Meniscus pathology, osteoarthritis and the treatment controversy

Knee Osteoarthritis: A Review of Pathogenesis and State-Of-The-Art Non-Operative Therapeutic Considerations

Being the most common musculoskeletal progressive condition, osteoarthritis is an interesting target for research. It is estimated that the prevalence of knee osteoarthritis (OA) among adults 60 years of age or older is approximately 10% in men and 13% in women, making knee OA one of the leading causes of disability in elderly population. Today, we know that osteoarthritis is not a disease characterized by loss of cartilage due to mechanical loading only, but a condition that affects all of the tissues in the joint, causing detectable changes in tissue architecture, its metabolism and function. All of these changes are mediated by a complex and not yet fully researched interplay of proinflammatory and anti-inflammatory cytokines, chemokines, growth factors and adipokines, all of which can be measured in the serum, synovium and histological samples, potentially serving as biomarkers of disease stage and progression. Another key aspect of disease progression is the epigenome that regulates all the genetic expression through DNA methylation, histone modifications, and mRNA interference. A lot of work has been put into developing non-surgical treatment options to slow down the natural course of osteoarthritis to postpone, or maybe even replace extensive surgeries such as total knee arthroplasty. At the moment, biological treatments such as platelet-rich plasma, bone marrow mesenchymal stem cells and autologous microfragmented adipose tissue containing stromal vascular fraction are ordinarily used. Furthermore, the latter two mentioned cell-based treatment options seem to be the only methods so far that increase the quality of cartilage in osteoarthritis patients. Yet, in the future, gene therapy could potentially become an option for orthopedic patients. In the following review, we summarized all of the latest and most important research in basic sciences, pathogenesis, and non-operative treatment.

Knee Osteoarthritis: A Review of Pathogenesis and State-Of-The-Art Non-Operative Therapeutic Considerations

Being the most common musculoskeletal progressive condition, osteoarthritis is an interesting target for research. It is estimated that the prevalence of knee osteoarthritis (OA) among adults 60 years of age or older is approximately 10% in men and 13% in women, making knee OA one of the leading causes of disability in elderly population. Today, we know that osteoarthritis is not a disease characterized by loss of cartilage due to mechanical loading only, but a condition that affects all of the tissues in the joint, causing detectable changes in tissue architecture, its metabolism and function. All of these changes are mediated by a complex and not yet fully researched interplay of proinflammatory and anti-inflammatory cytokines, chemokines, growth factors and adipokines, all of which can be measured in the serum, synovium and histological samples, potentially serving as biomarkers of disease stage and progression. Another key aspect of disease progression is the epigenome that regulates all the genetic expression through DNA methylation, histone modifications, and mRNA interference. A lot of work has been put into developing non-surgical treatment options to slow down the natural course of osteoarthritis to postpone, or maybe even replace extensive surgeries such as total knee arthroplasty. At the moment, biological treatments such as platelet-rich plasma, bone marrow mesenchymal stem cells and autologous microfragmented adipose tissue containing stromal vascular fraction are ordinarily used. Furthermore, the latter two mentioned cell-based treatment options seem to be the only methods so far that increase the quality of cartilage in osteoarthritis patients. Yet, in the future, gene therapy could potentially become an option for orthopedic patients. In the following review, we summarized all of the latest and most important research in basic sciences, pathogenesis, and non-operative treatment.

Identification of lncRNA and mRNA Biomarkers in Osteoarthritic Degenerative Meniscus by Weighted Gene Coexpression Network and Competing Endogenous RNA Network Analysis

BACKGROUND

Long noncoding RNAs (lncRNAs) play a crucial role in varieties of biological processes. This study is aimed at investigating meniscal degeneration-specific lncRNAs and mRNAs and their related networks in knee osteoarthritis (KOA).

METHODS

The dataset GSE98918, which included 24 meniscus samples and related clinical data, was downloaded from the Gene Expression Omnibus database. The differentially expressed lncRNAs and mRNAs in the meniscus between KOA and control groups were identified. Based on the enriched differentially expressed lncRNAs and mRNAs, we constructed the coexpression network using WGCNA (weighted correlation network analysis) and identified the critical module related to KOA. For mRNAs in the key module, gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses were carried out using the DAVID database. A competing endogenous RNA network (ceRNA) based on the screened mRNAs, lncRNAs, and related miRNAs was constructed to reveal presumptive biomarkers further. Finally, the hub lncRNAs and mRNAs were screened, and the diagnostic value was evaluated using a receiver operating characteristic (ROC) curve. Hub mRNAs were validated using the dataset GSE113825.

RESULTS

We screened 208 significantly differentially expressed lncRNAs and mRNAs in menisci between the KOA and non-KOA samples, which were enriched in sixteen modules using WGCNA, especially the green module. Coexpression network based on the enriched differentially expressed lncRNAs and mRNAs in the green module uncovered 5 lncRNAs and 56 mRNAs. The lncRNA-miRNA-mRNA ceRNA network revealed that lnc-HLA-DQA1-5, lnc-RP11-127H5.1.1-1, lnc-RTN2-1, IGFBP4 (insulin-like growth factor binding protein 4), and KLF2 (Kruppel-like factor 2) were significantly correlated with the meniscus degeneration of KOA. ROC curve analysis revealed that these hub lncRNAs and mRNAs showed excellent diagnostic value for KOA.

CONCLUSIONS

These hub lncRNAs and mRNAs were potential prognostic biomarkers for the meniscus degeneration of KOA. Further studies are required to validate these new biomarkers and better understand the pathological process of the meniscus degeneration of KOA.

Arthroscopic meniscectomy versus non-surgical or sham treatment in patients with MRI confirmed degenerative meniscus lesions: a protocol for an individual participant data meta-analysis

INTRODUCTION

Arthroscopic partial meniscectomy (APM) after degenerative meniscus tears is one of the most frequently performed surgeries in orthopaedics. Although several randomised controlled trials (RCTs) have been published that showed no clear benefit compared with sham treatment or non-surgical treatment, the incidence of APM remains high. The common perception by most orthopaedic surgeons is that there are subgroups of patients that do need APM to improve, and they argue that each study sample of the existing trials is not representative for the day-to-day patients in the clinic. Therefore, the objective of this individual participant data meta-analysis (IPDMA) is to assess whether there are subgroups of patients with degenerative meniscus lesions who benefit from APM in comparison with non-surgical or sham treatment.

METHODS AND ANALYSIS

An existing systematic review will be updated to identify all RCTs worldwide that evaluated APM compared with sham treatment or non-surgical treatment in patients with knee symptoms and degenerative meniscus tears. Time and effort will be spent in contacting principal investigators of the original trials and encourage them to collaborate in this project by sharing their trial data. All individual participant data will be validated for missing data, internal data consistency, randomisation integrity and censoring patterns. After validation, all datasets will be combined and analysed using a one-staged and two-staged approach. The RCTs' characteristics will be used for the assessment of clinical homogeneity and generalisability of the findings. The most important outcome will be the difference between APM and control groups in knee pain, function and quality of life 2 years after the intervention. Other outcomes of interest will include the difference in adverse events and mental health.

ETHICS AND DISSEMINATION

All trial data will be anonymised before it is shared with the authors. The data will be encrypted and stored on a secure server located in the Netherlands. No major ethical concerns remain. This IPDMA will provide the evidence base to update and tailor diagnostic and treatment protocols as well as (international) guidelines for patients for whom orthopaedic surgeons consider APM. The results will be submitted for publication in a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42017067240.

Meniscus Repair and Regeneration: A Systematic Review from a Basic and Translational Science Perspective

Meniscus injuries are among the most common athletic injuries and result in functional impairment in the knee. Repair is crucial for pain relief and prevention of degenerative joint diseases like osteoarthritis. Current treatments, however, do not produce long-term improvements. Thus, recent research has been investigating new therapeutic options for regenerating injured meniscal tissue. This review comprehensively details the current methodologies being explored in the basic sciences to stimulate better meniscus injury repair. Furthermore, it describes how these preclinical strategies may improve current paradigms of how meniscal injuries are clinically treated through a unique and alternative perspective to traditional clinical methodology.

Knee Arthroscopic Surgery in Middle-Aged Patients With Meniscal Symptoms: A 5-Year Follow-up of a Prospective, Randomized Study

Background:

Arthroscopic meniscal surgery is a common orthopaedic procedure in middle-aged patients, but the efficacy of this procedure has been questioned. In this study, we followed up the only randomized controlled trial that has shown a 1-year benefit from knee arthroscopic surgery with an exercise program compared with an exercise program alone.

Purpose:

To (1) evaluate whether knee arthroscopic surgery combined with an exercise program provided an additional 5-year benefit compared with an exercise program alone in middle-aged patients with meniscal symptoms, (2) determine whether baseline mechanical symptoms affected the outcome, and (3) compare radiographic changes between treatment groups.

Study Design:

Randomized controlled trial; Level of evidence, 1.

Methods:

Of 179 eligible patients aged 45 to 64 years, 150 were randomized to either a 3-month exercise program (nonsurgery group) or to the same exercise program plus knee arthroscopic surgery (surgery group) within 4 weeks. Radiographs were assessed, according to the Kellgren-Lawrence grade, at baseline and at the 5-year follow-up. The primary outcome was the change in Knee injury and Osteoarthritis Outcome Score (KOOS)–Pain (KOOS_PAIN) subscore from baseline to the 5-year follow-up. We performed an as-treated analysis.

