Distal femur fracture
Alerts and Notices
SynopsisCauses / typical injury mechanism: Distal femur fractures have 2 typical injury mechanisms that vary by age. Young patients sustain these injuries secondary to acute trauma with high-energy mechanisms. These fractures can also result from low-energy mechanisms, which tends to happen in elderly osteoporotic patients.
Classic history and presentation: Look for a history of trauma with a high-energy mechanism (eg, motor vehicle or motorcycle crash, struck pedestrian, fall from a height) or low-energy mechanism (eg, mechanical ground-level falls, rotational / twisting injuries).
Prevalence: Distal femur fractures account for < 1% of all fractures and 4%-6% of all femur fractures. Of these, 19%-54% are open fractures, most commonly Gustillo type III. High-energy mechanisms (approximately 58% of cases) are more common than low-energy mechanisms. Annual incidence in the United States is approximately 31 per million.
- Age – Bimodal age distribution. Young patients (aged 10-30 years) and older patients (aged 60-80 years).
- Sex / gender – Young patients are typically male, and older patients are typically women.
Pathophysiology: Excessive stress placed on the distal femur causes fracture. Displacement of the fracture is usually greater in high-energy mechanisms compared to low-energy mechanisms.
Grade / classification system: Müller AO / Orthopedic Trauma Association (OTA) classification for distal femur fractures:
- A – Extraarticular
- B – Partial articular
- C – Complete articular
S72.401A – Unspecified fracture of lower end of right femur, initial encounter for closed fracture
263232003 – Fracture of distal end of femur
Differential Diagnosis & Pitfalls
- Femoral shaft (diaphyseal) fracture
- Compartment syndrome
- Knee dislocation
- Patellar dislocation
- Patellar fracture
- Knee ligamentous injury – anterior cruciate ligament (ACL) injury, posterior cruciate ligament (PCL) injury, medial collateral ligament (MCL) injury, lateral collateral ligament (LCL) injury
- Multiligamentous knee injury
- Proximal tibia fracture
- Tibial plateau fracture
- Periprosthetic distal femur fracture
- Popliteal artery injury
- Quadriceps or patellar tendon rupture
- Morel-Lavallée lesion
Distal femur fracture