Emerging biologic augmentation strategies for meniscal repair: a systematic review.

BACKGROUND: Meniscal repair should be the gold standard. However, the meniscus is poorly vascularized and even an excellent meniscus repair may not heal. Therefore, numerous studies and systematic reviews have been carried out on platelet-rich plasma (PRP), mesenchymal stem cells (MSCs) and fibrin clots for meniscal augmentation, but the results remain controversial. This systematic review aimed to identify other emerging strategies for meniscal repair augmentation and to assess whether there are different avenues to explore in this field. METHODS: A systematic literature review was conducted in August 2022. PubMed, Ovid MEDLINE(R) all, Ovid All EBM Reviews, Ovid Embase and ISI Web of Science databases were searched. In Vivo animal and human studies concerning the biological augmentation of meniscal lesions by factors other than PRP, MSCs or fibrin clots were included. Cartilage-only studies, previous systematic reviews and expert opinions were excluded. All data were analyzed by two independent reviewers. RESULTS: Of 8965 studies only nineteen studies covering 12 different factors met the inclusion criteria. Eight studies investigated the use of growth factors for meniscal biologic augmentation, such as vascular endothelial growth factor or bone morphogenic protein 7. Five studies reported on cell therapy and six studies focused on other factors such as hyaluronic acid, simvastatin or atelocollagen. Most studies (n = 18) were performed on animal models with gross observation and histological evaluation as outcomes. Polymerase chain reaction and immunohistochemistry were also common. Biomechanical testing was the object of only two studies. CONCLUSIONS: Although several augmentation strategies have been attempted, none has yielded conclusive results, testifying to a lack of understanding with regard to meniscal healing. More research is needed to better understand the pathways that regulate meniscus repair and how to act positively on them. LEVEL OF EVIDENCE: Systematic review of case-control and animal laboratory studies.

Hypermobile lateral meniscus: A systematic review of current treatment options.

PURPOSE: The reliable data on the incidence of hypermobile lateral meniscus (HLM) and its clinical manifestations, diagnostic methods and therapeutic approaches are limited. This systematic study aimed to review available treatment options for HLM and the outcomes of each approach. METHODS: A systematic search was performed in four electronic databases (PubMed, EMBASE, Scopus, Web of Science) to identify studies in which arthroscopically confirmed cases of HLM were treated surgically or nonsurgically, and the required data comprising study characteristics, patient data, treatment approaches and outcome measures were extracted from eligible studies. RESULTS: Twenty studies with a total of 212 patients (138 males and 74 females) and 219 knees were included. The most frequently reported symptoms were locking sensations, knee pain, giving way and snapping. Treatments used by the studies were: radiofrequency energy in two studies; arthroscopic partial meniscectomy in one study; open surgery in two studies; and arthroscopic meniscal repair in 17 studies. Eleven studies used an all-inside repair method and an inside-out meniscal repair was reported in eight studies. Three studies reported the usage of posterior arthroscopy for therapeutic or diagnostic approaches. Evaluation of symptom resolution was the main outcome measurement for which almost all of the studies stated relief of symptoms after intervention. CONCLUSION: Despite the lack of definite consensus about the most appropriate intervention for HLM, therapeutic preference was directed towards arthroscopic all-inside and inside-out repair techniques. Although the surgeon's decision remains the key factor in choosing the most suitable treatment option for each individual, posterior arthroscopic meniscal repair may be considered as a better option for HLM treatment according to the findings of this review. LEVEL OF EVIDENCE: Level IV.

Evaluation and Treatment of Knee Pain: A Review.

