A Modified Extensile Anterior Approach to the Acetabulum and Anterior Column

Kristoff Corten

Joseph T. Moskal

Introduction

Implant failure modes such as instability, infection, loosening, and wear are becoming more prevalent.¹ Instability, infection, extensive bony defects, and soft tissue damage are the most important concerns and complications associated with revision surgery. More than 50% of revisions involve the acetabular component.¹ Paprosky et al² described a classification of acetabular defects that occur in cases of implant failure. Treating type 2 and 3 uncontained defects can be technically challenging because the surgeon has to use extensive reconstruction techniques in order to adequately restore the biomechanics of the hip with structural stability and equal leg length. Furthermore, neurovascular structures can be in jeopardy when complex pelvic reconstructive procedures are being conducted.

Direct anterior approach (DAA) total hip arthroplasty (THA) can also be used in more complex primary cases such as in developmental dysplasia, cerebral palsy, and Legg-Calve-Perthes disease, even after femoral and acetabular osteotomies.³ In these cases, the procedure is technically more demanding with a high risk for postoperative dislocation due to the complex anatomic abnormalities, altered anatomy, and/or the accompanying contractures.⁴^,⁵^,⁶^,⁷^,⁸ Therefore, a systematic and reproducible approach toward these difficult cases is required to minimize intra- and postoperative complications. In addition, a good access to the bony pelvic anatomy will allow the surgeon to understand the most important hurdles associated with the particular case.

In order to optimize the access to the pelvic bone, to minimize soft tissue damage, and to protect the pelvic neurovascular structures, an extensile anterior approach to the acetabulum can be used. This approach has been described by Ganz et al⁹^,¹⁰ to conduct periacetabular osteotomies (PAOs). This approach uses the Smith-Petersen interval and exposes the anterior column and the acetabulum along with its defects or altered bony anatomy. In this chapter, we describe a systematic modified extensile DAA surgical technique that allows surgical access to the pelvis, the acetabulum, and the anterior column.

Surgical Technique

The patient is in the supine position either on a regular operating room table or a specialized table depending on the surgeon’s preference. Spinal or general anesthesia is administered. Muscular relaxation is very important to optimize the exposure. Therefore, we have a low threshold to use general anesthesia for these often prolonged procedures. A modified Smith-Petersen approach to the hip is used.⁹^,¹⁰

Step 1

The incision starts along the iliac crest, over the anterior superior iliac spine (ASIS), and is directed distally over the tensor fascia lata (TFL; Figure 22.1). Subcutaneous flaps are raised medially and laterally, and care is taken to avoid the lateral femoral cutaneous nerve. The TFL fascia is incised and peeled off the TFL fibers. The interval between the TFL and the rectus femoris is identified, and the lateral circumflex vessels are coagulated.

FIGURE 22.1 A, A slightly curved incision is made, just lateral to the iliac crest. B, The ASIS is exposed by subperiosteally peeling off the abdominal muscle and sartorius-inguinal ligament aponeurosis (Left hip shown).

Step 2

Proximally, the aponeurosis of the external oblique muscle is subperiosteally peeled off the iliac crest and reflected medially along with the oblique abdominal muscles. The leg is slightly flexed. The aponeurosis of the sartorius and the inguinal ligament is then peeled off the ASIS (see Figure 22.1). The medial muscle envelope is lifted off the inner iliac table with a Hohmann retractor that rests subperiosteally on the pelvic brim (Figure 22.2). In case of an extensive medial defect, the retractor is put on the inner surface of the sciatic spine. The iliopsoas muscle is thus retracted medially (see Figure 22.2B and C). The anterior inferior iliac spine and the rectus femoris are identified.

FIGURE 22.2 A, The ASIS is exposed, and the Hohmann retractor is put on the inner table of the ileum underneath the iliacus muscle. B, In case the pelvic brim bone is deemed damaged due to a medial defect, a “reversed curved” blunt retractor is put on the ischial spine. C, This retractor retracts the iliacus muscle in the medial direction, exposing the full inner table and D, the anterior column. A sharp-tipped retractor is put just medial to the iliopectineal (pubic) eminence. Both retractors provide an excellent view on the anterior column (Left hip).

Step 3

The interval between the iliopsoas medially and the insertion of the rectus femoris and iliocapsularis laterally is identified and opened. This is an interval without any neurovascular structures, and it can be opened easily. A Langenbeck retractor is used to lift the iliopsoas off the iliopectineal eminence, and a sharp-tipped Hohmann retractor is put medially to the eminence. The tip of this retractor is fixed into to the pubic bone in order to safely retract the psoas medially (see Figure 22.2). The hip remains flexed.

Step 4: Complex Primary

For a complex primary case, the view on the anterior columns and acetabular rim is usually sufficient with this level of exposure. The procedure is continued with the incision of the anterior capsule followed by the neck osteotomy and head extraction. The inferior and superior capsule are then released. Releasing the capsular structures before acetabular exposure allows for a less forceful posterior retraction of the femur. This minimizes the risk of acetabular rim fractures caused by the retractors. It is important to identify the native center of rotation (Figure 22.3). This can be done by identifying the transverse acetabular ligament. The continuation of the procedure is very similar to a “regular” primary THA because reaming can be done under direct view of the often deficient pelvic and acetabular structures.

FIGURE 22.3 A, This patient with cerebral palsy had multiple surgeries and a dislocated femur on the right side with (B) a pseudoacetabulum superior to the native center of rotation. C, The extensile approach allowed assessment of the bony structures before gentle reaming. This minimizes the risk of iatrogenic bony defects. In addition, it allows for identifying and reaming the native acetabulum instead of the pseudoacetabulum. D, In these frail patients, the neurovascular anatomy can be distorted and in jeopardy during screw insertion. The vascular structures are protected with the finger on the medial side of the pelvic wing. E, The socket is located in the native center of rotation and not in the pseudoacetabulum.

Step 5: Revision

In case the view on the anterior column is insufficient, the rectus femoris tendon can be tenotomized as originally described by Ganz et al⁹^,¹⁰ (Figure 22.4). In these cases, the tendon can be sutured back at the end of the procedure. The tenotomy is approximately 1 cm distal from the insertion on the anterior inferior iliac spine.

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