The distal femur is the lower portion of the thigh bone, located just above the knee joint. It plays a fundamental role in leg movement and stability.
Anatomy and Role
The distal femur forms the upper part of the knee joint, articulating with the shinbone (tibia) and the kneecap (patella). This region includes two prominent rounded structures called the medial and lateral condyles. The medial condyle is positioned on the inner side of the femur and is larger, bearing more of the body’s weight.
The lateral condyle, located on the outer side, is smaller. Both condyles are covered with articular cartilage, a smooth, slippery substance that reduces friction and cushions the bones during knee flexion and extension. Above these condyles are smaller bony projections known as the medial and lateral epicondyles, which serve as attachment points for ligaments that stabilize the knee joint.
The distal femur forms the tibiofemoral joint, facilitating the bending (flexion) and straightening (extension) of the knee. It also contributes to the patellofemoral joint, where the patella glides over the femur. This allows for smooth, controlled movements, enabling activities like walking, running, and climbing stairs.
Common Issues
Fractures are frequent issues affecting the distal femur, resulting from significant trauma. In younger individuals, these fractures occur due to high-energy incidents like motor vehicle accidents, leading to complex breaks that may extend into the knee joint. Older adults are more susceptible to these fractures from low-energy events such as falls, due to weakened bones from osteoporosis.
Distal femoral fractures can be categorized by location and pattern. Supracondylar fractures occur just above the condyles, while intercondylar fractures extend into the joint surface, splitting the condyles. These intra-articular fractures involve the cartilage that lines the joint, potentially leading to long-term issues like arthritis.
Beyond fractures, other conditions affect the distal femur. Osteochondral defects involve damage to both the bone and overlying cartilage, caused by trauma or repetitive stress. Arthritis, such as osteoarthritis, can also impact the distal femur by causing the progressive breakdown of articular cartilage, leading to pain, stiffness, and reduced knee function.
Management Options
Management of distal femur issues, especially fractures, depends on the fracture type, severity, and patient’s overall health. Non-surgical treatments are reserved for less severe injuries, such as undisplaced fractures. These approaches may involve immobilizing the leg with a long-leg cast for 6 to 12 weeks, followed by a hinged knee brace.
Physical therapy accompanies both non-surgical and surgical treatments, starting with gentle range-of-motion exercises and progressing to more aggressive movements and weight-bearing activities as healing progresses. For more complex or displaced fractures, surgical intervention is required to restore stability and function.
Surgical options for distal femur fractures include internal fixation, where plates, screws, or rods hold the bone fragments in place as they heal. A locking plate may be used on the outside of the femur, or an intramedullary nail may be inserted into the bone’s hollow center. In severe cases, if the joint surface is extensively damaged or arthritis is advanced, a total knee replacement may be performed to replace the damaged bone and joint surfaces with artificial components.