Results:

A total of 102 patients completed the 5-year questionnaire. At the 5-year follow-up, both groups had significant improvement in KOOS_PAIN subscores, although there was no significant change from the 3-year scores. There was no between-group difference in the change in the KOOS_PAIN subscore from baseline to 5 years (3.2 points [95% CI, –6.1 to 12.4]; adjusted P = .403). In the surgery group, improvement was greater in patients without mechanical symptoms than in those with mechanical symptoms (mean difference, 18.4 points [95% CI, 8.7 to 28.1]; P < .001). Radiographic deterioration occurred in 60% of patients in the surgery group and 37% of those in the nonsurgery group (P = .060).

Conclusion:

Knee arthroscopic surgery combined with an exercise program provided no additional long-term benefit after 5 years compared with the exercise program alone in middle-aged patients with meniscal symptoms. Surgical outcomes were better in patients without mechanical symptoms than in patients with mechanical symptoms during the preoperative period. Radiographic changes did not differ between treatment groups.

Registration:

NCT01288768 (ClinicalTrials.gov identifier).

Three-dimensional finite-element analysis of aggravating medial meniscus tears on knee osteoarthritis

BACKGROUND

The biomechanical change during the medial meniscus damage in the process of knee osteoarthritis has not been explored. The purpose of this study was to determine the effect of aggravating medial meniscus degenerative tear on the progress of knee osteoarthritis through the finite-element simulation method.

METHODS

The three-dimensional digital model of a total-knee joint was obtained using a combination of magnetic resonance imaging and computed tomography images. Four types of medial meniscus tears were created to represent the aggravating degenerative meniscus lesions. Meniscectomy of each meniscal tear was also utilized in the simulation. The compression and shear stress of bony tissue, cartilage, and meniscus were evaluated, and meniscus extrusion of the healthy knee, postinjured knee, and postmeniscectomy knee were investigated under the posture of balanced standing.

RESULTS

Based on the results of finite-element simulation, the peak shear principal stress, peak compression principal stress, and meniscus extrusion increased gradually as the meniscus tears' region enlarged progressively (from 7.333 MPa to 15.14 MPa on medial femur and from 6 MPa to 20.94 MPa on medial tibia). The higher stress and larger meniscus extrusion displacement in all tests were observed in the flap and complex tears. The oblique tears also had a biomechanical variation of stress and meniscus extrusion in the knee joint, but their level was milder. Both the peak value of the stress and meniscus displacement increased after the meniscectomy.

CONCLUSION

In contrast to the damaged hemijoint, the stress applied on the healthy lateral hemijoint increased. The change of biomechanics was more obvious with the aggravation of meniscus injury. The advanced degenerative damage resulted in increasing stress that was more likely to cause symptomatic clinical manifestation in the knee joint and accelerate the progress of osteoarthritis. Moreover, we found that the meniscus injury caused higher stress concentration on the contralateral side of the joint. We also discovered that the meniscectomy can lead to more serious biomechanical changes, and although this technique can relieve pain over a period of time, it increased the risk of osteoarthritis (OA) occurrence.

THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE

It is clear that the meniscal lesions can cause osteoarthritic knee, but the biomechanical change during the meniscus damage period has not been explored. We have evaluated the variation of stress during the aggravating medial degenerative meniscus tears and the relationship in the process of knee OA through finite-element simulation. This study does favour to obtain a better understanding on the symptoms and pathological changes of OA. It also may provide some potential directions for the prophylaxis and treatment of OA.

Biomechanical analysis of the centralization procedure for extruded lateral menisci with posterior root deficiency in a porcine model

PURPOSE

The purpose of this study was to investigate the biomechanical properties of load distribution following a centralization procedure for extruded lateral menisci with posterior root deficiency in a porcine model.

METHODS

Six porcine knee joints were analyzed in a universal tester, as follows: 1) Intact; 2) Extrusion (meniscus extrusion was created by resecting the posterior root of the lateral meniscus, as well as the posterior synovial capsule); and 3) Centralization (two anchors were inserted at the lateral tibial plateau, and the meniscus was sutured to secure it close to the original position). Meniscus extrusion was evaluated using two markers put on the posterior cruciate ligament and the lateral meniscus, and the load distribution were assessed using a pressure mapping sensor system after applying a loading force of 200 N to the knee joint.

RESULTS

Distance between two markers (mm, Average; 95% CI) was larger in the extrusion group (21.9; 17.8, 25.6) than in the intact (18.1; 15.1, 22.7) or the centralization (15.3; 12.9, 18.0) groups. The contact area (mm²) in the middle of the meniscus was significantly smaller in the extrusion group (45.8; 18.5, 73.2) than in the intact (85.7; 72.1, 99.2) or the centralization (98.3; 88.8, 107.8) groups. The maximum contact pressure (MPa) in the tibial plateau was significantly higher in the extrusion group (0.37; 0.35, 0.40) than in the intact (0.29; 0.21, 0.37) or the centralization (0.29; 0.22, 0.36) groups.

CONCLUSIONS

The centralization procedure enabled a reduction of the meniscus extrusion in the lateral meniscus with posterior root deficiency and restored the maximum load and contact pressure to values close to those of the normal knee joint.

The Meniscus Tear: A Review of Stem Cell Therapies

Meniscal injuries have posed a challenging problem for many years, especially considering that historically the meniscus was considered to be a structure with no important role in the knee joint. This led to earlier treatments aiming at the removal of the entire structure in a procedure known as a meniscectomy. However, with the current understanding of the function and roles of the meniscus, meniscectomy has been identified to accelerate joint degradation significantly and is no longer a preferred treatment option in meniscal tears. Current therapies are now focused to regenerate, repair, or replace the injured meniscus to restore its native function. Repairs have improved in technique and materials over time, with various implant devices being utilized and developed. More recently, strategies have applied stem cells, tissue engineering, and their combination to potentiate healing to achieve superior quality repair tissue and retard the joint degeneration associated with an injured or inadequately functioning meniscus. Accordingly, the purpose of this current review is to summarize the current available pre-clinical and clinical literature using stem cells and tissue engineering for meniscal repair and regeneration.

Runx2 plays a central role in Osteoarthritis development

Osteoarthritis (OA) is the most common form of arthritis, is the leading cause of impaired mobility in the elderly, and accounts for more than a third of chronic moderate to severe pain. As a degenerative joint disorder, OA affects the whole joint and results in synovial hyperplasia, degradation of articular cartilage, subchondral sclerosis, osteophyte formation, and chronic pain. Currently, there is no effective drug to decelerate OA progression and molecular targets for drug development have been insufficiently investigated. Anti-OA drug development can benefit from more and precise knowledge of molecular targets for drug development. Runt-related transcription factor 2 (Runx2) is a key transcription factor controlling osteoblast and chondrocyte differentiation and is among the most promising potential therapeutic targets. Notably, Runx2 expression is upregulated in several murine OA models, suggesting a role in disease pathogenesis. In this review article, we summarized recent findings on Runx2 related to OA development and evaluated its potential as a therapeutic target.

The translational potential of this article

A better understanding of the role of Runx2 in osteoarthritis pathogenesis will contribute to the development of novel intervention of osteoarthritis disease.

Cell sources of inflammatory mediators present in bone marrow areas inside the meniscus

Purpose

To demonstrate the production of inflammatory mediators by cells located in bone marrow spaces inside rodent menisci.

Methods

Mice subjected to transection of the medial collateral and anterior cruciate ligaments and meniscotomy (osteoarthritis model) or to a sham procedure, as well as non-operated (naive) mice and rats, had knee joints excised. Tissues were stained with hematoxylin-eosin and tartrate-resistant acid phosphatase (TRAP). CD68⁺ cells, inducible nitric oxide synthase (iNOS), interleukin (IL)-1β, and tumor necrosis factor (TNF) expression were detected using immunohistochemistry.

Results

Lamellar ossified areas, bone-entrapped osteocytes and bone marrow spaces were found inside menisci of one week up to 6 months-old naïve mice, regardless of gender. Menisci from naive rats also showed the same pattern with bone marrow areas. CD68⁺ cells were identified in bone marrow areas inside the meniscus of mice. TRAP⁺ osteoclasts, and hematogenous precursors expressing IL-1β, TNF, and iNOS were identified inside bone marrow areas in meniscal samples from both naïve and sham operated mice. Quantitative immunoexpression of IL-1 β, TNF and iNOS was more intense, P = 0.0194, 0.0293, 0.0124, respectively, in mouse knees from mice sacrificed 49 days after being subjected to an osteoarthritis (OA) model as compared to sham operated animals.

Conclusion

We provide novel data showing that rodent menisci display bone marrow areas with cells able to produce inflammatory mediators. Immunoexpression of inflammatory mediators in those bone marrow areas is significantly more pronounced in mice subjected to experimental OA

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

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

Substantive molecular and histological changes within the meniscus with tears

BACKGROUND

The meniscus plays a vital role in the normal biomechanics of the knee. However, it is not well studied at the molecular level. The purpose of this study was to determine whether molecular and pathological changes in the meniscal tissue vary depending on the presence or absence of meniscal and/or anterior cruciate ligament tear (ACL).

METHODS

Six normal menisci (group A), seven simple torn menisci (group B) and seven torn menisci with concomitant anterior cruciate ligament tears (group C) were collected. We observed the pathological changes in the menisci and used real-time polymerase chain reaction along with immunohistochemistry and in situ hybridisation to examine the levels of ACAN, ADAMTS5, COL10A1, CEBPβ, MMP13 and miR-381-3p, miR-455-3p, miR-193b-3p, miR-92a-3p, respectively. Patients were scored preoperatively and postoperatively using the Lysholm Knee Scoring Scale and International Knee Documentation Committee Subjective Knee Evaluation Form.

