A Multicenter Study of Intertrochanteric and Pertrochanteric Fragility Fractures: Spanning Fixation Mitigates the Risk of Peri-Implant Fractures.

Abstract

BACKGROUND Whether the fixation of pertrochanteric and intertrochanteric fragility fractures impacts the risk of subsequent peri-implant fracture remains unclear. We hypothesized that peri-implant fracture after an index pertrochanteric or intertrochanteric fragility fracture is associated with fixation that does not reach the distal metaphysis (non-spanning fixation). METHODS Retrospective chart review was performed of patients treated for index pertrochanteric and intertrochanteric femoral fragility fractures at 2 health-care systems between January 1, 2005, and January 1, 2018. Cases were categorized by whether or not fixation reached the distal metaphysis (spanning compared with non-spanning). Kaplan-Meier survival analyses estimated cumulative incidences of peri-implant fracture stratified by patient, injury, and treatment characteristics, with hazard ratios (HRs) reported when significant. We also assessed whether spanning or non-spanning fixation was associated with a contralateral femoral fracture (a proxy for patient-related fracture risk). Significance was set at p < 0.05. RESULTS In this study, 913 patients with a median age of 80 years had a median follow-up of 5 months (interquartile range [IQR], 3 weeks to 2.7 years). The OTA/AO classification included 388 type 31-A1 fractures, 324 type 31-A2 fractures, and 201 type 31-A3 fractures. There were 18 subsequent peri-implant fractures (1.9%) and 40 subsequent contralateral femoral fractures (4.4%). The cumulative incidence of peri-implant fracture was lower over time (p < 0.01) with spanning fixation (0% prior to 1 year) compared with non-spanning (3.3% prior to 1 year). The HR of spanning fixation for the entire time period was 0.14 (95% confidence interval, 0.03 to 0.62; p < 0.01). Peri-implant fracture risk was greater with non-spanning plates (p < 0.01) and non-spanning nails (p < 0.01) than spanning fixation, with cumulative 1-year incidences of 3.5% for non-spanning plates, 2.6% for non-spanning nails, and 0% for spanning fixation. Peri-implant fracture was not associated with other variables (p > 0.05). Contralateral fracture was not associated with the fixation group (p = 0.77), tempering concern regarding potential bias. CONCLUSIONS Spanning fixation following pertrochanteric and intertrochanteric femoral fragility fractures mitigates the risk of a peri-implant fracture. However, the choice of fixation for a given patient requires that this risk be considered within the greater context of surgical decision-making. LEVEL OF EVIDENCE Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.