The proximal femur is exposed to substantial impact from normal activity on a daily basis; fracture of this normally strong bone in the absence of high-energy trauma is due to an underlying bone abnormality (insufficiency fracture, defined by normal stress on an abnormal bone).

Abnormal bone remodeling from prolonged osteoclast suppression is the theorized cause of bisphosphonate-associated fractures.

Radiographic findings include focal cortical thickening and transverse lucency through the lateral cortex (up to 98% specific). Findings may be very subtle, as in the index case. Fractures are usually close to the lesser trochanter. When complete, there may be a sharp medial projection or “medial spike”, usually associated with the distal fragment, where the fracture line transitions steeply from horizontal to vertical. Comminution is unusual.

In contrast to insufficiency fractures, fatigue fractures occur with abnormal stress on normal bone. These fractures tend to affect younger athletes rather than elderly patients with osteoporosis, and usually involve the medial rather than lateral cortex.

Bisphosphonate-associated fractures are often bilateral, and therefore, it is advisable to obtain radiographs of the contralateral femur to assess for clinically silent fractures when one is diagnosed.

Management options include discontinuation of bisphosphonates, trial of non-weight bearing, and prophylactic placement of an intramedullary fixation rod. Many orthopedic surgeons recommend prophylactic fixation of nondisplaced bisphosphonate-associated fractures, as progression to displacement is common and generally results in increased pain, morbidity, and cost to the patient.

Specific findings such as thickening of the lateral cortex, predominantly transverse orientation of the fracture line, and medial spike should be sought in all cases of subtrochanteric fracture in susceptible populations (elderly patients, patients with malignancy, etc.).