RESULTS

Compared with group A, the expression levels of ADAMTS5, COL10A1, CEBPβ, and MMP13 and all the miRNAs were increased while ACAN was down-regulated in groups B and C. Additionally, the gene expression and miRNA levels were higher in group C than that in group B, except for ACAN, which was lower. Several fibrochondrocytes strongly expressed ADAMTS5, CEBPβ, and MMP13 in groups B and C and had high levels of miR-381-3p and miR-455-3p than that in group A. Postoperative Lysholm and IKDC scores were higher in group B than in group C.

CONCLUSIONS

Our findings suggest that the meniscus tended to degenerate after it was injured, especially when combined with a torn ACL. The miRNAs investigated in this study might also contribute to meniscus degeneration. Patients with a combined injury patterns might have relatively worse joint function.

Extracorporeal Shockwave Therapy Accelerates the Healing of a Meniscal Tear in the Avascular Region in a Rat Model

BACKGROUND

The treatment of meniscal tears in the avascular region remains a clinical challenge. Extracorporeal shockwave therapy (ESWT) is a minimally invasive, safe, and effective therapy for various orthopaedic disorders. However, the therapeutic effect of ESWT on meniscal tears has not been reported.

PURPOSE

To evaluate the therapeutic effect of ESWT in the treatment of meniscal tears.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twelve-week-old male Wistar rats were divided into 3 groups (normal, ESWT-, and ESWT+). The authors made a full-thickness 2-mm longitudinal tear in the avascular region of the anterior horn in the latter 2 groups. At 1 week after surgery, the ESWT+ group received 800 impulses of shockwave at 0.22-mJ/mm² energy flux density in a single session. The authors performed a histological examination to evaluate meniscal healing (n = 10 for each group) and immunohistochemistry to analyze the expression of bromodeoxyuridine (BrdU; n = 5 for each group) and CCN family member 2/connective tissue growth factor (CCN2/CTGF; n = 5 for each group) at 2, 4, and 8 weeks after ESWT. The mRNA levels of CCN2, SOX 9, VEGF-a, aggrecan, Col1a2, and Col2a1 at the site of the meniscal tear at 4 weeks after ESWT were quantitatively evaluated by a real-time polymerase chain reaction (n = 5 for each group).

RESULTS

The meniscus healing scores in the ESWT+ group were significantly higher than those in the ESWT- group at 4 weeks and 8 weeks. The ratio of BrdU-positive cells was the highest in the ESWT+ group at all observation periods. The ratio of CCN2-positive cells was highest in the ESWT+ group at 4 and 8 weeks. In the ESWT+ group, real-time polymerase chain reaction revealed that the levels of CCN2, SOX9, aggrecan, and Col2a1 were upregulated (All significant data were P < .05).

CONCLUSION

ESWT promoted the healing of meniscal tears in the avascular area. ESWT stimulated proliferation of meniscal cells and the upregulation of cartilage-repairing factors such as CCN2, with the upregulation of cartilage-specific extracellular matrix expression.

CLINICAL RELEVANCE

ESWT may be an effective therapeutic option that promotes meniscal healing in the avascular region.

Total knee arthroplasty using modified measured resection: a five-year retrospective review of midterm outcomes

INTRODUCTION

Deforming arthrosis, or osteoarthritis, is the most common rheumatic disease that involves the musculoskeletal system. The purpose of this research is to perform a retrospective review of the quality of life of patients with knee arthrosis, who underwent total knee arthroplasty (TKA) no less than 5 years ago, to evaluate, based on the Knee Society Scoring System, the efficacy of a modified measured resection technique, and to investigate factors that affect the outcomes.

MATERIAL AND METHODS

The research sample consisted of 44 patients who had severe osteoarthrosis, Kellgren-Lawrence grade III and grade IV.

RESULTS

The post-operative complications occurred in seven knee joints. Among them there were 2 cases of infection, 2 cases of periprosthesis fracture, and 2 cases of aseptic instability, each pair accounting for 4.3%, and 1 case of femoropatellar pain (2.3%). The remaining 38 knee joints (84.8%) were free of complications.

CONCLUSIONS

Knee arthrosis is a serious health problem, given the significant rate of disability among patients and the significant reduction in the quality of life. Patients often seek medical help at the later stages of the disease, when pain is strong and knee function is significantly reduced. The approach to rehabilitation procedures and, in some cases, to lifestyle improvement should be more responsible.

Long-term Evaluation of Meniscal Tissue Formation in 3-dimensional-Printed Scaffolds With Sequential Release of Connective Tissue Growth Factor and TGF-β3 in an Ovine Model

BACKGROUND

Artificial meniscal scaffolds are being developed to prevent development of osteoarthritis after meniscectomy. Previously, it was reported that 3-dimensional (3D) anatomic scaffolds loaded with connective tissue growth factor (CTGF) and transforming growth factor β3 (TGF-β3) achieved meniscal regeneration in an ovine model. This was a relatively short-term study (3 months postoperative), and outcome analyses did not include magnetic resonance imaging (MRI).

PURPOSE

To evaluate long-term outcome of meniscal replacement with growth factor-laden poly-ε-caprolactone (PCL) scaffolds.

STUDY DESIGN

Controlled laboratory study.

METHODS

Anatomically shaped ovine meniscal scaffolds were fabricated from PCL with a 3D printer based on MRI data. Skeletally mature sheep (N = 34) were randomly allocated to 3 groups: scaffold without growth factor (0-µg group), scaffold with CTGF microspheres (µS) (5 µg) + TGF-β3 µS (5 µg) (5-µg group), and scaffold with CTGF µS (10 µg) + TGF-β3 µS (10 µg) (10-µg group). Unilateral medial meniscal replacement was performed. Animals were euthanized at 6 or 12 months. Regenerated meniscus, articular cartilage status, and synovial reaction were evaluated quantitatively with gross inspection, histology, and MRI. Kruskal-Wallis and Dunn tests were used to compare the 3 groups.

RESULTS

Remnants of the PCL scaffold were evident in the 6-month specimens and were decreased but still present at 12 months in most animals. There were no significant differences among groups in gross inspection, histology, or MRI for either meniscal regeneration or articular cartilage protection. All experimental groups exhibited articular cartilage degeneration as compared with control (nonoperated). In terms of synovitis, there were no clear differences among groups, suggesting that growth factors did not increase inflammation and fibrosis. MRI revealed that meniscal extrusion was observed in most animals (82.7%).

CONCLUSION

Previously, the combination of CTGF and TGF-β3 was shown to stimulate mesenchymal stem cells into a fibrochondrocyte lineage. CTGF and TGF-β3 did not aggravate synovitis, suggesting no adverse response to the combination of 3D-printed PCL scaffold combined with CTGF and TGF-β3. Further work will be required to improve scaffold fixation to avoid meniscal extrusion.

CLINICAL RELEVANCE

A significant advantage of this technique is the ability to print custom-fit scaffolds from MRI-generated templates. In addition, average-size menisci could be printed and available for off-the-shelf applications. Based on the 1-year duration of the study, the approach appears to be promising for meniscal regeneration in humans.

Long-term rates of knee arthroplasty in a cohort of 834 393 patients with a history of arthroscopic partial meniscectomy

Aims

The aim of this study was to determine the long-term risk of undergoing knee arthroplasty in a cohort of patients with meniscal tears who had undergone arthroscopic partial meniscectomy (APM).

Patients and Methods

A retrospective national cohort of patients with a history of isolated APM was identified over a 20-year period. Patients with prior surgery to the same knee were excluded. The primary outcome was knee arthroplasty. Hazard ratios (HRs) were adjusted by patient age, sex, year of APM, Charlson comorbidity index, regional deprivation, rurality, and ethnicity. Risk of arthroplasty in the index knee was compared with the patient’s contralateral knee (with vs without a history of APM). A total of 834 393 patients were included (mean age 50 years; 37% female).

Results

Of those with at least 15 years of follow-up, 13.49% (16 256/120 493; 95% confidence interval (CI) 13.30 to 13.69) underwent subsequent arthroplasty within this time. In women, 22.07% (95% CI 21.64 to 22.51) underwent arthroplasty within 15 years compared with 9.91% of men (95% CI 9.71 to 10.12), corresponding to a risk ratio (RR) of 2.23 (95% CI 2.16 to 2.29). Relative to the general population, patients with a history of APM were over ten times more likely (RR 10.27; 95% CI 10.07 to 10.47) to undergo arthroplasty rising to almost 40 times more likely (RR 39.62; 95% CI 27.68 to 56.70) at a younger age (30 to 39 years). In patients with a history of APM in only one knee, the risk of arthroplasty in that knee was greatly elevated in comparison with the contralateral knee (no APM; HR 2.99; 95% CI 2.95 to 3.02).

Conclusion

Patients developing a meniscal tear undergoing APM are at greater risk of knee arthroplasty than the general population. This risk is three-times greater in the patient’s affected knee than in the contralateral knee. Women in the cohort were at double the risk of progressing to knee arthroplasty compared with men. These important new reference data will inform shared decision making and enhance approaches to treatment, prevention, and clinical surveillance. Cite this article: Bone Joint J 2019;101-B:1071–1080.

