected on 20 healthy individuals and 30 individuals after a meniscectomy (mean ± SD, 5.7 ± 2.9 months postsurgery), with 12, 16, and 2 individuals who had medial, lateral, and both medial and lateral meniscectomy, respectively. The affected limb demonstrated lower TKJM (P < .001), KFM (P = .004), and KRM (P < .001) during late stance of walking compared with the healthy group. Lower TKJM and KFM were observed during running in the affected limb compared with the contralateral limb and healthy group. No significant differences were observed between contralateral and healthy limbs except for KRM during late stance of walking. Lower quadriceps strength was observed in the affected (P < .001) and contralateral limbs (P = .001) compared with the healthy group. Individuals after a meniscectomy also reported greater kinesiophobia (P = .006) and lower perceived knee function (31.1%; P < .001) compared with the healthy group.

Conclusion

After meniscectomy, individuals who sustained a traumatic meniscal injury showed lower TKJM in the affected limb compared with the contralateral limb and healthy individuals. This decrease in TKJM can be attributed to altered knee-loading strategies in the sagittal and transverse planes.

Clinical Relevance

Improving movement strategies, quadriceps strength, and kinesiophobia through rehabilitation approaches will allow individuals to load their knee appropriately when returning to sport.

Registration

NCT03379415 (ClinicalTrials.gov identifier).

The influence of meniscal pathology in the incidence of knee osteoarthritis: a review

IMPORTANCE

Knee osteoarthritis (OA) is a common cause of pain and disability in older persons, affecting approximately 14 million individuals in the USA. Meniscal damage is also common in this age group with a prevalence of 35% in a middle-aged and older community sample and 82% in persons with evidence of radiographic knee osteoarthritis. This paper systematically reviews evidence on the association of meniscal pathology and incident radiographic knee OA.

OBSERVATIONS

We included 15 articles, published between 2013 and 2021, assessing the relationship between meniscal pathology and OA incidence (Fig. 1). The menisci are crucial load-bearing structures, and the resulting increase in biomechanical stress due to meniscal damage increases the risk for OA development. While some discrepancies are present in the literature, a clinically meaningful association has been generally established between the presence of a meniscal tear or meniscal extrusion and subsequent development of incident OA. Of note, larger radial tears as well as complex and more severe tears exhibit the strongest association with the development of incident OA. The relationship between other features of meniscal morphology-such as meniscal volume and meniscal coverage-and incident OA is less clearly documented.

CONCLUSIONS AND RELEVANCE

The early detection of meniscal pathology can be used to trigger preventative and therapeutic strategies designed to avert or delay knee OA in this at-risk population.

Quantitative bone marrow lesion, meniscus, and synovitis measurement: current status

Imaging plays a pivotal role in osteoarthritis research, particularly in epidemiological and clinical trials of knee osteoarthritis (KOA), with the ultimate goal being the development of an effective drug treatment for future prevention or cessation of disease. Imaging assessment methods can be semi-quantitative, quantitative, or a combination, with quantitative methods usually relying on software to assist. The software generally attempts image segmentation (outlining of relevant structures). New techniques using artificial intelligence (AI) or deep learning (DL) are currently a frequent topic of research. This review article provides an overview of the literature to date, focusing primarily on the current status of quantitative software-based assessment techniques of KOA using magnetic resonance (MR) imaging. We will concentrate on the imaging evaluation of three specific structural imaging biomarkers: bone marrow lesions (BMLs), meniscus, and synovitis consisting of effusion synovitis (ES) and Hoffa's synovitis (HS). A brief clinical and imaging background review of osteoarthritis evaluation, particularly relating to these three structural markers, is provided as well as a general summary of the software methods. A summary of the literature with respect to each KOA assessment method will be presented overall as well as with respect to each specific biomarker individually. Novel techniques, as well as future goals and directions using quantitative imaging assessment, will be discussed.

Effect of limb alignment correction on medial meniscus extrusion under loading condition in high tibial osteotomy

Background

This study aimed to investigate the effect of high tibial osteotomy (HTO) on medial meniscus extrusion (MME) and the association between the changes in limb alignment and MME under weight-bearing (WB) conditions after HTO.

Methods

We included 17 patients with knee osteoarthritis (OA) who underwent HTO. MME was evaluated using ultrasonography in supine and unipedal standing positions. Knee alignment was evaluated radiographically using WB, whole-leg radiographs with the hip-knee-ankle angle (HKAA), percentage of the mechanical axis (%MA), medial proximal tibial angle (MPTA), and joint line convergence angle (JLCA). All measurements were performed serially at four time points: preoperative and 3, 6, and 12 months postoperative. Clinical outcomes were assessed by knee injury and osteoarthrosis outcome score (KOOS) and visual analogue scale (VAS) value for pain.

Results

Mean MME in the WB position was significantly greater than that in the supine position in the preoperative condition; however, MME in both supine and WB positions was significantly lowered postoperatively. The ΔMME, difference of MME between supine and WB positions, was significantly lowered postoperatively and maintained for up to 1 year. MME change in the WB position between preop and postoperative conditions was significantly correlated with change in HKAA and %MA at 1 year postoperative. KOOS and VAS score were significantly improved after HTO.

Conclusions

HTO correcting varus alignment can decrease MME in WB position and minimise the change in MME between supine and WB positions. The changes in MME after HTO were correlated with changes in the mechanical alignments.

