Direct Anterior Approach With Special Table for Primary Total Hip Arthroplasty

Indications and Contraindications

While several well-described approaches can be considered for routine THA, strict indications for anterior THA do not exist. A relative indication for using an anterior approach is patients who are at higher risk for postoperative posterior hip dislocation. This includes patients suffering from neurologic and neuromuscular conditions such as paresis or multiple sclerosis or patient factors such as cognitive impairment, substance abuse, or parkinsonism. Patients with prior anterior approaches to the hip—particularly with retained anterior hardware, such as in the case of some surgical arthrodeses—may be indicated for the approach. Additionally, patients suffering from collagen vascular disorders, such as Ehlers-Danlos, may be relatively indicated for an anterior approach.

Patients with personal hygiene issues, very large abdominal pannus, or with obvious skin irritation and/or fungal infection in the hip flexion crease are at risk for surgical site infection. In the author's own study, the hazard ratio for wound complications was 19.25 (95% confidence interval, 5.7–60.0; p = 0.001) in patients with a body mass index (BMI) greater than 40 when compared with normal BMI patients. Other contraindications to the use of DAA vary according to the surgeon's experience with extensile techniques and are relative. Primary arthroplasty situations requiring the use of a straight stems may prove problematic and may be a relative contraindication. Revision arthroplasty when more extensile femoral exposure is required—particularly with the need for an extended trochanteric osteotomy—is a relative contraindication for a DAA.

Preoperative Planning

In all patients with hip disease requiring THA, an anteroposterior (AP) standing pelvis, anterior proximal femur, and cross-table lateral radiographs of the hip with magnification markers are obtained. With careful attention to templating, the patient's limb length and femoral offset can be optimized, assisting with abductor mechanics and soft tissue tension.

Patient Positioning

The patient is placed in the supine position on the operative table. We elect to use a specialized operative bed that allows independent manipulation of the two legs with the ability to flex and extend, abduct, and adduct the operative extremity. There are a number of different options for a specialized orthopedic table; the surgeon's experience and bed cost and availability will affect choice. A perineal post is placed, and the patient is translated distally on the bed so that further translation of the patient does not occur when traction is applied. The patient's arms are extended at the side, which allows easy access for the anesthetic team. If the patient has limited range of motion of the shoulder, the arm may be secured on the patient's chest. If this is the ipsilateral upper extremity, it may cause difficulty during femoral broaching, particularly with an obese patient. The surgeon should take this into consideration during preoperative planning, and during femoral broaching.

A Mayo stand is brought in from the nonoperative side at the level of the patient's shoulders and kept above the patient's face to facilitate airway management by the anesthetic team throughout the surgical procedure and to protect the patient's face. The patient is typically raised to a height comparable to the upper abdomen of the surgeon, which facilitates a comfortable working height and visualization of the surgical field. Gel pads are placed on the arm boards beneath the upper extremities. The arms are secured in the supinated position. The protuberant abdomen or pannus of an obese patient is displaced to the nonoperative side using tape that is secured to the contralateral side of the operative bed.

Draping

The surgical field is clipped preoperatively with electric clippers shortly after entering the operative theater. This should be completed at a level of one hand breadth superior, medial, and lateral to the anterior superior iliac spine (ASIS) and then distally to about 6 to 8 inches cephalad to the knee. The field is cleansed with alcohol to remove any emollients or flaking skin. A nonsterile adhesive U-Drape is applied to the thigh about 6 to 8 inches cephalad of the knee and extended proximally, medially, and laterally to the ASIS by approximately one hand breadth. A second nonsterile plastic drape is applied proximally, connecting the two limbs of the U-Drape 4 to 5 cm above the iliac crest. The field is then sterilized with either chlorhexidine solution or iodine/alcohol solution.

A pair of adhesive sterile paper U-Drapes is used to circumscribe the field highlighted earlier. A bar drape is placed longitudinally on the operative and nonoperative sides of the bed. Two large drapes are secured to the bar at the patient's head and extended out from the patient to ensure that the arm boards and other equipment are fully covered during the procedure. The surgical field is marked for incision position and the skin is covered with the iodine-impregnated adhesive occlusive barrier drape.

The specialized table that we use has a hydraulic lift for a hook that passes beneath the proximal femur, assisting with femoral exposure. A small cut is made in the drapes over the nonsterile femoral hydraulic lift adapter. The sterile bracket for the femoral hook is placed on the lift. The area around the base of the bracket where the drapes have been split is isolated in a sterile manner with a strip of the iodine adhesive barrier.