Cyclic hydrostatic compress force regulates apoptosis of meniscus fibrochondrocytes via integrin α5β1

Meniscus is a semilunar fibrocartilaginous tissue, serving important roles in load buffering, stability, lubrication, proprioception, and nutrition of the knee joint. The degeneration and damage of meniscus has been proved to be a risk factor of knee osteoarthritis. Mechanical stimulus is a critical factor of the development, maintenance and repair of the meniscus fibrochondrocytes. However, the mechanism of the mechano-transduction process remains elusive. Here we reported that cyclic hydrostatic compress force (CHCF) treatment promotes proliferation and inhibits apoptosis of the isolated primary meniscus fibrochondrocytes (PMFs), via upregulating the expression level of integrin α5β1. Consequently, increased phosphorylated-ERK1/2 and phosphorylated-PI3K, and decreased caspase-3 were detected. These effects of CHCF treatment can be abolished by integrin α5β1 inhibitor or specific siRNA transfection. These data indicate that CHCF regulates apoptosis of PMFs via integrin α5β1-FAK-PI3K/ERK pathway, which may be an important candidate approach during meniscus degeneration.

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

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

Core-Shell Nanofibrous Scaffolds for Repair of Meniscus Tears

Electrospinning is an attractive method of fabricating nanofibers that replicate the ultrastructure of the human meniscus. However, it is challenging to approximate the mechanical properties of meniscal tissue while maintaining the biocompatibility of collagen fibers. Our objective was to determine if functionalizing polylactic acid (PLA) nanofibers with collagen would enhance their biocompatibility. We therefore used coaxial electrospinning to generate core-shell nanofibers with a core of PLA for mechanical strength and a shell of collagen to enhance cell attachment and matrix synthesis. We characterized the nanostructure of the engineered scaffolds and measured the hydrophilic and mechanical properties. We assessed the performance of human meniscal cells seeded on coaxial electrospun scaffolds to produce meniscal tissue by gene expression and histology. Finally, we investigated whether these cell-seeded scaffolds could repair surgical tears created ex vivo in avascular meniscal explants. Histology, immunohistochemistry, and mechanical testing of ex vivo repair provided evidence of neotissue that was significantly better integrated with the native tissue than with the acellular coaxial electrospun scaffolds. Human meniscal cell-seeded coaxial electrospun scaffolds may have potential in enhancing repair of avascular meniscus tears. Impact Statement The success of any tissue-engineered meniscus graft relies on its ability to mimic native three-dimensional microstructure, support cell growth, produce tissue-specific matrix, and enhance graft integration into the repair site. Polylactic acid scaffolds possess the desired mechanical properties, whereas collagen scaffolds induce better cell attachment and enhanced tissue regeneration. We therefore fabricated nanofibrous scaffolds that combined the properties of two biomaterials. These novel coaxial scaffolds more closely emulated the structure, mechanical properties, and biochemical composition of native meniscal tissue. Our findings of meniscogenic tissue generation and integration in meniscus defects have the potential to be translated to clinical use.

Isokinetic eccentric training is more effective than constant load eccentric training on the quadriceps rehabilitation following partial meniscectomy: A randomized clinical trial

OBJECTIVES

To compare the effects of conventional (constant load) eccentric training and isokinetic eccentric training on quadriceps muscle mass, strength and functionality of recreational athletes following partial meniscectomy.

DESIGN

Randomized controlled trial.

SETTING

XXXX, Brazil.

PARTICIPANTS

32 recreational male athletes (∼27 years old) who underwent partial meniscectomy performed a 6-week quadriceps strength training program in one of the experimental groups: conventional group (CG) or icokinetic group (IG).

MAIN OUTCOME MEASURES

Quadriceps muscle mass, strength, and patients' objective and self-reported function.

RESULTS

Both groups enhanced muscle mass, strength and functionality outcomes. The IG presented higher increases than CG for muscle mass (ES = 0.99-1.41), strength (ES = 1.48-2.35), and Lysholm score (ES = 1.0). The magnitude-based inference supports that results 'very likely' or 'almost certainly' favour IG compared to CG for all outcomes, except for the single leg hop test (i.e., between-group similar change).

CONCLUSION

After partial meniscectomy, isokinetic eccentric training is more effective than conventional eccentric training to restore quadriceps muscle mass, strength, and functional capacity.

Secondary Meniscal Tears in Patients With Anterior Cruciate Ligament Injury: Relationship Among Operative Management, Osteoarthritis, and Arthroplasty at 18-Year Mean Follow-up

BACKGROUND

Anterior cruciate ligament (ACL) injury is one of the most frequent orthopaedic injuries and reasons for time loss in sports and carries significant implications, including posttraumatic osteoarthritis (OA). Instability associated with ACL injury has been linked to the development of secondary meniscal tears (defined as tears that develop after the initial ACL injury). To date, no study has examined secondary meniscal tears after ACL injury and their effect on OA and arthroplasty risk.

PURPOSE

To describe the rates and natural history of secondary meniscal tears after ACL injury and to determine the effect of meniscal tear treatment on the development of OA and conversion to total knee arthroplasty (TKA).

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A geographic database of >500,000 patients was reviewed to identify patients with primary ACL injuries between January 1, 1990, and December 31, 2005. Information was collected with regard to ACL injury treatment, rates/characteristics of the secondary meniscal tears, and outcomes, including development of OA and conversion to TKA. Kaplan-Meier and adjusted multivariate survival analyses were performed to test for the effect of meniscal treatment on survivorship free of OA and TKA.

RESULTS

Of 1398 primary ACL injuries, the overall rate of secondary meniscal tears was 16%. Significantly lower rates of secondary meniscal tears were noted among patients undergoing acute ACL reconstruction within 6 months (7%) as compared with patients with delayed ACL reconstruction (33%, P < .01) and nonoperative ACL management (19%, P < .01). Of the 235 secondary meniscal tears identified (196 patients), 11.5% underwent repair, 73% partial meniscectomy, and 16% were treated nonoperatively. Tears were most often medial in location (77%) and complex in morphology (56% of medial tears, 54% of lateral tears). At the time of final follow-up, no patient undergoing repair of a secondary meniscal tear (0%) underwent TKA, as opposed to 10.9% undergoing meniscectomy and 6.1% receiving nonoperative treatment ( P = .28).

CONCLUSION

Secondary meniscal tears after ACL injury are most common among patients undergoing delayed surgical or nonoperative treatment of their primary ACL injuries. Secondary tears often present as complex tears of the medial meniscus and result in high rates of partial meniscectomy.

Knee osteoarthritis risk is increased 4-6 fold after knee injury - a systematic review and meta-analysis

OBJECTIVE

To estimate knee osteoarthritis (OA) risk following anterior cruciate ligament (ACL), meniscus or combined ACL and meniscus injury.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

MEDLINE, Embase, SPORTDiscus, CINAHL and Web of Science until November 2018.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Prospective or retrospective studies with at least 2-year follow-up including adults with ACL injury, meniscal injury or combined injuries. Knee OA was defined by radiographs or clinical diagnosis and compared with the contralateral knee or non-injured controls.

STUDY APPRAISAL AND SYNTHESIS

Risk of bias was assessed using the SIGN50 checklist. ORs for developing knee OA were estimated using random effects meta-analysis.

RESULTS

53 studies totalling ∼1 million participants were included: 185 219 participants with ACL injury, mean age 28 years, 35% females, 98% surgically reconstructed; 83 267 participants with meniscal injury, mean age 38 years, 36% females, 22% confirmed meniscectomy and 73% unknown; 725 362 participants with combined injury, mean age 31 years, 26% females, 80% treated surgically. The OR of developing knee OA were 4.2 (95% CI 2.2 to 8.0; I²=92%), 6.3 (95% CI 3.8 to 10.5; I²=95%) and 6.4 (95% CI 4.9 to 8.3; I²=62%) for patients with ACL injury, meniscal injury and combined injuries, respectively.

CONCLUSION

The odds of developing knee OA following ACL injury are approximately four times higher compared with a non-injured knee. A meniscal injury and a combined injury affecting both the ACL and meniscus are associated with six times higher odds compared with a non-injured knee. Large inconsistency (eg, study design, follow-up period and comparator) and few high-quality studies suggest that future studies may change these estimates.

CLINICAL RELEVANCE

Patients sustaining a major knee injury have a substantially increased risk of developing knee OA, highlighting the importance of knee injury prevention programmes and secondary prevention strategies to prevent or delay knee OA development.PROSPERO registration number CRD42015016900.

[Treatment of degenerative meniscal lesions : From eminence to evidence-based medicine]

BACKGROUND

The treatment of degenerative meniscal lesions has received increased attention since the publication of several Level 1 studies over the last few years. The following review of literature including the consensus statement given by ESSKA reports on the management of patients with degenerative meniscal lesions.

MATERIAL AND METHODS

The analysis includes the literature of Level 1 to 4 studies and the statement of the consensus group of ESSKA concerning the surgical or conservative management of these patients.

RESULTS

Meniscal lesions cause progression in osteoarthritis. Patients presenting a combination of degenerative meniscal lesion and osteoarthritis show inferior clinical outcome. The average clinical outcome after surgical treatment was 70 points based on the Lysholm score. Level 1 studies show no difference in clinical outcome. However, over 30% of these patients require arthroscopy at the second stage after an interval of 3 to 6 months. Patients presenting a flap tear or complaining about mechanical symptoms show poor outcome after conservative treatment.

