Minimally Invasive Anterior Approach to the Hip

The minimally invasive anterior approach to the hip is used mainly for elective joint replacement surgery but can also be used for reduction of displaced femoral neck fractures and drainage of hip joint infections. The approach preserves muscle and in expert hands may be associated with faster initial recovery from surgery. Because the approach gives less exposure of the joint the use of an image intensifier is advised by many to check the level of femoral neck osteotomy as well as the position of the acetabular component. The operation can be performed on a regular radiolucent table. Some surgeons however advocate the use of traction during femoral neck osteotomy and acetabular component insertion.

Position of Patient

Place the patient supine on the operating table (Fig. 8-2). This supine position permits the use of an image intensifier which is of great value in determining the position of prosthetic components in joint replacement surgery.

Landmarks and Incision

The anterior superior iliac spine is subcutaneous and is easily palpable in thin patients. In obese patients, it is covered by adipose tissue and is more difficult to find. To palpate it bring your thumbs up from beneath the bony protuberance.

Palpate the tip of the greater trochanter on the lateral aspect of the thigh.

Incision

Mark the tip of the greater trochanter and the anterior superior iliac spine with a skin marker. Make an 8-cm longitudinal incision beginning 1 cm below and 1 cm lateral to the anterior superior iliac spine. The center of the incision should be at the level of the tip of the greater trochanter (Fig.

8-18). Aim the incision in the direction of the fibular head.

Internervous Plane

One internervous plane is used between muscles supplied by the femoral nerve and muscles supplied by the superior gluteal nerve. Superficially this plane lies between the sartorius (femoral nerve) and the tensor fasciae latae (superior gluteal nerve); deeply the plane lies between the rectus femoris (femoral nerve) and the gluteus medius and minimus (superior gluteal nerve) (Fig. 8-4A,B).

Superficial Surgical Dissection

Divide the fascia covering the tensor fasciae latae at the medial edge of the muscle. Staying within the fascial sheath develop a plane between the sartorius muscle anteromedially and the tensor fasciae latae posterolaterally (Fig. 8-19). Staying within the fascial sheath will reduce the chances of damaging the lateral femoral cutaneous nerve.

Deepen this plane by blunt dissection to expose the interval between the rectus femoris and the tensor fasciae latae

The rectus femoris muscle is enclosed in a fascial sheath. Incise the anterior portion of the sheath to reveal the muscle and retract it medially. Then carefully incise the posterior aspect of the sheath to reveal the lateral circumflex vessels which are often large and need ligation.

Deep Surgical Dissection

Develop a plane between the rectus femoris muscle and the gluteus minimus muscle. Palpate the femoral head lying underneath the hip joint capsule. Overlying the capsule is some fat. Gently push this off the surface of the capsule using a swab and a rasparatory. Some muscular fibers take origin from the hip joint capsule and run down to be inserted just below the lesser trochanter (iliocapsularis). These fibers may need to be detached by sharp dissection to fully expose the hip joint capsule. Place a retractor on the inferior surface of the femoral neck (Fig. 8-20). The reflected head of the rectus muscle arises from a concavity just above the acetabulum. Develop a plane between the rectus and the hip joint capsule and carefully under direct vision place a retractor into the femoral head through the capsule. Perform an H-or L-shaped capsulotomy excising a portion of the capsule and replace the retractors within the hip joint (Fig. 8-21). One retractor lies inferior to the femoral neck, one superior to it, and the third is placed over the rim of the acetabulum ensuring that the tip of the retractor is directly in contact with bone. Divide the femoral neck checking the position of the osteotomy using an image intensifier (Figs. 8-22, 8-23, and 8-24).

Figure 8-18 Make an 8-cm longitudinal incision beginning 1 cm below and 1 cm lateral to the anterior superior iliac spine. Aim the incision toward the head of the fibula. The center of the incision should be at the level of the tip of the greater trochanter.

Figure 8-19 Identify the interval between sartorius and tensor fasciae latae and incise the deep fascia covering the tensor fasciae latae muscle at its medial edge.

Figure 8-20 Retract the tensor fasciae latae laterally to expose the rectus muscle covered by a fascial layer.

Figure 8-21 Incise the fascial sheath covering the anterior aspect of the rectus to expose the muscle.

Figure 8-22 Retract the rectus muscle medially to expose the fascia covering the posterior aspect of the muscle. Incise this fascial sheath longitudinally to reveal the lateral circumflex vessels.

Figure 8-23 Ligate the lateral circumflex vessels. Expose the anterior hip joint capsule covered by fatty tissue. Some fibers of psoas—the iliocapsularis muscle will need to be separated from the capsule by sharp dissection. Incise the anterior capsule of the hip joint longitudinally.

Figure 8-24 Position retractors around the superior and inferior aspects of the femoral neck. Place an anterior retractor over the anterior lip of the acetabulum under direct vision ensuring that the tip of the retractor is placed directly onto bone without any soft tissue intervention.

Dangers

Nerves

The lateral femoral cutaneous nerve (lateral cutaneous nerve of the thigh) reaches the thigh by passing over, behind, or through—usually over —the sartorius muscle, about 2½ cm below the anterior superior iliac spine. Three or more branches may exist whose course is very variable. The nerve must be preserved when you incise the fascia over the medial edge of the tensor fasciae latae; cutting it may lead to the formation of a painful neuroma and may produce an area of diminished sensation on the lateral aspect of the thigh (Fig. 8-14; see Fig. 8-5). Staying within the fascial sheath of the tensor fasciae latae will protect the nerve from damage.

The femoral nerve lies almost directly anterior to the hip joint itself, within the femoral triangle. Because the nerve is well medial to the rectus femoris, it is not really in danger unless you stray far out of plane to the wrong side of the sartorius and the rectus femoris. If you lose the correct plane during deep dissection, locate the femoral pulse by palpation. Within the femoral triangle, the artery lies medial to the nerve (Figs. 8-15 and 816).

Vessels

The ascending branch of the lateral femoral circumflex artery crosses the operative field, running proximally in the internervous plane between the tensor fasciae latae and the rectus femoris. It lies posterior to the posterior part of the fascial sheath that encloses the rectus femoris muscle. Ligate or coagulate it when you separate the two muscles (see Figs. 8-8, 815, 8-16, and 8-17).

How to Enlarge the Approach

This approach is a minimally invasive one. If you start to struggle and loose the surgical plane the approach can always be converted to the classic anterior approach. It is better to create more muscle damage than injure a vital structure or insert a prosthesis in an incorrect position.

Be aware however that this approach can be extended distally if required by splitting vastus lateralis (see Fig. 8-13).