Posteromedial capsular anatomy of the tibia for consideration of the medial meniscal support structure using a multidimensional analysis

Medial meniscal extrusion (MME) is a structural abnormality that leads to early knee osteoarthritis; however, its formation remains debated. For anatomical consideration of the mechanism underlying MME formation, we examined the capsular attachment on the posteromedial tibia and its layered association with the semimembranosus. Fourteen knees of eight body donors were analyzed in this study; six knees were grouped for macroscopic analysis, whereas four knees each were grouped for histological and phosphotungstic acid-enhanced micro-computed tomography analyses. The capsular attachment varied in width according to location and was not distant from the articular cartilage and posterior root. A portion of the posteromedial joint capsule formed the semimembranosus tendinous sheath. The dense fibrous membrane superficial to the semimembranosus, which was continuous from its tendinous sheath, existed as one of the layers of the joint capsule. The aforementioned findings were confirmed in all specimens. Based on the capsular attachment and its layered association with the semimembranosus, the conventional posteromedial knee ligaments may be only a part of the joint capsule divided into two layers by the semimembranosus. If the coordinated action of the joint capsule and semimembranosus partially contributes to the medial meniscus stability, such a structural problem may affect MME formation.

Visual Cascaded-Progressive Convolutional Neural Network (C-PCNN) for Diagnosis of Meniscus Injury

OBJECTIVE

The objective of this study is to develop a novel automatic convolutional neural network (CNN) that aids in the diagnosis of meniscus injury, while enabling the visualization of lesion characteristics. This will improve the accuracy and reduce diagnosis times.

METHODS

We presented a cascaded-progressive convolutional neural network (C-PCNN) method for diagnosing meniscus injuries using magnetic resonance imaging (MRI). A total of 1396 images collected in the hospital were used for training and testing. The method used for training and testing was 5-fold cross validation. Using intraoperative arthroscopic diagnosis and MRI diagnosis as criteria, the C-PCNN was evaluated based on accuracy, sensitivity, specificity, receiver operating characteristic (ROC), and evaluation performance. At the same time, the diagnostic accuracy of doctors with the assistance of cascade- progressive convolutional neural networks was evaluated. The diagnostic accuracy of a C-PCNN assistant with an attending doctor and chief doctor was compared to evaluate the clinical significance.

RESULTS

C-PCNN showed 85.6% accuracy in diagnosing and identifying anterior horn injury, and 92% accuracy in diagnosing and identifying posterior horn injury. The average accuracy of C-PCNN was 89.8%, AUC = 0.86. The diagnosis accuracy of the attending physician with the aid of the C-PCNN was comparable to that of the chief physician.

CONCLUSION

The C-PCNN-based MRI technique for diagnosing knee meniscus injuries has significant practical value in clinical practice. With a high rate of accuracy, clinical auxiliary physicians can increase the speed and accuracy of diagnosis and decrease the number of incorrect diagnoses.

Radiographic OA, bone marrow lesions, higher body mass index and medial meniscal root tears are significantly associated with medial meniscus extrusion with OA or medial meniscal tears: a systematic review and meta-analysis

PURPOSE

Medial meniscus extrusion (MME) refers to the protrusion of the medial meniscus beyond the tibial edge by more than 3 mm, leading to a deficiency of the hoop strain. MME commonly occurs in conjunction with osteoarthritis (OA) or medial meniscal tears (MMT). However, factors associated with concomitant MME in patients with OA or MMT have not been systematically reviewed. This study aims to perform a systematic review and meta-analysis to identify factors associated with concomitant MME in OA or MMT.

METHODS

The systematic review of the literature was performed according to PRISMA. A literature search was conducted in 4 databases. All original human studies that reported the available evidence on factors associated with concomitant MME in patients with OA or MMT were included. Pooled binary variables were analyzed by odds ratios (OR) and 95% CIs, and pooled continuous variables were evaluated by mean difference (MD) and 95% CIs.

RESULTS

Ten studies on OA (5993 patients) and eight studies on MMT (872 patients) met the inclusion criteria. The overall pooled incidence of MME was 43% (95% CI, 37-50%) for OA, 61% (95% CI 43-77%) for MMT, and 85% (95% CI 72-94%) for medial meniscal root tears (MMRT). For the population with OA, Factors significantly associated with MME included radiographic OA [OR 4.24; 95% CI 3.07-5.84; P < 0.0001], bone marrow lesions [OR, 3.35; 95% CI 1.61-6.99; P = 0.0013], cartilage damage [OR, 3.25; 95% CI 1.60-6.61; P = 0.0011], and higher body mass index (BMI) [MD, 1.81; 95% CI 1.15-2.48; P < 0.0001]. Factors strongly associated with increased risk of MME for MMT included medial meniscal root [OR, 8.39; 95% CI 2.84-24.82; P < 0.0001] and radial tears [OR, 2.64; 95% CI 1.18-5.92; P < 0.0001].

CONCLUSION

Radiographic OA, bone marrow lesions, cartilage damage, and higher BMI were significantly associated with concomitant MME with OA. Furthermore, medial meniscal root and radial tears were significantly associated with an increased risk of MME in patients with MMT.

LEVEL OF EVIDENCE

IV.

Quantitative CT of the knee in the IMI-APPROACH osteoarthritis cohort: Association of bone mineral density with radiographic disease severity, meniscal coverage and meniscal extrusion

OBJECTIVE

Osteoarthritis (OA) is a highly prevalent chronic condition. The subchondral bone plays an important role in onset and progression of OA making it a potential treatment target for disease-modifying therapeutic approaches. However, little is known about changes of periarticular bone mineral density (BMD) in OA and its relation to meniscal coverage and meniscal extrusion at the knee. Thus, the aim of this study was to describe periarticular BMD in the Applied Public-Private Research enabling OsteoArthritis Clinical Headway (APPROACH) cohort at the knee and to analyze the association with structural disease severity, meniscal coverage and meniscal extrusion.

DESIGN

Quantitative CT (QCT), MRI and radiographic examinations were acquired in 275 patients with knee osteoarthritis (OA). QCT was used to assess BMD at the femur and tibia, at the cortical bone plate (Cort) and at the epiphysis at three locations: subchondral (Sub), mid-epiphysis (Mid) and adjacent to the physis (Juxta). BMD was evaluated for the medial and lateral compartment separately and for subregions covered and not covered by the meniscus. Radiographs were used to determine the femorotibial angle and were evaluated according to the Kellgren and Lawrence (KL) system. Meniscal extrusion was assessed from 0 to 3.

