Role of Fibular Bone Graft in the
Treatment of Avascular Necrosis
In younger patients with early stages of avascular necrosis, head-saving procedures such as vascularized bone grafting may be done. The procedure is mainly done to delay the need for joint replacement surgery, however, with the advancement of implant technology and design, hip replacement surgeries offer excellent results even in young patients.
Avascular necrosis occurs as a result of bone death in the head of the femur. Bone death occurs due to disruption of the blood supply of the head of the femur. The disruption of the blood supply may occur as a result of direct trauma to the hip. Traumatic hip dislocations and fractures are commonly associated with avascular necrosis of the hip joint.
Long-term use of corticosteroids for medical diseases such as nephrotic syndrome, rheumatoid arthritis, etc, or secondary to abuse in athletes may lead to avascular necrosis. Avascular necrosis may also occur in patients with a history of alcohol abuse.
In the initial stages of avascular necrosis, there may not be any symptoms and the disease may only be diagnosed on a bone scan or an MRI. With the advancement of the disease, the patient may complain of groin pain that occurs on activity and as well on rest.
During the early stages before the collapse of the head of the femur, attempts are made to preserve the head of the femur. The preservation is aimed to decrease the pressure inside the head of the femur, revitalize the blood supply of the necrotic area, and prevent the collapse of the head of the femur.
The head preservation surgeries include core decompression, stem cell implantation, and bone grafts. With core decompression, the physician tries to reduce the pressure inside the head of the femur and prevent further advancement of the disease. Stem cell therapy in the form of bone marrow graft is done to possibly revitalize the blood supply.
Strut bone grafts such as fibular bone grafts provide not only graft material but also provide structural support to the head of the femur to prevent collapse. Vascularized fibular grafts additionally provide nutrients to the bone graft and are hypothesized to replace the necrotic bone with new bone through creeping substitution.
The fibula is the smaller of the two bones in the leg of the human. The fibula is present on the outer side of the leg. The graft is taken from the middle of the fibula leaving an adequate amount of bone at both ends to continue to provide structural support to the joints of the leg.
The surgeon harvests the graft along with the blood vessels of the bone. The surgeon then passes a wire from the side of the hip joint and serially reams the neck and head of the femur without breaching the subchondral region. The reaming helps to reduce the pressure inside the head of the femur.
The fibular graft is then passed inside the track formed inside the head and neck. A microsurgery technique is then used to attach the graft blood vessels to nearby blood vessels. The blood supply to the graft not only helps to maintain the graft integrity but also brings in bone cells that may slowly replace the dead bone in the head of the femur with new bone.
After the surgery, the patient is advised to follow precautions to protect the graft and to start physiotherapy to aid in early return back to daily activities. At 6 weeks the patients may start protected weight-bearing and slowly progress to complete weight-bearing.
The surgery although aims to preserve the head of the femur, avascular necrosis may still progress. The fibular graft surgery potentially however delays the need for joint replacement surgery. However, with improved techniques and outcomes, joint replacement surgery may be indicated even in young patients.
The joint replacement surgery alleviates the pain and deformity associated with avascular necrosis. Modern implants last on an average of 20 years or more and patients who may need eventual arthroplasty after vascularized bone graft are better suited for a primary arthroplasty.