DISCUSSION

Level 1 studies have focused on very selected patients. These patients do not represent the daily practice of orthopaedic surgeons. The findings of the level 1 studies should, therefore, not be generalized. According to the consensus statement of ESSKA, the treatment of degenerative meniscal lesions should start with conservative management. In the case of persistent symptoms, surgery should be considered after 3 months. In the case of mechanical symptoms, arthroscopy might be indicated earlier. Arthroscopy in advanced osteoarthritic knees is not indicated due to inferior clinical outcome.

Bone marrow lesion is associated with disability for activities of daily living in patients with early stage knee osteoarthritis

Osteoarthritis of the knee (knee OA) induces pain, loss of mobility and diminished activities of daily living (ADL). Although an understanding of the pathophysiology of early stage knee OA has been developed, the structural changes associated with disability for ADL in early stage knee OA are still unclear. The aim of the present study was to examine magnetic resonance imaging (MRI)-detected changes associated with disability for ADL in patients with early stage knee OA. One hundred and thirty-two patients with early stage medial knee OA (Kellgren-Lawrence grade ≤ 2) who first visited the outpatient clinic at our university hospital were included. They were also examined by 3.0-Tesla knee MRI. The OA-associated structural changes were scored using the Whole-Organ Magnetic Resonance Imaging Score (WORMS), and clinical manifestations were evaluated by the Japanese Knee Osteoarthritis Measure (JKOM). Median quartile regression was used for the analysis. Cartilage lesion, subchondral bone attrition and osteophytes were observed in all patients. Bone marrow lesions (BMLs) and synovitis were observed in 60% and 55% of the patients, respectively. Subchondral cysts and ligament changes were observed in 6% and 17% of the patients, respectively. Pain severity of the patients was associated with medial cartilage lesions (coefficient 2.50, 95% confidence interval 0.61-4.40, p < 0.01). Disability for ADL of the patients was associated with BMLs in the medial side of the knee joint (0.82, 0.21-1.02, p = 0.04). BMLs in the medial side of the knee joint were associated with disability for ADL of patients with early stage medial knee OA.

Meniscal body extrusion and cartilage coverage in middle-aged and elderly without radiographic knee osteoarthritis

OBJECTIVES

To determine meniscal extrusion and cartilage coverage on magnetic resonance (MR) images and factors associated with these parameters in knees of middle-aged and elderly persons free from radiographic tibiofemoral osteoarthritis (OA).

METHODS

Seven hundred eighteen persons, free of radiographic tibiofemoral OA, aged 50-90 years from Framingham, MA, USA, were included. We measured meniscal extrusion on 1.5 T MRI of both knees to evaluate both medial and lateral meniscal body extrusion and cartilage coverage. We also determined meniscal morphology and structural integrity. The multivariable association with age, body mass index (BMI), and ipsilateral meniscal damage was also evaluated.

RESULTS

The mean meniscal body extrusion medially was 2.7 mm and laterally 1.8 mm. The tibial cartilage coverage was about 30% of ipsilateral cartilage surface (both compartments). The presence of ipsilateral meniscal damage was associated with more extrusion in only the medial compartment, 1.0 mm in men and 0.6 mm in women, and less cartilage coverage proportion, -5.5% in men and -4.6% in women.

CONCLUSIONS

Mean medial meniscal body extrusion in middle-aged or older persons without radiographic tibiofemoral OA approximates the commonly used cutoff (3 mm) to denote pathological extrusion. Medial meniscal damage is a factor associated with medial meniscal body extrusion and less cartilage coverage.

KEY POINTS

• Medial meniscal extrusion in middle-aged/older persons without OA is around 3 mm. • Lateral meniscal extrusion in middle-aged/older persons without OA is around 2 mm. • Meniscal damage is associated with medial meniscal extrusion and less cartilage coverage.

Subgroups of patients with osteoarthritis and medial meniscus tear or crystal arthropathy benefit from arthroscopic treatment

PURPOSE

The purpose of this study was to perform a systematic review of prospective randomized controlled trials comparing arthroscopic treatment for knee osteoarthritis (OA) with either other therapeutic interventions or sham treatment.

METHODS

A systematic search for randomized controlled trials (RCT) about arthroscopic treatment (AT) for knee OA was performed according to the PRISMA guidelines. Arthroscopic treatment included procedures such as lavage, debridement and partial meniscectomy of the knee. Data source was PubMed central.

RESULTS

Fourteen articles could be included. Five studies compared interventive AT with either sham surgery, lavage or diagnostic arthroscopy. Nine trials compared AT with another active intervention (exercise, steroid injection, hyaluronic acid injection). In ten trials, the clinical scores improved after arthroscopic treatment of knee OA in comparison to the baseline. In seven trials, there was a significant difference in the final clinical outcome with higher scores for patients after arthroscopic OA treatment in comparison to a control group. In four trials, the intention to treat analysis revealed no significant difference between arthroscopic OA treatment and the control group. In one of those trials, which compared arthroscopic partial meniscectomy (APM) with exercise, the cross over rate from exercise to AT was 34.9%. The clinical scores of cross-over patients improved after APM. In one study, the subgroup analysis revealed that patients with tears of the anterior two-thirds of the medial meniscus or any lateral meniscus tear had a higher probability of improvement after arthroscopic surgery than did patients with other intraarticular pathology. There was no difference in the side effects between patients with AT and the control group. Despite acceptable scores in the methodological quality assessment, significant flaws could be found in all studies. These flaws include bad description of the exact surgical technique or poor control of postoperative use of non-steroidal anti-inflammatory drugs (NSAID).

CONCLUSION

Results of RCTs comparing AT with other treatment options were heterogeneous. AT in OA patients is not useless because there is evidence that a subgroup of patients with non-traumatic flap tears of the medial meniscus or patients with crystal arthropathy benefit from arthroscopy. This topic has a high relevance because several health insurances do not reimburse arthroscopy for patients with OA anymore. The results of these randomized studies, however, should be interpreted with care because in many studies, the use of other therapeutic variables such as pain killers or NSAIDs was not controlled or reported.

LEVEL OF EVIDENCE

I.

Long-term Results After Repair of Isolated Meniscal Tears Among Patients Aged 18 Years and Younger: An 18-Year Follow-up Study

BACKGROUND

Meniscal repair is desirable over resection to prevent postmeniscectomy arthritis, especially among young and active patients. However, long-term data are currently lacking following isolated meniscal repair, particularly in the pediatric population.

PURPOSE/HYPOTHESIS

To report long-term follow-up of isolated meniscal tears treated by meniscal repair in a pediatric and adolescent population and to compare those results with previous midterm follow-up data reported. The authors hypothesized that these patients would have satisfactory function and reoperation rates at long-term follow-up.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Forty-four patients aged ≤18 years undergoing repair of an isolated meniscal tear (without concomitant anterior cruciate ligament injury) between 1990 and 2005 were included. At the time of final follow-up, recurrent tear, reoperations, and International Knee Documentation Committee (IKDC) and Tegner scores were determined. With logistic regression, the overall failure among tear types was calculated. Wilcoxon rank sum analysis were performed to calculate the differences in clinical outcome for different time points, and Spearman coefficients were calculated for Tegner and IKDC with different variables.

RESULTS

At a mean follow-up of 17.6 years (range, 13.1-25.9 years), 32 patients with 33 isolated meniscal repairs (29 male, 3 female) with a mean age of 16.1 years (range, 9.9-18.7 years) at surgery were included in this study. At early follow-up, the overall failure rate was 14 of 33 (42%); complex tears (80%) and bucket-handle tears (47%) had higher overall failure rates when compared with simple tears (18.2%), although only complex tears had a significantly higher failure rate. However, no further failures occurred since midterm follow-up with any tear type. At final follow-up, the mean IKDC score was 92.3, which was significantly increased when compared with preoperative (65.3, P < .0001) and midterm (90.2, P = .01) scores. The mean Tegner score (6.5) was significantly lower than both preoperative (8.3, P < .0001) and midterm (8.4, P < .0001) scores. There was no difference in Tegner or IKDC score for patients with successful versus failed repair.

CONCLUSION

In conclusion, while there was a high early failure rate, this study demonstrated overall good to excellent long-term clinical outcomes after isolated meniscal repair in an adolescent population, even for those requiring reoperation. Early failure and reoperation rates were variable, depending on tear type, with complex multiplanar tears having more failures at short-term follow-up. However, at long-term follow-up, IKDC and Tegner scores were not significantly different for those with complex tears as compared with other tear types.

Effect of Lower Limb Alignment in Medial Meniscus-Deficient Knees on Tibiofemoral Contact Pressure

Background:

Degenerative medial meniscal tears and subsequent partial meniscal resection compromise meniscal function and lead to an overload of the medial compartment. In addition, lower limb alignment plays a key role in load distribution between the medial and lateral knee compartments, and varus alignment is a potential risk factor for medial osteoarthritis.

Purpose/Hypothesis:

The purpose of this biomechanical study was to investigate the effect of valgus and varus alignment on peak pressure and contact area in knees with concomitant horizontal medial meniscal tears and subsequent leaflet resection. It was hypothesized that varus alignment in combination with meniscal loss leads to the highest peak pressure within the medial compartment.

Study Design:

Controlled laboratory study.

Methods:

Six fresh-frozen human cadaveric knees were axially loaded using a 1000-N compressive load in full extension with the mechanical axis rotated to intersect the tibial plateau at 40%, 45%, 50%, 55%, and 60% of its width (TPW) to simulate varus and valgus alignment. Tibiofemoral peak contact pressure and contact area of the medial and lateral compartments were determined using pressure-sensitive foils in each of 4 different meniscal conditions: intact, 15-mm horizontal tear of the posterior horn, inferior leaflet resection, and resection of both leaflets.

