Risk factors for reoperation after treatment of femoral neck fractures with an uncemented hemiarthroplasty; a retrospective single center registry study

Patients treated with hip hemiarthroplasty following femoral neck fracture are at risk of developing complications, which may lead to reoperation. There is a lack of knowledge regarding patient-related risk factors for reoperation, allowing for informed shared decision making before implant selection in patients with femoral neck fractures. The objectives were to 1) identify the risk of reoperation after surgery, and 2) evaluate risk factors for reoperation. This was a single-center retrospective study of a consecutive, population-based cohort of patients with displaced femoral neck fractures, treated with hemiarthroplasty at a University Hospital, from January 1st, 2010 to December 31st, 2016. Events (reoperation) were extracted from a register. As death was considered a competing event for reoperation, a subdistribution, and a cause-specific Cox model was fitted to identify independent risk factors. Kaplan–Meier analysis was used to address patient survival, and differences in survival were evaluated by the Log-Rank test. Variables were defined pre-analysis and included in a Cox multivariate model. Seven hundred seventy two stems were identified for analyses for the reoperation cohort, 37 stems suffered from implant failure, necessitating reoperation. Cumulative incidence of reoperation was 4% (95% CI 3- 5%) and 5% (95% CI 3–7%) at 1 and 8 years respectively. In cause-specific hazard models, the absence of dementia was an independent protective factor (HR 0.45 (0.22–0.90)), and smoking was a risk factor (HR 2.30 (1.11–4.77)). The cumulative incidence of reoperation for patients suffering from dementia was 7% (95% CI 3–7%) compared to 4% (95% CI 3–6%), p = 0.100 for patients not suffering from dementia after eight years. For patients who smoke the eight-year cumulative incidence was 9% (95% CI 4–14%) compared to 4% (95% CI 3–6%) for non-smokers, p = 0.042. The survival probability one year after index surgery for patients who later underwent reoperation did not differ from those who did not undergo reoperation (66% (95% CI 6–70%) vs 60% (95% CI 41–73%), p = 0.800). In this register-based study, we observed an association between smoking, dementia and reoperation. While causality cannot be assumed due to the study design, these findings suggest that smoking and dementia may be important factors to consider clinically. Smoking and dementia as risk factors for reoperation warrants further investigation in larger prospective studies.