�Atypical� atypical femur fractures and use of bisphosphonates

Abstract

SummaryBackground. Atypical femur fractures (AFFs) present a rare but serious condition associated with use of bisphosphonates. Underlying mechanisms and clinical risk factors remain unclear. According to the diagnostic criteria formulated by the ASBMR, a lateral localization of an AFF is required. Case history. We present a patient who developed bilateral leg pain while using an oral bisphosphonate and aromatase inhibitor in the course of adjuvant treatment for breast cancer. Initially she was diagnosed with bone metastases and received radiotherapy on the right femur. However, the bilateral periosteal reactions of the subtrochanteric femur are highly suggestive of AFFs. Our case meets all criteria for AFF except that she presented with lesions at the medial side of the femur. Therefore they could be best described as "atypical" atypical femur fractures. Discussion. Since the pathogenesis of AFFs is not fully understood, we cannot rule out that AFFs also occur in the medial femur or in other weight-baring bones. Hence we propose that medial stress reactions belong to a spectrum of atypical fractures associated with use of antiresorptive drugs. The localization may depend on yet unknown biomechanical factors.

Screening for Atypical Femur Fractures Using Extended Femur Scans by DXA

“…These findings suggest that the lateral cortex should be the main focus when evaluating the extended femur scan for AFFs, which are by definition located on the lateral cortex, although medially located AFFs have previously been reported. (28,29) Our results are in line with the few studies on this topic so far. A case description in 2010 first suggested that an extended femur scan on DXA corresponds with radiologic characteristics of AFF on a bone scintigraphy, computed tomography, and conventional radiography.…”

“…Because very subtle cortical irregularities cannot with certainty be discarded as AFF, screening by DXA may lead to unnecessary X‐rays as was the case in 3 of our patients with focal irregularities of the medial cortex. These findings suggest that the lateral cortex should be the main focus when evaluating the extended femur scan for AFFs, which are by definition located on the lateral cortex, although medially located AFFs have previously been reported …”

Successive Ipsilateral Atypical Fractures of the Left Femoral Neck and the Diaphysis: Case Report and Review of the Literature

“…It is known that they change the bone matrix composition, which lead to highly mineralized collagen. This may result in a generalized suppression of bone to remodel, leading to the accumulation of micro-damage, and this could affect the intracortical repair and ultimately lead to a complete stress fracture [7] .…”

Atypical Femur Fractures and Cortical Thickening in Osteoporotic Patients Treated with Bisphosphonates

“…The studies with alendronate and risedronate show that patients with osteoporosis will have an anti-fracture effect for at least 5 years. Continued usage over 5 years needs annual re-evaluation, considering factors such as fracture history, BMD, newly diagnosed disorders, other medications known to affect skeletal tatus [2][3][4][5][6] and as in our case, the appearance of radiographic features such as cortical thickening and some clinical features such as the appearance of prodromal symptoms like aching pain in the thigh [7]. For those patients who are considered to have moderately-elevated risk fracture, continuation of BP therapy should be strongly considered [3].…”

“…However, a recent concern has arisen about the association between the use of BPs and the appearance of atypical femur fractures (AFF), a rare type of atraumatic or minimal trauma femur fracture occurring below the great trocanter [2]. This rare complication, with a rate of 3.2-50 cases per 10,000 person-years, may be due to the prolonged half-life of BP and their effect on fracture remodelling, although there is not a final explanation for the physiopathology of these fractures [3][4][5].…”