The aim of this study was to determine the incidence of second hip fracture.

A prospective cohort study include 2682 patients aged 50 years or more admitted with a hip fracture over a 4 year period. Mortality data were available for all patients and survival analysis was performed to determine the incidence of second hip fracture. The mean age-specific incidence rates of primary hip fracture in the population were calculated to serve as a baseline.

95 patients (3.5%) sustained a sequential, contralateral hip fracture within the study period. The mean age at first hip fracture was 82 years and the mean interval between fractures was 316 days. Fracture morphology was similar on both sides in 69% of cases. Survival analysis demonstrated that the incidence of second hip fracture at 1 year was 2.8% (95% CI: 2.0–3.6), 2 years was 5.7% (95% CI: 4.3–7.1) and 3 years was 7.3% (95% CI: 5.4–9.2). The relative risk of hip fracture in patients who had already sustained one hip fracture was 2.4 times above that of matched controls. Assistance with activities of daily living was identified as a risk for second hip fracture (p=0.026, 95% CI: 1.058, 2.466). The odds ratio for sustaining a second hip fracture compared with the incidence of primary hip fracture in the normal population aged 55–64 years was 47.5 xs; 65–74 years was 15 xs; 75–84 years was 3.7x and 85+ years was 1x.

The risk of sustaining a second contralateral hip fracture is substantial. In younger patients preventative measures can be targeted at the individual who has sustained a fracture whereas in more elderly patients, preventative measures need to address the population as a whole.