The medial collateral ligament (MCL) of the knee is one of the most injured ligaments in both contact and non-contact athletic settings. As a primary stabilizer against valgus stress, the MCL is particularly vulnerable during pivoting, cutting, or direct lateral impact to the knee. MCL injuries account for approximately 7–10% of all knee injuries and are especially prevalent in high-demand sports such as football, soccer, and skiing. The management of these injuries is largely guided by the severity of the tear, with Grade I and II injuries (partial tears) typically managed non-operatively. However, the optimal treatment strategy for Grade III injuries, which involve complete ligament disruption, remains a topic of ongoing debate. Conservative management—consisting of bracing, protected weightbearing, and physiotherapy—has long been the mainstay of treatment for isolated Grade III MCL injuries. Historically, outcomes with non-operative approaches have been favorable, with many patients regaining functional stability and returning to sport without surgical intervention. Nevertheless, several studies have reported persistent valgus laxity, delayed return to activity, and residual functional impairment in a subset of patients managed conservatively. These concerns have led some clinicians to advocate for early surgical repair or reconstruction, particularly in athletes or those with combined ligament injuries, to restore native stability and potentially expedite return to high-level physical activity. Despite multiple clinical trials and observational studies, no clear consensus has emerged regarding whether surgery or conservative treatment yields superior outcomes in terms of functional recovery and return to sport. Prior systematic reviews and meta-analyses have predominantly focused on joint stability, ligamentous healing, or radiographic parameters. However, patient-centered outcomes such as return-to-sport (RTS) rates and range of motion (ROM)—both critical metrics for guiding treatment decisions in active populations—have not been systematically and quantitatively evaluated. The purpose of this meta-analysis is to bridge this evidence gap by synthesizing data from randomized controlled trials (RCTs) comparing surgical and non-surgical treatments for Grade III MCL injuries in adults. We aim to evaluate whether one approach offers a measurable advantage in facilitating return to pre-injury activity levels and achieving full range of motion. By focusing on functional recovery outcomes, this study seeks to inform evidence-based clinical decision-making and guide individualized treatment planning for patients with high-grade MCL injuries.

1. Search strategy and selection criteria This systematic review and meta-analysis were conducted in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines and was registered prospectively in PROSPERO (International Prospective Register of Systematic Reviews, CRD42025643217). A comprehensive literature search was performed across MEDLINE (via PubMed), Embase, Web of Science, and the Cochrane Central Register of Controlled Trials (CENTRAL) from database inception to July 2025. The search strategy included a combination of keywords and MeSH terms related to medial collateral ligament injuries and treatment strategies. Search terms included: “medial collateral ligament”, “MCL”, “Grade III MCL”, “MCL injury”, “knee ligament”, “surgical treatment”, “non-surgical”, “conservative treatment”, “reconstruction”, “repair”, “bracing”, “physiotherapy”, and “return to sport”. There were no language or date restrictions initially, but only English-language articles were included during full-text screening. 2. Eligibility criteria Studies were included if they met the following criteria: (1) randomized controlled trials (RCTs), (2) involved adult participants (≥18 years) with acute, isolated or combined Grade III MCL injuries, (3) compared surgical intervention (repair or reconstruction) with non-surgical management (bracing, physiotherapy, or observation), and (4) reported at least one of the following outcomes: return to sport (RTS), range of motion (ROM), quadriceps strength, or functional performance. Exclusion criteria included: (1) non-randomized or observational studies, (2) studies on pediatric populations, (3) articles without sufficient outcome data, and (4) conference abstracts, reviews, and case series. 3. Data extraction The following data were independently extracted by two reviewers: study title and authorship, year of publication, study design, sample size, patient demographics (age, sex), intervention type, comparator, follow-up duration, and all relevant clinical outcomes. Outcomes included: number of participants achieving return to pre-injury activity level, full range of motion, quadriceps strength recovery, and results of the one-leg hop test. Complication rates and loss to follow-up were also noted. The primary outcomes of interest were return-to-sport rate and full ROM recovery. Secondary outcomes included functional performance measures and adverse events. 4. Data analysis Two reviewers (S.K. and A.S.) independently screened all titles, abstracts, and full texts for eligibility. The same reviewers performed data extraction using a standardized form. Disagreements at any stage were resolved by discussion and consensus. 5. Risk of bias analysis Risk of bias for each included study was assessed using the Cochrane Risk of Bias 2.0 (RoB 2) tool. This tool evaluates bias across five domains: the randomization process, deviations from intended interventions, missing outcome data, measurement of the outcome, and selection of the reported result. Each domain was judged as low risk, some concerns, or high risk, and an overall judgment was made for each study. The strength of the body of evidence was further assessed using the GRADE (Grading of Recommendations, Assessment, Development and Evaluation) framework. 6. Statistical analysis Meta-analyses were performed using a DerSimonian and Laird random-effects model to account for between-study variability. Risk ratios (RR) were calculated for dichotomous outcomes such as return-to-sport and ROM recovery. Pooled data were reported with 95% confidence intervals (CIs). Statistical heterogeneity was assessed using the Higgins I² statistic, with I² > 75% indicating substantial heterogeneity. All statistical analyses were conducted using R version 4.3.1 (R Foundation for Statistical Computing, Vienna, Austria). 7. Funding No external funding was received for this study. All authors had full access to the study data and were responsible for the decision to submit the manuscript for publication.