Importance: Approximately 5% of all primary care visits in adults are related to knee pain. Osteoarthritis (OA), patellofemoral pain, and meniscal tears are among the most common causes of knee pain. Observations: Knee OA, affecting an estimated 654 million people worldwide, is the most likely diagnosis of knee pain in patients aged 45 years or older who present with activity-related knee joint pain with no or less than 30 minutes of morning stiffness (95% sensitivity; 69% specificity). Patellofemoral pain typically affects people younger than 40 years who are physically active and has a lifetime prevalence of approximately 25%. The presence of anterior knee pain during a squat is approximately 91% sensitive and 50% specific for patellofemoral pain. Meniscal tears affect an estimated 12% of the adult population and can occur following acute trauma (eg, twisting injury) in people younger than 40 years. Alternatively, a meniscal tear may be a degenerative condition present in patients with knee OA who are aged 40 years or older. The McMurray test, consisting of concurrent knee rotation (internal or external to test lateral or medial meniscus, respectively) and extension (61% sensitivity; 84% specificity), and joint line tenderness (83% sensitivity; 83% specificity) assist diagnosis of meniscal tears. Radiographic imaging of all patients with possible knee OA is not recommended. First-line management of OA comprises exercise therapy, weight loss (if overweight), education, and self-management programs to empower patients to better manage their condition. Surgical referral for knee joint replacement can be considered for patients with end-stage OA (ie, no or minimal joint space with inability to cope with pain) after using all appropriate conservative options. For patellofemoral pain, hip and knee strengthening exercises in combination with foot orthoses or patellar taping are recommended, with no indication for surgery. Conservative management (exercise therapy for 4-6 weeks) is also appropriate for most meniscal tears. For severe traumatic (eg, bucket-handle) tears, consisting of displaced meniscal tissue, surgery is likely required. For degenerative meniscal tears, exercise therapy is first-line treatment; surgery is not indicated even in the presence of mechanical symptoms (eg, locking, catching). Conclusions and Relevance: Knee OA, patellofemoral pain, and meniscal tears are common causes of knee pain, can be diagnosed clinically, and can be associated with significant disability. First-line treatment for each condition consists of conservative management, with a focus on exercise, education, and self-management.

Meniscus Root Tears: A Clinical Review.

ABSTRACT: Meniscus root tears are important to recognize early given their potentially devastating consequences on joint health. This injury results in the lost ability of the meniscus to transfer axial loads into hoop stress; therefore, it is functionally equivalent to a complete meniscectomy. This causes rapid progression of osteoarthritis and increased need to total knee arthroplasty in a previously healthy joint. Despite these consequences, root tears have only been discussed in the orthopedic literature in the last 10 to 15 years and have not been routinely integrated into nonoperative sports medicine education. It is important for all nonoperative sports medicine providers to properly diagnose and triage this injury early in its course to maximize joint preservation efforts. The goal of this manuscript is to review the anatomy, presentation, natural history, imaging, and treatment options for meniscal root tears.

Blood in the joint: effects of hemarthrosis on meniscus health and repair techniques.

Injury to the meniscus is common and frequently leads to the development of post-traumatic osteoarthritis (PTOA). Many times meniscus injuries occur coincident with anterior cruciate ligament (ACL) injuries and lead to a bloody joint effusion. Hemarthrosis, or bleeding into the joint, has been implicated in degeneration of joint tissues. The goal of this review paper is to understand the pathophysiology of blood-induced joint damage, the possible effects of blood on meniscus tissue, and the implications for current meniscus repair techniques that involve the introduction of blood-derived products into the joint. In this review, we illustrate the similarities in the pathophysiology of joint damage due to hemophilic arthropathy (HA) and osteoarthritis (OA). Although numerous studies have revealed the harmful effects of blood on cartilage and synovium, there is currently a gap in knowledge regarding the effects of hemarthrosis on meniscus tissue homeostasis, healing, and the development of PTOA following meniscus injury. Given that many meniscus repair techniques utilize blood-derived and marrow-derived products, it is essential to understand the effects of these factors on meniscus tissue and the whole joint organ to develop improved strategies to promote meniscus tissue repair and prevent PTOA development.

Arthroscopic Partial Meniscectomy versus Physical Therapy for Degenerative Meniscal Tear: a Systematic Review.

