The Clinical and Radiological Effect of Abnormal Axis after Cervical Arthroplasty

OBJECTIVE: The clinical outcomes according to the radiological results after cervical total disc replacement (TDR) are not well established. Here, the authors reviewed the clinical results according to the asymmetry in radiographs. METHODS: This retrospective analysis included patients after TDR (Mobi-C(R) disc) with at least 12 months follow up, and the clinical and radiological data were obtained preoperatively and postoperatively for 12 months. Clinical outcome measures numerical rating scale (NRS) score for neck pain, visual analog scale (VAS) for arm pain, and the Oswestry disability index (ODI) value. The asymmetries of TDRs were evaluated on the anterior-posterior (AP) and the lateral radiographs, and the radiographic adjacent segment degenerations were evaluated for 12 months. RESULTS: A total of 24 patients (one level cervical TDR; 10 male and 14 female; aged 41.50+/-8.35 years) were included in this study. The clinical results including NRS for neck pain, VAS for arm pain, and ODIs were similar between the normal and asymmetrized TDRs in AP and lateral radiographs. The radiographic adjacent segment degenerations were significantly increased in deviated TDRs (AP>10 mm asymmetry and lateral>10 mm asymmetry). CONCLUSION: Asymmetrical location of TDR is not related to the clinical outcomes, but related to the risk of radiographic adjacent disc segment degeneration.

Comparative Analysis of Cervical Disc Arthroplasty Using Two Types of Artificial Cervical Discs: Bryan(R) versus Mobi-C(R)

OBJECTIVE: Since the 1990s, due to postoperative loss of mobility and adjacent segmental disease after anterior cervical fusion, many different types of cervical artificial discs have been developed as alternative implants. The purposes of this study are investigation and comparison of radiographic and clinical outcomes between two different types of prostheses, Bryan(R) and Mobi-C(R). METHODS: We retrospectively evaluated 33 patients who were treated for cervical degenerative disc disease that resulted in radiculopathy and/or myelopathy between May 2004 and April 2009. Seventeen patients underwent Bryan(R) cervical disc arthroplasty and sixteen patients underwent Mobi-C(R) arthroplasty. The radiographic outcomes were assessed by measuring the cervical lordosis, segmental lordosis, range-of-motion (ROM) of the cervical spine (C2-7), functional segmental unit (FSU), prosthesis' shell and the upper adjacent segment. The clinical results were evaluated according to the Visual Analogue Scale (VAS) for axial pain and radiculopathy, Odom's criteria, and the modified Prolo's economic and functional outcome rating scale. RESULTS: The age of the study population ranged from 24 to 69 years with a mean age of 48 years vs. 46 years in the Bryan(R) and Mobi-C(R) groups, respectively. The mean duration of follow-up was 23.7 months in the Bryan(R) group and 11.3 months in the Mobi-C(R) group. The changes of overall cervical sagittal angle were not significantly different between two groups, but the increase of segmental sagittal angle (0.85degrees in Bryan(R), 8.04degrees in Mobi-C(R)), ROM of the FSU(-0.51degrees in Bryan(R), 2.47degrees in Mobi-C(R)) and ROM of the shell (1.77degrees in Bryan(R), 5.28degrees in Mobi-C(R)) were significantly higher in Mobi-C(R) group than in Bryan(R) group (p<0.05). The clinical results were not significantly different between two groups. CONCLUSION: The Mobi-C(R) prosthesis showed more favorable radiographic results than that of the Bryan(R) prosthesis, however, the clinical outcomes were similar in both groups. Large-scale and long-term follow-up studies are needed to confirm our results.

Comparative Analysis of Cervical Arthroplasty Using Mobi-C(R) and Anterior Cervical Discectomy and Husion Using the Solis(R) -Cage

OBJECTIVE: Although anterior cervical discectomy and fusion (ACDF) is the standard treatment for degenerative cervical disc disease, concerns regarding adjacent level degeneration and loss of motion have suggested that arthroplasty may be a better alternative. We have compared clinical and radiological results in patients with cervical disc herniations treated with arthroplasty and ACDF. METHODS: We evaluated 53 patients treated for cervical disc herniations with radiculopathy, 21 of whom underwent arthroplasty and 32 of whom underwent ACDF. Clinical results included the Visual Analogue Scale (VAS) score for upper extremity radiculopathy, neck disability index (NDI), duration of hospital stay and convalescence time. All patients were assessed radiologically by measuring cervical lordosis, segmental lordosis and segmental range-of-movement (ROM) of operated and adjacent disc levels. RESULTS: Mean hospital stay (5.62 vs. 6.26 days, p<0.05) and interval between surgery and return to work (1.10 vs. 2.92 weeks, p<0.05) were significantly shorter in the arthroplasty than in the fusion group. Mean NDI and extremity VAS score improved after 12 months in both groups. Although it was not significant, segmental ROM of adjacent levels was higher in the fusion group than in the arthroplasty group. And, segmental motion of operated levels in arthroplasty group maintained more than preoperative value at last follow up. CONCLUSION: Although clinical results were similar in the two groups, postoperative recovery was significantly shorter in the arthroplasty group. Although it was not significant, ROM of adjacent segments was less in the arthroplasty group. Motion of operated levels in arthroplasty group was preserved at last follow up.

