Abstract
Chronic ulnar collateral ligament (UCL) injuries of the thumb differ from acute tears in tissue quality and surgical options, yet the relative merits of direct repair versus anatomic reconstruction remain uncertain. We conducted a Preferred Reporting Items for Systematic reviews and Meta-Analyses-aligned systematic review synthesising operative techniques, rehabilitation protocols, outcomes, and complications for chronic, closed thumb metacarpophalangeal (MCP) joint UCL injuries in adults. Two reviewers independently screened studies and extracted data; risk of bias was appraised with Risk Of Bias In Non-randomized Studies - of Interventions (ROBINS-I) and the National Institutes of Health case-series tool, and certainty was judged with Grading of Recommendations, Assessment, Development and Evaluation (GRADE). Of 22 241 records identified, 336 were screened after automation and deduplication; 54 full texts were assessed and 24 studies met inclusion (n = 331; 19 case series, 5 case reports); no randomised or comparative trials were found. Direct repair (± suture anchors) was rarely feasible in chronic lesions. Most series described anatomic reconstruction using tendon autograft - commonly palmaris longus, with flexor carpi radialis or plantaris alternatives - fixed with interference screws, suture anchors, or transosseous pull-out techniques. Immobilisation typically lasted 4 to 6 weeks; some cohorts used temporary MCP joint Kirschner wire fixation for ~6 weeks. Across heterogeneous reporting, reconstruction generally restored stability and improved function, with low re-rupture rates; however, sample sizes were small and overall risk of bias was fair to poor, limiting certainty. For chronic thumb UCL insufficiency without established MCP joint arthritis, anatomic reconstruction is the predominant and most consistently successful operative strategy. These findings support the standardisation of outcome reporting and rehabilitation protocols and highlight the need for multicentre comparative trials to define optimal management options.