BACKGROUND: Meniscal tears are commonly observed in patients with knee osteoarthritis (OA), however, clinical significance of such lesions detected by magnetic resonance imaging is in many cases unclear. This study aimed to determine the clinical effectiveness of arthroscopic partial meniscectomy (APM) compared with non-operative care in patients with knee OA. METHOD: We used existing systematic reviews with updates of latest studies. Three randomized controlled studies were selected, where two studies compared the effects of APM plus physical therapy (PT) with PT alone and one compared APM alone and PT alone. While 1 study exclusively included OA patients, 2 studies included 21.1 and 12% of patients with no radiographic OA. Patients with knee locking were unanimously excluded. RESULTS: Upon comparison of APM plus PT and PT alone, there was no significant difference observed in knee function, physical activity, or adverse events. Knee pain was observed to be significantly lower in the APM plus PT group at 6 months, but there was no difference between the two groups at 12 and 24 months. With respect to the comparison between APM alone and PT alone, PT was non-inferior based on the criteria for knee function during 24 months; however, knee pain was significantly reduced in the APM alone group. CONCLUSIONS: Our study showed that knee pain was significantly improved in the APM group compared to non-operative care group at 6 months and over 24 months. Our result was based on only 3 randomized controlled trials (RCTs) revealing a significant knowledge gap, hence demanding more high-quality RCTs in OA patients. TRIAL REGISTRATION: PROSPERO Identifier: CRD42020215965.

Development of osteoarthritis in patients with degenerative meniscal tears treated with exercise therapy or surgery: a randomized controlled trial.

OBJECTIVE: To evaluate progression of individual radiographic features 5 years following exercise therapy or arthroscopic partial meniscectomy as treatment for degenerative meniscal tear. DESIGN: Randomized controlled trial including 140 adults, aged 35-60 years, with a magnetic resonance image verified degenerative meniscal tear, and 96% without definite radiographic knee osteoarthritis. Participants were randomized to either 12-weeks of supervised exercise therapy or arthroscopic partial meniscectomy. The primary outcome was between-group difference in progression of tibiofemoral joint space narrowing and marginal osteophytes at 5 years, assessed semi-quantitatively by the OARSI atlas. Secondary outcomes included incidence of radiographic knee osteoarthritis and symptomatic knee osteoarthritis, medial tibiofemoral fixed joint space width (quantitatively assessed), and patient-reported outcome measures. Statistical analyses were performed using a full analysis set. Per protocol and as treated analysis were also performed. RESULTS: The risk ratios (95% CI) for progression of semi-quantitatively assessed joint space narrowing and medial and lateral osteophytes for the surgery group were 0.89 (0.55-1.44), 1.15 (0.79-1.68) and 0.77 (0.42-1.42), respectively, compared to the exercise therapy group. In secondary outcomes (full-set analysis) no statistically significant between-group differences were found. CONCLUSION: The study was inconclusive with respect to potential differences in progression of individual radiographic features after surgical and non-surgical treatment for degenerative meniscal tear. Further, we found no strong evidence in support of differences in development of incident radiographic knee osteoarthritis or patient-reported outcomes between exercise therapy and arthroscopic partial meniscectomy. TRIAL REGISTRATION: www.clinicaltrials.gov (NCT01002794).

Can even experienced orthopaedic surgeons predict who will benefit from surgery when patients present with degenerative meniscal tears? A survey of 194 orthopaedic surgeons who made 3880 predictions.

