Surgical treatment can be divided into three categories:

The “at-risk hip” is thought to be in children less than five with a hip that has significant adduction and flexion contractures, minimal subluxation, and a Migration Index less than 30 % [19]. Early treatment is thought to be mandatory to prevent progression of subluxation. Almost always, bilateral surgery is indicated in the setting of spasticity even if only one hip is showing signs of early subluxation [20, 21]. Hip flexor releases include tenotomy of the rectus femoris origin, the tensor fasciae latae, and a release of the psoas tendon over the brim of the pelvis. Adductor tenotomy, usually just the longus and brevis, may also be necessary. When the hamstrings are also contracted as demonstrated by decreased straight leg raise and a decreased popliteal angle, distal hamstring lengthening is also indicated. Muscles are usually released until 50° of symmetric hip abduction is obtained. Infection and hematoma are the two most common complications of this procedure and are relatively rare [22]. Results of these procedures are fairly good. Silver and colleagues reported only 20 % of hips progressed to subluxation [23]. Cornell and colleagues found that 83 % of patients who underwent adductor tenotomies had hips that remained stable [24]. It is clear that the degree of subluxation of the hip at the time of tenotomy plays a big role in the outcome of soft-tissue-only procedures, and so strict indications for this treatment group should not be compromised [25].

When muscle imbalance persists and subluxation is present, a varus derotation osteotomy (VDRO) of the hip and appropriate muscle releases are necessary. A varus closing wedge osteotomy is made at the intertrochanteric level, and usually a 90° blade plate is used for internal fixation. Neck-shaft angle should be corrected to 90–100° of varus [26]. Concurrent tenotomies are performed to balance the forces around the hip joint. The most common complications of a VDRO are loss of fixation and fracture [8]. Many patients develop prominence of hardware and removal is frequent [11]. Brunner and Baumann noted that children less than 4 years old lost varus correction 96 % of the time and recommended a delay in surgery if possible until 8–10 years old [27]. Hoffer and colleagues reported on VDRO outcomes and concluded that it was a good procedure for hip subluxation but was inadequate to treat CP hip dysplasia [28]. Tylkowski and colleagues were able to keep reduction of 16/18 hips after a 3-year follow-up [29]. Overall, a VDRO used in concert with other procedures adequately reorients the center of the hip away from the lesser trochanter and tips the femoral head into the acetabulum.

In addition to the muscle procedures and a VDRO, acetabular insufficiency must be addressed by an osteotomy, either a periacetabular (e.g., Dega or Ganz) or an innominate osteotomy (e.g. Salter). There are more complications associated with these surgeries. Postoperative fracture, pathologic fracture of the femur, pulmonary complications, and decubitus ulcers have all been reported [11]. Dietz and Knutson found that 79 % of hips undergoing a Chiari-type pelvic osteotomy were completely joint pain-free at 7-year follow-up [30]. Further, Osterkamp and colleagues reported that only two of nine hips redislocated after an acetabular osteotomy [31]. Shelf procedures in general appear to do well in patients with CP hip dysplasia. Overall, hip stability was obtained in 83–95 % of patients that underwent a shelf type acetabular osteotomy [32]. When the femoral head and acetabulum are deformed to the point that they are nonreconstructable, which occurs over time when the head is no longer protected in the acetabulum, reducing it into the acetabulum becomes more complex. Painful dislocated hips in the adult or young adult may require a Castle procedure (hip resection), a Schantz osteotomy (valgus osteotomy), a total hip replacement, or a hip fusion. These procedures are salvage operations that should be reserved only for patients with severely deformed, irreducible, and painful hips.

Hip subluxation/dislocation in the CP patient is an acquired condition and therefore preventable. The most severely involved child is at greatest risk. Frequent clinical and radiographic observation is essential. Before subluxation, the at-risk hip can be treated with muscle releases, but once subluxation occurs, VDRO and possible acetabular procedures are required to provide a stable and painless hip.