CHAPTER OUTLINE
Indications and Contraindications 114
Preoperative Planning 115
Technique 115
Patient Positioning 115
Skin Incision 116
Deep Dissection 116
Dislocation and Femoral Neck Osteotomy 117
Femoral Preparation 118
Acetabular Exposure 118
Acetabular Reaming 119
Wound Closure 119
Perioperative and Postoperative Management 120
Complications 120
Summary 120
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The operation can be done either with the patient in the supine position with a bump placed under the ipsilateral sacroiliac joint or in the lateral decubitus position.
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The skin incision should begin several centimeters above the palpated tip of the greater trochanter and extended distally 10 to 15 cm along the midline.
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The tensor is split the length of the incision from distal to proximal extending posteriorly into the gluteal fascia. This helps eliminate the potential problem of a tight posterior sling, which can make dislocation difficult.
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With the leg externally rotated, the medius and minimus are released independently from their most inferior borders to the anterosuperior corner of the trochanter leaving 5 mm of tendon behind for reattachment.
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Acetabular exposure is enhanced by releasing the reflected head of the rectus femoris from the ilium.
The direct lateral approach was first described by Kocher in 1903. It was popularized in 1982 by Hardinge, who expanded on the key points of several earlier methods for approaching the hip laterally. The approach offers several advantages for hip arthroplasty, including retention of the posterior capsule with a reduced likelihood of dislocation. It also provides excellent exposure of the acetabulum without iatrogenic flexion of the pelvis, which can lead to problems in achieving correct acetabular placement. The approach has gained wide support; however, many surgeons remain concerned about the questionable injury that the approach inflicts on the abductor muscles. Lester Borden is credited with accurately describing the anatomy of the gluteus medius and minimus attachments and providing the basis for anatomic repair procedures. With improved repair techniques, concerns about persistent limps and heterotopic ossification were thus lessened. The approach described by Borden has been further modified to eliminate the release of the vastus muscle, and for several years it was referred to as the anterolateral approach. This name has now been dropped in view of the development of another muscle-sparing approach to the hip, which has also been described as “anterolateral.” The approach described here, then is more currently named a modified version of the direct lateral approach.
INDICATIONS AND CONTRAINDICATIONS
The direct lateral approach can be used for most routine primary total hip procedures (both cemented and cementless) and for resurfacing of the hip. It can also be extended distally for extensive visualization of the femur.
This approach is contraindicated in patients who have had prior proximal femur fractures that have healed in a flexed alignment ( Fig. 13-1 ). Leg lengthening of more than 2 cm is difficult using this approach because it is difficult to repair the hip abductors when the hip is lengthened.
PREOPERATIVE PLANNING
Planning is accomplished in two phases. The first involves selection of the approach. A series of questions that address any extrinsic factors related to the selection of approach should be considered:
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Is there any preexisting hardware that must be removed?
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How much does the leg need to be lengthened? If it must be lengthened more than 2 cm the direct lateral approach should not be used.
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Are there any bony deformities or soft tissue deficits that will affect the reconstruction? For example, flexed femoral malunions are better approached posteriorly.
The second phase of planning is based on a working knowledge of the goals of prosthesis placement to optimize postarthroplasty hip function and maximize the recovery rate. Bony landmarks that can be identified intraoperatively are noted on preoperative radiographs to allow optimal prosthesis placement ( Fig. 13-2 ) :
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The acetabulum should be medialized to the floor of the fovea to reduce the body weight lever arm and lower demand on the abductor muscles ( Fig. 13-3 ).
FIGURE 13-3
The red horizontal line represents the “body weight lever arm” while the black horizontal line represents the femoral offset. Medializing the acetabulum reduces the load on the hip while increasing the offset improves the mechanical advantage of the abductors.
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The center of rotation should be restored so that the inferior edge of the socket corresponds with the acetabular outlet to aid in restoring the working length of the abductors.
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The abduction angle should approximate 45 degrees. The prominence of the inferior cotyledons can be used as a guide to abduction ( Fig. 13-4 ).
FIGURE 13-4
The lined bone seen along the inferior acetabulum is the inferior cotyledons and is visible intraoperatively. The degree of bone visible provides a check to confirm abduction.
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The version should match the normal opening angle of the native joint. A line connecting the palpated sciatic notch with the posterior acetabular wall is parallel to the normal opening angle of the socket.
