The influence of different posterior fusion procedures on adjacent-segment degeneration in patients with atlantoaxial dislocation

English Keywords:Atlantoaxial dislocation  Atlantoaxial fusion  Occipitocervical fusion  Adjacent-segment degenera?鄄tion

English Abstract:

  【Abstract】 Objectives: To investigate the influence of two different posterior fusion procedures on adjacent-segment degeneration in patients with atlantoaxial dislocation. Methods: From June 2000 to June 2010, a total of 43 patients with atlantoaxial dislocation undergoing fusion were reviewed retrospectively. According to the fusion methods, all patients were divided into atlantoaxial fusion group(23 cases) and occipitocervial fusion group(20 cases). Sub-axial subluxation(SAS) and range of motion(ROM) of C2-3 was measured during final follow-up. Standard ratio of height of cervical intervertebral space to height of inferior vertebral body(S value) and sagittal angles in each group were measured at preoperation and during final follow-up. The results were compared statistically. Results: The preoperative JOA score, S value and C2-7 sagittal angles of the two groups had no significant difference(P＞0.05). The mean follow-up time of the two groups was 7.40±1.51 and 6.97±1.32 years respectively, which showed no significant difference between two groups(P＞0.05). The incidence of SAS was 8.7% for atlantoaxial fusion group and 35% for occipitocervical fusion group, which showed significant difference between two groups(P<0.05). The S value of C2-3 was smaller at postoperative final follow-up than preoperation in both groups, but the value in occipitocervical fusion group decreased significantly than in atlantoaxial fusion group(P<0.05). The ROM of C2-3 in the atlantoaxial fusion group and occipitocervical fusion group was 3.78°±3.01° and 1.45°±1.72° at final follow-up respectively, which showed significant difference between two groups(P<0.05). C2-7 sagittal angles in atlantoaxial fusion group decreased from 15.16°±5.66° to 12.40°±9.34°(P<0.05), C2-7 sagittal angles in occipitocervical fusion group decreased from 15.54°±6.54° to -0.22°±12.45°(P<0.05), which showed significant difference between two groups(P<0.05). Conclusions: Compared with occipitocervical fusion, atlantoaxial fusion appears less incidence of degeneration of lower adjacent segments. It is strongly recommended that the occipitocervical fusion should be determined carefully.