Over 10% of Surgically Treated High-Energy Pelvic Fractures are Associated with Undiagnosed Ligamentous Knee Injuries: An Epidemiologic Study in Italy’s Largest Trauma Centre

Purpose To evaluate the prevalence of undiagnosed ligamentous knee injuries in patients surgically treated for high-energy pelvic ring or acetabular fractures and propose a mechanism to diagnose these briefly post-hospital discharge. Methods A retrospective observational study was conducted at Italy’s largest trauma centre. Medical records from 2018–2023 were reviewed to identify patients who underwent surgical treatment for pelvic or acetabular fractures. Eligible patients were contacted for a structured telephone interview, which included a questionnaire on knee symptoms and the International Knee Documentation Committee (IKDC) score. Associations between demographic factors, trauma mechanism, and knee outcomes were statistically analyzed. Results Fifty-nine patients (mean age 55 years, 72.9% male) were enrolled. Undiagnosed knee ligament injuries were present in 11.9%, with an additional 8.5% reporting persistent knee symptoms. The average time to diagnosis was 6.4 months post-discharge. Patients involved in road traffic accidents showed a significantly higher incidence of knee injuries (34.8%) compared to those who fell from height (3.9%) (p = 0.049). Patients who had undergone ligament reconstruction had significantly lower IKDC scores (62.0 ± 8.2) than non-surgical cases (82.4 ± 12.1, p = 0.0002). No association was found with age or sex. Conclusion Ligamentous knee injuries are frequently overlooked in the acute management of high-energy pelvic fractures, particularly in road traffic accidents. A systematic knee assessment before discharge or early outpatient imaging should be considered to improve detection and outcomes.