Femoral Neck Complications in Isolated Femoral Neck Fractures Versus Ipsilateral Femoral Neck and Shaft Fractures

There are limited data on the difference in outcomes between patients with isolated femoral neck fractures (IsoFN) and those with a femoral neck and ipsilateral femoral shaft fracture (IpsiFNS) in terms of osteonecrosis, nonunion, and revision surgery rates. We hypothesized that displaced IsoFN fractures would have higher rates of femoral neck nonunion, osteonecrosis, and hip revision surgery than displaced IpsiFNS fractures. Comparisons were made to determine the relationship between these outcomes and other variables.

A retrospective review of patients age 18 to 55 years from 2005 to 2020 at two level-I trauma academic institutions was performed, identifying 107 patients in total (IpsiFNS 51, IsoFN 56). The review analyzed the rates of displacement, osteonecrosis, nonunion, and revision surgery. Further comparisons were made to determine the effect of reduction quality, fixation method, and reduction type on these outcomes.

Patients with displaced IsoFN had a significantly higher nonunion, revision surgery and osteonecrosis rate (38.5%, 38.5%, 17.3%) than in patients with IpsiFNS (6.7%, 13.3%, 0%; P = 0.004, P = 0.010, P = 0.016 respectively). There was a relationship between nonunion and femoral neck fixation with fully threaded screws (P = 0.036 and P = 0.004). Among patients who underwent an open reduction, nonunion rates were significantly higher for displaced IsoFN than for displaced IpsiFNS (7.4% vs. 43.2%, P = 0.008). Osteonecrosis rates had a relationship with reduction quality (P = 0.044).

Patients with a displaced isolated femoral neck fractures are at higher risk for nonunion, osteonecrosis, and revision surgery than those with a displaced femoral neck fracture associated with an IpsiFNS. Quality of reduction had a relationship with osteonecrosis rates. An open approach to the neck reduction was associated with nonunion at a higher rate in displaced IsoFN than in displaced IpsiFNS. A fixation construct of multiple cancellous independent screws that included fully threaded screws had higher odds for nonunion.