Effect of cervical disc arthroplasty on adjacent segment degeneration

English Keywords:Cervical disc replacement  Adjacent segment degeneration  Adjacent segment disease

English Abstract:

  【Abstract】 Objective：To investigate the adjacent segment degeneration after single level cervical disc arthroplasty.Method：Patients received single level cervical arthroplasty in our institute were reviewed retrospectively.Up to October 2010，a total of 80 patients gained at least 20 months′ follow-up.There were 8 cases of C3/4，15 C4/5，49 C5/6 and 8 C6/7.41 patents received Bryan Disc cervical prosthesis and 39 received ProDisc-C prosthesis.Adjacent segment degeneration was evaluated on X-ray and magnetic resonance imaging（MRI） at preoperative and final follow-up.X-ray based adjacent segment degeneration included the presence of any of the following parameters：narrowing of disc space＞10%，new anterior or/and extended osteophyte formation，calcification of anterior longitudinal ligament.Cervical disc degeneration was evaluated according to Miyazaki′s grading system based on T2-weighted MRI.Result：The mean follow-up period was 38 months（range，20-64 months）.Of 160 segments at final follow-up，8 distal adjacent segments were excluded due to unavailability of X-ray，adjacent segment degeneration was observed in 21 of 152 segments（13.8%） based on X-ray findings.The rate of adjacent segment degeneration for Bryan disc group was 10.0%，which was lower than that of ProDisc-C group（18.1%）.47 patients gained MRI follow-up，and adjacent segment degeneration was observed in 14 of 94 segments（14.9%）.The rate of MRI-based adjacent segment degeneration for Bryan Disc group was 12.5%，which was also lower than that of ProDisc-C group（22.7%）.No adjacent segment disease developed at final follow-up.Conclusion：Less than 15% cases develop adjacent segment degeneration 38 months after cervical disc arthroplasty，and the effect may vary between different prosthesis.