Background: Cervical disc arthroplasty is a new technique for treating degenerative cervical disease. Its goal is to avoid the degeneration of adjacent levels by preserving motion at the treated level. The aims of this study were to evaluate the radiologic outcomes of Bryan cervical disc replacement and the degenerative status of adjacent segments.
Methods: Twenty-two patients at a single center underwent discectomy and implantation of Bryan cervical disc. The mean follow-up period was 60 months (57 - 69 months). Twenty patients underwent single-level arthroplasty and two underwent arthroplasty at two levels. The levels of surgery included C3/4 (3 levels), C4/5 (2 levels), C5/6 (18 levels) and C6/7 (1 level). Radiographic evaluation included dynamic X-ray examination and magnetic resonance imaging (MRI) at baseline and at final follow-up.
Results: On X-ray examination, the range of motion (ROM) at the operated level was 7.2° (2.5° - 13.0°) at baseline and 7.8° (1.0° - 15.0°) at final follow-up (P > 0.05). Heterotopic ossification around the prosthesis was observed in eight levels, and two levels showed loss of motion (ROM < 2°). MRI showed worsening by a grade at the upper level in 2/22 patients, and worsening by a grade at the lower level in 3/22, according to Miyazaki's classification. No further impingement of the ligamentum flavum into the spinal canal was observed at adjacent levels, though the disc bulge was slightly increased at both the adjacent upper and lower levels at final follow-up.
Conclusions: Arthroplasty using Bryan cervical disc prosthesis resulted in favorable radiologic outcomes in this study. Disc degeneration at adjacent levels may be postponed by this technique.