RESULTS

Mean BMD differed significantly between each anatomic location at both the femur and tibia (p < 0.001) in patients with KL0. Tibial regions assumed to be covered with meniscus in patients with KL0 showed lower BMD at Sub (p < 0.001), equivalent BMD at Mid (p = 0.07) and higher BMD at Juxta (p < 0.001) subregions compared to regions not covered with meniscus. Knees with KL2-4 showed lower Sub (p = 0.03), Mid (p = 0.01) and Juxta (p < 0.05) BMD at the medial femur compared to KL0/1. Meniscal extrusion grade 2 and 3 was associated with greater BMD at the tibial Cort (p < 0.001, p = 0.007). Varus malalignment is associated with significant greater BMD at the medial femur and at the medial tibia at all anatomic locations.

CONCLUSION

BMD within the epiphyses of the tibia and femur decreases with increasing distance from the articular surface. Knees with structural OA (KL2-4) exhibit greater cortical BMD values at the tibia and lower BMD at the femur at the subchondral level and levels beneath compared to KL0/1. BMD at the tibial cortical bone plate is greater in patients with meniscal extrusion grade 2/3.

Earlier and More Severe Cartilage Degeneration Occurs After Meniscal Tears in Juvenile Rabbits Compared with Adults

OBJECTIVE

To compare the severity of cartilage degeneration after meniscal tears between juvenile and adult rabbits.

DESIGN

This study included 20 juvenile rabbits (2 weeks after birth) and 20 adult rabbits (6 months after birth). Meniscal tears were prepared in the anterior horn of medial menisci of right knees. Rabbits were sacrificed at 1, 3, 6, and 12 weeks postoperatively. Cartilage degenerations in the medial femoral condyle and medial tibial plateau were evaluated macroscopically and histologically. The semiquantitative assessment of cartilage degeneration was graded by macroscopic Outerbridge scoring system and histological Osteoarthritis Research Society International (OARSI) scoring system.

RESULTS

In juvenile rabbits, the morphologically intact cartilage and normal extracellular matrix architecture were observed at the first week postoperatively. Mild uneven cartilage surface and toluidine blue depletion in the medial femoral condyle were observed on histological assessment at 3 weeks postoperatively. The worsened cartilage deterioration demonstrating chondral fibrillation, prominent cell death, and glycosaminoglycan (GAG) release was observed at 6 and 12 weeks postoperatively. In adult rabbits, only mild cartilage degeneration was observed in the medial femoral condyle at 12 weeks postoperatively. The outcomes of Outerbridge and OARSI scores were consistent with the aforementioned findings in juvenile and adult rabbits.

CONCLUSIONS

Our study validated that earlier and more severe cartilage degenerations were observed in juvenile rabbits after meniscal tears compared with adult rabbits. Moreover, the post-tear cartilage degeneration demonstrated regional specificity corresponded to the tear position. However, caution is warranted when extrapolating results of animal models to humans.

Modeling the Impact of Meniscal Tears on von Mises Stress of Knee Cartilage Tissue

The present study aims to explore the stressed state of cartilage using various meniscal tear models. To perform this research, the anatomical model of the knee joint was developed and the nonlinear mechanical properties of the cartilage and meniscus were verified. The stress–strain curve of the meniscus was obtained by testing fresh tissue specimens of the human meniscus using a compression machine. The results showed that the more deteriorated meniscus had greater stiffness, but its integrity had the greatest impact on the growth of cartilage stresses. To confirm this, cases of radial, longitudinal, and complex tears were examined. The methodology and results of the study can assist in medical diagnostics for meniscus treatment and replacement.

Healthy and Osteoarthritis-Affected Joints Facing the Cellular Crosstalk

Osteoarthritis (OA) is a chronic, progressive, severely debilitating, and multifactorial joint disease that is recognized as the most common type of arthritis. During the last decade, it shows an incremental global rise in prevalence and incidence. The interaction between etiologic factors that mediate joint degradation has been explored in numerous studies. However, the underlying processes that induce OA remain obscure, largely due to the variety and complexity of these mechanisms. During synovial joint dysfunction, the osteochondral unit undergoes cellular phenotypic and functional alterations. At the cellular level, the synovial membrane is influenced by cartilage and subchondral bone cleavage fragments and extracellular matrix (ECM) degradation products from apoptotic and necrotic cells. These "foreign bodies" serve as danger-associated molecular patterns (DAMPs) that trigger innate immunity, eliciting and sustaining low-grade inflammation in the synovium. In this review, we explore the cellular and molecular communication networks established between the major joint compartments-the synovial membrane, cartilage, and subchondral bone of normal and OA-affected joints.

Grinding, Clicking, and Pivot Pain Resolve in Most Patients After Knee Arthroscopy

PURPOSE

To determine whether knee arthroscopy alleviates the symptom constellation of knee grinding/clicking, catching/locking, and pivot pain.

METHODS

One-year follow-up data from 584 consecutive subjects who underwent knee arthroscopy from August 2012 to December 2019 were collected prospectively. Subjects reported frequency of knee grinding/clicking, catching/locking, and/or pivot pain preoperatively and 1 and 2 years postoperatively. A single surgeon performed each procedure and documented all intraoperative pathology. We measured the postoperative resolution or persistence of these symptoms and used multivariable regression models to identify preoperative demographic and clinical variables that predicted symptom persistence. We also assessed changes in the Pain, Activities of Daily Living, and Quality of Life subscales of the Knee Injury and Osteoarthritis Outcome Score (KOOS).

RESULTS

Postoperative symptom resolution was more likely for grinding/clicking (65.6%) and pivot pain (67.8%) than for catching/locking (44.1%). Smoking status, overweight/obesity, absence of meniscal tear, and number of compartments with focal cartilage lesions predicted persistence of 1 or more patient-reported knee symptoms. KOOS subscale scores consistently improved by at least one standard deviation. Individuals who had resolution of patient-reported knee symptoms exhibited roughly 2-fold improvements in KOOS Pain, ADL and Quality of Life scores compared with those whose symptoms persisted. Persistence of pivot pain was associated with the least improvement of the 3 KOOS subscales.

