The correlation between the occipitocervical angle of Takami and the curvature of lower cervical in patients after occipitocervical fusion

English Keywords:Basilar invagination  Takami′s occipitocervical angle  C2-C7 Cobb angle  Subaxial cervical alignment  Occiptocervical fusion

English Abstract:

  【Abstract】 Objectives: By analyzing the correlation between Takami′s occipitocervical angle(TOCA) and lower cervical curvature after occipitocervical fusion and comparing with the normal group, the optimal TOCA angle of occipitocervical fixed is determined. Methods: Lateral cervical radiographs of 50 adults(control group) without cervical deformity, cervical degeneration, cervical trauma and surgery were collected, and TOCA and C2-C7 Cobb angle were measured respectively to statistically analyzed. Retrospective analysis of 17 patients with basilar invagination(BI group) who underwent posterior occipitocervical fusion surgery in our hospital from January 2010 to December 2016 and were followed up successfully, TOCA and C2-C7 Cobb angles were measured preoperative, immediate postoperative and at final follow-up on lateral cervical radiographs. Based on the TOCA of immediate postoperative and refer to the normal TOCA, patients were divided into group A, B and C(group A, TOCA<83°; group B, TOCA was 83°-89°; group C, TOCA>89°). The TOCA and C2-C7 Cobb angle in the preoperative and immediate postoperative and final follow-up in each group A, B and C, as well as in the control group, were collected for t-test and Pearson correlation analysis. Results: The mean value of TOCA in control was 86.2°±2.7°, and the C2-C7 Cobb angle was 17.4°±3.9°. In control and in preoperative and final follow-up of BI group, the TOCA and C2-C7 Cobb angle had positively correlated(P<0.05). In group A, the C2-C7 Cobb angle between the preoperative and final follow-up had no statistical difference(P>0.05), however, for C2-C7 Cobb angle in group A, the mean value was reduced from 15.4°±3.5° before surgery to 11.7°±2.6° at final follow-up. In group B, the C2-C7 Cobb angle between the pre-operative(20.0°±4.5°) and final follow-up(21.8°±4.7°) had no statistical difference(P>0.05), and in group C, the C2-C7 Cobb angle between preoperative(21.6°±2.3°) and final follow-up(30.0°±4.3°) had a statistical difference(P<0.05). Conclusions: During the craniocervical fusion in patients with BI, the TOCA should be fixed in the range of 83°-89°, it can reduce the impact on the curvature of the lower cervical spine.