OBJECTIVES: To examine the ability of surgeons to predict the outcome of treatment for meniscal tears by arthroscopic partial meniscectomy (APM) and exercise therapy in middle-aged patients. DESIGN AND SETTING: Electronic survey. Orthopaedic surgeon survey participants were presented 20 patient profiles. These profiles were derived from a randomised clinical trial comparing APM with exercise therapy in middle-aged patients with symptomatic non-obstructive meniscal tears. From each treatment group (APM and exercise therapy), we selected five patients with the best (responders) and five patients with the worst (non-responders) knee function after treatment. 1111 orthopaedic surgeons and residents in the Netherlands and Australia were invited to participate in the survey. INTERVENTIONS: For each of the 20 patient profiles, surgeons (unaware of treatment allocation) had to choose between APM and exercise therapy as preferred treatment and subsequently had to estimate the expected change in knee function for both treatments on a 5-point Likert Scale. Finally, surgeons were asked which patient characteristics affected their treatment choice. MAIN OUTCOMES: The primary outcome was the surgeons' percentage correct predictions. We also compared this percentage between experienced knee surgeons and other orthopaedic surgeons, and between treatment responders and non-responders. RESULTS: We received 194 (17%) complete responses for all 20 patient profiles, resulting in 3880 predictions. Overall, 50.0% (95% CI 39.6% to 60.4%) of the predictions were correct, which equals the proportion expected by chance. Experienced knee surgeons were not better in predicting outcome than other orthopaedic surgeons (50.4% vs 49.5%, respectively; p=0.29). The percentage correct predictions was lower for patient profiles of non-responders (34%; 95% CI 21.3% to 46.6%) compared with responders (66.0%; 95% CI 57.0% to 75.0%; p=0.01).In general, bucket handle tears, knee locking and failed non-operative treatment directed the surgeons' choice towards APM, while higher level of osteoarthritis, degenerative aetiology and the absence of locking complaints directed the surgeons' choice towards exercise therapy. CONCLUSIONS: Surgeons' criteria for deciding that surgery was indicated did not pass statistical examination. This was true regardless of a surgeon's experience. These results suggest that non-surgical management is appropriate as first-line therapy in middle-aged patients with symptomatic non-obstructive meniscal tears. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03462134.

How do the costs of physical therapy and arthroscopic partial meniscectomy compare? A trial-based economic evaluation of two treatments in patients with meniscal tears alongside the ESCAPE study.

OBJECTIVES: To examine whether physical therapy (PT) is cost-effective compared with arthroscopic partial meniscectomy (APM) in patients with a non-obstructive meniscal tear, we performed a full trial-based economic evaluation from a societal perspective. In a secondary analysis-this paper-we examined whether PT is non-inferior to APM. METHODS: We recruited patients aged 45-70 years with a non-obstructive meniscal tear in nine Dutch hospitals. Resource use was measured using web-based questionnaires. Measures of effectiveness included knee function using the International Knee Documentation Committee (IKDC) and quality-adjusted life-years (QALYs). Follow-up was 24 months. Uncertainty was assessed using bootstrapping techniques. The non-inferiority margins for societal costs, the IKDC and QALYs, were €670, 8 points and 0.057 points, respectively. RESULTS: We randomly assigned 321 patients to PT (n=162) or APM (n=159). PT was associated with significantly lower costs after 24 months compared with APM (-€1803; 95% CI -€3008 to -€838). The probability of PT being cost-effective compared with APM was 1.00 at a willingness to pay of €0/unit of effect for the IKDC (knee function) and QALYs (quality of life) and decreased with increasing values of willingness to pay. The probability that PT is non-inferior to APM was 0.97 for all non-inferiority margins for the IKDC and 0.89 for QALYs. CONCLUSIONS: The probability of PT being cost-effective compared with APM was relatively high at reasonable values of willingness to pay for the IKDC and QALYs. Also, PT had a relatively high probability of being non-inferior to APM for both outcomes. This warrants further deimplementation of APM in patients with non-obstructive meniscal tears. TRIAL REGISTRATION NUMBERS: NCT01850719 and NTR3908.

Intra-Articular Injection of Stromal Cell-Derived Factor 1α Promotes Meniscal Healing via Macrophage and Mesenchymal Stem Cell Accumulation in a Rat Meniscal Defect Model.

