Analysis Of Factors Affecting The Surgical Outcome For Patients With Cervical Degenerative Disease

Part 1 Strain on adjacent level intervertebral disc after one-or two-level anterior cervical discectomy and fusionObjective: Cervical spondylosis is a disease caused by cervical disc degeneration,which can lead to cervical cord or nerve root compression.Multilevel cord compressions are more and more common.Anterior cervical discectomy and fusion(ACDF)is a common method to treat cervical spondylosis.This study was aimed to study the effect of one-or two-level ACDF on adjacent intervertebral disc by biomechanical test,which can be contributed to explain adjacent segment degeneration.Methods: A total of 6 male goats C3-T1 cervical specimens were used in this investigation.The specimens were tested intact and then underwent single-level ACDF(C5-6)and two-level ACDF(C5-7).Testing was performed in displacement control under flexion,extension and axial rotation loading modes.Intervertebral disc pressures were recorded at adjacent intervertebral disc(C4-5).Results: Under flexion,extension and axial rotation loading modes,the C4-5 intervertebral disc pressures in groups with one-or two-level ACDF were significantly higher than intact condition(P<0.05).Under flexion and extension loading modes,the C4-5 intervertebral disc pressures in two-level ACDF group were significantly higher than one-level ACDF group(P<0.05).Under axial rotation loading modes,the C4-5 intervertebral disc pressures in two-level ACDF group were not significantly higher than one-level ACDF group(P>0.05).Conclusion: Adjacent intervertebral disc pressures after one-or two-level ACDF were significantly higher than intact condition under flexion,extension and axial rotation loading modes.Adjacent intervertebral disc pressures after two-level ACDF were significantly higher than one-level ACDF under flexion and extension loading modes.Part 2 Cervical developmental canal stenosis and adjacent segment degeneration after anterior cervical arthrodesisObjective: Adjacent segment degeneration(ASD)is known to occur after anterior cervical arthrodesis.However,it is not known whether cervical developmental canal stenosis enhances the risk of ASD.The purpose of this study was to explore whether cervical developmental canal stenosis could be used as a predictor of ASD after anterior cervical decompression and fusion(ACDF).Methods: We enrolled 141 patients who had undergone ACDF for cervical myelopathy and/or radiculopathy,and had at least 6 years of follow-up.In standard radiographs of cervical spine in lateral view,cervical developmental canal stenosis was evaluated and all patients were divided into two groups: stenosis(n= 63)and non-stenosis(n= 78).Radiographic ASD was assessed according to the criteria of Kellgren and Lawrence and correlated with symptomatic ASD.Clinical and radiological parameters were compared between the groups.The primary outcome was the rate of radiographic ASD after initial ACDF.The incidence of symptomatic ASD was assessed by Kaplan-Meier method.Results: Radiographic ASD and symptomatic ASD developed in 46.8% and 18.4% of all patients,respectively.There was a significant association between developmental canal stenosis and radiographic ASD.The area under the receiver operating characteristic(ROC)curve of preoperative anteroposterior(AP)diameter of cervical canal for predicting radiographic ASD was 0.756.13.0 mm was the cut-off value of preoperative AP diameter of cervical canal predicting radiographic ASD.Kaplan-Meier analysis predicted a disease-free survival rate of symptomatic ASD in 97.2% of patients at 5 years and 78.0% at 10 years after ACDF.There was no significant difference in survival rates of the adjacent segment between the two groups via log-rank analysis(P= 0.102).Conclusion: Developmental canal stenosis can increase the rate of radiographic ASD after initial ACDF.The cut-off value of 13.0 mm for preoperative AP diameter of cervical canal had the highest validity for predicting radiographic ASD.Part 3 Predictors of surgical outcome in cervical spondylotic myelopathyObjective: The association between intramedullary increased signal intensity(ISI)on T2-weighted magnetic resonance imaging(MRI)and surgical outcome in cervical spondylotic myelopathy(CSM)remains controversial.The purpose of this study is to assess the impact of quantitative signal change ratio(SCR)on the surgical outcome for CSM.Methods: The prospective study included 108 consecutive patients who underwent surgical treatment for CSM.The Japanese Orthopaedic Association(JOA)score and recovery rate were used to evaluate clinical outcomes.JOA recovery rate less than 50% was defined as a poor clinical result.The SCR was defined as the signal intensity at the level of ISI or severely compressed cord(in cases with no ISI)divided by the signal intensity at the C7-T1 disc level.Age,sex,body mass index,duration of symptoms,surgical technique,preoperative JOA score,levels of compression,preoperative SCR,preoperative C2-7 angle,preoperative C2-7 range of motion(ROM)were assessed.Results: Forty patients(37.0%)had a recovery rate of less than 50%.Multivariate logistic regression analysis revealed that a higher preoperative SCR and a longer duration of symptoms were significant risk factors for a poor clinical outcome.Receiver operating characteristic(ROC)curve analysis showed that the optimal preoperative SCR cutoff value as a predictor of poor clinical result was 1.46.The area under the ROC curve of preoperative SCR for predicting a poor surgical outcome was 0.844.Conclusion: Preoperative SCR significantly reflected the surgical outcome in patients with CSM.Patients with SCR greater than or equal to 1.46 can experience poor recovery after surgery.