TECHNIQUE
Patient Positioning
The patient is placed on the operating table in the lateral decubitus or the supine position, depending on the preference of the surgeon. If the supine position is used, it will be easier to displace the femur posteriorly during acetabular exposure if a bump is placed beneath the buttock under the sacroiliac joint. Care should be taken to ensure that the bump is medial to the hip so that the femur will fall posteriorly away from the acetabulum. When using the lateral decubitus position, considerable care should be taken to position the patient’s pelvis so that a line connecting the two anterior superior iliac spines is vertical when viewed from the end of the table as well as from the side.
Once the patient is correctly positioned, it is critical that he or she be stabilized by kidney rests, deflectable beanbags, or other available devices. The dependent leg is flexed at both the knee and hip so that the hip is flexed 50 to 60 degrees and the tibia lies as perpendicular as possible to the long axis of the table. This position prevents the patient from rolling excessively in either direction.
For the purpose of this description, the 12-o’clock position in the wound refers to the cephalic direction in the sagittal plane.
Skin Incision
SURGEON: The skin of the hip should be palpated to identify bony landmark locations and generate an outline of the greater trochanter to be drawn on the skin. The skin incision is started 2 to 4 cm above the anterior tip of the greater trochanter and carried distally along the anterior aspect of the femoral shaft. An incision length of 10 to 15 cm is adequate for most patients. In obese patients, the incision may need to be extended to allow an unencumbered approach for femoral broaching. When the supine position is used, the incision is direct, straight along the middle of the femur, and extends several centimeters cephalad to the trochanter. When the lateral decubitus position is used, the incision is angled slightly posterior ( Fig. 13-5 ).
ASSISTANT: As the subcutaneous tissue and fat are incised, the tissue can be begun to be retracted with a pair of blunt retractors or general-use rakes. The subcutaneous fat should be cut to the full length of the incision.
Deep Dissection
SURGEON: The tensor fasciae latae and iliotibial band can be seen anteriorly. The gluteal fascia comes in posteriorly at an angle. The interval between the tensor fasciae latae and the gluteus maximus fascia is identified by first visibly determining the divergent fibers of the two muscles and then palpating with a finger to identify a soft spot where the tissue is thinned. A cut is made from distal to proximal beginning in the anterior third of the tensor fascia and extending cephalad and posterior into the gluteal fascia. A finger can be passed under the fascia to protect the abductor muscle. The release should extend proximal and posterior enough to release tension across the posterior trochanter. The gluteal fascia can create a very tight posterior sling that can make it difficult or impossible to dislocate the femoral head without excessive femoral rotation. Because such rotation can cause damage to the abductor muscles, it is important to extend the release of the gluteal fascia posteriorly in order to release tension on this posterior sling. A Charnley-type retractor can then be placed below the deep fascia to expose the trochanter and the gluteus medius muscle.
ASSISTANT: The leg is gently lifted or abducted to allow the surgeon to insert a finger under the tensor to protect the abductor muscle belly as the deep fascia is split. Care is taken to ligate the superior gluteal artery to reduce bleeding. After the deep fascia has been opened, a narrow Hohmann retractor is placed at the inferior border of the medius tendon and a second Hohmann retractor is placed at the posterior corner of the trochanter to help the surgeon visualize the true extent of the muscular attachment of the abductor. The leg should be gently externally rotated to stretch the abductors. The foot should be resting on the front edge of the table with the hip slightly flexed to help increase the ease of releasing the tendon.
SURGEON: Now that the medius muscle is in full view, a finger can be passed under the inferior border of the muscle to release about a third to half of the tendon from the femur from distal to proximal. Care should be taken to leave 3 or 4 mm of soft tissue on the femur for good tendon to tendon repair. Forceps can be used to check the width and quality of the cuff of tissue left behind on the femur as the inferior one third to one half of both the medius and minimus are released ( Fig. 13-6 ). The release should be carried proximally to the anterosuperior corner of the trochanter. At the proximal extent of the release, one can turn away from the trochanter up into the muscle belly, moving parallel to its fibers for a distance of about 3 cm. A release extending more than 3 or 4 cm could result in damage to the superior gluteal nerve. The cut gluteus medius muscle can now be retracted anteriorly to expose the gluteus minimus, which should then be released in a similar fashion. The inferior or caudal portion of the minimus blends with the medius into a conjoined tendon. It is easier to repair the minimus if this conjoined tendon is left intact. This leaves only the joint capsule.
