This is the first report of surgical treatment for Perthes disease using shelf acetabuloplasty. The surgery is simple and results were good for fast pain relief. Medium-term outcomes were reported with follow-up from five to ten-years.
Perthes disease (sometimes referred to as Legg-Calvé-Perthes) is the collapse of the hip joint due to a loss of blood supply. It occurs most often in children between the ages of four and eight.
In this condition, the blood supply to the capital femoral epiphysis (growth center of the hip) is disturbed, causing the bone in this area to die. The blood supply eventually returns, and the bone heals. How the bone heals determines how much problem the condition will cause. This condition can lead to serious problems in the hip joint later in life.
To help prevent deformity and keep a stable hip, surgery may be needed. The children in this study had severe Perthes with hinged abduction confirmed by X-rays. Hinge abduction is the abnormal movement of the hip that occurs when a femoral head, deformed by Perthes disease does not slide as it should within the acetabulum (hip socket).
In such cases, a large portion of the femoral head is not under the acetabulum. As a result, during hip movement, a portion of the bone and cartilage from the deformed femoral head gets pinched against the acetabular rim. It is a painful condition that can be corrected surgically.
Shelf acetabuloplasty is the use of grafted bone to build a shelf to deepen the socket. Strips of bone are taken from the pelvis. They are inserted into a slot cut into the acetabulum. Enough bone is grafted to cover the front and sides of the uncovered femoral head. This procedure is possible when the femoral head is not flat or too large for the size of the socket.
In this study, 27 children with unilateral (one-sided) Perthes disease were treated with a shelf acetabuloplasty. Ages ranged from three to 14. All had hinge abduction confirmed by a special X-ray called arthrogram. Dye was injected into the joint and a series of X-rays were taken. The joint can be imaged this way from many angles in real time.
Results were reported in terms of pain, limp, and deformity. Pain relief was right away and remained that way for most of the children. In a few children, activity brought on some mild pain from time to time. Limp was improved or eliminated in all but one child. Hip motion also improved in the majority of the patients.
Special care was taken to avoid damage to the acetabular growth plate. The surgeon placed a needle where the cartilage rim met the growth plate. All efforts were made to stay away from this area. As a result, there were no cases of injury to the acetabular growth cartilage.
The authors recommend dynamic arthrograms for any children with Perthes reporting increased pain and loss of motion. If the acetabulum is too vertical (socket if facing outward rather than downward), an osteotomy is advised. A wedge- or pie-shaped piece of bone is removed to change the angle of the femur (thigh bone). This creates a sharper angle and aligns the femoral head more sharply into the acetabulum.
Osteotomy is not appropriate if the arthrogram shows hinge abduction. Instead, treatment may include traction and casting to realign the hip. When surgery is needed, a different type of osteotomy called valgus extension osteotomy has been used.
Now, shelf acetabuloplasty has also been shown effective as a way to treat severe cases of Perthes. In addition to fast pain relief, this procedure has the advantage of fostering acetabular growth. Pressure up through the femur during weight-bearing exerts forces on the growing femoral head and stimulates growth. With the shelf in place, proper formation of a round femoral head (avoiding a flattening effect) is possible. This procedure is not possible unless the femoral head has the potential to remodel.