The effect of the difference in C(2–7) angle on the occurrence of dysphagia after anterior cervical discectomy and fusion with the zero-P implant system

OBJECTIVES: To investigate the effect of the difference in C(2–7) angle on dysphagia after anterior cervical discectomy and fusion (ACDF) with the Zero-P Implant System. METHODS: A retrospective analysis of 181 patients who underwent ACDF with the Zero-P Implant System and had at least one year of follow-up from January 2011 to November 2018 was performed. All patients were divided into a non-dysphagia group and a dysphagia group to explore the effect of the difference between postoperative and preoperative C(2–7) angle (dC(2–7)A) on postoperative dysphagia. At the same time, other possible related factors including the difference between postoperative and preoperative O-C2 angle (dO-C2A), sex, age, body mass index (BMI), intraoperative time, estimated blood loss, diabetes mellitus, hypertension, smoking, alcohol consumption, prevertebral soft-tissue swelling (PSTS), the highest segment involved in the surgery and the levels of surgery segments were analyzed. RESULTS: In total, the non-dysphagia group comprised 139 patients and the dysphagia group comprised 42 patients. The single-factor analysis showed that smoking, PSTS and dC(2–7)A were significantly different between the two groups (P < 0.05). Spearman’s correlation coefficient showed no significant correlation between the degree of dysphagia and dC(2–7)A (P > 0.05). The results of the multiple-factor analysis with an ordinal logistic regression model showed that smoking, PSTS and dC(2–7)A were significantly associated with the incidence of dysphagia (P < 0.05). CONCLUSIONS: The postoperative C(2–7) angle has an important effect on the occurrence of dysphagia in patients undergoing Zero-P implant system interbody fusion surgery.