Internal fixation is currently the standard of care for Garden I and II femoral neck fractures in the elderly. However, there may be a degree of posterior tilt on the preoperative lateral radiograph above which failure is likely, and primary arthroplasty would be preferred. The purpose of this study was to determine the association between posterior tilt and the risk of subsequent arthroplasty following internal fixation of Garden I and II femoral neck fractures in the elderly.

This study represents a secondary analysis of data collected in the FAITH trial, an international multicenter randomized controlled trial comparing the sliding hip screw to cannulated screws in the management of femoral neck fractures in patients aged 50 years or older. For each patient who sustained a Garden I or II femoral neck fracture and had an adequate preoperative lateral radiograph, the amount of posterior tilt was categorized as < 2 0 degrees or ≥20 degrees. Multivariable Cox proportional hazards analysis was used to assess the association between posterior tilt and subsequent arthroplasty during the two-year follow-up period, while controlling for potential confounders.

Of the 555 patients in the study sample, posterior tilt was classified as ≥20 degrees for 67 (12.1%) and < 2 0 degrees for 488 (87.9%). Overall, 13.2% (73/555) of patients underwent subsequent arthroplasty in the 24-month follow-up period. In the multivariable analysis, patients with posterior tilt ≥20 degrees had a significantly increased risk of subsequent arthroplasty compared to those with posterior tilt < 2 0 degrees (22.4% (15/67) vs 11.9% (58/488), Hazard Ratio (HR) 2.22, 95% confidence interval (CI) 1.24–4, p=0.008). The other factor associated with subsequent arthroplasty was age ≥80 (p=0.03).

In this study of patients with Garden I and II femoral neck fractures, posterior tilt ≥20 degrees was associated with a significantly increased risk of subsequent arthroplasty. Primary arthroplasty should be considered for Garden I and II femoral neck fractures with posterior tilt ≥20 degrees, especially among older patients.