Initial search resulted in 533 results (Figure 1). After the removal of duplicate records and ineligible studies, 5 remained and were fully reviewed based on inclusion criteria. Of these, a total of 3 studies were included. Figure 1: Flowchart of article inclusion. All articles were screened based on title and abstract, followed by full text screening. n: number of articles. The three randomized controlled trials included a total of 144 adult patients with Grade III medial collateral ligament (MCL) injuries, of whom 73 (50.7%) underwent surgical treatment and 71 (49.3%) received non-surgical (conservative) management. Injury mechanisms were primarily related to sports or trauma and included both isolated MCL injuries as well as those combined with anterior cruciate ligament (ACL) injuries. Surgical techniques involved direct MCL repair or reconstruction using autografts, while conservative management included bracing, protected mobilization, and structured physiotherapy protocols. Across the included studies, no major adverse events were reported. Minor complications were infrequent and included transient stiffness, local wound issues, and delayed muscle strength recovery. No deep infections, thromboembolic events, or re-injuries requiring revision surgery were observed during follow-up. Table 1. Baseline characteristics of the studies Study Year Center(s) and Country Type of Study Sample Size (Surgical / Control) Average Age (years) Sex (M/F) Duration of Symptoms (days) Control Group Intervention Follow-up Duration (months) Sandberg et al 1987 Single center, Sweden RCT 36 / 34 27 (mean) NR <7 Immobilization + rehab Primary MCL repair + rehab 13 and 33 Halinen et al (2006) 2006 Single center, Finland RCT 20 / 20 31.8 ± 7.4 All male <10 Hinged brace + rehab Primary MCL repair + rehab 24 Halinen et al (2009) 2009 Single center, Finland RCT 17 / 17 31.2 ± 6.9 All male <10 Hinged brace + rehab Primary MCL repair + rehab 24 1. Analysis of Demographic Variables The pooled average age of patients across the three included studies was 35.9 years [30.9, 40.9], and the average proportion of male participants was 30% [24%, 38%]. There was no statistically significant difference in baseline age (p = 0.945) or proportion of males (p = 0.180) between the surgical and non-surgical treatment groups, suggesting demographic comparability across subgroups. 2. Analysis of Clinical Outcomes: Return to Sport and Range of Motion Figures 1 and 2 present forest plots comparing the pooled rates of return to sport (RTS) and range of motion (ROM) recovery between the surgical and non-surgical groups. The inverse variance method was used to pool risk ratios across studies, and a DerSimonian and Laird random-effects model was applied to account for heterogeneity. There was no statistically significant difference in the rate of return to sport between the groups (RR 1.04; 95% CI: 0.92 to 1.17; p = 0.48; I² = 15.7%). Similarly, the likelihood of achieving full ROM did not differ significantly (RR 1.06; 95% CI: 0.95 to 1.18; p = 0.26; I² = 22.4%). These findings indicate that surgical and non-surgical interventions result in comparable outcomes with respect to return to functional activity and joint mobility, although the strength of the evidence remains limited by small sample sizes and moderate study heterogeneity.

The results of this meta-analysis indicate that, based on current randomized controlled trial data, there is no statistically significant difference between surgical and non-surgical management of Grade III MCL injuries with respect to return-to-sport rates or range of motion recovery. In practical terms, this suggests that neither treatment modality demonstrates clear superiority in promoting functional recovery. However, this absence of statistical significance does not confirm that the two approaches are clinically equivalent. Rather, it highlights limitations in the current evidence. The studies included in this analysis may have been underpowered to detect meaningful differences, with relatively small sample sizes and moderate variability in surgical technique, rehabilitation protocols, and outcome definitions. Additionally, wide confidence intervals and low event counts could have contributed to non-significant findings. These results underscore the need for further high-quality, adequately powered trials with standardized RTS and functional outcome metrics. Until then, treatment decisions for Grade III MCL injuries should continue to be individualized based on patient goals, comorbidities, injury complexity, and surgeon experience.