The stromal-cell-derived factor-1α (SDF-1) is well-known for playing important roles in the regeneration of tissue by enhancing cell migration. However, the effect of SDF-1 in meniscal healing remains unknown. The purpose of this study is to investigate the effects of intra-articular injection of SDF-1 on meniscus healing in a rat meniscal defect model. The intra-articular SDF-1 injection was performed at meniscectomy and one week later. Macroscopic and histological assessments of the reparative meniscus were conducted at one, two and six weeks after meniscectomy in rats. In the macroscopic evaluation, the SDF-1 group showed an increase in the size of the reparative meniscus at six weeks after meniscectomy compared to the phosphate-buffered saline (PBS) injection (no-treatment) group. Histological findings showed that intra-articular injection of SDF-1 enhanced the migration of macrophages to the site of the regenerative meniscus at one and two weeks after meniscectomy. CD68- and CD163-positive cells in the SDF-1 group at one week after meniscectomy were significantly higher than in the no-treatment group. CD163-positive cells in the SDF-1 group at two weeks were significantly higher than in the no-treatment group. At one week after meniscectomy, there were cells expressing mesenchymal-stem-cell-related markers in the SDF-1 group. These results indicate the potential of regenerative healing of the meniscus by SDF-1 injection via macrophage and mesenchymal stem cell accumulation. In the present study, intra-articular administration of SDF-1 contributed to meniscal healing via macrophage, CD90-positive cell and CD105-positive cell accumulation in a rat meniscal defect model. The SDF-1-CXCR4 pathway plays an important role in the meniscal healing process. For potential clinical translation, SDF-1 injection therapy seems to be a promising approach for the biological augmentation in meniscal injury areas to enhance healing capacity.

Meniscofibular ligament: how much do we know about this structure of the posterolateral corner of the knee: anatomical study and review of literature.

PURPOSE: The present study is a systematic review of a relatively unknown structure of the posterolateral corner of the knee, the meniscofibular ligament (MFL), aiming at summarizing and broadening current scientific knowledge regarding this ligament anatomy, function, imaging and injury. MATERIALS AND METHODS: A systematic review was performed according to the PRISMA guidelines. Medline (PubMed) and Cochrane Library databases were reviewed for every kind of study reporting on the MFL through December 2019. Due to between-study differences in (anatomy, function, imaging, injury) examining the ligament, the findings were summarized from each study, but the results were not pooled. RESULTS: The MFL is a ligament extending between the inferolateral portion of lateral meniscus, just anterior to the popliteus tendon, and the fibular head. It provides stability to the posterolateral corner of the knee joint, it can be demonstrated in magnetic resonance imaging and magnetic resonance arthrography and has a potential role in lateral meniscus injuries. Further research is required to clearly understand the prognosis and management of MFL injury. CONCLUSION: The current systematic review, focusing only on the MFL of the knee, summarizes the existing knowledge on anatomy, gross morphology, histology, function, biomechanics and imaging and contributes to the further understanding of the MFL.

The effect of anti-gravity training after meniscal or chondral injury in the knee. A systematic review.

Reduced impact loading or anti-gravity training has recently been introduced as a new tool in the rehabilitation of orthopaedic conditions that require restricted weight bearing. The purpose of this strategy is to speed up the functional rehabilitation while at the same time protect the healing structures from harmful effects associated with impact loading. Anti- gravity treadmills (AlterG ® ) and harness suspension devices seem to be the two most promising techniques. It is however today unclear how effective these devices are. The purpose of our study was therefore to perform a systematic literature review on the actual technology available and its effect on impact load reduction, as well as its effectiveness in accelerating functional recovery after meniscal and chondral injury to the knee. The results from our work demonstrate that only a limited number of studies are available, usually of moderate quality. The data suggest a variable effect on cartilage regeneration, and a potential for accelerated functional recovery in gait and running dynamics both with anti-gravity treadmill as well as suspension harness systems.

Effect of physical therapy on early knee osteoarthritis with medial meniscal posterior tear assessed by MRI T2 mapping and 3D-to-2D registration technique: A prospective intervention study.

