Background: Intraoperative femoral fracture is a well-known complication to primary total hip arthroplasty (THA). Experimental studies have suggested that intraoperative fractures may affect implant survival. How-ever, available clinical data are sparse.

Methods: We used data from the Danish Hip Arthroplasty Registry to identify patients treated with a primary THA due to primary osteoarthritis in Denmark between 1995 and 2005 (n=39478). Data was linked to two national Danish databases to conduct time dependent implant survival analyses. Implant survival and relative risk estimates were calculated for patients treated conservatively and patients treated with osteosynthesis after sustaining intraoperative femoral fractures during THA surgery. The reference group was THA’s performed without sustaining intraoperative femoral fracture. Furthermore we assessed the relative risk for reoperations and readmission to an orthopaedic department 3 months postoperatively.

Results: 282 patients (0.7%) were treated conservatively due to intraoperative femoral fracture and 237 patients (0.6%) were treated with osteosynthesis. The Kaplan– Meier survival plots revealed a significant poorer THA survival after osteosynthesis of intraoperative femoral fractures. In the 0–6 months postoperative period the adjusted relative risk (RR) for revision was 1.5 (95% CI: 1.1–1.7) for patients treated conservatively. In the same period the adjusted RR for revision was 5.7 (3.3–10.0) for patients treated with osteosynthesis. In the period 6 months to 11 years postoperatively we did not find any significant differences in the RR for revision among the groups.

Interpretation: Intraoperative fractures increase the relative risk for revision the first 6 postoperative months. Therefore, patients should be informed about the risk for revision when sustaining an intraoperative femoral fracture. Further, initiatives aimed at reducing the risk of revision in the first 6 months following THA should be considered in patients with intraoperative fractures including immediate revision of the stem to a larger stem with distal fixation and restricted weight bearing.