Posterior cruciate ligament involvement leads to inferior outcomes in multiligament knee injuries involving the medial collateral ligament: A systematic review and meta-analysis.

Abstract

Multiligament knee injuries (MLKIs) involving the medial collateral ligament (MCL) present unique challenges in surgical management and postoperative rehabilitation. This systematic review and meta-analysis aimed to evaluate postoperative patient-reported outcomes in patients with MCL-involved MLKIs, with a minimum follow-up of 2 years. A systematic search, registered in PROSPERO (CRD42022364292) of MEDLINE, Embase, Web of Science and the Cochrane Library databases was conducted to identify surgical outcome-based studies on MLKIs with MCL involvement, published between January 2000 and October 2024, with at least 2 years of follow-up. Studies including nonoperative treatment, arthroplasty, paediatric populations and technique articles were excluded. Data extracted included study design, patient demographics, follow-up duration, anatomical region of injury and graft reconstruction type. Patient-reported outcomes included Lysholm score, International Knee Documentation Committee (IKDC) score and Tegner activity scale. A random-effects meta-analysis was performed. After applying inclusion and exclusion criteria, 20 studies with a total of 479 patients (all with MCL-involved MLKIs) were included. The mean patient age at surgery was 35.6 years, and the average follow-up was 4.1 years (range 2-12.7 years). At 2-year follow-up, the mean Lysholm score was 86.0 (95% confidence interval [CI]: 82.0-89.9) (p = 0.020). The mean IKDC score at 2 years was 75.8 (95% CI: 69.4-82.2) (p < 0.001). Patients whose injuries did not involve the posterior cruciate ligament (PCL) demonstrated significantly higher IKDC scores than those with PCL involvement (92.0 vs. 71.2, p < 0.001). Lysholm scores followed a similar pattern (92.0 vs. 84.4, p = 0.020). Overall, these findings indicate that PCL-based medial-sided MLKIs have poorer functional outcomes than those without PCL involvement. According to this meta-analysis of MCL-involved MLKIs with a minimum 2-year follow-up, patients can expect to maintain around 75%-80% of knee function at 2 years. Notably, MCL-involved MLKIs without PCL involvement demonstrated higher IKDC and Lysholm scores compared with those who had combined MCL-PCL injuries, underscoring the greater complexity and poorer prognosis associated with PCL-based MLKIs. PROSPERO Registration number: CRD42022364292. Level IV, systematic review and meta-analysis.