Investigating the incidence of concomitant lower-extremity and pelvic fractures in patients with multiligament knee injuries

BACKGROUND: Multiligament knee injuries (MLKIs) often result from high-energy trauma in polytrauma patients. They may coincide with other musculoskeletal injuries, especially fractures of the ipsilateral lower extremity (LE) or pelvis. Understanding these fracture patterns can guide surgical planning and improve patient outcomes. The study aim is to describe the ligamentous injury patterns of combined ipsilateral LE or pelvic fractures with surgically treated MLKIs.

METHODS: A retrospective cohort study was conducted from April 2008 to August 2024. Patients who sustained tibial plateau (TP), femoral condyle (FC), fibular, tibial shaft, femoral shaft, or pelvic fractures, concurrent with surgically treated MLKIs, were included. Ligament injuries (anterior cruciate [ACL], posterior cruciate [PCL], medial collateral [MCL], and lateral collateral [LCL]) were categorized by number (≥ 2) and pattern (ACL-based, PCL-based, or bicruciate). Comparisons were made between fracture and non-fracture groups.

RESULTS: Among 211 patients (69% male; mean age 28.3 ± 12.9 years), 36% (75/211) had fractures, with 19% (17/75) requiring operative fixation. TP fractures were the most common (57%), followed by FC (47%) and pelvic fractures (16%). ACL-based injuries (65%) were predominant, while PCL-based injuries were less frequent in fracture patients (4% versus 13% in the non-fracture group). ACL/LCL injuries were significantly more common in the fracture group (29% versus 18%, p = 0.049). Two-ligament injuries accounted for 71% (53/75) of fracture cases.

CONCLUSIONS: More than one-third of patients with MLKI sustained concomitant LE fractures, with TP fractures occurring most frequently. ACL/LCL and ACL/PCL/LCL patterns showed particularly high fracture rates, whereas PCL-based MLKIs were more common without fractures.