The third objective in DDH management is the correction of persisting hip dysplasia. Persisting dysplasia should be corrected during growth to prevent osteoarthritis.
Dysplasia may involve the femur, the acetabulum, or both. The most pronounced deformity is in the acetabulum. The most severe dysplasia includes subluxation. Subluxation and dysplasia cause osteoarthritis, which may begin during the teen years. Disability occurs later with simple dysplasia.
Femoral Dysplasia The proximal femur is anteverted and the head may not be spherical due to the dislocation. The deformity may be due to ischemic necrosis.
Acetabular dysplasia is the most pronounced deformity and includes shallowness and anterolateral orientation of the socket.
Acetabulofemoral relationship The femoral head is subluxated if not concentric with the acetabulum. The head may also be lateralized following growth with the head subluxated. The acetabulum often becomes saucer shaped, causing instability.
The femoral head may be spherical or aspherical as a result of ischemic necrosis. The fit with the acetabulum may be congruous or incongruous. Asypherical incongruity is common because, over years of growth, the acetabulum assumes a shape to match that of the femoral head.
Timing of correction Correct hip dysplasia as soon as it is evident that the rate of correction is unsatisfactory, preferably before age 5 years. Establish a time line of a series of AP radiographs of the pelvis taken at 4–6 month intervals during infancy and early childhood. Measure the acetabular index, note the smoothness of the acetabular roof (sourcil), and observe the development of the medial acetabulum (tear drop). Assess by studying the sequence of films. Perform a pelvic osteotomy if the AI remains abnormal and the other features remain dysplasic after 2 to 3 years of observation. Avoid delaying an obvious need for correction.
Principles of correction
Proper correction of hip dyplasia in DDH follows these certain basic principles:
Correct the primary or most severe deformity. This is usually the acetabular deformity.
Correction should be adequate. If the deformity is severe, combine a pelvic and femoral osteotomy or perform a shelf operation.
Avoid creating incongruity. Avoid the Pemberton procedure in the older child. Consider the shelf or Chiari procedure if aspherical congruity is present.
Medialize the lateralized hip in the older child with a Chiari osteotomy.
Articular cartilage is more durable than fibrocartilage as develops in the shelf and Chiari procedures.
Reconstructive procedures These are procedures that provide articular cartilage for load bearing. Select the appropriate procedure based on the site of deformity, age, severity, and congruity. The choices are numerous.
Femoral osteotomy Femoral shortening is essential in the older child with unreduced DDH. Remove just enough bone to allow reduction. Reduce the neck–shaft angle by about 20°. Limit rotational correction to about 20°.
Salter osteotomy This is the best choice for correcting mild deformities at any age. The osteotomy will reduce the AI about 10°–15° and the CE angle by 10°.
Pemberton osteotomy This is the best choice for bilateral or moderate to severe dysplasia [B] in children under the age of 6 years.
Dega osteotomy The osteotomy is more posterior in the ilium, providing posterior and lateral coverage most suitable for neurodysplasia correction.
Triple osteotomies Several types are available. They provide the best choice for correcting moderate dysplasia in adolescence when spherical congruity is present. These procedures are technically challenging.
Ganz osteotomy This periacetabular osteotomy allows major correction appropriate just before or after skeletal maturity. The procedure is technically challenging.
Sutherland procledure This procedure is a double innominate osteotomy seldom performed because correction is limited.
Salvage procedures These procedures create an articular surface of fibrocartilage that is more prone to degeneration with time.
Chiari osteotomy This is appropriate when the hip is lateralized and severely dysplasic. It may be used with aspherical congruity. Avoid excessive medialization. Coverage is by fibrocartilage.
Shelf procedure This procedure enlarges the acetabulum with fibrocartilage. It is versatile and may be considered for severe dysplasia without lateralization when aspherical congruity exists. This is the least risky of the major procedures.