Influence of the artificial disc size on cervical artificial disc replacement / 中国组织工程研究

ABSTRACT

BACKGROUND: The size of artificial disc is not exactly identical to cervical vertebral endplate. However, the effect of implant size on cervical disc replacement has not yet been clearly identified. OBJECTIVE: To evaluate the effect of Bryan disc size on cervical artificial disc replacement. METHODS: Totally 71 patients with cervical degenerative disease underwent single-level Bryan disc replacement from December 2003 to December 2007 were enrolled. The average age was (45.90±8.12) years old, and all patients were followed up for more than 10 years. The artificial disc size was measured using lateral X-ray films, and expressed as (Bryan artificial disc's footprint sagittal diameter×2) / (upper endplate sagittal diameter + lower endplate's sagittal diameter)×100%. X-ray films were photographed to measure motion range of the treated segment before surgery, 3 months after surgery, and during final follow-up. Clinical outcomes, including Japanese Orthopaedic Association score, Neck Disability Index and Odom's scores, were evaluated before and after operation. Observational indexes of different disc sizes (≥95% and <95% groups) were compared and analyzed. RESULTS AND CONCLUSION: (1) There were 49 patients in the ≥95% group and 22 patients in the <95% group. (2) At 3-month follow-up, range of motion was significantly smaller in the <95% group than in the ≥95% group (P < 0.01). At the final follow-up, range of motion was significantly smaller in the <95% group than in the ≥95% group (P < 0.05). (3) At final follow-up, improvement rate of Japanese Orthopaedic Association score was (70.65±32.58)% in the <95% group and (68.83±38.85)% in the ≥95% group, and no significant difference was detected between the two groups (P > 0.05). (4) At final follow-up, Neck Disability Index decreased by (10.82±7.50)% in the <95% group, and (12.61±8.51)% in the ≥95% group, and no significant difference was detected between the two groups (P > 0.05). (5) At final follow-up, Odem's score results showed excellent in 10 cases (45%), good in 9 cases (41%) and average in 3 cases (14%) in the <95% group; and excellent in 26 cases (53%), good in 20 cases (41%) and average in 3 cases (6%) in the ≥95% group, and no significant difference was detected between the two groups (P > 0.05). (6) Results suggest that different sizes of artificial disc replacement have obtained good functional recovery, but small artificial disc may impact the range of motion. We should try to avoid placing the artificial disc smaller than 95%.