To study the risk factors for contralateral hip fracture within 2 years after primary hip fracture surgery in elderly patients.

A retrospective study was conducted of the 1,962 elderly patients who had been surgically treated for hip fractures at Department of Orthopaedic Trauma, Beijing Jishuitan Hospital from May 2015 to April 2018. They were 573 males and 1,389 females; the median age of primary hip fracture was 81 (75, 86) years. They were divided into 2 groups according to whether a contralateral hip fracture occurred or not within 2 years after primary hip surgery: 134 patients in the contralateral fracture group and 1,828 ones in the contralateral fracture-free group. The duration from primary hip fracture to secondary contralateral fracture was recorded. The χ² test and Mann-Whitney U test were used to compare between the 2 groups their gender, age, walking ability, laboratory indexes upon admission, concomitant internal diseases, Charlson comorbidity index (CCI), duration from admission to surgery, duration from admission to discharge and complications during follow-up. The risk factors for contralateral hip fracture within 2 years after primary hip surgery were determined by the Cox's proportional hazard regression model.

In the elderly patients with hip fracture, the 2-year cumulative incidence of secondary contralateral hip fracture was 6.83%(134/1,962) and the median duration from primary surgery to secondary contralateral hip fracture was 365 (189, 611) d. The risk factors for contralateral hip fracture were female (RR=2.081, 95%CI: 1.351 to 3.207, P=0.001), concomitant peripheral vascular disease (RR=5.876, 95%CI: 2.922 to 11.818, P< 0.001), concomitant chronic obstructive pulmonary disease (RR=3.750, 95%CI: 1.897 to 7.413, P< 0.001), progressively higher CCI (RR=1.363, 95%CI: 1.223 to 1.519, P<0.001), complicated pneumonia (RR=3.606, 95%CI: 2.054 to 6.332, P<0.001), complicated urinary infection (RR=7.670, 95%CI: 4.441 to 13.248, P<0.001), and complicated deep venous thrombosis (DVT) (RR=7.389, 95%CI: 3.992 to 13.677, P<0.001).

The risk factors for contralateral hip fracture within 2 years after primary hip fracture surgery in elderly patients may be female, concomitant peripheral vascular disease and chronic obstructive pulmonary disease, progressively higher CCI, and complicated pneumonia, urinary infection and DVT.

Hip fractures; Risk factors; Osteoporosis; Aged