Risk Factors for Dysphagia After Anterior Cervical Discectomy and Fusion With the Zero-P Implant System: a Retrospective Study With Minimum of 2 Years Follow-up

OBJECTIVE To evaluate the risk factors for dysphagia after anterior cervical discectomy and fusion (ACDF) with the Zero-P Implant System by multidimensional analysis and investigated the predictive values of these risk factors for dysphagia. METHODS A retrospective analysis of 260 patients who underwent ACDF with the Zero-P Implant System and had at least 2 year of follow-up were performed. All patients were divided into a non-dysphagia group and a dysphagia group. Sex, age, body mass index (BMI), intraoperative time, estimated blood loss, diabetes mellitus, hypertension, smoking, alcohol consumption, prevertebral soft-tissue thickness, the levels of surgery, O-C2 angle, C2-7 angle, T1 slope and segmental angle were analyzed. The Modified Japanese Orthopaedic Association (JOA) scoring system was used to determine functional status. NDI was used to evaluate neck pain and disability. The Bazaz grading system was chosen to evaluate dysphagia after surgery. Postoperative cerebrospinal fluid (CSF) leakage, infection, and dysphagia were recorded in both groups. An independent t-test was used to compare quantitative variables, a chi-square test was used to compare qualitative data between the two groups. To eliminate the influence of confounding factors, logistic regression was performed for multifactor regression of factors. The results were regarded as significant when the P-values were less than 0.05 in this study. RESULTS In total, the non-dysphagia group comprised 70 patients and the dysphagia group comprised 190 patients, with an average age of 58.33 ± 4.68 years (ranging, 42-82 years). These patients were followed up for 28.5 ± 3.5 months (range, 24-32 months). For clinical outcomes, both groups demonstrated significant improvement in the NDI and JOA scores (P < 0.001). According to the Bazaz dysphagia grading system, mild, moderate, and severe dysphagia were found in 50, 17, and 3 patients, respectively. In total, 37.1% (n = 26) had resolved by 3 month, 38.6% (n = 27) by 6 months, and 17.1% (n = 12) by 12 months. Chi-square test results indicated that number of operated levels, operation time dT1 slope, dO-C2 angle, dC2-7 angle, segmental angle and dPSTT were associated with a high incidence of dysphagia. Multivariate logistic regression analysis showed that number of operated levels, operation time, dC2-7 angle and dPSTT were significantly associated with postoperative dysphagia. CONCLUSIONS More operated levels, more operation time, more dC2-7 angle and dPSTT were the risk factors for postoperative dysphagia. In additional, sufficient preoperative preparation, evaluation combined with proficient and precise surgical treatment were suggested to reduce the incidence of postoperative dysphagia when ACDF was performed.