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There Is an Association Between Varus Proximal Femoral Geometry and Atypcal Femoral Fractures in Postmenopausal Women Under Chronic Bisphosphonate Treatment?

Rui Cardoso Genrinho2, S P Silva, C Mazeda2, P Vilas Boas2, B Figueiredo2, J Brenha1, A Barcelos2

1Orthopedic Department and 2Rheumatology Department, Centro Hospitalar do Baixo Vouga Centro, Aveiro – Portugal

Background: Bisphosphonates (BPs) are the first-line treatment of osteoporosis post-menopausal women. There is increasing evidence associating atypical femoral fractures (AFFs) with prolonged exposure to BPs therapy. The cause of these fractures is unknown and likely multifactorial.

Purpose: To evaluate the hypothesis that patients with AFFs under prolonged BPs therapy were associated to a varus proximal femoral geometry.

Methods: We retrospectively studied osteoporotic women, aged 50 or older, who were under BPs therapy. Women under BP treatment with AFF (group A) were compared with women under BP treatment without fractures on the inferior limb (group B). The femoral neck-shaft angle was measured on the radiographs of both groups. 

Results: A total of twenty-three osteoporotic menopausal women under BPs therapy were included: eleven in group A and twelve in group B. The mean neck-shaft angle of the women in group A differed significantly from group B (p<0.05). Side-to-side comparison in patients with a unilateral pathologic involvement and an asymptomatic contralateral lower limb did not demonstrate any significant difference between the neck-shaft angles in the two limbs.

Conclusion: Patients on chronic bisphosphonate therapy who presented with AFF had more varus proximal femoral geometry than those who took bisphosphonates without sustaining a lower limb fracture. Varus proximal femoral geometry may help to better identify patients at risk for fracture after long-term bisphosphonate use.

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