CONCLUSIONS

Two in three patients with grinding/clicking or pivot pain experience symptom resolution after knee arthroscopy, although catching/locking is more likely to persist. Smoking status, overweight/obesity, absence of meniscal tear, and number of compartments with focal cartilage lesions predict symptom persistence after knee arthroscopy.

LEVEL OF EVIDENCE

Therapeutic Level IV, retrospective cohort analysis of prospective data.

Molecular crosstalk between articular cartilage, meniscus, synovium, and subchondral bone in osteoarthritis

AIMS

Osteoarthritis (OA) is a common degenerative joint disease worldwide, which is characterized by articular cartilage lesions. With more understanding of the disease, OA is considered to be a disorder of the whole joint. However, molecular communication within and between tissues during the disease process is still unclear. In this study, we used transcriptome data to reveal crosstalk between different tissues in OA.

METHODS

We used four groups of transcription profiles acquired from the Gene Expression Omnibus database, including articular cartilage, meniscus, synovium, and subchondral bone, to screen differentially expressed genes during OA. Potential crosstalk between tissues was depicted by ligand-receptor pairs.

RESULTS

During OA, there were 626, 97, 1,060, and 2,330 differentially expressed genes in articular cartilage, meniscus, synovium, and subchondral bone, respectively. Gene Ontology enrichment revealed that these genes were enriched in extracellular matrix and structure organization, ossification, neutrophil degranulation, and activation at different degrees. Through ligand-receptor pairing and proteome of OA synovial fluid, we predicted ligand-receptor interactions and constructed a crosstalk atlas of the whole joint. Several interactions were reproduced by transwell experiment in chondrocytes and synovial cells, including TNC-NT5E, TNC-SDC4, FN1-ITGA5, and FN1-NT5E. After lipopolysaccharide (LPS) or interleukin (IL)-1β stimulation, the ligand expression of chondrocytes and synovial cells was upregulated, and corresponding receptors of co-culture cells were also upregulated.

CONCLUSION

Each tissue displayed a different expression pattern in transcriptome, demonstrating their specific roles in OA. We highlighted tissue molecular crosstalk through ligand-receptor pairs in OA pathophysiology, and generated a crosstalk atlas. Strategies to interfere with these candidate ligands and receptors may help to discover molecular targets for future OA therapy.Cite this article: Bone Joint Res 2022;11(12):862-872.

Internal tibial torsion is associated with medial meniscus posterior horn tears

PURPOSE

Risk factors for meniscal tears play a decisive role in deciding on treatment and rehabilitation. The purpose of this study was to investigate the effect of tibial rotation on medial meniscus posterior horn tears (MMPHTs).

METHODS

This study is a retrospective case-control study. Fifty patients with meniscal tears and 57 knees with intact meniscus were compared. Tibial rotation, femoral version, tibial slope and knee varus were measured in each participant. Knee osteoarthritis was classified according to the Kellgren-Lawrence classification. Demographic characteristics were noted.

RESULTS

There were significant differences in the mean tibial torsion angles and mean mechanical axes between the groups. The mean tibial rotation and mean mechanical axis were 26.3° ± 6.7 and 3.7° ± 2.7 in the MMPHT group and 30.3° ± 8.4 and 2.05° ± 2.7 in the control group, respectively (p = 0.008, p = 0.002).

CONCLUSION

The current retrospective study has shown that tibial rotation is markedly reduced in patients with MMPHTs. Although the actual mechanism is not clear, the internal torsion of the tibia causes a decrease in the foot progression angle and increases the knee adduction moment, which in turn increases the medial tibial contact pressure. Internal torsion of the tibia, such as knee varus, may play a role in the aetiology of MMPHTs by this way. Whilst there was a significant difference in the mean varus and tibial torsion between the groups, there was no significant difference in the mean femoral version or tibial slope.

LEVEL OF EVIDENCE

III.

Increased medial meniscus extrusion led to worse clinical outcomes after medial opening-wedge high tibial osteotomy

PURPOSE

Given that no studies have assessed the correlation between improvements in medial meniscus extrusion (MME) and clinical outcomes after medial opening-wedge high tibial osteotomy (MOWHTO), the present study aimed to measure the improvement in MME after MOWHTO and to investigate the correlation between the remaining postoperative MME and MOWHTO clinical outcomes by subgroup analysis.

METHODS

This study included 79 patients (80 knees) who underwent MOWHTO with a minimum follow-up of 2 years. MME was measured pre- and postoperatively through magnetic resonance imaging after an average of 19.8 months following MOWHTO surgery. Clinical outcomes were evaluated according to the Knee Injury and Osteoarthritis Outcome Score (KOOS), the Tegner Activity Scale, and the Short-Form 36 questionnaire. In subgroup analysis, postoperative MME was classified into non-pathologic (≤ 3 mm) and pathologic (> 3 mm) groups. The clinical outcomes of the two groups were compared using Mann-Whitney U tests. A regression analysis was performed to determine the preoperative and postoperative characteristics associated with the improvement of MME.

RESULTS

The mean (± standard deviation) values for pre- and postoperative MME were 3.6 (± 1.8) mm and 2.8 (± 1.5) mm, respectively (p < 0.001). In the subgroup analysis of postoperative MME, the non-pathologic group showed better improvement of KOOS than the pathologic group. Preoperative hip-knee-ankle angle was correlated with the improvement of medial meniscal extrusion in both univariate (p = 0.049) and multivariate (p = 0.015) analyses.

CONCLUSION

The MME improved after MOWHTO, and the clinical outcomes were better for patients with a postoperative MME of less than 3 mm than for those with more than 3 mm. MME improvement after MOWHTO was correlated with preoperative varus alignment of the lower extremities.

