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Distal femur fracture
Other Resources UpToDate PubMed

Distal femur fracture

Contributors: Matthew F. Barra MD, Sandeep Mannava MD, PhD
Other Resources UpToDate PubMed


Causes / 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.
Risk factors: Osteopenia, osteoporosis, and proximal or distal femur implants that act as stress risers (ie, total knee replacement, intramedullary nail, plate and screw combo).

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

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Diagnostic Pearls

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Differential Diagnosis & Pitfalls

  • Femoral shaft fracture
  • Acute compartment syndrome
  • Knee joint dislocation
  • Patellar dislocation
  • Patellar fracture
  • Knee ligamentous injury – Anterior cruciate ligament injury, Posterior cruciate ligament injury, Medial collateral ligament knee injury, Lateral collateral ligament knee injury
  • Knee joint dislocation
  • Proximal tibia fracture
  • Tibial plateau fracture
  • Periprosthetic distal femur fracture
  • Popliteal artery entrapment syndrome
  • Quadriceps tendon rupture or Patellar tendon rupture
  • Morel-Lavallée lesion

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Last Reviewed:01/14/2021
Last Updated:01/14/2021
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Distal femur fracture
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