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The direct lateral approach is an anterolateral approach to the hip that involves dissection through the gluteus medius and minimus.
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There are many variations, which essentially differ by the amounts of gluteus medius and minimus that are released from the trochanter and whether the release is performed with or without a bony fragment.
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The dissection commences in the vastus lateralis and curves in a lazy-S fashion along the anterior lateral aspect of the trochanter, culminating in dissection into the gluteus medius and minimus.
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Sharp dissection into the gluteus medius and minimus limits trauma to the abductor mechanism, and the dissection should not extend farther than 3 to 4 cm into the muscle, in an effort to preserve innervation to the abductor mechanism.
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The exposure is extremely extensile and can be extended distally into the vastus lateralis as required to complete the operative intervention.
The direct lateral approach to the hip has been widely used for both primary and revision total hip arthroplasty. By definition the direct lateral approach to the hip involves entrance to the hip joint via a split in the gluteus medius and minimus. Many variations of the direct lateral approach have been described and are generally characterized by the amount of abductor mechanism released from the greater trochanter and whether the abductor is released directly or with a bony fragment. Perhaps the most widely popularized description of the direct lateral approach is the Hardinge variation. This approach was popularized with the introduction of the Porous Coated Anatomic (PCA) total hip arthroplasty system (Howmedica, Rutherford, NJ). The key feature of the Hardinge approach involves detachment of approximately 50% to 60% of the abductor mechanism from the greater trochanter. This feature facilitates exposure of both the acetabulum and the proximal femur for implant placement. For surgeons concerned about tendon-to-tendon healing, Dall described a technique of releasing the abductor with a bony fragment. At the conclusion of the operative intervention, the fragment was approximated with either suture or cerclage wire. The advantages touted for this variation were direct bone to bone healing. Since 1985 the current authors have used their own specific modification of the direct lateral approach. This modification was originally described in collaboration with our practice by Frndak and colleagues for primary total hip arthroplasty and by Head and colleagues for revision total hip arthroplasty. The essential difference in this modified technique involves the preservation of at least 60% to 75% of the attachment of the abductor mechanism to the greater trochanter. We release only 25% to 30% of the abductor from the greater trochanter. Therefore the major advantage of our modification is maintenance of a significant attachment of the abductor mechanism, which allows for a more rapid return of function and minimizes postoperative limping, one of the major criticisms of this technique.
INDICATIONS AND CONTRAINDICATIONS
The direct lateral approach to the hip can be used for both primary and revision total hip arthroplasty ( Fig. 36-1 ). It represents our preferred method of surgical approach. The major advantage of the direct lateral approach is the ability to effectively visualize both the acetabulum and the proximal femur. We have used this approach to perform simple primary total hip arthroplasty and have extended it to perform complex acetabular reconstruction and femoral reconstruction. The major advantage of the direct lateral approach as reported in nearly all literature on this topic is the postoperative stability afforded by the approach. This advantage has been clearly demonstrated in revision total hip arthroplasty. One of the more frequently performed current revision hip arthroplasties involves isolated acetabular liner exchange. Although liner exchange may appear to both the surgeon and the patient to be a relatively simple operative intervention, it has been plagued by postoperative dislocation when performed via a posterior approach. On the other hand, we have experienced a relatively low incidence of dislocation for isolated liner exchange when performed via a direct lateral approach. Our findings have been validated by several other reports. Therefore a specific indication for revision hip arthroplasty through a direct lateral approach would be isolated acetabular liner exchange in an effort to prevent the unwanted complication of dislocation. We use the direct lateral approach for all revision hip arthroplasties, even those that have been previously performed via a posterior approach. The only relative contraindication to our use of the direct lateral approach involves those cases in which total absence of any posterior soft-tissue structures of the proximal femur is noted on exposure. This posterior so-called “bald eagle” is more appropriately approached posteriorly with an attempt at soft-tissue reconstruction at the conclusion of the operative intervention.
PREOPERATIVE PLANNING
Regardless of the surgical approach contemplated, appropriate preoperative planning for revision hip arthroplasty must be undertaken. Appropriate radiographic studies, implant selection, and determination of the need for bone graft and/or bone graft supplements are paramount in this process. When one elects to perform the revision procedure with a direct lateral approach, preoperative radiographs should be evaluated carefully for the presence of heterotopic ossification. In the presence of Brooker III or IV heterotopic ossification or risk factors for heterotopic ossification such as ankylosing spondylosis, prophylaxis either with preoperative or immediate postoperative radiation or use of indomethacin should be considered.
TECHNIQUE
After induction of regional, general, or combined anesthetic, leg length determination should be performed with the patient in the supine position. The patient is then placed in the lateral decubitus position with the operative side facing the operative field. Various devices are available to secure the patient in the appropriate position. Having used a variety of devices, we currently recommend the use of a peg board. This device is suited for patients of all sizes. It provides secure positioning with little concern for loss of positioning during the surgical intervention. The main technical peril is that all pegs should be adequately padded to prevent pressure and ultimately skin breakdown. Furthermore, anterior pegs should be positioned so they do not limit range of motion, specifically flexion, adduction, and internal rotation.
The hip and entire lower extremity should be prepared and draped using a standard technique. With leg length in the supine position having been noted, leg length in the decubitus position should now be recorded using the previously described well leg down technique. This technique involves aligning the heels and noting the relationship of the knees. In primary procedures the cephalad portion of the greater trochanter is identified with a spinal needle. The incision is then placed over the greater trochanter, generally two thirds proximal and one third distal to the most cephalad point of the greater trochanter (see Fig. 36-1 ). The incision is canted posteriorly approximately 30 degrees. In revision arthroplasty, previous incisions are noted. A laterally based incision is planned, incorporating as much as possible of the previous incisions (see Fig. 36-1 ). This lateral incision should be situated directly over the greater trochanter. The distance proximal and distal to the tip of the greater trochanter is related proportionally to the extent of the revision procedure. The dissection is carried out through the skin and subcutaneous tissues to the level of the fascia lata, which is incised along the line of the incision. The anterior and posterior myofascial sleeves are retracted, exposing the lateral aspect of the femur ( Fig. 36-2 ). In primary surgeries the gluteus medius and minimus are elevated from the anterior aspect of the femur starting laterally and moving medially. The capsule is elevated in continuity with the gluteus minimus ( Fig. 36-3 ).
