Restore cervical sagittal alignment by cervical disc arthroplasty and systematic total bilateral uncuscectomy in severe spondylosis: A prospective study

INTRODUCTION: Severe spondylosis is common and represents contraindication to achieve cervical disc arthroplasty (CDA). RESEARCH QUESTION: Is it possible to restore cervical sagittal alignment using an adequate prosthetic model and performing systematic bilateral total uncuscectomy (or uncinectomy), even in cases of severe spondylosis ? MATERIAL AND METHODS: We propose a prospective clinical and radiological study comparing the evolution of preoperative and postoperative cervical sagittal balance 1 year after the interposition of a prosthesis with mobile bearing and systematic total uncuscectomy. VAS for brachialgia and cervicalgia, NDI, Odom's criteria, C2–C7 Cobb angle, C2–C7 SVA, T1 slope, C2 slope, C1–C2 Cobb angle, and segmental Cobb angle were analyzed preoperatively and 1 year postoperatively. RESULTS: 73 patients for a total of 129 levels treated were analyzed. Patients showed significant improvements in VASb, VASc, NDI, and Odom's criteria one year after surgery without clinical differences in the severe spondylosis subgroup (41 patients for 77 levels treated). Our results showed an increase in the C2–C7 Cobb angle postoperatively and a better correlation between T1 slope and C2–C7 Cobb angle postoperatively than preoperatively. Postoperative radiological results were similar between the spondylosis and non-spondylosis subgroups. However preoperative C2–C7 Cobb angle and preoperative ROM were lower in the severe spondylosis subgroup. DISCUSSION AND CONCLUSION: This study showed the possibility of restoring cervical sagittal balance by performing cervical disc arthroplasty with systematic uncuscectomy, even in cases of severe spondylosis. Moreover, we propose a simplified mathematical formula to preoperatively evaluate the lack of angulation to restore sagittal cervical alignment.