Abstract
Introduction
Metal on metal hip resurfacing (MoM HR) is attractive for young active patients. Patients with osteonecrosis of the femoral head (ONFH) are relatively young. HR can be an option of treatment, however, long-term stability of the femoral component is a concern because of the necrotic lesion in the femoral head. There is also a concern of ARMD for MoM implants. The purpose of this study is review a 10 year outcome of a consecutive patients with ONFH who underwent MoM HR.
Methods
The subjects of this study were 30 hips of 26 patients with ONFH who underwent HR between 1998 and 2004. There were 21 hips of 18 males and 9 hips of 8 females. The average age at operation was 40 years (range, 20–63 years). 19 ONFHs were induced by steroid and 11 ONFHs were alcohol related. According to the Japanese Investigation Committee classification, there were 8 hips with Type C1 and 22 hips with Type C2. There were 16 hips in stage 3A, 7 hips in Stage 3B, and 7 hips in Stage 4. Operation was performed through a posterior approach. A fragile necrotic bone was curettage thoroughly and the defect was filled with cement.
Results
The average Harris hip score improved from 61 preoperatively to 97 at the final follow-up. The average radiographic inclination of the cup was 43 degrees (34–54 degrees) and the average anteversion was 12 degrees (4– 22 degrees). There was no dislocation. One hip had a late hematogenous infection at 9 years after surgery. Two hips of two patients with alcoholic ONFH had a mechanical loosening of the femoral component at 10 year and 13 years after surgery. The survivorship with revision for aseptic loosening as the endpoint was 96% at 10 years. There was no ARMD by ultrasound echo screening. There was no stress shielding of the femur at the final radiographic examination.
Conclusion
Our over 10 year results of MoM HR for ONFH showed a high Harris hip score without dislocation. Although this series included the initial learning curve of the HR procedure, the survivorship with revision for aseptic loosening as the endpoint at 10 years was high. There was no ARMD by ultrasound echogram. MoM HR is a good option of treatment for ONFH.
