A femoral osteotomy (FO) is any surgical procedure that cuts through the femur to change its relationship to the hip or to the knee. To treat hip dysplasia, the doctor cuts through the femoral head and rotates it anteriorly or posteriorly -- to the front or to the back. This creates better coverage of the acetabulum over the femoral head. An L-shaped plate and several pins reattach the femoral head to the femoral body. The bone knits back together with this support in place.
Photo courtesy Lauren Giovannoni and Sarah Court
Due to the plate and pins, an external body cast is not necessary. The patient will spend several weeks post-surgery using crutches and several months in physical therapy to strengthen the hip and leg muscles. Follow-up X-rays will determine the progress of the femoral head as it knits itself to the femoral body. After a year, an optional second surgery can be performed to remove the metal plate. This surgery can be performed in conjunction with a periacetabular osteotomy (PAO) if needed to create the best possible femoral-acetabular coverage. Labrum repair and other soft-tissue arthroscopic procedures may also be performed at the time of surgery.
The FO was developed in the early part of the 20th century, so it isn't performed as often as the more recently developed PAO. However, for patients whose dysplasia has as much to do with the angle of the femoral head (coxa vara or coxa valga) as with the shape of the acetabulum, it can be the appropriate choice. As with any osteotomy, there are short- and long-term benefits to using the patient's own bone.
The surgery is a 2- to 3-hour procedure. An incision is made on the outside of the hip, and the vastus lateralis muscle, which is part of the quadriceps, is lifted to access the femur beneath. This is typically the only muscle affected by the surgery, which reduces the severity of nerve damage in the area.
Once postoperative swelling has diminished, the patient will be aware of the plate to a varying degree, depending on individual sensitivity and physical size. Awareness and daily discomfort are the major factors that contribute to the decision to undergo a second surgery to remove the hardware. In any event, the plate must stay in place for 12 months to give the bone sufficient opportunity to heal.
The second surgery is relatively simple: The surgeon goes in about halfway along the initial incision and removes the plate and pins. The largest hole created by the top of the metal pin in the femoral head is filled with synthetic bone filler, and the lower holes fill in on their own, requiring another, shorter period of time on crutches post-surgery. Overall, however, this surgery requires far less hospital time and physical therapy than other surgeries.
Major complications include infection, neurovascular injury, nonunion of bone, inability to obtain or maintain a full correction, postoperative pain and continued degeneration of cartilage. Other complications include deep vein thrombosis and painful hardware. However, the likelihood of any of these complications is roughly 1 percent.
Overall, hip range of motion, gait, pain, leg-length discrepancy and patient satisfaction are improved from femoral osteotomy, and a successful surgery may reduce or even entirely remove the need for a total hip replacement (THR) during the patient's lifetime. However, should a THR become necessary, the FO, like the PAO, supports the necessary alignment of the hip joint. Next, we'll examine the use of THR as a treatment for hip dysplasia.