A femur fracture is a break in the femur bone, the leg bone that extends from the hip down to the knee joint. Since the femur is one of the largest and strongest bones in the human body, it is not a common break and usually occurs only after a serious trauma like a car accident or sporting injury. A fractured femur is a serious trauma that can cause severe pain and limit mobility unless treated and repaired by medical professionals.

There are three kinds of femur fractures: a spiral or transverse fracture, which is a crack in the bone without a break; a comminuted fracture, which is when the bone is splintered or crushed in multiple places; and an open fracture, when the bone breaks completely. Compound fractures, which are a combination of any of these breaks, may also occur when a leg is broken.

Sudden trauma is the most common cause of a broken leg. Other conditions, such as bone cysts or osteoporosis, can also make a person more susceptible to a femur fracture. A fracture of the leg is very painful and almost always requires immediate medical attention in order to repair.

To treat a fractured femur, doctors will usually put the leg in a cast. This restricts movement of the leg bone, allowing it time to heal. In some cases, surgery may also be performed. A common surgery to treat a broken femur bone is called open reduction. In an open reduction surgery, the doctor places metal rods and nails in the leg to stabilize the femur fracture so it can heal in place.

Casts, rods, and nails are usually used for several months to repair a broken femur bone. During this time, a person will usually have restricted mobility. Use of crutches, a wheelchair, or a cane is common. Strenuous activity involving the leg is not only ill-advised during this time, but almost entirely impossible, as it is usually so constrained in a cast or other restrictive devices that it can't move.

After the cast and any metal hardware is removed from a leg and the bone has healed, physical therapy may be needed to restore complete mobility and range of motion to the leg that suffered the femur fracture. This can take several weeks or months to complete, and in some cases a limp or lack of mobility may remain for years after the bone has healed.