LEVEL OF EVIDENCE

III (Retrospective cohort study).

Patient's subjective knee function 3-5 years following partial meniscectomy or meniscus repair compared to a normal population: a retrospective cohort study

Purpose

Evaluate patient-reported knee function after arthroscopic partial meniscectomy (APM) and meniscus suture repair in two different age cohorts compared with a normal population.

Method

Arthroscopic meniscus surgery was performed on 421 patients at Skåne University Hospital from 2010 to 2014, with a mean (SD) follow-up of 4.2 (1.4) years. Patients and controls were divided into two age cohorts; 18-34 years (younger) and 35-54 years (middle-aged) as well as according to surgery performed; either solely meniscus surgery or with concurrent anterior cruciate ligament reconstruction (ACLR). The outcome is measured with the five subscales of the Knee and Osteoarthritis Outcome Score (KOOS).

Results

No significant difference in outcome after all studied types of meniscus surgeries between younger-aged and middle-aged patients.Younger patients with APM or meniscus suture repair, with or without, ACLR score lower than the normal population in all subscales of KOOS (p<0.001), except in Activities of Daily Living (ADL) for meniscus suture patients.Middle-aged patients with APM score lower in all subscales than the normal population (p≤0.009). Those with meniscus suture repair score lower than the normal population only for the subscales Sport/Rec and quality of life (p<0.001).Both younger-aged and middle-aged patients achieve better KOOS values after meniscus suture repair and ACLR than after all other combinations of surgery.

Conclusion

Patients with meniscus injuries do not reach the same KOOS score as the normal population, irrespective of age or type of meniscus surgery performed. However, combined with ACLR in younger-aged and middle-aged patients, meniscus suture gives a better subjective outcome than isolated meniscus surgery.

Degenerative Meniscus in Knee Osteoarthritis: From Pathology to Treatment

Knee osteoarthritis is a common degenerative joint disease characterized by chronic knee pain and disability in daily living. The lesion can involve the cartilage as well as the synovium, bone, ligaments, and meniscus, indicating a complicated pathology for knee osteoarthritis. The association with the meniscus has recently attracted much attention. Meniscal tears can initiate and progress knee osteoarthritis, with deleterious effects on the important roles of the meniscus in load distribution, shock absorption, and stability of the knee joint. Degenerative meniscus lesions are commonly observed in elderly people, but they have less impact on the prognosis of osteoarthritis. However, they are often accompanied by meniscal extrusion, which substantially decreases the hoop function of the meniscus and increases the risk of knee osteoarthritis. When surgical treatment is necessary, meniscal tears should be repaired to the greatest extent possible to preserve meniscus function. Long-term studies show better clinical outcomes and less degenerative osteoarthritis changes following meniscal repair than following partial meniscectomy. For meniscal extrusion repair, centralization techniques have been proposed that involve suturing the meniscus-capsule complex to the edge of the tibial plateau. Advancements in orthobiologics, such as platelet-rich plasma or stem cell therapy, have the potential to prevent the initiation or progression of osteoarthritis.

Cartilage and Meniscus Injuries Are More Common in Patients Undergoing Delayed Multiligament Reconstruction

The purpose of this study was to describe the pattern of meniscus and cartilage pathology in multiligament knee injuries (MLKIs) and determine the relationship between surgical timing and injury mechanism with degree of intra-articular injury. Patients with surgically treated MLKIs over a 15-year period were retrospectively reviewed and grouped based on surgical intervention, time to intervention, and injury mechanism. The presence or absence of meniscus and chondral injury were recorded at the time of surgery. Surgical intervention within 6 weeks of injury was deemed acute, while surgery occurring more than 6 weeks from injury was classified as delayed. Over the 15-year study period, 207 patients with MLKIs were identified. Compared with acutely managed patients, the delayed intervention group had significantly more meniscus (p = 0.03) and cartilage (p < 0.01) pathology. Meniscus injury rates in MLKIs sustained during sporting activity did not differ from nonsporting injuries (p = 0.63). However, the nonsporting group had significantly more chondral injuries (p < 0.01). High-energy injury mechanism was associated with increased cartilage (p = 0.02), but not meniscus (p = 0.61) injury rates. In conclusion, surgical reconstruction of MLKIs delayed for more than 6 weeks was associated with increased meniscus and cartilage pathology.

Knee Joint Menisci Are Shock Absorbers: A Biomechanical In-Vitro Study on Porcine Stifle Joints

The aim of this biomechanical in vitro study was to answer the question whether the meniscus acts as a shock absorber in the knee joint or not. The soft tissue of fourteen porcine knee joints was removed, leaving the capsuloligamentous structures intact. The joints were mounted in 45° neutral knee flexion in a previously validated droptower setup. Six joints were exposed to an impact load of 3.54 J, and the resultant loss factor (η) was calculated. Then, the setup was modified to allow sinusoidal loading under dynamic mechanical analysis (DMA) conditions. The remaining eight knee joints were exposed to 10 frequencies ranging from 0.1 to 5 Hz at a static load of 1210 N and a superimposed sinusoidal load of 910 N (2.12 times body weight). Forces (F) and deformation (l) were continuously recorded, and the loss factor (tan δ) was calculated. For both experiments, four meniscus states (intact, medial posterior root avulsion, medial meniscectomy, and total lateral and medial meniscectomy) were investigated. During the droptower experiments, the intact state indicated a loss factor of η = 0.1. Except for the root avulsion state (−15%, p = 0.12), the loss factor decreased (p &lt; 0.046) up to 68% for the total meniscectomy state (p = 0.028) when compared to the intact state. Sinusoidal DMA testing revealed that knees with an intact meniscus had the highest loss factors, ranging from 0.10 to 0.15. Any surgical manipulation lowered the damping ability: Medial meniscectomy resulted in a reduction of 24%, while the resection of both menisci lowered tan δ by 18% compared to the intact state. This biomechanical in vitro study indicates that the shock-absorbing ability of a knee joint is lower when meniscal tissue is resected. In other words, the meniscus contributes to the shock absorption of the knee joint not only during impact loads, but also during sinusoidal loads. The findings may have an impact on the rehabilitation of young, meniscectomized patients who want to return to sports. Consequently, such patients are exposed to critical loads on the articular cartilage, especially when performing sports with recurring impact loads transmitted through the knee joint surfaces.

