Distal Femur Fractures

Distal femur fractures are fractures involving the distal 15 cm of the femur extending from the metaphyseal region to the articular surface of the knee joint. These fractures represent approximately 4–7% of all femoral fractures and around 0.4% of all fractures in adults. They are important injuries because they frequently involve the knee joint and may lead to significant functional impairment if not managed appropriately.

Distal femur fractures demonstrate a bimodal distribution. High-energy trauma such as road traffic accidents is the most common cause in younger individuals, whereas elderly patients typically sustain these fractures after low-energy falls due to osteoporotic bone. Complex fracture patterns, intra-articular involvement, and associated soft-tissue injuries make these fractures challenging to treat.

Modern management emphasizes early surgical fixation to restore limb alignment, achieve anatomical reduction of the articular surface, and allow early mobilization of the knee joint.

The distal femur consists of two condyles that articulate with the tibial plateau and patella to form the knee joint. The distal femur includes both metaphyseal and intra-articular regions.

• Medial and lateral femoral condyles
• Intercondylar notch
• Metaphyseal flare of distal femur
• Articular surface of knee joint

The popliteal artery and tibial nerve lie posterior to the distal femur, making them vulnerable in high-energy injuries. The quadriceps muscle group exerts strong deforming forces on fracture fragments.

The distal femur is subjected to substantial axial loads during weight bearing. Because the metaphyseal region transitions from strong cortical bone to cancellous bone, fractures in this area often exhibit comminution and instability.

• Quadriceps pull causes extension deformity
• Adductor muscles cause varus angulation
• Hamstrings may cause posterior displacement

Understanding these deforming forces is important for achieving proper reduction during surgical fixation.

• Accounts for 4–7% of femur fractures
• Bimodal age distribution
• Higher incidence in elderly women due to osteoporosis
• High-energy trauma common in young males

• High-energy trauma such as motor vehicle accidents
• Direct blow to the knee
• Fall from height
• Low-energy falls in elderly osteoporotic patients
• Periprosthetic fractures following knee arthroplasty

The AO/OTA classification system is widely used to categorize distal femur fractures.

• Pain around the knee
• Inability to bear weight
• Swelling and deformity
• Limited knee motion
• Possible open fracture

Neurovascular examination is essential because popliteal artery injury may occur in high-energy trauma.

• AP and lateral radiographs of knee
• Full length femur radiographs
• CT scan with 3D reconstruction

CT imaging is particularly useful for evaluating intra-articular fractures and planning surgical fixation.

• Restore limb alignment
• Achieve anatomical reduction of articular surface
• Provide stable fixation
• Allow early knee mobilization

• Malunion
• Nonunion
• Knee stiffness
• Post-traumatic arthritis
• Infection

• AO classification type 33
• Bimodal distribution of injury
• Early mobilization essential to prevent stiffness
• Locked plating commonly used for comminuted fractures