Results:

The effect of alignment on peak pressure (normalized to the neutral axis) within the medial compartment in cases of an intact meniscus was measured as follows: varus shift resulted in a mean increase in peak pressure of 18.5% at 45% of the TPW and 37.4% at 40% of the TPW, whereas valgus shift led to a mean decrease in peak pressure of 8.7% at 55% of the TPW and 23.1% at 60% of the TPW. Peak pressure changes between the intact meniscus and resection within the medial compartment was less in valgus-aligned knees (0.21 MPa at 60% TPW, 0.59 MPa at 50% TPW, and 0.76 MPa at 40% TPW). Contact area was significantly reduced after partial meniscal resection in the neutral axis (intact, 553.5 ± 87.6 mm²; resection of both leaflets, 323.3 ± 84.2 mm²; P < .001). This finding was consistent in any alignment.

Conclusion:

Both partial medial meniscal resection and varus alignment led to an increase in medial compartment peak pressure. Valgus alignment prevented medial overloading by decreasing contact pressure even after partial meniscal resection. A horizontal meniscal tear did not influence peak pressure and contact area even in varus alignment.

Clinical Relevance:

As a clinical consequence, partial meniscal resection should be avoided to maintain the original biomechanical behavior, and the mechanical axis should be taken into account if partial meniscectomy is necessary.

Hybrid ACL reconstruction in a 6-year-old female with fibular hemimelia

Fibular hemimelia is a rare congenital malformation that is commonly associated with other lower limb abnormalities. This is a unique case of a bicruciate ligament, anterior cru ciate ligament/posterior cruciate ligament (ACL/PCL) deficiency in a 6-year-old female with fibular hemimelia in which we describe an ACL reconstruction using autograft–allograft hybrid technique. This case focuses on the technical aspects of an ACL reconstruction using a physeal-sparing technique with a hybrid ACL graft in a pediatric patient with fibular hemimelia. When evaluating patients with fibular hemimelia, it is important to consider implications of treatment in a stepwise manner as this condition commonly presents with other abnormalities that will most likely require multiple procedures, including limb lengthening.

Introduction of an MR-based semi-quantitative score for assessing partial meniscectomy and relation to knee joint degenerative disease: data from the Osteoarthritis Initiative

OBJECTIVES

To develop an MR-based semi-quantitative meniscus scoring technique for postoperative assessment of the degree of meniscal resection, to test its reproducibility, and to study the relationship between the amount of resection and degenerative disease burden.

METHODS

We studied the right knee of 135 participants from the Osteoarthritis Initiative that underwent meniscal surgery an average of 14 years previously. The amount of meniscal resection was assessed on baseline 3.0-T MRIs and calculated as meniscus resection score (MenRS) with a range of 0 to 18. Knee abnormalities at baseline and 48 months were graded using a modified Whole-Organ Magnetic Resonance Imaging Score (WORMS). Subjects were also stratified according to meniscal resection performed after injury versus without preceding injury. Statistical analysis included intra-class correlation coefficient (ICC) to determine reproducibility as well as regression models and partial correlations to correlate MenRS with WORMS outcomes.

RESULTS

ICC values for intra- and inter-observer reproducibility of MenRS were 0.980 and 0.977, respectively. Overall, the amount of meniscal resection showed a significant correlation with baseline WORMS grades: higher MenRS was associated with higher total WORMS grades (p = 0.004) and cartilage (p = 0.004) and ligament (p < 0.001) subscores. However, no significant association between MenRS and change in WORMS grades over 48 months was found. The relationship between MenRS and baseline WORMS grades did not change after adjusting for a reported history of knee injury.

CONCLUSIONS

Postoperative assessment of the knee following partial meniscectomy using the newly developed MenRS showed excellent reproducibility and significant cross-sectional correlation with WORMS gradings.

KEY POINTS

• The newly developed semi-quantitative MR-based meniscal resection score demonstrated excellent reproducibility. • A significant correlation between the amount of meniscal resection measured using the newly developed score and the degree of overall knee joint degenerative disease and cartilage defects was found.

Surgical Feasibility of a One-Stage Cell-Based Arthroscopic Procedure for Meniscus Regeneration: A Cadaveric Study

IMPACT STATEMENT

Meniscus injury remains the most common indication for orthopedic surgery, but loss of functioning meniscus tissue is strongly correlated with development of early osteoarthritis. However, current clinical options for tissue engineering of the meniscus are limited. This study demonstrates the feasibility of combining human meniscus cells with mesenchymal stromal cells to enhance a meniscus scaffold for meniscus regeneration in a one-stage solution for partial meniscal deficiency.

Short cracks in knee meniscus tissue cause strain concentrations, but do not reduce ultimate stress, in single-cycle uniaxial tension

Tears are central to knee meniscus pathology and, from a mechanical perspective, are crack-like defects (cracks). In many materials, cracks create stress concentrations that cause progressive local rupture and reduce effective strength. It is currently unknown if cracks in meniscus have these consequences; if they do, this would have repercussions for management of meniscus pathology. The objective of this study was to determine if a short crack in meniscus tissue, which mimics a preclinical meniscus tear, (a) causes crack growth and reduces effective strength, (b) creates a near-tip strain concentration and (c) creates unloaded regions on either side of the crack. Specimens with and without cracks were tested in uniaxial tension and compared in terms of macroscopic stress-strain curves and digital image correlation strain fields. The strain fields were used as an indicator of stress concentrations and unloaded regions. Effective strength was found to be insensitive to the presence of a crack (potential effect < 0.86 s.d.; β = 0.2), but significant strain concentrations, which have the potential to lead to long-term accumulation of tissue or cell damage, were observed near the crack tip.

Effects of surgical treatment for acromegaly on knee MRI structural features

Acromegalic arthropathy is a common complication of acromegaly and harms the quality of life of the patients even after acromegaly is in long-term remission. A recent study demonstrated by knee MRI the characteristic structural features of acromegalic arthropathy. However, the effects of treatment for acromegaly on such structural features are almost unknown. This study was undertaken to analyze the effects of transsphenoidal surgery (TSS) on acromegalic arthropathy and elucidate whether knee MRI findings are reversible or irreversible. We analyzed 22 patients with acromegaly (63.7% females, median age 58 years) by knee MRI at diagnosis. Out of these 22 patients, 16 who underwent TSS (68.9% female, median age 58 years) were also subjected to knee MRI 2 months after TSS. As for X-ray undetectable findings, MRI detected synovial thickening, bone marrow lesion, ligament injury and meniscus injury in 22.7%, 22.7%, 4.7% and 59.1% of the patients, respectively. With respect to the 16 patients who underwent TSS, clinical and structural improvements were observed respectively in 100%, 66.7% and 66.7% of the patients who showed knee joint pain, synovial thickening and bone marrow lesion before TSS. However, no patient showed structural improvement of meniscus injury after TSS. In acromegalic arthropathy, synovial thickening and bone marrow lesions are reversible while meniscus injury is irreversible. Because all those findings are associated with the exacerbation of arthropathy, they may be therapeutic targets for preventing the progression of arthropathy by endocrinological and orthopedic intervention.

In situ formation of hydrophobic clusters to enhance mechanical performance of biodegradable poly(l-glutamic acid)/poly(ε-caprolactone) hydrogel towards meniscus tissue engineering

The preparation of scaffolds represents a huge challenge for meniscus tissue engineering, as there are particular biomechanical and biodegradability requirements. Here, an amphiphilic polymer was prepared by grafting hydrophobic poly(ε-caprolactone) (PCL) with short chains onto hydrophilic biodegradable poly(l-glutamic acid) (PLGA). PLGA-g-PCL was then crosslinked with triethylene glycol (TEG) to form a chemically crosslinked network (CCN), followed by the in situ formation of stable hydrophobic PCL clusters inside the preformed CCN to increase the strength and elasticity of the hydrogel. The spindle-like PCL clusters in the hydrogel were observed to possess a mean size of 5-10 μm on the long axis and 3-4 μm on the minor axis, with no crystallization according to WAXS. Owing to the hydrophobic association of PCL, the swollen CCN was secondarily crosslinked and stiffened. Dynamic mechanical analysis (DMA) demonstrated excellent rebound resilience, and the maximum compressive strength of all the PLGA-g-PCL hydrogels was greater than 0.60 MPa with a maximum strain of about 70%, which represented significant increases in comparison with a PLGA hydrogel. Owing to the short chains of PCL, degradation of the PLGA-g-PCL hydrogel was accelerated within 3 months in vivo. A hydrogel carrying adipose-derived stem cells (ASCs) effectively regenerated meniscus-like tissue in vivo and preserved the corresponding articular cartilage from degeneration over a 16 week period.

Trends in Incidence of ACL Reconstruction and Concomitant Procedures Among Commercially Insured Individuals in the United States, 2002-2014

Background:

Few population-based descriptive studies on the incidence of anterior cruciate ligament (ACL) reconstruction and concomitant pathology exist.

Hypothesis:

Incidence of ACL reconstruction has increased from 2002 to 2014.

Study Design:

Descriptive clinical epidemiology study.

Level of Evidence:

Level 3.

