The Incidence of Atypical Femoral Fractures in Patients with Rheumatic Disease: Yamagata Prefectural Committee of Atypical Femoral Fractures (YamaCAFe) Study

Atypical femoral fractures (AFFs) have been reported to occur with minimal or spontaneous subtrochanteric and femoral shaft fractures with a characteristic transverse pattern, compared with typical femoral fractures in young patients with high-energy trauma. AFFs are related to long-term use of bisphosphonates (BPs), glucocorticoids and rheumatic diseases. We have estimated a blind analysis of AFFs in rheumatic patients receiving BPs and glucocorticoids ordinary over a long time in all Yamagata prefectural area through radiographic examination. The 123 AFFs including suspected cases over six years were collected and reviewed by two independent orthopedic surgeons. We found 86 patients with a total of 99 AFFs between 2009 and 2014 (1.43 cases/100,000 person/year). Of these 99 AFFs, 11 were in 8 rheumatic patients including three patients with bilateral AFFs. The incidence of AFFs in rheumatic patients had trend to increase from 2012. The mean age of all 8 patients was 54.9 years. All 8 patients received BPs and 7/8 received prednisolone (PSL). The mean dose of PSL was 14 mg/day. Compared to patients with unilateral AFFs, those with bilateral AFFs in rheumatic patients were on a higher dose of PSL (20 mg/day vs. 7 mg/day) and had less femoral neck-shaft angle (129° vs. 136°, p < 0.05). In conclusion, the incidence of AFFs in rheumatic patients showed a trend to increase from 2012 to 2014 in Yamagata prefecture. Careful management of AFFs is of particular importance in rheumatic patients who have taken high doses of PSL and have small femoral neck-shaft angle.