Preoperative Meniscal Extrusion Predicts Unsatisfactory Clinical Outcomes and Progression of Osteoarthritis after Isolated Partial Medial Meniscectomy: A 5-Year Follow-Up Study

The objective of this study was to examine the association between preoperative meniscal extrusion of patients undergoing partial medial meniscectomy with clinical outcomes and progression of osteoarthritis and to determine the extent of meniscal extrusion associated with unsatisfactory clinical outcomes and progression of osteoarthritis. Ninety-five patients who underwent partial medial meniscectomy with a minimum follow-up of 5 years were retrospectively reviewed. Preoperative meniscal extrusion was evaluated with magnetic resonance imaging. Patients were assessed preoperatively and postoperatively with Lysholm and International Knee Documentation Committee (IKDC) subjective scores for clinical outcomes and with IKDC radiographic scale for osteoarthritis. An ANOVA (Analysis of Variance) was used to analyze the variations in meniscal extrusion and the clinical and radiological outcomes. A regression analysis was performed to identify factors that affect preoperative medial meniscus extrusion and that influence results after partial meniscectomy. An optimal cutoff value for meniscal extrusion associated with unsatisfactory clinical outcomes and progression of osteoarthritis was established. Significance was set at p < 0.05. The mean ± SD preoperative and postoperative Lysholm scores were 59.6 ± 15.5 versus 83.8 ± 13.1 (p < 0.001) and the mean preoperative and postoperative IKDC subjective scores were 59.4 ± 16.8 versus 82.0 ± 15.8 (p < 0.001). Meniscal extrusion greater than 2.2 mm (sensitivity, 84%; specificity, 81%) and 2.8 mm (sensitivity, 73%; specificity, 85%) was associated with unsatisfactory (poor/fair) Lysholm and IKDC subjective scores, respectively. The progression of osteoarthritis, characterized as a change of at least one category on the IKDC radiographic scale, occurred when meniscal extrusion was greater than 2.2 mm (sensitivity, 63%; specificity, 75%). Patients with higher body mass index (BMI) had significantly greater meniscal extrusion that patients with normal BMI (p < 0.001). The medial meniscus was more extruded in patients with horizontal and root tears. In conclusion, patients with preoperative meniscal extrusion of 2.2 mm or greater had unsatisfactory clinical outcomes and progression of osteoarthritis after partial medial meniscectomy at a minimum of 5 years follow-up. Higher BMI and horizontal and root tears were associated with greater preoperative meniscal extrusion.

Serial Improvement of Medial Meniscus Extrusion Following Medial Open-Wedge High Tibial Osteotomy Does Not Correlate With Clinical Outcomes and Arthroscopic Articular Cartilage Improvement

PURPOSE

To assess serial change up to 2 years in medial meniscus extrusion (MME) following medial open-wedge high tibial osteotomy (MOWHTO) and to determine whether postoperative changes in MME correlated with clinical outcomes and arthroscopic articular cartilage status.

METHODS

This study included 26 patients from December 2016 to March 2018 who underwent MOWHTO for primary medial osteoarthritis with varus malalignment. Second-look arthroscopy with plate removal was performed at postoperative 2 years. MME was consecutively measured using coronal magnetic resonance imaging at preoperative and postoperative 3 months, 6 months, 1.5 years, and 2 years. We also assessed which preoperative parameters could reflect the postoperative changes in MME and evaluated whether postoperative clinical outcomes and arthroscopic articular cartilage improvement would be influenced by the MME changes.

RESULTS

Regarding the postoperative serial changes in MME values, significant improvement in MME was noted from postoperative 6 months (P = .003), and thereafter, mean MME was further improved with time until postoperative 2 years (P < .001). Regarding the correlation between preoperative parameters and MME changes, preoperative medial proximal tibial angle (MPTA) showed significant correlations in univariate and multivariate analysis (P = .004 and P = .004, respectively). Meanwhile, changes in MME were not correlated with postoperative clinical outcomes or arthroscopic articular cartilage improvement.

CONCLUSION

After MOWHTO, MME improved with time and was significantly correlated with preoperative MPTA. However, the changes in MME after MOWHTO did not reflect postoperative clinical and arthroscopic articular cartilage improvement.

LEVEL OF EVIDENCE

IV, case series.

Meniscus position and size in knees with versus without structural knee osteoarthritis progression: data from the osteoarthritis initiative

OBJECTIVE

To explore whether and which quantitative 3D measures of medial and/or lateral meniscus position and size are associated with subsequent medial femorotibial structural progression of knee osteoarthritis and to determine the correlation between central slice and total meniscus measures.

MATERIALS AND METHODS

Knees with radiographic osteoarthritis from Osteoarthritis Initiative participants with longitudinal medial MRI-based cartilage thickness and radiographic joint space width (JSW) loss over 12 months were selected. These 37 structural progressor knees (64.7 ± 8.0y, 30.2 ± 4.6 kg/m², 35% men) were matched 1:1 to 37 non-progressor knees (64.6 ± 9.8y, 30.2 ± 4.4 kg/m², 35% men) without cartilage thickness or JSW loss. Quantitative measures of meniscus position and size were computed from manual segmentations of coronal baseline MRIs. Cohen's D was used as measure of effect size.

RESULTS

Maximum extrusion distance of the total medial meniscus and mean extrusion in the central 5 and in the central slice were greater for progressor than non-progressor knees (Cohen's D 0.58-0.66). No significant differences were observed for medial tibial coverage or mean extrusion (entire meniscus). Among medial meniscus morphology measures, only mean height differed between progressor vs non-progressor knees (Cohen's D 0.40). Among lateral meniscus measures, height and volume were greater in progressor vs. non-progressor knees (Cohen's D 0.46-0.83). Mean extrusion measures were highly correlated between the entire meniscus and the central (r = 0.88) or the central 5 (r = 0.93) slices.

