Interprosthetic Femur Fractures: A Multi-Center Retrospective Study.

Objectives: To identify practices for treating interprosthetic femur fracture (IFFs) and determine factors that positively impact patient outcomes.

Methods: Design: Retrospective cohort study.

Setting: Fifteen trauma centers in the United States.

Patient Selection Criteria: Patients aged 50 to 90 years who underwent operative fixation of an AO/OTA 32 A-B-C type IFF fracture from 2011 to 2021 were included. Patients who underwent revision arthroplasty at the time of fixation or were non-ambulatory were excluded.

Outcome Measures And Comparisons: The primary outcome was union rate. Secondary outcomes included post-operative complications, revision surgery, mortality, and change in ambulation status. Univariate analyses using Chi-square tests, Fisher's exact tests, and analysis of variance were performed to detect associations between demographic, injury, and surgical characteristics with post-operative outcomes.

Results: One hundred thirty-nine patients were included, with 110 (79%) females and median age 78 [range, 57-90]. Distal one-third fractures were most common 68% (N=95). One hundred eighteen (85%) patients were treated with a lateral plate, 8% (N=11) were treated with nail-plate combination and 7% (N=10) were treated with dual plates. The median time to full-weight bearing (FWB) was 2.5 months. Dual plate combination was associated with the fastest time to FWB (p = 0.048) at two weeks. 61% (n=85) of patients returned to baseline ambulation status (100% [11] IMN/plate, 60% [71] lateral plate and 25% [3] dual plate) with patients treated with nail-plate had higher rates of return to baseline function (p = 0.009). The overall mortality rate was 13% and associated with greater than 1 comorbidity (p = 0.022).

Conclusions: A spanning lateral plate was the most common fixation of IFF in our study. Patients with dual fixation were more likely to return to baseline ambulatory status, particularly those with intramedullary nail/plate combination. The mortality rate at one year was 11% and comorbidity burden was associated with higher risk of mortality.

Level Of Evidence: Therapeutic Level III.