Methods:

The Truven Health Analytics MarketScan Commercial Claims and Encounters database, which contains insurance enrollment and health care utilization data for approximately 158 million privately insured individuals younger than 65 years, was used to obtain records of ACL reconstructions performed between 2002 and 2014 and any concomitant pathology using Current Procedures Terminology (CPT) and International Classification of Diseases, Ninth Revision (ICD-9) codes. The denominator population was defined as the total number of person-years (PYs) for all individuals in the database. Annual rates were computed overall and stratified by age, sex, and concomitant procedure.

Results:

There were 283,810 ACL reconstructions and 385,384,623 PYs from 2002 to 2014. The overall rate of ACL reconstruction increased 22%, from 61.4 per 100,000 PYs in 2002 to 74.6 per 100,000 PYs in 2014. Rates of isolated ACL reconstruction were relatively stable over the study period. However, among children and adolescents, rates of both isolated ACL reconstruction and ACL reconstruction with concomitant meniscal surgery increased substantially. Adolescents aged 13 to 17 years had the highest absolute rates of ACL reconstruction, and their rates increased dramatically over the 13-year study period (isolated, +37%; ACL + meniscal repair, +107%; ACL + meniscectomy, +63%). Rates of isolated ACL reconstruction were similar for males and females (26.1 vs 25.6 per 100,000 PYs, respectively, in 2014), but males had higher rates of ACL reconstruction with concomitant meniscal surgery than females.

Conclusion:

Incidence rates of isolated ACL reconstruction and rates of concomitant meniscal surgery have increased, particularly among children and adolescents.

Clinical Relevance:

A renewed focus on adoption of injury prevention programs is needed to mitigate these trends. In addition, more research is needed on long-term patient outcomes and postoperative health care utilization after ACL reconstruction, with a focus on understanding the sex-based disparity in concomitant meniscal surgery.

Meniscal extrusion and degeneration during the course of osteoarthritis in the Murine collagenase-induced osteoarthritis model

Meniscal damage is, despite its major role in knee osteoarthritis (OA), often neglected in OA animal models. We evaluated structural meniscal degeneration during the course of OA in the murine collagenase-induced OA (CIOA) model. To investigate this, OA was induced in the knee joints of 33 male C57BL/6 mice by an intra-articular injection of 10U collagenase. The mice were sacrificed after 1, 3, 7, 14, 28, and 56 days, and the knees were harvested and processed for histological analysis. As control, six knees were obtained from 16-week-old mice in which no OA was induced. Meniscal damage, meniscal extrusion, and articular cartilage damage were evaluated on thionin-stained sections. Associations between parameters of interest were evaluated with Spearman rho correlation tests. When compared to non-OA knees, meniscal extrusion was visible from day 1 onwards and meniscal degeneration had a tendency to increase over time. The meniscus damage appeared around the same time as articular cartilage damage (day 14-28) and was statistically significantly more pronounced anterior than posterior, and no differences were seen between medial and lateral menisci. Meniscus and articular cartilage damage were moderately associated in the CIOA knees (ρ = 0.57; 95%CI [0.23-0.78]). Our findings suggest that the CIOA model is a valuable model to study the role of meniscal damage during OA progression and can support the development of future preventative treatment strategies. © 2018 The Authors. Journal of Orthopaedic Research® Published by Wiley Periodicals, Inc. on behalf of the Orthopaedic Research Society. J Orthop Res 36:2416-2420, 2018.

A 12-week supervised exercise therapy program for young adults with a meniscal tear: Program development and feasibility study

OBJECTIVE

To describe the development and feasibility of an exercise therapy program for treatment of young adults (18-40 years of age) with a meniscal tear.

METHODS

Researchers and experienced physical therapists developed a 12-week supervised neuromuscular and strengthening exercise therapy program based on clinical expertise and available evidence. Six patients (age range 22-39 years) considered eligible for meniscal surgery by an orthopedic surgeon underwent the program. Patients completed the Knee Injury and Osteoarthritis Outcome Score (KOOS) and evaluated the program during a semi-structured qualitative interview. Feedback from patients was included to finalize the exercise therapy program.

RESULTS

Median improvements (Range) in KOOS subscales were 15 (0-33) for Pain, 11 (-11 to 50) for Symptoms, 16 (3-37) for Function in daily living, 23 (10-45) for Function in sport and recreation, and 9 (-6 to 31) for Quality of life. The patients found the program relevant and effective with only a few short-lasting adverse events and important clinical improvements after four to ten weeks. Physical therapist supervision was considered important. No patients wanted surgery up to 6 month after the exercise therapy program.

CONCLUSION

A neuromuscular and strengthening exercise therapy program was feasible and showed important improvement in a small group of young adults with meniscal tears.

Translation, validation, and cross-cultural adaption of the Western Ontario Meniscal Evaluation Tool (WOMET) into German

PURPOSE

The Western Ontario Meniscal Evaluation Tool (WOMET) was developed in order to investigate the health-related quality of life of patients with meniscal pathologies. The aim of the present study was to translate and validate the WOMET into German.

METHODS

A standardized forward backward translation of the WOMET into German was first performed. One hundred ninety-two patients with isolated meniscal tears completed the German version of the WOMET as well as the Western Ontario McMasters University Arthritis Index, and the Knee Osteoarthritis Outcome Score. Furthermore, reliability, construct validity, feasibility, internal consistency, ceiling, and floor effects were then calculated.

RESULTS

Excellent feasibility (85.4% fully complete questionnaire), internal consistency (Cronbach's α = 0.92), and test-retest reliability (ICC, r = 0.90) were found. The standard error of measurement and the minimal detectable change were ±4.6 and 12.7 points, respectively. All predefined hypothesises were confirmed. No floor or ceiling effects were found.

CONCLUSIONS

The presented German version of the WOMET is a valid and reliable tool for investigating the health-related quality of life of German-speaking patients with meniscal pathologies.

LEVEL OF EVIDENCE

Cross-sectional study, Level II.

Clinical efficacy of meniscus plasty under arthroscopy in middle-aged and elderly patients with meniscus injury

Clinical efficacy of meniscal plasty and total meniscectomy under arthroscopy in treating middle-aged and elderly patients with meniscus injury were explored. One hundred and fifteen elderly patients with meniscal injuries treated in the First Peoples Hospital of Wujiang District Suzhou from May 2012 to October 2014 were retrospectively analyzed. They were randomly divided into meniscal plasty group (experimental group) and total meniscectomy group (control group). Length of stay, operation time and VAS between the two groups were compared. Knee function was evaluated before the surgery and at the final follow-up using IKDC 2000 and Lysholm score. The differences of postoperative clinical efficacy and complications in both groups were observed. Postoperative IKDC 2000 and Lysholm score in the experimental group were superior to those of control group (P<0.001). There was no significant difference in the relieving effect of knee pain between the two types of procedures (P>0.05). Shorter operation time was found in control than that of experimental group. We did not observe remarkable differences in length of stay and postoperative complication rate between the two groups (P>0.05). Both meniscal plasty and total meniscectomy under arthroscopy can effectively relieve knee pain in a short time. Meniscal plasty could remarkably alleviate the progression of knee osteoarthritis, maintain knee function and improve daily life of affected population. We considered that meniscal plasty should be served as the preferred approach in treating middle-aged and elderly patients with meniscus injury.

Phenotypic instability of chondrocytes in osteoarthritis: on a path to hypertrophy

Articular chondrocytes are quiescent, fully differentiated cells responsible for the homeostasis of adult articular cartilage by maintaining cellular survival functions and the fine-tuned balance between anabolic and catabolic functions. This balance requires phenotypic stability that is lost in osteoarthritis (OA), a disease that affects and involves all joint tissues and especially impacts articular cartilage structural integrity. In OA, articular chondrocytes respond to the accumulation of injurious biochemical and biomechanical insults by shifting toward a degradative and hypertrophy-like state, involving abnormal matrix production and increased aggrecanase and collagenase activities. Hypertrophy is a necessary, transient developmental stage in growth plate chondrocytes that culminates in bone formation; in OA, however, chondrocyte hypertrophy is catastrophic and it is believed to initiate and perpetuate a cascade of events that ultimately result in permanent cartilage damage. Emphasizing changes in DNA methylation status and alterations in NF-κB signaling in OA, this review summarizes the data from the literature highlighting the loss of phenotypic stability and the hypertrophic differentiation of OA chondrocytes as central contributing factors to OA pathogenesis.

Low 1-Year Return-to-Sport Rate After Anterior Cruciate Ligament Reconstruction Regardless of Patient and Surgical Factors: A Prospective Cohort Study of 272 Patients

BACKGROUND

There is insufficient knowledge about the way that concomitant injuries affect the short-term likelihood of a return to a knee-strenuous sport after anterior cruciate ligament (ACL) reconstruction. Hypotheses/Purpose: The purpose was to study whether patient characteristics, concomitant injuries, and graft choice at primary ACL reconstruction can predict return to sport (RTS) 1 year after surgery. The hypotheses were that younger age at the time of ACL reconstruction would positively affect RTS, while the presence of concomitant injuries would negatively affect RTS 1 year after surgery.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Data were extracted from a rehabilitation-specific register and the Swedish National Knee Ligament Register. Twelve months after surgery, all patients were evaluated for RTS via the Tegner Activity Scale. The primary outcome was a return to knee-strenuous sport, defined as a Tegner Activity Scale ≥6. Univariable and multivariable logistic regression analyses were performed with patient characteristics, concomitant knee injuries, and graft choice as independent variables.

