Objective: To explore the midterm efficacy of superelastic cage implantation for the treatment of osteonecrosis of femoral head (ONFH).
Methods: From July 1996 to January 1998, 54 patients (75 hips) of ONFH were treated with superelastic cage and followed up. Among 54 patients, 5 patients were lost to follow up and 3 patients were dead of myocardial infarction, renal failure and gastric cancer, respectively. Forty-six patients completed follow up including 32 males and 14 females, aged from 21 to 61 with an average of 39 years old. Twenty-nine hips were classified as Ficat Stage II and 36 as Stage II. Harris score was 58.20 +/- 13.82. All patients were evaluated both clinically and radiographically.
Results: Postoperatively, forty-six patients (65 hips) were followed up for 86 to 125 months with an average of 8 years and 8 months. Harris score was 80.78 +/- 18.77. Twenty-nine hips were rated excellent, 21 good, 2 fair and 13 poor. A total of 76.9% of overall clinical results were rated as good or excellent. Eight hips (12.3%) with the cage broken were turned to total hip replacement. Radiographic evaluation: 16 hips (24.6%) rated as grade I , 34 (52.3%) grade II and 15 (23.1%) grade III.
Conclusion: Superelastic cage implantation is one of alternative treatments for ONFH at early and midterm stages. However, long-term follow-up is needed to know whether it is able to cure ONFH and whether cages will be broken as time passes by.