Objectives: The purpose of this study was to verify that exercise aimed at improving knee kinematics in early-stage knee osteoarthritis (OA) patients with medial meniscus posterior root tears (MMPRTs) reduces knee adduction angle during gait and prevents rapid cartilage degeneration in the medial compartment of the knee.Methods: Subjects were randomly assigned to an adapting alignment exercise (AAE) group, with the goal of improving knee kinematics, and a muscle training and exercise (MTE) group. Before the start of the six-month intervention and following its completion, we performed an analysis of knee kinematics during gait using a 3D-to-2D registration technique and identified the area of cartilage degeneration using MRI T2 mapping.Results: The amount of change between pre- and post-intervention measurements of the maximum angle of adduction was 0.48° (95% CI: -0.14, 1.09) in the MTE group and -0.40° (-0.84, 0.04) in the AAE group (p = .039). The amount of change in the area of cartilage degeneration according to MRI T2 mapping expressed as MTE/AAE group was 7.7 mm2 (-0.4, 15.8)/-2.7 mm2 (-10.8, 5.3) at the posterior knee (p = .043).Conclusion: AAE could be a potential treatment method that improves the natural course of knee OA with MMRPTs.

Efficacy of platelet-rich plasma in arthroscopic repair for discoid lateral meniscus tears.

BACKGROUND: To evaluate the clinical results of arthroscopic repair with or without platelet-rich plasma (PRP) for tears of the discoid lateral meniscus (DLM). METHODS: Twenty-nine patients with DLM tears within a stable knee were arthroscopically treated with meniscal suture repair. Of those, 14 were augmented with platelet-rich plasma (PRP), and 15 were performed without PRP augmentation. Patients were evaluated at baseline (the day before surgery) and then 12 and 24 months after the last injection. Evaluation included the Lysholm score, and Ikeuchi grade, Visual analogue score (VAS) for pain and failure rate. Failure was defined by patients developing symptoms of joint line pain, locking, swelling or requiring repeat arthroscopy. RESULTS: There was no difference in the failure rate in the PRP group (1 of 14) compared with the non-PRP group (2 of 15) (P = 0.58). Statistically significant improvement in Lysholm score, Ikeuchi grade and VAS for pain was documented at the last follow-up compared with baseline in both PRP and non-PRP group. No significantly difference was found between the PRP group and non-PRP group on Lysholm score, Ikeuchi grade and VAS for pain at the last follow-up. In the univariate analysis of each variable, younger age (P = 0.036) and longer follow-up duration (P = 0.043) were statistically associated with a better function improvement. Whereas in multivariate analysis, only younger age (P = 0.004) was significantly associated with a better function improvement. CONCLUSION: With regard to clinical evaluations in arthroscopic repair for DLM tears, PRP group had similar effect in pain relief and functional improvement to non-PRP group at mid-term follow-up. Future larger prospective studies with a longer follow-up are needed to determine whether PRP should be used with DLM repair.

Cost-Effectiveness Analysis of Needle Arthroscopy Versus Magnetic Resonance Imaging in the Diagnosis and Treatment of Meniscal Tears of the Knee.

PURPOSE: To determine whether needle arthroscopy (NA) compared with magnetic resonance imaging (MRI) in the diagnosis and treatment of meniscal tears is cost-effective when evaluated over a 2-year period via patient-reported outcomes. The hypothesis is that improved diagnostic accuracy with NA would lead to less costly care and similar outcomes. METHODS: A Markov model/decision tree analysis was performed using TreeAge Pro 2017 software. Patients were evaluated for degenerative and traumatic damage to the lateral/medial meniscus. Assumed sensitivities and specificities were derived from the medical literature. The direct costs for care were derived from the 2017 Medicare fee schedule and from private payer reimbursement rates. Costs for care included procedures performed for false-positive findings and for care for false-negative findings. Effectiveness was examined using the global knee injury and osteoarthritis outcome score (KOOS). Patients were evaluated over 2 years for costs and outcomes, including complications. Dominance and incremental cost-effectiveness were evaluated, and 1- to 2-way sensitivity analysis was performed to determine those variables that had the greatest effect. The consolidated economics evaluation and reporting standards checklist for reporting economic evaluations was used. RESULTS: NA was less costly and had similar KOOS versus MRI for both the medial/lateral meniscus with private pay. Costs were less for both Medicare and private pay for medial meniscus, $780 to $1,862, and lateral meniscus, $314 to $1,256, respectively. CONCLUSIONS: Based on the reported MRI incidence of false positives with the medial meniscus and false negatives with the lateral meniscus and based on assumed standards of care, more costly care is provided when using MRI compared with NA. Outcomes were similar with NA compared with MRI. LEVEL OF EVIDENCE: Level II, economic and decision analysis.

