How do surgically treated multiligamentous knee injuries affect overall complication rate and especially stiffness? A systematic review

Background Multiligamentous knee injuries (MLKIs), defined as injuries involving at least two of the four primary knee ligaments, are rare but severe, with potentially limb- or life-threatening complications. Despite numerous publications, the low incidence and heterogeneity of injury patterns limit high-level evidence for optimal surgical timing, technique, and management of complications. This systematic review aims to consolidate the available evidence on MLKI surgery complications, with a particular focus on arthrofibrosis as the underlying cause of stiffness, infection, and graft failure. Methods This systematic review was conducted following Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) 2020 guidelines and registered in the International Prospective Register of Systematic Reviews (PROSPERO) (no. CRD42024618025). A comprehensive search of PubMed, EMBASE, and MEDLINE from January 2013 to November 2024 identified studies reporting complications in surgically treated MLKIs with at least a 12-month follow-up. The studies were screened independently by two reviewers. Data on demographics, injury mechanisms, surgical techniques, and complication outcomes were extracted. Study quality was assessed using the Methodological Index for Non-Randomized Studies (MINORS). Results A total of 33 studies with 2863 patients met the inclusion criteria. The mean age was 32.4 years (standard deviation, SD +/- 5.37), with males constituting 69.4% of the sample. Arthrofibrosis was the most common complication, requiring surgical management in 8.4% of cases. Graft failure was reported in 5%, while infection, the third most common complication, occurred in 2.86% of cases. Management of lack of range of motion varied, with manipulation under anesthesia and arthroscopic arthrolysis utilized. Surgical timing also influenced outcomes; 54.2% of patients underwent acute surgery (< 21 days), which seems to be associated with increased stiffness rates. Conclusions This systematic review highlights the complexity of managing MLKIs, with a 19.2% overall complication rate. Stiffness demanding reoperation remains a rare but a significant challenge, underscoring the need for standardized treatment protocols. However, the included studies demonstrate heterogeneity and lack high methodological rigor, highlighting the need to account for these limitations.