General Session: Cervical Motion Preservation

Presented by: J. Zigler - View Audio/Video Presentation (Members Only)

Author(s):

J. Zigler(1), Z.J. Liu(2), C.C. Niu(3), C.-K. Park(4), C.K. Park(5)

(1) Texas Back Institute, Plano, TX, United States
(2) Peking University Third Hospital, Beijing, China
(3) Chang Gung Memorial Hospital, Taoyuan Hsien, Taiwan, Republic of China
(4) Kangnam St. Mary’s Hospital, Seoul, Korea, Republic of
(5) Leon Wiltse Memorial Hospital, Suwon-si, Korea, Republic of

Abstract

Introduction: In multiple FDA-regulated trials in the United States, cervical total disc replacement (TDR) produced results similar or superior to anterior cervical discectomy and fusion (ACDF). The purpose of this study was to compare cervical TDR to ACDF in a prospective, randomized, multinational study in Asia.

Methods: The study involved 9 sites in 5 countries (Korea, Taiwan, Hong Kong, China, and Singapore) and was patterned after FDA-regulated TDR trials in the US, but also accommodated multinational participation. After signing consent, patients were randomized to TDR or ACDF using an interbody cage with synthetic graft and no anterior plate. The original design was to enroll 300 patients randomized in a 2:1 ratio of TDR:ACDF with 7 year follow-up. Due to slow enrollment, 120 patients were included (81 TDR, 39 ACDF) and outcomes reported for 3-year follow-up (>77%; follow-up rates after that were < 50%). A composite success criteria was defined to be >20% NDI score improvement, neurological status improved/maintained, no device removals, revisions, re-operations, or supplemental fixation at the index level, and no adverse events related to the implant or procedure. Radiographic assessment was conducted by an independent core lab.

Results: There were no significant differences between the groups based on demographic factors or level(s) operated. At 36 month follow-up TDR success rate of 83.1% was statistically non-inferior to ACDF 79.3%. Mean NDI scores improved significantly in both groups and remained so throughout 3-year follow-up (Figure 1). Table 1 provides results on the other outcome assessments. The only significant differences were the satisfaction score and the mean percentage improvement in NDI scores being significantly greater for ACDF at 36 months. Mean range of motion of the TDR level(s) was 8.5o at 36 months and there were no cases of bridging bone, device subsidence, or device migration. There were 2 re-operations, both at an adjacent segment, after TDR (2.5%): one emergent ACDF 3 days post-operative for weakness and another patient underwent posterior decompression 34 months post-operative. With ACDF, there was one re-operation (2.6%), a posterior laminoplasty at the index and both adjacent levels 35 months post-operative.

Discussion: Despite challenges with enrollment and long-term follow-up, this study supports that multinational studies are feasible. ACDF results appeared to be somewhat better than in the US trials. The overall study results were similar to the US studies in that TDR was found to be a viable alternative to fusion in appropriately selected patients.

Figure 1

Table 1