[Effectiveness evaluation of Prodisc-C prosthesis for more than 10 years follow-up after total cervical disc replacement].

OBJECTIVE: To evaluate long-term radiographic and clinical effectiveness of total cervical disc replacement (TDR) with Prodisc-C prosthesis at a minimum of 10 years follow-up.
METHODS: The clinical data of 118 patients with cervical disc degeneration disease (CDDD) treated with TDR by using Prodisc-C prosthesis between December 2005 and April 2008 were retrospectively analyzed. There were 66 males and 52 females, with the age of 25-62 years (mean, 46.8 years). There were 38 cases of cervical spondylotic radiculopathy, 28 cases of cervical spondylotic myelopathy, and 52 cases of mixed cervical spondylotic myelopathy. The operative segments were C 3-7, including 90 cases of single segment, 20 cases of continuous double segments, and 8 cases of continuous three segments. A total of 154 Prodisc-C prostheses were used during the operation. The clinical effectiveness was evaluated by pain visual analogue scale (VAS) score, neck disability index (NDI), Japanese Orthopaedic Association (JOA) score, and Odom grade before and after operation. Imaging evaluation indicators included range of motion (ROM), sagittal lordosis angle, intervertebral disc height (IDH), and prosthesis displacement, subsidence, loosening, locking, and heterotopic ossification (HO), adjacent segment degeneration (ASD), and other complications. Patients were grouped according to whether HO or ASD occurred or not, the ROM of surgical segment was compared.
RESULTS: All patients were followed up 121-150 months (mean, 135.8 months). No revision operation was performed during the follow-up period. The VAS, NDI, JOA scores and Odom grades were significantly improved at 1 week after operation and last follow-up when compared with preoperative ones ( P<0.05); VAS and NDI scores were further improved at last follow-up than those at 1 week after operation ( P<0.05); there was no significant difference in JOA scores and improvement rates between at 1 week after operation and at last follow-up ( P>0.05). The ROM of the whole cervical spine and the operative segment decreased at 1 week and 10 years after operation when compared with preoperative ones ( P<0.05), but there was no significant difference in the other time points ( P>0.05); there was no significant difference in the ROM between the upper adjacent segment (UAS) and the lower adjacent segment (LAS) at each time point after operation ( P>0.05). There was no significant difference in sagittal lordosis angle of cervical spine before and after operation ( P>0.05); the sagittal lordosis angle of operative segment increased significantly at 1 week, 6 months, 1 year, and 2 years after operation ( P<0.05). The IDH of operative segment was significantly improved at each time point after operation ( P<0.05), but there was no significant difference in IDH between UAS and LAS at each time point after operation ( P>0.05). No prosthesis displacement, subsidence, or loosening occurred at each time point after operation. There was no significant difference of the prosthetic displacement and subsidence distance between all time points after 6 months after operation ( P>0.05). At last follow-up, the incidence of prosthetic locking/fusion was 10.4%, showing no significant difference when compared with 6 months (1.9%) ( P<0.05). The incidence of upper ASD and lower ASD was 1.3% and 2.6% respectively at 1 week after operation. The incidence of upper ASD and lower ASD increased gradually with time prolonging, and there were significant differences between different time points ( P<0.05). The ROM of operative segment in ASD group was lower than that in non-ASD group at each time point after operation, but there was no significant difference ( P>0.05). HO appeared in 58.4% of the segments at 6 months after operation, and the incidence of HO increased significantly with time, which was significantly different from that at 6 months after operation ( P<0.05). The ROM of operative segments in HO group was significantly lower than that in non-HO group at 6 months, 2 years, 5 years, and 10 years after operation ( P<0.05).
CONCLUSION: TDR has little effect on adjacent segments, although there are some imaging complications, it has no significant effect on the improvement of overall clinical effectiveness. Prodisc-C prosthesis can provide long-term, safe, and definite clinical effectiveness in the treatment of CDDD.