Ulnar collateral ligament (UCL) injuries of the thumb metacarpophalangeal (MCP) joint, commonly known as gamekeeper’s thumb or skier’s thumb, represent one of the most frequently encountered ligamentous injuries of the hand. These injuries carry significant clinical importance across both athletic and general populations. This narrative review examines the anatomy, etiology, epidemiology, pathophysiology, clinical evaluation, imaging modalities, and management strategies for thumb UCL injuries. This narrative review synthesizes current evidence from peer-reviewed literature identified through PubMed and Google Scholar, including landmark studies, systematic reviews, and clinical series, supplemented by established reference texts. A thorough review of the current literature demonstrates that partial UCL tears respond well to conservative management with immobilization, while complete ruptures—particularly those complicated by Stener lesions, which occur in an estimated 40–87% of complete tears—typically require surgical intervention. Imaging modalities, including ultrasound and MRI, play complementary roles in diagnosis, with MRI demonstrating superior specificity for distinguishing displaced from non-displaced tears. Surgical repair yields excellent outcomes, with systematic reviews reporting return-to-play rates exceeding 98% in athletic populations, though generalizability to non-athletic cohorts remains limited. Conservative management of partial tears also demonstrates favorable results, with success rates exceeding 90% reported in clinical series, though high-quality comparative data remain sparse. Limitations of the current evidence base include reliance on retrospective surgical cohorts, heterogeneous outcome measures, and a relative paucity of prospective comparative studies evaluating conservative versus operative management across diverse patient populations. This review synthesizes published evidence with particular attention to diagnostic accuracy of imaging modalities, prevalence and significance of Stener lesions, and evidence-based treatment thresholds—areas in which recent literature has provided important new data. Early recognition and appropriate management are essential to preventing chronic instability and long-term functional impairment.