CONCLUSIONS

3D maximum and central medial meniscus extrusion may serve as predictors for subsequent structural progression. Central meniscus extrusion measures could substitute 3D extrusion measurement across the entire meniscus.

Effect of Suppression of Rotational Joint Instability on Cartilage and Meniscus Degeneration in Mouse Osteoarthritis Model

OBJECTIVE

Joint instability and meniscal dysfunction contribute to the onset and progression of knee osteoarthritis (OA). In the destabilization of the medial meniscus (DMM) model, secondary OA occurs due to the rotational instability and increases compressive stress resulting from the meniscal dysfunction. We created a new controlled abnormal tibial rotation (CATR) model that reduces the rotational instability that occurs in the DMM model. So, we aimed to investigate whether rotational instability affects articular cartilage degeneration using the DMM and CATR models, as confirmed using histology and immunohistochemistry.

DESIGN

Twelve-week-old male mice were randomized into 3 groups: DMM group, CATR group, and INTACT group (right knee of the DMM group). After 8 and 12 weeks, we performed the tibial rotational test, safranin-O/fast green staining, and immunohistochemical staining for tumor necrosis factor (TNF)-α and metalloproteinase (MMP)-13.

RESULTS

The rotational instability in the DMM group was significantly higher than that of the other groups. And articular cartilage degeneration was higher in the DMM group than in the other groups. However, meniscal degeneration was observed in both DMM and CATR groups. The TNF-α and MMP-13 positive cell rates in the articular cartilage of the CATR group were lower than those in the DMM group.

CONCLUSIONS

We found that the articular cartilage degeneration was delayed by controlling the rotational instability caused by meniscal dysfunction. These findings suggest that suppression of rotational instability in the knee joint may be an effective therapeutic measure for preventing OA progression.

Post-Traumatic Osteoarthritis Assessment in Emerging and Advanced Pre-Clinical Meniscus Repair Strategies: A Review

Surgical repair of meniscus injury is intended to help alleviate pain, prevent further exacerbation of the injury, restore normal knee function, and inhibit the accelerated development of post-traumatic osteoarthritis (PTOA). Meniscus injuries that are treated poorly or left untreated are reported to significantly increase the risk of PTOA in patients. Current surgical approaches for the treatment of meniscus injuries do not eliminate the risk of accelerated PTOA development. Through recent efforts by scientists to develop innovative and more effective meniscus repair strategies, the use of biologics, allografts, and scaffolds have come into the forefront in pre-clinical investigations. However, gauging the extent to which these (and other) approaches inhibit the development of PTOA in the knee joint is often overlooked, yet an important consideration for determining the overall efficacy of potential treatments. In this review, we catalog recent advancements in pre-clinical therapies for meniscus injuries and discuss the assessment methodologies that are used for gauging the success of these treatments based on their effect on PTOA severity. Methodologies include histopathological evaluation of cartilage, radiographic evaluation of the knee, analysis of knee function, and quantification of OA predictive biomarkers. Lastly, we analyze the prevalence of these methodologies using a systemic PubMed® search for original scientific journal articles published in the last 3-years. We indexed 37 meniscus repair/replacement studies conducted in live animal models. Overall, our findings show that approximately 75% of these studies have performed at least one assessment for PTOA following meniscus injury repair. Out of this, 84% studies have reported an improvement in PTOA resulting from treatment.

Influence of Menisci on Tibiofemoral Contact Mechanics in Human Knees: A Systematic Review

Purpose: Menisci transfer axial loads, while increasing the load-bearing tibiofemoral contact area and decreasing tibiofemoral contact pressure (CP). Numerous clinical and experimental studies agree that an increased CP is one predominant indicator for post-traumatic osteoarthritis (PTOA) of the knee joint. However, due to the immense variability in experimental test setups and wide range of treatment possibilities in meniscus surgery, it is difficult to objectively assess their impact on the CP determination, which is clearly crucial for knee joint health. Therefore, the aim of this systematic review is to investigate the influence of different meniscal injuries and their associated surgical treatments on the CP. Secondly, the influence of different test setups on CP measurements is assessed. On the basis of these results, we established the basis for recommendations for future investigations with the aim to determine CPs under different meniscal states. Methods: This review was conducted in accordance with the PRISMA guidelines. Studies were identified through a systematic literature search in Cochrane, PubMed and Web of Science databases. Literature was searched through pre-defined keywords and medical subject headings. Results: This review indicates a significant increase of up to 235% in peak CP when comparing healthy joints and intact menisci with impaired knee joints, injured or resected menisci. In addition, different test setups were indicated to have major influences on CP: The variety of test setups ranged from standard material testing machines, including customized setups via horizontal and vertical knee joint simulators, through to robotic systems. Differences in applied axial knee joint loads ranged from 0 N up to 2,700 N and resulted unsurprisingly in significantly different peak CPs of between 0.1 and 12.06 MPa. Conclusion: It was shown that untreated traumatic meniscal tears result in an increased CP. Surgical repair intervention were able to restore the CP comparable to the healthy, native condition. Test setup differences and particularly axial joint loading variability also led to major CP differences. In conclusion, when focusing on CP measurements in the knee joint, transparent and traceable in vitro testing conditions are essential to allow researchers to make a direct comparison between future biomechanical investigations.

Occupational risk factors for meniscal lesions: a systematic review and meta-analysis

BACKGROUND

Meniscal lesions are common and are associated with the development of knee osteoarthritis. Knee-straining activities at work such as kneeling or squatting cause high biomechanical stresses on the knee joints that can lead to acute or chronic injuries. The objective of this systematic review is to update the evidence on the potential relationship between occupational risk factors and meniscal lesions.

