Abstract
Anterior supine intermuscular total hip arthroplasty (ASI-THA) has emerged as a muscle sparing, less-invasive procedure. The anterior interval is both intermuscular and internervous, providing the advantages of little or no muscle dissection, and a true minimally invasive alternative. It is versatile, with reported use expanding beyond the primary realm to revision and resurfacing THA as well as treatment of acute fracture in elderly patients, who due to their diminished regenerative capacity may benefit more from the muscle-sparing nature of the anterior approach. The ASI approach involves the use of a standard radiolucent operative table with the table extender at the foot of the bed and the patient supine. Fluoroscopy is used in every case. A table-mounted femur elevator is utilised to facilitate femoral preparation.
A retrospective review identified 824 patients undergoing 934 consecutive primary ASI-THA performed between January 2007 and December 2010. Age averaged 63.2 years (27–92), BMI averaged 29.9 kg/m2 (16.9–59.2). Gender was 49% males and 51% females. Stem types were short in 82% and standard length in 18%. Follow-up averaged 23.1 months (1–73). Operative time averaged 63.1 minutes (29–143). Blood loss averaged 145.3 minutes (25–1000). Transfusion rate was 3.3% (30 of 914) in single procedures and 80% (8 of 10) in simultaneous bilateral procedures. Length of stay averaged 1.7 days (1–12). Intraoperatively there were 3 calcar cracks and 1 canal perforation treated with cerclage cables. There were 6 wound complications requiring debridement. Four hips had significant lateral femoral cutaneous nerve parathesias not resolved at 12 months. One femoral nerve palsy occurred. At up to 73 months follow-up there have been 21 revisions (2.2%): 2 infection, 1 malpositioned cup corrected same day, 5 metal complications, 2 dislocations, 2 loose cups with one requiring concomitant stem revision secondary to inability to disarticulate trunnion, 1 femoral subsidence and 8 periprosthetic femoral fractures.
Primary THA can be safely performed utilising this muscle-sparing approach. We did not see an alarmingly high rate of complications. Instead, rapid recovery and quick return to function were observed. ASI-THA appears to be safe. The recovery advantage utilising this surgical approach is irrefutable. There are complications, most notably periprosthetic femur fracture. The rate, however, appears to be low and decreases with increased experience. There is no need for a special operative or fracture table to perform the procedure. Whether the complication rate is higher with the use of these expensive devices is unknown, but our results demonstrate a 2.2% reoperation rate with the use of the ASI approach performed on a standard OR table. Continued refinement of the technical aspects of ASI-THA may lessen the complication rate.
