Femur

The femur is the thigh bone and the single bone of the upper leg. It is the longest, largest, and strongest bone in the human body. Proximally it articulates with the hip socket (acetabulum) at the hip joint, and distally it articulates with the tibia and patella at the knee joint. It transmits the body's weight from the pelvis to the lower leg during standing, walking, and running.

In an adult male, the femur averages approximately 45–48 cm (17–19 inches) in length, representing about 26% of a person's height. It is capable of withstanding compressive forces of approximately 1,700–7,700 N under normal conditions. Despite its strength, the femoral neck is a common fracture site in osteoporotic elderly individuals because of its trabecular bone composition and angulated geometry.

Femoral fractures are classified by location: femoral head fractures (typically from hip dislocations), femoral neck fractures (common in elderly with osteoporosis — often called hip fractures), intertrochanteric fractures, subtrochanteric fractures, femoral shaft fractures (requiring high-energy trauma), and distal femur fractures near the knee. Femoral neck fractures in the elderly carry significant morbidity and mortality and usually require surgical fixation or hip replacement.