METHODS

We searched the Medline, Embase and Web of Science databases until August 2021 to identify epidemiological observational studies on the association between occupational risk factors and meniscal lesions. Study selection, data extraction and risk of bias assessment were performed independently by two reviewers. Effect measures were extracted from individual studies and pooled with random effects meta-analysis. Heterogeneity analyses were conducted. We used GRADE (Grades of Recommendations, Assessment, Development and Evaluation) to assess the overall quality of evidence.

RESULTS

The database search resulted in 11,006 references, and 46 additional studies were identified through hand search. Twenty-two studies (represented in 25 publications) met the predefined eligibility criteria and nine records were included in the meta-analysis. There was only one study with an overall low risk of bias. Significant associations between occupational risk factors and the development of meniscal lesions were found for kneeling (effect size (ES) 2.15, 95% CI 1.67-2.76), squatting (ES 2.01, 95% CI 1.34-3.03), climbing stairs (ES 2.28, 95% CI 1.58-3.30), lifting and carrying weights ≥ 10 kg (ES 1.63, 95% CI 1.35-1.96), lifting and carrying weights ≥ 25 kg (ES 1.56, 95% CI 1.08-2.24), playing football on a professional level (ES 5.22, 95% CI 3.24-8.41), working as a hard coal miner (ES 5.23, 95% CI 2.16-12.69) and floor layers (ES 1.99, 95% CI 1.43-2.78). The overall quality of evidence according GRADE was moderate to low.

CONCLUSION

We found consistent evidence of an increased risk of meniscal lesions by occupational knee-straining exposures. Our findings are important for the development of preventive strategies to reduce work-related knee disorders and work absence.

TRIAL REGISTRATION

PROSPERO (registration no. CRD42020196279 ).

The Perimensical Capsule: Potential Supporting Structure Surrounding Meniscus

This study analyzed the morphological and biomechanical characteristics of perimeniscal capsule in knee joint thus establishing the roles of these tissues. A total of 10 human cadaver knees were used in this study. Medial meniscus and the adjacently surrounding joint capsules were harvested then sectioned both axially and coronally, followed by scanning electron microscopy analysis. The medial meniscus (anterior, middle, posterior) and the adjacent perimeniscal capsules (superior, peripheral) were biomechanically assessed to ascertain the tensile modulus. Among the perimeniscal capsules, the peripherally located capsules were morphologically different from the superiorly located capsules: The peripheral perimeniscal capsule was thicker and showed circumferentially oriented fibers whereas the superior perimeniscal capsule fibers were thinner and arranged in vertical orientation. The peripheral capsule also yielded significantly greater tensile modulus compared with the superior capsule biomechanically. We conclude that depending on its anatomical location, the perimeniscal capsule consists of fibers of varying orientations. This may be important in maintaining the circumferential hoop tension of the meniscus especially in the presence of circumferentially oriented and thick peripheral capsule fibers, which coincidentally have higher tensile modulus.

Post-traumatic osteoarthritis progression is diminished by early mechanical unloading and anti-inflammatory treatment in mice

OBJECTIVE

Post-traumatic osteoarthritis (PTOA) is a degenerative joint disease initiated by injury. Early phase (0-7 days) treatments often include rest (unloading) and anti-inflammatory medications, but how those early interventions impact PTOA progression is unknown. We hypothesized that early unloading and anti-inflammatory treatment would diminish joint inflammation and slow PTOA progression.

DESIGN

Mice were injured with non-invasive ACL rupture followed by hindlimb unloading (HLU) or normal cage activity (ground control: GC) for 7 days, after which all mice were allowed normal cage activity. HLU and GC mice were treated with daily celecoxib (CXB; 10 mg/kg IP) or vehicle. Protease activity was evaluated using in vivo fluorescence imaging, osteophyte formation and epiphyseal trabecular bone were quantified using micro-computed tomography, and synovitis and articular cartilage were evaluated using whole-joint histology at 7, 14, 21, and 28 days post-injury.

RESULTS

HLU significantly reduced protease activity (-22-30% compared to GC) and synovitis (-24-50% relative to GC) at day 7 post-injury (during unloading), but these differences were not maintained at later timepoints. Similarly, trabecular bone volume was partially preserved in HLU mice at during unloading (-14-15% BV/TV for HLU mice, -21-22% for GC mice relative to uninjured), but these differences were not maintained during reloading. Osteophyte volume was reduced by both HLU and CXB, but there was not an additive effect of these treatments (HLU: -46%, CXB: -30%, HLU + CXB: -35% relative to vehicle GC at day 28).

CONCLUSIONS

These data suggest that early unloading following joint injury can reduce inflammation and potentially slow PTOA progression.

Association between medial meniscus extrusion under weight-bearing conditions and pain in early-stage knee osteoarthritis

PURPOSE

This study aimed to investigate the association between the severity of medial meniscus extrusion (MME) under weight bearing and pain in patients with early-stage knee osteoarthritis (OA).

METHODS

Twenty-eight patients with symptomatic early-stage knee OA (Kellgren and Lawrence grade ≤ 2) who visited our outpatient clinic between 2016 and 2018 were included in this cross-sectional study (mean age: 58.0 ± 11.6 years, female: n = 10). MME was evaluated under weight-bearing conditions using ultrasonography. Patients were divided into two groups according to the severity of MME under weight bearing: those with MME ≥ 3 mm were assigned to the severe group, whereas those with MME < 3 mm were assigned to the mild group. The knee injury osteoarthritis outcome score (KOOS) system was used to evaluate knee pain. The incidence of bone marrow lesions (BMLs) was evaluated using magnetic resonance images.

RESULTS

The KOOS pain score was significantly lower in the severe group than in the mild group (P < 0.05). The incidence of BMLs was significantly higher in the severe group (69%) than in the mild group (7%) (P < 0.001).

CONCLUSION

Patients with early-stage knee OA who have greater MME under weight-bearing have more intense knee pain and a higher incidence of BMLs.