Results of disc prosthesis after a minimum follow-up period of 2 years

This study analyzed retrospectively 46 patients undergoing artificial disc replacement.

To assess the clinical and radiographic outcomes of patients who had Charitè SB III disc prosthesis.

Results of disc prosthesis have been reported only at very short-term follow-up periods; preoperative diagnosis and criteria used to evaluate the clinical outcomes were not reported.

Forty-six patients who had had a disc prosthesis were evaluated clinically and radiographically at least 2 years after surgery. Preoperative diagnosis included disc degeneration in 22 patients and failed disc excision in 24 patients. Disc prosthesis was implanted at a single vertebral level in 36 patients and at two levels in 10 patients. Follow-up evaluation was performed after an average of 3.2 years (range, 2-5 years).

Sixty-three percent of patients reported satisfactory results. The success rate was 69% in patients who underwent isolated disc replacement and 77% in those with no previous back surgeries. Seven patients who had unsatisfactory results underwent posterolateral fusion without removing the artificial disc. Two patients underwent removal of the prosthesis. No failure of the implants or loosenings or wear of the polyethylene core were found. Vertebral motion averaged 9 degrees at the operated levels and 16 degrees at the adjacent levels.

A wrong surgical indication, rather than failure of the prosthesis, appears to be the main cause of unsatisfactory results of disc replacement at medium-term evaluations. Prospective and longer term studies are needed to establish whether disc prosthesis may offer advantages compared with spinal fusion.