[A 10-year follow-up study of indications for artificial cervical disc replacement]

Objective: To investigate the influence of the preoperative factors on the segmental range of motion (ROM) during long-term follow-up after artificial cervical disc replacement (ACDR), so as to further improve the selection of surgical indications for ACDR. Methods: Retrospective analysis was performed on 71 patients with cervical degenerative diseases who underwent single-segment Bryan ACDR in Beijing Jishuitan Hosptial from December 2003 to December 2008, and a 10-year clinical follow-up was conducted. Among the patients, 44 were males and 27 were females, with a mean age of (45±8) years at operation. The mean follow-up time was (129±14) months. Preoperative and follow-up imaging evaluation including measurement of the segmental range of motion (ROM) by cervical X-ray, and preoperative height of intervertebral space was measured by cervical lateral X-ray. According to CT and coronal reconstruction, the grade of paravertebral ossification (PO) was assessed. Clinical symptoms assessment including the Japanese Orthopaedic Association scoring (JOA), the Neck Disability Index (NDI) evaluation was performed preoperatively. Multivariate logistic regression analysis was used to analyze the influencing factors of the range of motion of the surgical segment during follow-up. The best cut-off value was calculated by receiver operating characteristic (ROC) curve. Results: The preoperative and follow-up ROM at the operated segment was 9.7°±4.5° and 8.7°±5.4°, respectively (P>0.05). Univariate analysis revealed that the postoperative segmental ROM was not significantly correlated with the factors including the surgical level, gender, age, and preoperative clinical diagnosis (1: Radiculopathy; 2: Myelopathy; 3: Mixed type), preoperative segmental ROM, preoperative JOA score and preoperative NDI score (all P>0.05), and was significantly correlated with imaging diagnosis (1: cervical disc herniation; 2: degenerative cervical stenosis), preoperative PO grade (both P<0.05). The multi-factor analysis showed that preoperative segmental ROM (OR=1.228, 95%CI:1.012-1.489, P<0.05) and PO grade (OR=0.190, 95%CI: 0.085-0.424, P<0.05) had significance in the overall test, but imaging diagnosis had no significance in the overall test (P>0.05). The optimal cutoff value of preoperative segmental ROM and PO grade was 9.185° and grade 2.5 assessed by ROC curve, and the area under the ROC curve was 0.86 and 0.72, respectively. Conclusions: ACDR surgery can achieve satisfactory long-term effects for patients with nerve root type, spinal cord type and mixed type cervical degenerative diseases, and effectively retain the overall ROM of the cervical spine and the ROM of replacement segments. Patients with good preoperative segmental ROM and lower PO levels have a greater chance of obtaining good segmental ROM in the long-term postoperatively.