What is an atypical femoral fracture ?
- Also known as Bisphosphonate-related proximal femoral fractures.
- Type of insufficiency fracture.
- Usually in patients on long term bisphosphonates (>3-5 years).
- Can be bilateral in up to 60% of cases, always screen the opposite femur.
- Changes first occur on the lateral femoral cortex.
- Subtrochanteric , transverse orientation, lack of comminution cortical beak; occur with low velocity trauma.
- Associated with poor healing.
What are the diagnostic criteria for an atypical femoral fracture (AFF)?
According to the American Society for Bone and Mineral Research Taskforce, 4 of the 5 major criteria are necessary for the diagnosis of AFF.[1]
| Major Criteria (4 out of 5 necessary) | Minor Criteria (not necessary for diagnosis) |
| Minima trauma | Increased cortical thickness of the femoral diaphysis |
| Fracture originating at the lateral cortex and being substantially transverse | Bilaterality |
| Complete fractures extending through both cortices | Delayed fracture healing. |
| Localized periosteal or endosteal cortical thickening | A prodrome of thigh or groin pain. |
| Minimal comminution at most |
What is the management for atypical femoral fractures?
Conservative management: It is reasonable to discontinue bisphosphonates, adequate calcium and vitamin D intake should be ensured, and teriparatide should be considered for those who appear not to heal with conservative therapy [1]. Results are poor and patient may eventually need surgical management.
Surgical management:
Femoral subtrochanteric and shaft fractures are usually treated with intramedullary (IM) nailing or plating
Detailed discussion with video:
A more detailed overview of proximal femoral fractures can be found here:
Proximal Femoral Fractures
References:
- Managing Osteoporosis Patients after Long-Term Bisphosphonate Treatment.
- Grainger & Allison’s Diagnostic Radiology
