ObjectiveIn this study, we investigated whether interleukin (IL)-37 ameliorates experimental osteoarthritis (OA).MethodsThe effects of IL-37 were investigated in collagenase-induced OA (CiOA) and destabilization of the medial meniscus (DMM). Human IL-37-adenovirus (ad-IL-37) was injected into the affected knee joint 4 and 18 days after the induction of OA. Luciferase-adenovirus was injected as control. Mice were sacrificed for histology at early and late stage of OA development. Interleukin-37 protein expression was confirmed by immunohistochemistry. Cartilage damage, osteophyte size and joint capsule thickness were measured. The effectiveness of ad-IL-37 was confirmed in vitro in human OA fibroblasts using real-time qualitative polymerase chain reaction (RT-qPCR) and Western blotting.ResultsInterleukin-37 protein expression was visible for at least 7 days after injection. At day 28, 10 days after the second injection, no clear synovial IL-37 staining was found any more, in both models. At day 28 of CiOA, ad-IL-37 significantly reduced articular cartilage damage and this was still reduced, although not significantly, at the late time point (day 42). In the DMM model, significant beneficial effect of IL-37 on cartilage damage was found at the late time point. In both OA models ad-IL-37 injections reduced the size of osteophytes.ConclusionInterleukin-37 ameliorated OA-induced articular cartilage damage and osteophyte formation in both models.

IntroductionCartilage lesions of the knee frequently result from acute traumatic injuries and pose significant challenges, particularly in young and active patients. While many involve osteochondral lesions, isolated chondral defects also occur. Traditional treatment focuses on fixation when viable subchondral bone is present; however, managing chondral-only lesions remains controversial due to limited intrinsic healing capacity.MethodsA systematic review was conducted, screening over 300 studies since August 2023. Inclusion criteria required (1) English-language studies, (2) reports on isolated chondral fragment fixation, and (3) a minimum of 6 months of follow-up. Eighteen studies met these criteria. Data on patient demographics, lesion characteristics, fixation methods, clinical outcomes, and functional scores were extracted.ResultsA total of 76 patients (mean age: 14.3 ± 3.7 years) were analyzed. Males comprised 80.3% of the cohort. The mean follow-up was 40.3 months (range: 7-171), and the mean chondral fragment size was 4.28 cm2. The most common lesion locations were the lateral femoral condyle (34.2%), trochlea (32.2%), patella (25%), and medial femoral condyle (8.6%). Healing occurred in 96% of cases, and 86% of patients returned to sports at an average of 10.3 ± 6.1 months. Younger patients (≤14 years) had a significantly higher RTS rate (OR: 5.8; P = 0.0427). Functional scores (IKDC, KOOS, Marx, Tegner) demonstrated excellent postoperative outcomes.ConclusionDespite prior concerns regarding chondral-only fixation, this study demonstrates high healing rates and favorable functional outcomes. Direct fixation is a viable strategy, particularly in adolescents and young adults. Further prospective trials are needed to validate these findings.