Innominate Osteotomy

Indications

Developmental dislocation of the hip (dislocated hip)

Acetabular dysplasia and subluxation of the hip in the child and adolescent

Pitfalls

• Contraindicated for neuromuscular dislocation or subluxation

Controversies

• Experience with this procedure after closure of the acetabular triradiate growth plate has been mixed. Periacetabular or triple osteotomy should be considered instead of innominate osteotomy in the adolescent.

Examination/Imaging

Anteroposterior (Fig. 1A) and frog-leg view radiographs are obtained.

A supine anteroposterior radiograph with the thighs fully abducted and internally rotated is obtained to predict postoperative congruency of the hip when the hip is subluxated (Fig. 1B).

• This will also determine the need for capsulotomy and capsulorrhaphy as well as provide an indirect measure of femoral anteversion and the possible need for a supplemental derotation osteotomy of the femur.

Surgical Anatomy

The surgeon should be familiar with the following anatomic structures:

• Bones (Fig. 2A): iliac apophysis, iliac crest, greater sciatic notch, acetabular labrum and lateral acetabular epiphysis

• Muscles and ligamentous complexes (Fig. 2B): sartorius and tensor fascia femoris, straight head of the rectus femoris, transverse acetabular ligament, ligamentum teres, iliopsoas muscle/tendon

• Nerves (Fig. 2C): lateral femoral cutaneous nerve of the thigh, superior gluteal nerve

• Vessels in the greater sciatic notch and the surrounding soft tissues of the ilium (see Fig. 2C)

Positioning

The child is placed supine with a bolster beneath the ipsilateral thorax to achieve a 30° elevation of the ipsilateral pelvis (Fig. 3).

Pearls

• Do not place the bolster under the ipsilateral hemipelvis as this will interfere with appropriate surgical draping.

Portals/Exposures

A transverse “bikini line” incision is made centered on and just distal to the anterior superior iliac spine.

The interval between the sartorius and tensor fascia femoris is separated, taking care to protect the lateral femoral cutaneous nerve of the thigh.

If capsulorrhaphy is to be done for dislocation, the straight head of the rectus femoris is separated from the hip joint capsule, tagged with a suture, and divided just distal to the anterior inferior iliac spine.

The iliac apophysis is split equally with a scalpel from the anterior inferior iliac spine to the junction of the anterior and middle thirds of the iliac crest.

The iliac crest is stripped subperiosteally both medially and laterally to the greater sciatic notch (Fig. 4A and 4B). Rang sciatic notch retractors (Fig. 5) facilitate protection of the superior gluteal nerve and vessels in the notch and the surrounding soft tissues when cutting the ilium with the Gigli saw.