The Impact of Magnetic Resonance Imaging on the Diagnosis of High-Energy Ipsilateral Femoral Neck and Shaft Fractures

Objective: To evaluate the most common femoral shaft fracture morphology associated with an ipsilateral femoral neck fracture in high-energy blunt trauma using magnetic resonance imaging (MRI). Design: Retrospective review. Setting: Level 1 trauma center. Patients/Participants: 219 consecutive patients sustaining 228 femoral shaft fractures from high-energy blunt trauma. Main Outcome Measurements: Fracture patterns were analyzed using the OTA/AO classification system. In addition, location of the fracture was measured as the distance from the distal aspect of the lesser trochanter to the center of the femoral shaft fracture. Results: An OTA/AO 31 type fracture was seen in 16.5% (20/121) of patients presenting with OTA/AO 32-A type fractures, 12% (6/50) of patients with OTA/AO 32-B type fractures, and 26.3% (15/57) of patients with OTA/AO 32-C type fractures. The fractures that occurred in the middle or distal third of the femur shaft constituted 95.1% (39/41). Conclusions: In this cohort, patients with middle and distal third OTA/AO 32-C type fractures had the highest association with an ipsilateral OTA/AO 31 type fracture. OTA/AO 32-A2 and 32-A3 type fractures had the highest association with femoral neck fractures seen only on MRI. The data presented suggest continued usage of the rapid sequence pelvic MRI for all patients with high-energy femoral shaft fractures in whom a femoral neck fracture was not seen on an x-ray or a computed tomography scan.