Capacitive coupling as an adjunctive treatment for avascular necrosis.

The purpose of this study was to determine the effectiveness of capacitive coupling, a noninvasive method for applying electrical stimulation to biologic tissues, when used as an adjunct to decompression and grafting in the treatment of avascular necrosis (AVN) of the femoral head. It also compared the results of core decompression and grafting with nonoperative management. Forty patients with Stages I-III AVN of the femoral head were treated with core decompression and grafting. All wore capacitive coupling units with electrodes placed over the femoral head continuously for six months. One-half of these units were active and one-half were inactive. Patients were followed for two to four years. Results were determined by preoperative and postoperative Harris ratings, quantitative roentgenographic measurements, and the number of hips that required total hip arthroplasty (THA). After all evaluations were completed, patients were divided into stimulated and nonstimulated groups. Patients in both groups were similar regarding gender, etiology, and roentgenographic stage of involvement. Results were also compared to 55 hips previously treated symptomatically, without surgery or electrical stimulation. There were no fractures, infections, or other significant complications in any of the hips operated on. Hips treated with decompression and grafting, both with and without electrical stimulation, were more satisfactory than hips treated symptomatically in regard to roentgenographic progression and the need for THA. There was, however, no indication that the addition of capacitive coupling gave better results than decompression and grafting alone.