Predictors of Perioperative Vancouver B Periprosthetic Femoral Fractures Associated With the Direct Anterior Approach to Total Hip Arthroplasty.

Background: There is an association between intraoperative and postoperative femoral fractures and the direct anterior approach (DAA) to total hip arthroplasty (THA). The purpose of our study is to identify risk factors for Vancouver B fractures and to establish a predictable timeline for when these occur.

Methods: We retrospectively identified patients with Vancouver B periprosthetic femoral fractures (n = 49) after 11,509 elective primary cementless THA procedures through the DAA between 2012 and 2018 at a single institution. Fracture patients were matched to nonfracture patients (n = 267) by date of surgery and surgeon. Clinical and radiographic factors were collected for multivariable analysis to identify predictors of fracture.

Results: Periprosthetic Vancouver B femoral fracture incidence was 0.4%. 48 (98%) fractures were postoperative. Fractures occurred at an average of 44 days after surgery (range: 1 to 653 days) with >85% of fractures occurring in the first 6 weeks postoperatively. Significant variables predictive of fracture included >3 degrees valgus and >5 degrees varus coronal stem malalignment, Dorr B and C femoral geometry, lower canal flare index (2.75 vs 3.20), advanced age, increased comorbidities, greater stem canal fill, and right-sided procedures.

Conclusion: Despite an overall low rate of Vancouver B perioperative periprosthetic femoral fractures, it is a devastating complication that typically presents within the first 6 weeks after DAA THA surgery. The risk is increased in patients with unfavorable proximal femoral geometry, coronal stem malalignment, advanced age, increased comorbidities, and right-sided procedures.