The Radiological And Clinical Outcomes Of Zero-P Implant In One-level ACDF:A Retrospective Study

Part 1:The relationship between the degree of the T1 Slope and the incidence of cage subsidence following one-level ACDF with Zero-P.Objective:To determine the relationship between the degree of the T1 Slope and the incidence of cage subsidence following one-level ACDF with Zero-P.Methods:288 patients underwent one-level ACDF with Zero-P from May 2011 and August 2015 were collected.According to the inclusion and exclusion criteria,49 patients were incorporated into the group.Among them,25 were male and 24 were female.Parameters including cervical lordosis(CL),T1 slope,CSVA,segmental angle(SA),segmental height(SH)on plane radiographs.The difference between the SH of the following and follow-up was marked as ?SH and subsidence was defined as more than 3mm of ?SH.The difference between the alignments between follow-up and preoperative were marked as ?CL,?T1S,?CSVA,and ?SA.VAS and NDI were used to access the clinical outcomes.Risk factors of subsidence were determined using multivariate logistic regression.Results:The distribution of surgical levels were as follows:2 in C4/5,36 in of C5/6 and 11 in C6/7.The mean age was 45.86±7.95(from 33 to 68)and the mean BMI was 27.16±2.29.14 patients smoke.The mean surgery time was 95.7min ranging from 70 to 130 min.The mean amount of bleeding was 52 ml ranging from 10 to 100 ml.The depression and implanting were successful,and serious complications occurred in none of the patients.The mean clinical follow-up was 48.3 months(range 24-75 months).VAS and NDI were improved after surgeries and at the follow-ups.The angles of T1S?SA?CL were correlated with clinical outcomes.The occurrence of subsidence was negatively correlated with outcomes.A cutoff value of T1S?18°significantly predicted subsidence(sensitivity:73.7%,specificity:73.3%)and a lower T1 S was associated with a higher risk of subsidence(LR=7.7,P=0.001).Conclusion:A lower T1S(T1S?18°)pre-operation could be a risk factor of subsidence following one-level ACDF with Zero-P.Part 2:The relationship between the change of segmental angle and the incidence of dysphagia following one-level ACDF with Zero-P.Objective:To determine the relationship between the change of segmental and the incidence of dysphagia following one-level ACDF with Zero-P.Methods:288 patients underwent one-level ACDF with Zero-P from May 2011 and August 2015 were collected.According to the inclusion and exclusion criteria,92 patients were incorporated into the group.Among them,53 were male and 24 were female.Parameters including cervical lordosis(CL),T1 slope,CSVA,segmental angle(SA)and prevertebral soft-tissue thickness(PST)on plane radiographs.The difference between the alignments between postoperative and preoperative were marked as dCL,dT1 S,dSA and dPST.The occurrence of dysphagia was graded according to Bazaz criteria.Risk factors of dysphagia were determined using multivariate logistic regression.Results:The distribution of surgical levels was as follows:5 in C4/5,67 in of C5/6 and 20 in C6/7.The mean age was 47.04±8.72(from 33 to 68)and the mean BMI was 27.5±2.5.31 patients smoke.the mean surgery time was 93.3min ranging from 50 to 130 min.The mean amount of bleeding was 42.6ml ranging from 10 to 100 ml.The depression and implanting were satisfactory,and serious complications occurred in none of the patients.The mean clinical follow-up was 46.6 months(range 24-75 months).12 patients complained about dysphagia in one week following the surgeries and were distributed into Group A.10 of them were mild and 2 were moderate.The others were distributed into Group B.No difference was found in age,gender,smoking,operation time,BMI and surgical level between the two groups.The difference of amount of bleeding,PST,dSA and dCL in Group A and Group B were detected(P<0.05).The occurrence of dysphagia was significantly correlated with dSA.A cutoff value of dSA?8° significantly predicted dysphagia(sensitivity:86%,specificity:83.3%)and higher dSA was associated with a higher risk of dysphagia(LR=14.4,P<0.001).Conclusion:The values of ?SA were correlated significantly with occurrence of dysphagia.A higher dSA(dSA?8°)could be a risk factor of dysphagia following one-level ACDF with Zero-P.