Antero-Lateral Subgluteal Mini-Incision Navigated Hip Replacement

Introduction: Purpose of mini-invasive hip arthroplasty, is least damage to skin and muscles. Unlike Roettinger modification to Watson-Jones, our approach requires no special table or instruments. Besides, direction of skin incision is perpendicular to interval between glutei and tensor muscles, thus called a Crisscross Approach. Incision is at direction of retractors causing less skin damage; and parallel to femur allowing expansion. No tendon or muscles are severed achieving a true inter-muscular non invasive approach. Unlike anterior approach, femoral circumflex vessels and lateral femoral cutaneous nerve are spared. Material and Methods: 240 prospective patients underwent mini-invasive crisscross technique since December 2006. A standard non-cemented hip was implanted. Previously disrupted hip muscles patients were excluded. In the operating room, patients were secured in a lateral decubitus position with the pelvis flexed at 20°–30° to allow operated leg to extend beyond the table to be placed in a standard plastic bag. The anterior superior iliac spine (ASIS), the greater trochanter (GT) and its tubercle are identified and marked. A line is drawn between ASIS and GT tubercle representing the interval between the glutei and the tensor fascia lata muscles. Another line representing the skin incision is drawn perpendicular. It may be curved a little toward the femur starting two inches inferior and posterior to ipsilateral ASIS extending distally for 3 inches or more for obese or muscular patients. The Crisscross Approach starts with a skin incision being made as above and through the subcutaneous fat identifying the inter-muscular interval between the glutei and the tensor fascia lata. Sharp dissection is made in the connecting fascia only and blunt dissection is needed to separate the two muscles. A branch of the superior gluteal nerve proximally crossing from the glutei to the tensor fascia lata may be encountered but it should not be disturbed as long as blunt dissection is maintained. Curved retractors are placed one above and the other below the femoral neck exposing the anterior capsule. Incision is made in the capsule and the retractors are re-placed to better expose the femoral neck. The appropriate level of neck is osteotomized and the head is extracted as routine. Acetabulum is further exposed by placing the curved retractors at about mid anterior and mid posterior. The final appropriate cup size and orientation is implanted routinely. Before exposing the femoral canal the deep fascia at the junction of the glutei and the vastus lateralis should be incised (about 2–3 inches). This will tremendously help femoral canal exposure. Then the surgeon is positioned anterior, the patient is made fully paralyzed and the table is tilted 20°–30° posteriorly (away from the surgeon). Hip extended 20°–30°, externally rotated to 80°–90° and adducted with a retractor underneath femoral neck and a curved one on greater trochanter to protect the glutei. Leg is allowed to drop in a bag (posteriorly). Canal finder is helpful to avoid going through the cortex Broaching or reaming and final implant insertion as routine. Posterior capsule need not be disturbed; however, the superior and inferior capsule should be detached from the neck to allow better exposure of the femoral canal. Closure starts with one or two stitches in the remainder of the capsule. Then suture deep fascia at the junction of glutei and vastus lateralis with absorbable suture. Finally, subcutaneous fat and skin are closed as routine. Results: There was no major neurovascular damage or complications related to this exposure. Follow up to a maximum of 75 months revealed no deep infection and no dislocation or fracture. We undersized three stems at the beginning but that did not require re-operation. Surgery time averaged 15 minutes longer but that was reduced as we gained experience. Cup position was navigated and postoperative CT scan confirmed satisfactory cup and stem position. One case that had an undersized prosthesis settling to about half an inch short which required a 3/8 inch insole for the patient to wear. Rehab goals were met after 4–6 sessions in all patients. Patients were allowed to go home on two crutches in 2–3 days. Full weight bearing was allowed in 2–4 weeks. No limping noted at 3 months follow up. Discussion: Crisscross approach differs by transecting no tendon or muscles, requiring no special table or instruments with incision parallel to femur facilitating expansion and reducing skin damage resulting in true non-invasive approach.