Early Radiological Analysis of Cervical Arthroplasty with Bryan and Mobi-C Cervical Disc Prosthesis

OBJECTIVE: We investigated whether there are any different results in the overall sagittal alignment, neutral functional spine unit (FSU) angle and segmental FSU ROM (range of motion) angle from the patients undergone by cervical arthroplasty with two kinds of artificial cervical disc prostheses, Bryan and Mobi-C cervical disc. METHODS: Twenty eight patients underwent anterior cervical discectomy and implantation of artificial cervical disc prosthesis; Eighteen of them underwent operation with Bryan and the rest of them with Mobi-C cervical disc prosthesis. These patients consist of fourteen females and fourteen males with mean age 46.9 years old and 9.4 months mean follow-up period. There were 4 cases of C 4-5, 18 cases of C 5-6 and 6 cases of C 6-7 level. We measured overall sagittal alignment, neutral FSU angle and segmental FSU ROM angle using lateral radiographs preoperatively and postoperatively. The clinical outcome was evaluated by neck disability index(NDI). RESULT: The average angle of overall sagittal alignments was changed from -17.45degrees preoperatively to -14.21degrees postoperatively in Bryan cervical disc group. It decreased 3.24degrees in cervical lordosis. However, in Mobi-C cervical disc group, the average angle of overall sagittal alignments was changed from -10.33degrees preoperatively to -16.89degrees postoperatively. It increased 6.56degrees in cervical lordosis. The averages of neutral FSU angles were -1.14degrees preoperatively and -3.26degrees postoperatively in Bryan cervical disc group, and were -0.93degrees preoperatively and -9.7degrees postoperatively in Mobi-C cervical disc group. The averages of segmental FSU ROM angles were 11.18degrees preoperatively and 10.61degrees postoperatively in Bryan cervical disc group, and was 8.31degrees preoperatively and 13.6degrees postoperatively in Mobi-C cervical disc group. NDIs were 24.0 preoperatively and 5.9 postoperatively in Bryan cervical disc group, and 24.7 preoperatively and 8.7 postoperatively in Mobi-C cervical disc group. CONCLUSION: Postoperative cervical lordosis and segmental FSU ROM angle were increased in Mobi-C cervical disc group (p<0.05). To preserve segmental motion and avoid adjacent segment degeneration is to the focus in cervical arthroplasty. To preserve cervical lordosis after operation is physiologic than postoperative cervical kyphosis. It remains controversial whether cervical kyphosis influences clinical outcome after anterior cervical operation. The results of this study show that the technical and mechanical improvement of Bryan cervical disc prosthesis may be considered.

Early Clinical Experience with the Mobi-C Disc Prosthesis

PURPOSE: We have experienced 23 patients who had underwent cervical disc replacement with Mobi-C disc prosthesis and analyzed their radiological results to evaluate its efficacy. PATIENTS AND METHODS: This study was performed on 23 patients with degenerative cervical disc disease who underwent CDR with Mobi-C disc prosthesis from March 2006 to June 2006. RESULTS: The age of the study population ranged from 31 to 62 years with mean of 43 years, and 16 male and 7 female cases. Regarding axial pain, the average preoperative VAS score was 6.47 +/- 1.4, while at final follow-up it was 1.4 +/- 0.7 (p < 0.001). The preoperatively VAS score for radiculopathy was 6.7 +/- 0.7 compared with an average score of 0 +/- 0 at the final follow-up (p < 0.001). At postoperative 6th month, Odom's criteria were excellent, good, or fair for all 23 patients (100%). 7 patients (30.4%) were classified as excellent, 15 patients (65.2%) as good, and 1 patients (4.4%) as fair. Prolo economic and functional rating scale was average 8.9 +/- 0.7 at postoperative 6th month. ROM in C2-7, ROM of FSU, and ROM in upper adjacent level were well preserved after CDR. CONSLUSION: This report would be the first document about the CDR with Mobi-C disc prosthesis in the treatment of degenerative cervical disc disease. CDR with Mobi-C disc prosthesis provided a favorable clinical and radiological outcome in this study. However, Long-term follow-up studies are required to prove its efficacy and ability to prevent adjacent segment disease.