The 6-m timed hop test is a prognostic factor for outcomes in patients with meniscal tears treated with exercise therapy or arthroscopic partial meniscectomy: a secondary, exploratory analysis of the Odense-Oslo meniscectomy versus exercise (OMEX) trial.

PURPOSE: To identify the prognostic factors for 2-year patient-reported outcomes in middle-aged patients with degenerative meniscal tears treated with exercise therapy (ET) or arthroscopic partial meniscectomy (APM). METHODS: One hundred and seven patients, with mean age 49.6 (SD 6.2) years and BMI 25.7 (SD 3.7), were included in this analysis of data from the OMEX trial ( http://www.clinicaltrials.gov NCT01002794). Linear and Poisson regression models were built to explore the associations between potential prognostic factors (patient characteristics, knee function-related and disease-related factors) and 2-year patient-reported outcomes: the Knee Injury and Osteoarthritis Outcome Score (KOOS) subscales Pain, Symptoms, ADL, Sport/Rec, QoL and 5-point Global Rating of Change scales for knee pain (GRC Pain) and function (GRC Function). Analyses were performed for the whole cohort and for the two treatment groups (n = 55 and 52) with adjustments for age, sex, BMI and baseline KOOS. RESULTS: For the whole cohort, a 1-s better baseline 6-m timed hop test result was associated with 3.1-7.1 points better 2-year scores for all KOOS subscales (95% CIs 1.1-5.2 to 4.1-10.1 points). A 1.61-2.80 s better test was associated with scores equivalent to previously calculated clinical relevant differences for each KOOS subscale. For the groups of patients treated with ET and APM, respectively, 2.09-3.60 s and 0.63-1.99 s better tests were associated with clinical relevant differences. For the whole cohort, a 1-s better test was associated with 26% (95% CI 15-38%) and 22% (95% CI 11-34%) higher possibility for better or much better GRC Pain and Function scores. Patients treated with ET had 17% (95% CI 2-33%) increased possibility for better or much better GRC Pain score, and patients treated with APM had 65% (95% CI 32-108%) and 70% (95% CI 38-109%) increased possibility for better or much better GRC Pain and Function scores. CONCLUSIONS: The 6-m timed hop test result was a significant prognostic factor for 2-year patient-reported outcomes in middle-aged patients with degenerative meniscal tears, especially in those treated with APM. LEVEL OF EVIDENCE: II.

The Natural History of Meniscus Tears.

BACKGROUND: In order to determine whether treatments are effective in the treatment of meniscus tears, it is first necessary to understand the natural history of meniscus tears. The purpose of this paper is to review the literature to ascertain the natural history of meniscus tears in children and adolescents. METHODS: A search of the Pubmed and Embase databases was performed using the search terms "meniscus tears," "natural history of meniscus tears," "knee meniscus," "discoid meniscus," and "natural history of discoid meniscus tears." RESULTS: A total of 2567 articles on meniscus tears, 28 articles on natural history of meniscus tears, 8065 articles on "menisci," 396 articles on "discoid meniscus," and only 2 on the "natural history of discoid meniscus" were found. After reviewing the titles of these articles and reviewing the abstracts of 237 articles, it was clear that there was little true long-term natural history data of untreated meniscus tears nor whether treating meniscus tears altered the natural history. Twenty-five articles were chosen as there was some mention of natural history in their studies. CONCLUSIONS: There are few long-term data on untreated meniscal tears or discoid meniscus, or tears in children and adolescents. The literature suggests that there is a higher incidence of chondral injury and subsequent osteoarthritis, but there are many confounding variables which are not controlled for in these relatively short-term papers.

