Treatment of Osteonecrosis of the Femoral Head by Core Decompression , Bone Grafting , and Electrical Stimulation

Core decompression is one of the more popular procedures for the treatment of early stages of avascular necrosis (AVN) of the femoral head. However, the controversy regarding its safety and effectiveness continues. In an attempt to clarify the situation, we are reporting on a large series of cases performed by a single surgeon with long-term follow-up. This is a prospective study in which results have been evaluated using objective clinical parameters and quantitative radiographic measurements. The classical core decompression, modified by using three decompression tracks and placing a loosely fitted cancellous graft into the larger central core, was performed on 406 hips with AVN between 1981 and 1995. Of these hips, 94 were also treated with electrical stimulation; 74 with direct current and 20 with capacitive coupling. Hips ranged from Stage I (pre-radiographic) to Stage IV (femoral head flattening without acetabular involvement). Results were determined by change in Harris hip score (HHS), extent of radiographic progression, and the need for total hip replacement (THR). Five complications occurred after the 406 procedures: 2 fractures, both resulting from falls; 1 non-fatal pulmonary embolism; 1 femoral thrombophlebitis; and 1 pneumonia. There was a minimum 2to 14-year follow-up on 297 of the hips. Of these, 107 (36%) required THR at a mean of 29 months. THR was performed in 26% of hips in Stage I; 34% in Stage II; 31% in Stage III (crescent sign); and 48% in Stage IV. Results were correlated with the size of the necrotic lesion. In Stages I and II THR was performed in 22%, 39%, and 40% of small (A), medium (B), and large (C) lesions, respectively. In hips not requiring THR, 39% were radiographically stable and the mean HHS improved by 10 points. No significant difference was noted in relation to etiology. No differences were noted between hips treated with or without supplemental electrical stimulation. Core decompression with bone grafting, if carefully performed, has a very low complication rate. In cases treated before femoral head collapse, the outcome is significantly better than with symptomatic or conservative treatment. Results are correlated with both the stage of AVN and the size of the necrotic lesion.