【Abstract】 Objective To investigate the early effectiveness of the Discover cervical artificial disc replacement in treating cervical spondylosis. Methods Qualified for the selective standard, 24 patients with cervical spondylosis were treated between March 2010 and March 2011. Of 24 patients, 13 patients underwent anterior cervical decompression and fusion (ACDF) (ACDF group, between March 2010 and September 2010) and 11 patients underwent Discover cervical artificial disc replacement (CADR group, between September 2010 and March 2011). There was no significant difference in gender, age, disease duration, lesions typing, and affected segments between 2 groups (P gt; 0.05). The operative time, blood loss, and complications were recorded. Japanese Orthopaedic Association (JOA) scores, Neck Disability Index (NDI) scores, and Odom’s scores were used to evaluate the postoperative effectiveness. In CADR group, the cervical range of motion (ROM) in all directions, and prosthesis eccentricity were measured before and after operation. Results Symptoms disappeared and no complication occurred after operation in the patients of 2 groups. The patients were followed up 12 to 18 months (mean, 15.3 months) in ACDF group and 6 to 12 months (mean, 9.6 months) in CADR group. The NDI scores in CADR group were significantly higher than those in ACDF group at 1, 3, and 6 months (P lt; 0.05), but no significant difference was observed in JOA score improvement rate between 2 groups (P gt; 0.05). According to Odom’s score at last follow-up, the results were excellent in 6 cases, good in 4 cases, and fair in 3 cases with an excellent and good rate of 76.92% in ACDF group, and were excellent in 9 cases, good in 1 case, and poor in 1 case with an excellent and good rate of 90.91% in CADR group, showing no significant difference (χ2=3.000, P=0.223). The patients in CADR group had significant limit of cervical joint ROM in flexion and extension and right bending at 1 month (P lt; 0.05), but cervical joint ROM restored after 3 months. The ROMs of left bending at 3 months and 6 months were bigger than preoperative value (P lt; 0.05). Meanwhile, ROM in left bending were bigger than that in right bending in replaced segment and upper segment (P lt; 0.05), and the ROM difference between left bending and right bending in upper segment was 2 times higher than that in the replaced segment; a marked linear correlation (P lt; 0.05) existed between the ROM difference and prosthesis eccentricity, and prosthesis bias had bigger ROM in lateral bending. Conclusion Discover cervical artificial disc replacement for treatment of cervical spondylosis can provide a good effectiveness and cervical postoperative movement function. As a new prosthesis, it has some merits such as simple operative steps and less complications.
ObjectiveTo evaluate the influence of the shell angle of cervical artificial disc on long-term effectiveness of cervical artificial disc replacement (CADR).MethodsThe clinical data of 71 patients who were treated with single-level CADR with Bryan prosthesis between December 2003 and December 2007 and followed up more than 10 years, were retrospectively analyzed. There were 44 males and 27 females with an age of 26-69 years (mean, 45.9 years). According to the shell angle of the cervical artificial disc which was measured on the postoperative lateral X-ray film, the patients were divided into kyphotic group (shell angle was negative) and non-kyphotic group. The following evaluation indexes before operation and at last follow-up were compared between 2 groups. Radiographic indexes included the range of motion (ROM) of cervical spine, the ROM of operated level, Cobb angle of operated level (the negative value indicated that the segmental kyphosis occurred at operated level), paravertebral ossification (PO) grades (grades 3 and 4 were high grade PO). Clinical indexes included Japanese Orthopaedic Association (JOA) score, neck disability index (NDI), and overall effectiveness evaluation (Odom criteria).ResultsThere were 24 patients in kyphotic group and 47 patients in non-kyphotic group. There was no significant difference in baseline data including gender, age, and operated level between 2 groups (P>0.05). All the patients in 2 groups were followed up 121-165 months (mean, 128 months). There was no significant difference in preoperative ROM of cervical spine and ROM of operated level between 2 groups (P>0.05); but the preoperative Cobb angle of operated level in kyphosis group was significantly lower than that in non-kyphotic group (t=2.636, P=0.013). There was no significant difference in ROM of cervical spine at last follow-up between 2 groups (t=1.393, P=0.168), however, the ROM and the Cobb angle of operated level in kyphotic group were significantly lower than those in non-kyphotic group (P<0.05). According to the Cobb angle of operated level at last follow-up, there were 9 patients (37.5%) with segmental kyphosis in kyphotic group and 7 patients (14.9%) in non-kyphotic group, showing significant difference (χ2=4.651, P=0.031). There was a significant difference in PO grades between 2 groups (Z=2.894, P=0.004) at last follow-up. In kyphotic group, there were 10 patients (41.7%) with low grade PO and 14 patients (58.3%) with high grade PO; and in non-kyphosis group, there were 36 patients (76.6%) with low grade PO and 11 patients (23.4%) with high grade PO. There was no significant difference in JOA scores and NDI before operation and at last follow-up, and the JOA improvement rate, NDI decline, and Odom criteria score at last follow-up between 2 groups (P>0.05).ConclusionThe shell angle of cervical artificial disc may lead to a decrease in the postoperative segmental ROM, and an increased occurrence of segmental kyphosis and high incidence of PO.