[Minimally invasive anterolateral surgical approach for total hip arthroplasty: seven-year results]

To evaluate the results of using the minimally invasive surgical-anterolateral approach (MIS-AL) for total hip arthroplasty at 7-year follow-up.

A total of 188 patients operated on between January 2005 and March 2006 were invited to come for check-up. Of them, 132 had a complete follow-up including examination at one and 7 years post-operatively. Forty-seven patients did not respond, four had died and five underwent revision arthroplasty. The evaluation was based on the Harris Hip Score, percent and school markings and radiographic analysis.

The patient was operated on in the lateral position. A short incision (5 to 8 cm) was made above the junction of the greater trochanter and the anterior superior iliac spine. The hip was accessed through a natural separation between the gluteus medius and the tensor fasciae latae. After joint capsule resection, femoral elevators were applied and femoral neck osteotomies were performed. The first was done on the leg in an orthograde position and the other as well as femoral head extraction were carried out on the leg with the knee flexed 90 degrees and hip external rotation of 90 degrees. Using reamers and rasps, the bone of both the acetabulum and the femur was prepared for implantation of a cementless or cemented prosthesis. A standard antibiotic prophylaxis and an antithrombotic therapy were administered. The patients were allowed to walk with 30 kg of weight on the operated leg from the 2nd post-operative day; walking with full weight-bearing without external support was allowed in patients with cemented implants at 6 weeks and in those with cementless implants at 3 months after surgery.

The group evaluated consisted of 69 men and 63 women, with an average age of 64.75 years at surgery. The average pre-operative Harris Hip Score was 46. At 7 years after surgery the average hip score increased to 89.125. Of the 132 patients, 128 were satisfied with the outcome; the average rating was 94% and the average school mark was 1.34. The outcome assessment by the same patients at 1 post-operative year included the average values of 90.55 for the hip score, and 97% and 1.17 for percent and school marking of satisfaction, respectively. Better outcomes were achieved in the patients with cementless hip replacement.

Our results, which are in agreement with the published data, show that the results of mid-term assessment of MIS-AL procedures are not superior to those achieved by the conventional approach. Even well documented prospective randomised studies comparing minimally invasive and standard techniques have failed to report any advantages of one method over the other in any of the characteristics studied, which included haemoglobin levels, X-ray findings, patient mobilisation, length of hospital stay, pain intensity, and scoring system results (Harris Hip Score, McMaster University Osteoarthritis Index or Short Form-12). Many studies have focused on looking for characteristics of better early results after minimally invasive techniques but, so far, the findings have been comparable for both methods or are of no great importance.

The minimally invasive technique for total hip replacement is no revolution in this field but is an alternative for a selected category of patients whose condition in the early post-operative period would benefit from less-invasive surgery. The MIS-AL approach does not replace the conventional total hip arthroplasty. It may play a role early after surgery but has no superior outcomes in the long-term post-operative period. In well indicated cases it is the method of choice with good mid-term results.