The influence of Dorr type and femoral fixation on outcomes following total hip arthroplasty for acute femoral neck fractures: A multicenter study.

INTRODUCTION: The American Academy of Orthopaedic Surgeons guidelines report moderate evidence for cementing femoral stems for hip fractures, mainly derived from hemiarthroplasty literature. This is the first large, non-registry study examining the influence of femoral fixation, implant type, patient characteristics, and radiographic factors on outcomes after total hip arthroplasty (THA) for acute femoral neck fractures.

METHODS: A multicenter retrospective study was performed of 709 THA cases (199 cemented, 510 cementless) for femoral neck fractures from 2006 to 2020 at three large academic institutions. Demographics, perioperative characteristics, and radiographs were reviewed. Kaplan-Meier survivorship curves were generated for multiple outcomes. Univariate and multivariate analyses were performed with p≤0.05 denoting significance.

RESULTS: Cementless stems had a higher all-cause aseptic femoral revision rate (5.1 vs 0.5%, p=0.002) and periprosthetic femoral fracture rate (4.3 vs 0%, p=0.001). Each successive Dorr type had a higher fracture rate with cementless implants: 2.3%, 3.7%, and 15.9% in Dorr A, B, and C, respectively (p<0.001). Logistic regression analyses confirmed that cementless stems (p=0.02) and Dorr C bone (p=0.001) are associated with periprosthetic fractures; collared implants and prophylactic cables did not protect against fractures. There was no difference in rates of dislocation, septic revision, or mortality between groups.

CONCLUSIONS: Cementless stems during THA for femoral neck fractures have a higher aseptic femoral revision rate, specifically for periprosthetic fractures. Dorr C bone was particularly prone with an alarmingly high fracture rate. All fractures occurred in cementless cases, suggesting that cemented stems may minimize this complication.