The prevalence of fracture extension in displaced femoral neck fractures in the elderly: A pilot study

OBJECTIVE: Arthroplasty is the common treatment for intracapsular femoral neck fractures in the elderly. Recent studies have shown that there may be more overall complications related to uncemented hemiarthroplasty compared to cemented, including more subsidence, intraoperative fractures, and postoperative fractures. Uncemented femoral components rely on a press fit, and the risk of these complications would be expected to increase in patients with unrecognized distal extension of femoral neck fractures. The purpose of this study is to determine the frequency of fracture extension of displaced femoral neck fractures in the elderly population. METHODS: The electronic medical record database at our institution was retrospectively reviewed to search for consecutive reports from 2005 to 2015 of patients 65 years or older that sustained an intracapsular femoral neck fracture who had computed tomography (CT) examinations of the injury. Exclusion criteria were CTs that were not fine cut (<1.5 mm cuts) or occult femoral neck fractures that were seen only on magnetic resonance imaging. This resulted in 60 patients that were included in the study. Within this subset of patients, the CT scans were reassessed to look for extension of the fracture beyond the boundaries of the femoral neck. Of particular interest, were fracture lines that extended distal to the femoral neck, since these have the potential to affect the fit of an uncemented femoral stem. Data on subject age, gender, body mass index (BMI), and bone mineral density (BMD) were also collected, and it was determined if these demographics were predictive in patients having fracture extension. Treatment and follow-up data were collected for the patients as well. RESULTS: Seven of 60 patients were identified to have fracture extension of intracapsular femoral neck fractures. The frequency of fracture extension of intracapsular femoral neck fractures distal to the femoral neck was 8.3% (5/60). All cases of fracture extension were nondisplaced or minimally displaced. 60% (3/5) of the distal fracture extensions were not diagnosed preoperatively by the radiologists or the treating orthopaedic surgeons. There was not a statistically significant difference when comparing age, gender, BMI, or BMD of the population group with distal fracture extension to that of the rest of the patient cohort. CONCLUSIONS: To our knowledge, this is the first study to report the frequency of fracture extension of displaced femoral neck fractures in the elderly population. The 8.3% rate of distal fracture extension in elderly femoral neck fractures may help explain the higher rate of subsidence, postoperative fracture and intraoperative fracture when applying uncemented hemiarthroplasty compared to cemented arthroplasty. It is important to be aware of the potential for this phenomenon.