Disentangling the cause of atypical femur fractures associated with the use of bisphosphonates

Recruitment & Eligibility

Status: Completed

Sex: Not specified

Target Recruitment: 100

Inclusion Criteria

Inclusion criteria
In order to be eligible to participate in this study, a subject must meet all of the following criteria:;- Patients must be 18 years or older.
- Patients known with a recent or past atypical femur fracture based on ASBMR criteria or
suggested revised radiological criteria. ;ASBMR criteria
Two reports of a Task Force of the American Sociey for Bone and Mineral Research (ASBMR) resulted in diagnostic criteria for AFF. The fracture must be located along the femoral diaphysis from just distal to the lesser trochanter to just proximal to the supracondylar flare. Major features describe a localized periosteal or endosteal thickening of the lateral cortex at the fracture site and a fracture line with a transverse orientation that may become oblique as it progresses medially across the femur. The fracture must be non-comminuted or minimally comminuted and is associated with no or minimal trauma (fall from standing height or less). Complete fractures extend through both cortices and may be associated with a medial spike, while incomplete fractures only involve the lateral cortex. At least four out of five major features must be present. Minor features include generalized increased cortical thickness of the femoral diaphysis, prodromal pain, bilateral fracture and delayed fracture healing. ;Alternative criteria
The ASBMR criteria are internationally acknowledged, although they remain subject of debate. For instance, Feldstein et al. (Incidence and demography of femur fractures with and without atypical features, 2012) described considerable differences between patients with only major features and patients with both major and minor features. It may be that only the latter group is truly atypical. Furthermore, cortical thickness does not appear to be a relevant feature. Therefore, patients with fractures that meet criteria suggested by Schilcher et al. (Atypical femoral fractures are a separate entity, characterized by highly specific radiographic features. A comparison of 59 cases and 218 controls, 2013) are also included. According to these alternative criteria, a fracture angle between 75° and 105°, a local callus reaction and fracture location at the diaphysis are features strongly related with bisphosphonate-associated AFF.

Exclusion Criteria

- The exclusion criteria as mentioned by the ASBMR Task Force consensus: fractures of the
femoral neck, intertrochanteric fractures with spiral subtrochanteric extension, pathologic
fractures associated with primary or metastatic bone tumors, periprosthetic fractures and miscellaneous bone diseases (e.g., Paget's Disease, fibrous dysplasia). ;- Patients from whom no written informed consent was obtained.