An osteotomy is a surgical procedure that involves cutting and reshaping a bone. Pelvic osteotomy involves reorienting or restructuring the acetabulum or hip socket to better accommodate the head of the femur or thighbone. This reduces pain, improves movement, and prevents injury at the hip joint.
The acetabulum develops to accommodate the head of the femur that articulates with it. Poor development of the acetabulum, known as acetabular dysplasia, can occur due to congenital or developmental disorders. A characteristic feature of hip dysplasia is increased stress due to irregular contact between the acetabulum and femoral head. This can lead to pain, limping, degenerative joint disease, and dislocation.
Pelvic osteotomy enhances the area of contact between the femoral head and the acetabulum so that stresses are distributed more appropriately over a larger area.
Pelvic osteotomy is indicated in various hip disorders such as developmental dysplasia of the hip involving acetabular dysplasia, subluxation and dislocation, avascular necrosis of the capital femoral epiphysis (Legg-Calve-Perthes-Disease), and neuromuscular hip instability.
Pelvic osteotomies vary depending on the anatomy of the joint, its maturity, and the underlying disease. They are broadly divided into 3 categories:
- Redirectional osteotomies which alter the orientation of the acetabulum.
- Reshaping osteotomies which change the shape and volume of the acetabulum
- Salvage or augmentation osteotomies to improve the coverage of the femoral head.
Common osteotomy procedures include:
This is a type of redirectional osteotomy that orients the acetabulum over the femoral head. It is recommended for children between the ages of 18 months and 6 years. The procedure involves making a transverse cut in the iliac bone just above the acetabulum and rotating the pelvic fragment such that the acetabulum lies above the femoral head. The corrected position is secured by inserting a wedge-shaped bone graft taken from the iliac bone into the gap created by the osteotomy and stabilizing it with wires.
Pemberton osteotomy is a type of reshaping osteotomy that is ideal for bilateral, moderate to severe hip dysplasia in children under 6 years of age. In this procedure, the acetabulum is rotated to change the direction and increase the depth of the socket. Osteotomy cuts are made around the acetabulum. The cut margins of the acetabulum are then rotated downwards to cover the femoral head. This position is maintained by a wedge of bone taken from the iliac crest.
Chiari osteotomy is a salvage osteotomy performed for severe acetabular dysplasia. It is recommended for children over 10 years of age who have failed to achieve adequate coverage of the femoral head through other types of osteotomies. It can treat cases of hip subluxation and early osteoarthritis. In this procedure, osteotomy of the ilium is performed following which the acetabulum is displaced medially. The femoral head is supported by part of the ilium along with the interposed capsule forming a shelf over it.
Following the procedure, your child will be placed in a hip spica cast that immobilizes the hip joint and will remain in the hospital for several days. Weight-bearing on the hip should be avoided and your child will require assistance with basic activities. Pain medication and antibiotics are administered. A physical therapist will provide instructions on how to carry out regular activities and will work with your child to gradually improve function.
Risks and complications
Pelvic osteotomies, although the best option for hip dysplasias are associated with certain risks and complications. The complications of pelvic osteotomies are rare but can include the following:
- Injuries to the nerves and blood vessels
- Intra-articular damage
- Delayed union between bone grafts
- Heterotopic ossification: Formation of bone in places where it normally does not occur, usually in the soft tissues.
The goal of pelvic osteotomy is to preserve natural bone and intervene at a young age to provide a well-functioning hip joint and avoid hip replacement. Each type of pelvic osteotomy has its benefits and potential complications. Your doctor will determine what is best for you.