Atypical femoral fractures after anti-osteoporotic medication: a Korean multicenter study.

Abstract

PURPOSE: Increasing numbers of atypical femoral fractures have been reported

among long-term bisphosphonate users. We evaluated clinical characteristics of

atypical femoral fractures throughout Korean multicenter studies. METHODS: We

retrospectively analysed the bone mineral density, prodromal symptoms before

femoral fracture, and medication history of osteoporosis in 76 cases of atypical

femoral fracture. RESULTS: The mean age of cases was 71.4 +/- 8.8 (range, 43-89)

years old. The mean follow-up period after the fracture operation was 24.5 +/-

12.9 (range, 12-79) months. BMI was 23.2 +/- 3.0 on average. The mean BMD of

femur was -1.9 +/- 1.4 (range, -4.8 to 1.3). Prodromal symptoms including thigh

pain before femoral fracture appeared in 22 (28.9 %) of 76 patients. All patients

included in the study used bisphosphonate. The duration of taking bisphosphonate

before fracture was 36.8 +/- 50.8 (one-204 months) months. Fifty-seven (75 %) of

76 patients were taking the medication for more than three years. Delayed union

occurred in 43 (56.5 %) of 76 patients. Delayed union was defined as a fractured

bone that did not completely heal within six months of injury. The group of

having taken anti-osteoporotic medication for more than three years showed

relatively longer union period compared to that for a shorter period medication

group (4.8 +/- 2.5 months vs 9.3 +/- 3.7 months, p = 0.017). The delayed union

developed in 43 (56.5 %) of 76 patients and showed a significantly higher

incidence in the group with long-term therapy (five/43 vs 38/43, p = 0.021). The

bilateral femoral fractures developed in 23 (30.2 %) of 76 patients and showed a

high incidence in the group medicated more than three years (two/23 vs 21/23, p =

0.039). CONCLUSIONS: The longer bisphosphonates are used, the more the cases of

delayed union and the more frequent the development of bilateral fractures

following unilateral fractures. With regard to the delayed union, the methods of

the acceleration of fracture healing may be beneficial in atypical femoral

fracture patients who had been receiving long-term bisphosphonates therapy.

Careful observation is required for contra-lateral femurs due to a high incidence

of bilateral atypical femoral fractures.