Femoral Neck Fractures: Incidence, Reasons, and Risk Factors of Conversion From Hemiarthroplasty to Total Hip Arthroplasty.

Background: There is controversy over the choice of hemiarthroplasty (HA) versus total hip arthroplasty for treatment of femoral neck fractures in geriatric patients, especially those who are relatively healthy and active. A concern for selection of HA is that the patients may later require conversion to THA.

Methods: All geriatric patients with femoral neck fractures who underwent HA were identified in the national PearlDiver data set. Patients were required to have 5 years of follow-up, and incidence of conversion was determined. Univariable and multivariable analyses were conducted to determine factors associated with conversion. The timing of conversion and reasons for conversions were determined.

Results: A total of 7,501 patients were identified with femoral neck fractures who underwent initial treatment with HA. Of those, 173 (2.3%) underwent conversion to THA within 5 years. On multivariable analysis, conversion was associated with patients being younger than 75 years (odds ratio: 1.64, P = 0.002) and having a higher Elixhauser Comorbidity Index (odds ratio: 1.04 per point, P = 0.018). Of the conversions performed over a five year period, 109 patients (63.0%) were within the 1st year. The most common reason for conversion to THA was degenerative causes (67.6%).

Conclusions: Overall, there was a low rate (2.3%) of conversion from HA to THA for those who were tracked for 5 years after HA for femoral neck fracture. This low conversion rate is supportive that HA offers a durable answer for most patients for whom this treatment choice is pursued.

Levels of evidence: III.