Bone Marrow Aspirate Concentrate for the Treatment of Avascular Meniscus Tears in a One-Step Procedure-Evaluation of an In Vivo Model.

Avascular meniscus tears show poor intrinsic regenerative potential. Thus, lesions within this area predispose the patient to developing knee osteoarthritis. Current research focuses on regenerative approaches using growth factors or mesenchymal stem cells (MSCs) to enhance healing capacity within the avascular meniscus zone. The use of MSCs especially as progenitor cells and a source of growth factors has shown promising results. However, present studies use bone-marrow-derived BMSCs in a two-step procedure, which is limiting the transfer in clinical praxis. So, the aim of this study was to evaluate a one-step procedure using bone marrow aspirate concentrate (BMAC), containing BMSCs, for inducing the regeneration of avascular meniscus lesions. Longitudinal meniscus tears of 4 mm in size of the lateral New Zealand White rabbit meniscus were treated with clotted autologous PRP (platelet-rich plasma) or BMAC and a meniscus suture or a meniscus suture alone. Menisci were harvested at 6 and 12 weeks after initial surgery. Macroscopical and histological evaluation was performed according to an established Meniscus Scoring System. BMAC significantly enhanced regeneration of the meniscus lesions in a time-dependent manner and in comparison to the PRP and control groups, where no healing could be observed. Treatment of avascular meniscus lesions with BMAC and meniscus suturing seems to be a promising approach to promote meniscus regeneration in the avascular zone using a one-step procedure.

Short-Term Outcomes of Percutaneous Trephination with a Platelet Rich Plasma Intrameniscal Injection for the Repair of Degenerative Meniscal Lesions. A Prospective, Randomized, Double-Blind, Parallel-Group, Placebo-Controlled Study.

Meniscal tears are the most common orthopaedic injuries, with chronic lesions comprising up to 56% of cases. In these situations, no benefit with surgical treatment is observed. Thus, the purpose of this study was to investigate the effectiveness and safety of percutaneous intrameniscal platelet rich plasma (PRP) application to complement repair of a chronic meniscal lesion. This single centre, prospective, randomized, double-blind, placebo-controlled study included 72 patients. All subjects underwent meniscal trephination with or without concomitant PRP injection. Meniscal non-union observed in magnetic resonance arthrography or arthroscopy were considered as failures. Patient related outcome measures (PROMs) were assessed. The failure rate was significantly higher in the control group than in the PRP augmented group (70% vs. 48%, P = 0.04). Kaplan-Meyer analysis for arthroscopy-free survival showed significant reduction in the number of performed arthroscopies in the PRP augmented group. A notably higher percentage of patients treated with PRP achieved minimal clinically significant difference in visual analogue scale (VAS) and Knee injury and Osteoarthritis Outcome Score (KOOS) symptom scores. Our trial indicates that percutaneous meniscal trephination augmented with PRP results in a significant improvement in the rate of chronic meniscal tear healing and this procedure decreases the necessity for arthroscopy in the future (8% vs. 28%, P = 0.032).

Current concepts in the techniques, indications and outcomes of meniscal repairs.

Knee arthroscopy for meniscal tears is one of the most commonly performed orthopaedic procedures. In recent years, there has been an increasing incidence of meniscal repairs, as there are concerns that meniscectomy predisposes patients to early osteoarthritis. Indications for meniscal repair are increasing and can now be performed in older patients who are active, even if the tear is in the avascular zone. Options for meniscal tear management broadly fall into three categories: non-operative management, meniscal repair or meniscectomy. With limited evidence directly comparing each of these options optimal management strategies can be difficult. Decision making requires thorough assessment of patient factors (e.g. age and comorbidities) and tear characteristics (e.g. location and reducibility). The purpose of this paper is, therefore, to review the management options of meniscal tears and summarize the evidence for meniscal tear repair.