Epidemiology and Postoperative Outcomes of Atypical Femoral Fractures in Older Adults: A Systematic Review

To review the literature on epidemiology and postoperative outcomes particularly surgical, functional and quality of life of atypical femoral fractures (AFFs) in the older population (aged ≥65 years) using the first and second American Society of Bone Mineral Research (ASBMR) Task Force consensus definition.

Electronic search for articles on AFFs and bisphosphonates published in English was performed. Eligible studies were reviewed systematically in relation to (a) the epidemiology of AFFs in older people and (b) postoperative outcomes of AFFs.

Twenty-three studies on AFFs were included: 14 on epidemiology and 11 on treatment outcomes (two articles reported on both aspects). The epidemiological studies showed that the incidence of AFFs is low (3.0-9.8 per 100,000 person-years) but relative risk increased with longer duration of bisphosphonates use, especially after more than three years. Most cases of AFFs occurred in older people aged 65 years and above. However, in six studies, the mean age of patients with bisphosphonate-related AFFs is younger than those with typical proximal femoral fractures (mean age range of 66-75 years versus 75-89 years respectively). Varying postoperative and functional outcomes have been reported but differences in study population, management approaches and endpoints may account for these variations. For incomplete AFFs, prophylactic surgical intervention is potentially beneficial.

The benefits of bisphosphonates in reducing osteoporotic fractures still outweigh the risk of AFFs in view of its low absolute risk, when the ASBMR Task Force criteria for this type of fracture were applied. The risk of AFFs in different age groups is not well defined but tends to affect the younger patients more (aged <65 years) as compared to the older population (aged ≥65 years). Evidence supporting different types of treatment in AFFs such as intramedullary or extramedullary surgical devices and the use of teriparatide, a parathyroid hormone analogue, is not yet well established.