Preop planning. A reconstruction of the labrum is anticipated in case of radiographic signs of generalized impingement in accordance to specific signs for labral stretching such as the recess sign (Fig. 2). On a preoperative x-ray of the pelvis, the lateral center-edge angle of Wiberg is defined [5, 6]. This angle should be ≤39° and a rim trimming is planned with a resection of 1 mm for every degree of over-coverage [7]. The patient should be informed about the potential need for allograft tissue.

Procedure. The surgical dislocation is performed according to the technique described by Ganz et al. [8]. In brief, the patient is positioned in lateral decubitus. The Gibson approach is conducted and the tip of the greater trochanter is identified in 30° of internal rotation (Fig. 3). The piriformis and gluteus minimus muscles are identified. The trochanteric branch of the medial circumflex artery is identified and a Z-shaped step-cut osteotomy of the trochanter is made. Approximately 3 mm of the tip of the trochanter are left in place. Care is taken to leave the anterior cortex intact in order to fracture the cortex, which will ensure anterior stability when the osteotomized fragment is put back in place. The gluteus minimus muscle is then carefully released from the underlying capsule, which will be incised in a Z-shape to avoid damaging the medial femoral circumflex artery at the level of the femoral neck (Fig. 4). The femoral head is then dislocated out of the acetabulum with an external rotation-flexion maneuver. The ligamentum teres is cut with a curved scissors, which then allows for posterior dislocation of the head beyond the posterior rim. Anterior, superior, and posterior retractor placement provides full visualization of the hip joint and the acetabular rim (Fig. 5).

The hip joint is inspected and the labrum is then circumferentially detached from the acetabular rim. Most often the labrum is thinned and will not provide sufficient coverage of the head to ensure an adequate sealing function (Fig. 6). A semitendinosus allograft is used because it is long enough (8–15 cm), will be thick enough to provide adequate coverage, and is not associated with comorbidities of the graft harvesting. Therefore, the semitendinosus allograft is preferred to reconstruct the labrum. The graft is thawed and prepared during rim trimming. The length of the graft can be measured with the debrided labrum or with a pliable caliper. Both tendon ends are secured to an ACL-preparation kit with an absorbable suture (Vicryl 1) using a Krackow stitch. A tubular double loop is created using a baseball stitch with absorbable sutures (Vicryl 2/0). Both tendon strands are sewn to each other over the full length of the graft (Fig. 7).