Session IV - Geriatrics

The Second Hip Fracture: Risk Factors and Incidence

Thomas M. Lawrence, MD; Russell Wenn, MD; Christopher White; Christopher G. Moran, MD; Nottingham University Hospital, Nottingham, United Kingdom

Purpose: We determined the incidence of second contralateral hip fracture and investigated factors that may predispose to the problem.

Methods: A prospective audit of all patients admitted with hip fracture was undertaken over a 3.5-year period. Independent research assistants collected data on a standardized questionnaire. The database was linked to the Office for National Statistics, where all deaths in our country are registered, giving accurate mortality data. Patients sustaining sequential contralateral hip fractures within the study period were identified and data examined. Patients under 50 years of age, those with periprosthetic fractures, bilateral simultaneous fractures, and implant failure were excluded from the study. The time interval between fractures was calculated, and survivorship analysis was used to determine the incidence of contralateral hip fracture. Patients were withdrawn from the analysis at the end of the follow-up period or death. The similarity of fracture patterns and patients' social circumstances and medical comorbidities were analyzed. No routine treatment for osteoporosis was instigated during the study period.

Results: The study group comprised 2335 patients, of whom 78 (3.3%) sustained sequential contralateral hip fractures. The mean age of the contralateral group was 81 years and 81% were female. The mean interval between fractures was 308 days. Survival analysis demonstrated that the incidence of second hip fracture at 3 months was 1.0% (95% CI, 0.6, 1.5), at 1 year was 2.8% (95% CI, 2.0, 3.6), at 2 years was 5.7% (95% CI, 4.3, 7.1), and at 3 years was 7.3% (95% CI, 5.4, 9.2). The incidence of second hip fracture was observed to be linear. Sex did not influence risk of second fracture. Institutionalized patients had a greater risk of second side fracture (P = 0.001) as did patients who were housebound (P <0.001). Patients mobilizing with a frame also had an increased risk of contralateral fracture (P <0.001). Regression analysis did not identify any medical comorbidity (including cardiovascular, respiratory, renal, neurologic, or diabetic) as a risk factor. Thirty-six (46%) patients sustained contralateral intracapsular fractures, and 21 (27%) had contralateral extracapsular fractures. Similar fracture patterns in both hips were seen in 73%.

Conclusions: This is the first prospective study on second hip fracture with accurate mortality data for all patients, providing important information on the natural history of the second hip fracture without intervention to treat osteoporosis. The linear nature of the incidence suggests that second hip fracture is a significant problem and that measures to reduce this risk should be considered for all patients with hip fracture.