The DAA to the hip is well described in the literature. ^1-4 Prior studies have identified many benefits of this approach when used for total hip arthroplasty (THA), including a lower dislocation rate, a true intermuscular and internervous plane, less postoperative pain, a quicker recovery, and fewer postoperative restrictions. ^1-7 However, multiple disadvantages are also reported, including early femoral loosening, lateral femoral cutaneous nerve injury, intraoperative fracture, longer operative times, increased blood loss, and complications with the use of traction. ^{2 , 8} The majority of the published studies evaluate and describe the approach being performed in the supine position, often with the use of traction tables or femoral hooks. The anterior approach in the lateral decubitus position offers the same benefits of the supine anterior approach with potential for improved femoral exposure and the patient in a position more familiar to many hip surgeons and operating room staff without the need for specialized tables.

To our knowledge, the DAA to the hip in the lateral decubitus position was first described in the literature as the “MicroHip” technique. ^{9 , 10} The MicroHip approach differs from the standard anterior approach by using a skin incision extending from the anterior aspect of the midpoint of the greater trochanter toward the anterior superior iliac spine, whereas the deep dissection is similar using the Smith-Peterson interval. ⁹ Additionally, the femur is brought into hyperextension, adduction, and external rotation for exposure and preparation. ¹⁰ The anterior lateral decubitus intermuscular approach has also been described using the standard DAA incision and interval while the surgeon stands posterior to the patient for acetabular preparation and then moves anteriorly for femoral exposure. ¹¹ Both approaches resulted in improved outcomes with an acceptable component position and comparable complications. ^9-11 Carta and Fortina ¹¹ evaluated 150 THAs performed via the anterior lateral decubitus intermuscular approach with no femoral revisions for aseptic loosening attributed to the easier exposure and improved visualization of the femur. This chapter describes our technique for performing the DAA in the lateral decubitus position.

Standard preoperative radiographs are obtained and evaluated. These images include weight-bearing anteroposterior pelvis and cross-table lateral radiographs. Templating is used and offers unique challenges to preparing for THA compared with other approaches because the lesser trochanter is not as readily accessible for determining the level of the femoral neck osteotomy. Other landmarks must be used to localize the site of the osteotomy, or further inferomedial capsular release should be performed to identify the lesser trochanter as a reference for the osteotomy. We prefer to use alternative landmarks to localize the site of the osteotomy. Most often, the femoral head-neck junction is used, and the distance between the junction and the templated femoral stem is measured. Other potential landmarks include the prominent inferior edge of the femoral head, large inferior osteophytes, and the sulcus at the junction of the greater trochanter and the base of the superior femoral neck (Figure 11.1). Anesthesia is preferably performed with a short-acting single-shot spinal with sedation plus a periarticular injection and multimodal perioperative pain medication to allow for ambulation within a few hours of the operation.

The surgery uses a standard operating table with the use of a pegboard for pelvic stabilization. The MorphBoard Leg Extension System (Innovative Medical Products, Inc., Plainville, CT, USA) or a similar device allows for the use of pegs to stabilize the patient as well as a posterior cutout to allow the operative leg to be brought into hyperextension, adduction, and external rotation for femoral exposure (Figure 11.2). Standard equipment for THA is used, including straight acetabular reamers, impactors, and femoral broaches.

The patient is placed in the lateral decubitus position on a pegboard as described, and the operative extremity is draped in a standard fashion. The preoperative leg lengths palpated at the patient’s heels are measured. The operative leg is placed on a padded Mayo stand in a slightly extended and externally rotated position. The planned incision is marked out starting two fingerbreadths lateral and one fingerbreadth distal to the anterior superior iliac spine (Figure 11.3). The incision extends 8 to 10 cm, aiming distally toward the lateral border of the patella. The skin is incised, and the fascia over the tensor fascia lata (TFL) is identified. Hemostasis is obtained and the fascia incised. The distal medial edge of the fascial incision is elevated, and the TFL is bluntly dissected off of its undersurface. The TFL is then retracted laterally, and the fascial incision is extended both distally and proximally.