Risk factors for intraoperative calcar fracture in cementless total hip arthroplasty

Background and purpose — Intraoperative periprosthetic fem- oral fracture is a known complication of cementless total hip arthroplasty (THA). We determined the incidence of—and risk factors for—intraoperative calcar fracture, and assessed its influ- ence on the risk of revision. Patients and methods — This retrospective analysis included 3,207 cementless THAs (in 2,913 patients). 118 intraoperative calcar fractures were observed in these hips (3.7%). A control group of 118 patients/hips without calcar fractures was randomly selected. The mean follow-up was 4.2 (1.8–8.0) years. Demo- graphic data, surgical data, type of implant, and proximal femur morphology were evaluated to determine risk factors for intraop- erative calcar fracture. Results — The revision rates in the calcar fracture group and the control group were 10% (95% CI: 5.9–17) and 3.4% (CI: 1.3– 8.4), respectively. The revision rate directly related to intraopera- tive calcar fracture was 7.6%. The Hardinge approach and lower age were risk factors for calcar fracture. In the fracture group, 55 of 118 patients (47%) had at least one risk factor, while only 23 of118 patients in the control group (20%) had a risk factor (p = 0.001). Radiological analysis showed that in the calcar fracture group, there were more deviated femoral anatomies and proximal femur bone cortices were thinner. Interpretation — Intraoperative calcar fracture increased the risk of revision. The Hardinge approach and lower age were risk factors for intraoperative calcar fracture. To avoid intraopera- tive fractures, special attention should be paid when cementless stems are used with deviant-shaped proximal femurs and with thin cortices.