RESULTS

A total of 272 patients (51% female) with a mean ± SD age of 25.0 ± 9.2 years were included. In the multivariable analysis, a favorable odds ratio (OR) for returning to sport was found for patients of male sex (OR, 2.58; 95% CI, 1.43-4.65; P = .0016), younger age at the time of ACL reconstruction (OR, 2.32; 95% CI, 1.59-3.33; P < .0001), a higher preinjury score on the Tegner Activity Scale (OR, 1.45; 95% CI, 1.13-1.87; P = .0038), and an absence of injury to the meniscus (OR, 1.92; 95% CI, 1.10-3.36; P = .023) and medial collateral ligament (OR, 7.61; 95% CI, 1.42-40.87; P = .018). In addition, the absence of cartilage injury was favorable in terms of RTS in the univariable analysis (OR, 2.48; 95% CI, 1.40-4.39; P = .0018).

CONCLUSION

Positive predictors of a return to knee-strenuous sport 1 year after ACL reconstruction were male sex, younger age, a high preinjury level of physical activity, and the absence of concomitant injuries to the medial collateral ligament and meniscus.

Patient-reported symptoms and changes up to 1 year after meniscal surgery

Background and purpose - Detailed information on the symptoms and limitations that patients with meniscal tears experience is lacking. This study was undertaken to map the most prevalent self-reported symptoms and functional limitations among patients undergoing arthroscopic meniscal surgery and investigate which symptoms and limitations had improved most at 1 year after surgery. Patients and methods - Patients aged 18-76 years from the Knee Arthroscopy Cohort Southern Denmark (KACS) undergoing arthroscopic meniscal surgery were included in this analysis of individual subscale items from the Knee Injury and Osteoarthritis Outcome Score and 1 question on knee stability. Severity of each item was scored as none, mild, moderate, severe, or extreme. Improvements were evaluated using Wilcoxon's signed-rank test and effect size (ES). Results - The most common symptoms were knee grinding and clicking, knee pain in general, pain when twisting and bending the knee and climbing stairs (88-98%), while the most common functional limitations were difficulty bending to the floor, squatting, twisting, kneeling, and knee awareness (97-99%). Knee pain in general and knee awareness improved most 1 year after meniscal surgery (ES -0.47 and -0.45; p < 0.001), while knee instability and general knee difficulties improved least (ES 0.10 and -0.08; p < 0.006). Interpretation - Adults undergoing surgery for a meniscal tear commonly report clinical symptoms and functional limitations related to their daily activities. Moderate improvements were observed in some symptoms and functional limitations and small to no improvement in others at 1 year after surgery. These findings can assist the clinical discussion of symptoms, treatments, and patients' expectations.

Knee menisci segmentation using convolutional neural networks: data from the Osteoarthritis Initiative

OBJECTIVE

To present a novel method for automated segmentation of knee menisci from MRIs. To evaluate quantitative meniscal biomarkers for osteoarthritis (OA) estimated thereof.

METHOD

A segmentation method employing convolutional neural networks in combination with statistical shape models was developed. Accuracy was evaluated on 88 manual segmentations. Meniscal volume, tibial coverage, and meniscal extrusion were computed and tested for differences between groups of OA, joint space narrowing (JSN), and WOMAC pain. Correlation between computed meniscal extrusion and MRI Osteoarthritis Knee Score (MOAKS) experts' readings was evaluated for 600 subjects. Suitability of biomarkers for predicting incident radiographic OA from baseline to 24 months was tested on a group of 552 patients (184 incident OA, 386 controls) by performing conditional logistic regression.

RESULTS

Segmentation accuracy measured as dice similarity coefficient was 83.8% for medial menisci (MM) and 88.9% for lateral menisci (LM) at baseline, and 83.1% and 88.3% at 12-month follow-up. Medial tibial coverage was significantly lower for arthritic cases compared to non-arthritic ones. Medial meniscal extrusion was significantly higher for arthritic knees. A moderate correlation between automatically computed medial meniscal extrusion and experts' readings was found (ρ = 0.44). Mean medial meniscal extrusion was significantly greater for incident OA cases compared to controls (1.16 ± 0.93 mm vs 0.83 ± 0.92 mm; P < 0.05).

CONCLUSION

Especially for medial menisci an excellent segmentation accuracy was achieved. Our meniscal biomarkers were validated by comparison to experts' readings as well as analysis of differences w.r.t groups of OA, JSN, and WOMAC pain. It was confirmed that medial meniscal extrusion is a predictor for incident OA.

Willingness of older adults to participate in a randomized trial of conservative therapies for knee pain: A prospective preference assessment

Background

In preparation for a trial of physical therapy (PT) for patients with degenerative meniscal tear and knee osteoarthritis, we conducted a prospective preference assessment -- a methodology for estimating the proportion of eligible subjects who would participate in a hypothetical randomized trial.

Methods

We identified patients seeking care from the practices of five orthopedic surgeons. Patients completed a survey asking about their willingness to participate in a hypothetical trial, their treatment preferences, their knee pain, and demographic variables.

Results

We approached 201 eligible patients, of whom 67% (95% confidence interval [CI] 60%, 73%) completed questionnaires. Of these, 24% (95% CI 17%, 31%) were definitely and 39% (95% CI 31%, 47%) were probably willing to participate in the trial. Thirty-three percent (95% CI 23%, 43%) of subjects with no treatment preference were definitely willing to participate as compared to 9% (95% CI 1%, 17%) with treatment preference (p = .001). Patients with higher educational attainment also stated a greater willingness to participate than those with less education (p = .06). In multivariable logistic regression analysis, those with no treatment preferences had greater adjusted odds of stating they would definitely participate than those with a defined treatment preference (OR 5.2, 95% CI 1.7, 16.2), while subjects with an associate's degree or greater were more likely to state they would definitely participate than those with less education (OR 3.9, 95% CI 1.1, 14.1).

Conclusion

In this prospective preference assessment, 63% (95% CI 55%, 71%) of subjects with degenerative meniscal tear expressed willingness to participate in a trial of PT modalities. Individuals with no treatment preferences were more likely to state they would participate than were those with higher education. This methodology can help investigators estimate recruitment rates, anticipate generalizability of the trial sample and create strategies to facilitate enrollment.

Annual trends in arthroscopic meniscus surgery: Analysis of a national database in Japan

Background

The importance of meniscus preservation is widely recognized. There have been a few studies describing trends in meniscectomy and meniscus repair in the United States; however, they presented differing results. We reported annual trends in meniscus surgery, using a national database in Japan.

Methods

We interrogated the Diagnosis Procedure Combination database, which represents approximately half of all hospital admissions in Japan. We included the patients who underwent meniscectomy and meniscus repair between July 2007 and March 2015. The diagnosis, age and sex of each patient were recorded.

Results

We identified 83,105 patients: 69,310 underwent meniscectomy; 13,416 underwent meniscus repair and 379 underwent both in a single admission. The proportion of patients undergoing meniscus repair rose from 7.0% in 2007 to 25.9% in 2014 (p < 0.001), while the proportion undergoing meniscectomy fell from 92.8% in 2007 to 73.3% in 2014 (p < 0.001). Among patients under 30 years old, the proportions undergoing meniscus repair or meniscectomy in 2014 were 50.3% versus 48.3%, respectively. A bimodal age distribution was observed for meniscectomy, with peaks at 10–19 years of age and 60–69 years of age, whereas most patients undergoing meniscus repair were 10–19 years of age.

Conclusions

We found characteristic trends where the popularity of meniscus repair increased rapidly at the expense of meniscectomy in Japan during the study period. In the last survey year, the proportion of meniscus repair exceeded that of meniscectomy in those younger than 30 years. Meniscectomy was undertaken most often in adolescents and early old age, while meniscus repair was undertaken most often in adolescents.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

LEVEL OF EVIDENCE

III.

Transcriptome comparison of meniscus from patients with and without osteoarthritis

OBJECTIVE

To assess the impact of osteoarthritis (OA) on the meniscus by comparing transcripts and biological processes in the meniscus between patients with and without OA.

DESIGN

RNA microarrays were used to identify transcripts differentially expressed (DE) in meniscus obtained from 12 OA and 12 non-OA patients. The non-OA specimens were obtained at the time of arthroscopic partial meniscectomy. Real-time PCR was performed on selected transcripts. Biological processes and gene-networking was examined computationally. Transcriptome signatures were mapped with 37 OA-related transcripts to evaluate how meniscus gene expression relates to that of OA cartilage.

RESULTS

We identified 168 transcripts significantly DE between OA (75 elevated, 93 repressed) and non-OA samples (≥1.5-fold). Among these, CSN1S1, COL10A1, WIF1, and SPARCL1 were the most prominent transcripts elevated in OA meniscus, POSTN and VEGFA were most highly repressed in OA meniscus. Transcripts elevated in OA meniscus represented response to external stimuli, cell migration and cell localization while those repressed in OA meniscus represented histone deacetylase activity (related to epigenetics) and skeletal development. Numerous long non-coding RNAs (lncRNAs) were DE between the two groups. When segregated by OA-related transcripts, two distinct clustering patterns appeared: OA meniscus appeared to be more inflammatory while non-OA meniscus exhibited a "repair" phenotype.

CONCLUSIONS

Numerous transcripts with potential relevance to the pathogenesis of OA are DE in OA and non-OA meniscus. These data suggest an involvement of epigenetically regulated histone deacetylation in meniscus tears as well as expression of lncRNAs. Patient clustering based on transcripts related to OA in articular cartilage confirmed distinct phenotypes between injured (non-OA) and OA meniscus.