Low-energy Distal Femur Fractures in Patients Over 50 years old: Protecting the Femoral Neck Reduces Risk of Subsequent Hip Fracture.

Objectives: To determine the rate of subsequent ipsilateral proximal femur fractures after fixation of low energy distal femur fractures among patients ≥ 50 years old and to evaluate whether fixation protecting the femoral neck mitigates the risk of subsequent ipsilateral hip fracture.

Methods: Designs: A retrospective comparative study.

Setting: Four academic level I trauma centers.

Patient population: Included were patients aged 50 years or older treated with open reduction internal fixation of a low energy distal femur fracture (AO/OTA 33 A, B, or C) from 2005 to 2024 without prior proximal femur implant.

Outcome measures and comparisons: Patient demographics, comorbidities, injuries, fixation type, and subsequent hip fracture were evaluated and compared based on femoral neck protection.

Results: Femoral neck protection was employed for 103 patients (80 women, 77.7%) with median age 77 years (IQR 70 to 84) and was not employed among 517 patients (424 women, 82.0%) with median age 71 years (IQR 63 to 82). Twenty-six subsequent ipsilateral hip fractures occurred. Two were immediately adjacent to prior fixation, and 24 were distant from prior fixation. Subsequent ipsilateral fractures occurred more often without femoral neck protection (26/517, 5.0%) than when the femoral neck was protected (0/103, 0%), p = 0.013. The cumulative rate of hip fracture in the absence of femoral neck protection at 1, 2, 3, and 4 years postoperatively was 2.4%, 4.0%, 5.6% and 7.2%, respectively, while the cumulative rate remained at 0% throughout follow up in the setting of femoral neck protection (log-rank p = 0.031).

Conclusion: Patients ≥ 50 years old with low energy distal femur fractures had a clinically significant risk of subsequent ipsilateral hip fracture that increased steadily with time. Fixation protecting the femoral neck during distal femur fracture treatment was associated with a significantly reduced risk of subsequent ipsilateral hip fracture.

Level of evidence: Level III, therapeutic study.