| OBJECT:To investigate the correlation between the preoperativecenter of gravity of the head-C7 sagittal vertical axis(CGH-C7SVA)and the prognosis of patients with OPLL(Ossifcation of the posterior longitudinal ligament)undergoing the double-door LAMP and each cervical sagittal plane parameter.METHODS:In this study,a retrospective analysis was performed on 50 patients who underwent the double-door LAMP for cervical OPLL between September 2020 and September 2021,and all 50 patients had positive cervical K-lines and no cervical kyphosis.Preoperative imaging data were collected from these 50 patients who underwent the double-door LAMP,i.e.,the following sagittal parameters were measured on the preoperative cervical frontal X-ray: center of gravity of the head-C7 sagittal vertical axis(CGH-C7SVA),cervical 2-C7 sagittal vertical axis(C2-C7SVA),and cervical 2-C7 sagittal vertical axis(C2-C7SVA).sagittal vertical axis(C2-C7 sagittal vertical axis,C2-C7SVA),cervical lordosis(CL),and first thoracic slope(T1 slope,T1S).The preoperative Japanese Orthopaedic Association Scores(JOA,Japanese Orthopaedic Association Scores)of these patients were also recorded.A prognostic questionnaire was administered to the 50 cervical OPLL patients who underwent double-opening surgery for a 1-year follow-up period,and the Neck disability index(NDI),postoperative JOA score,and recovery rate of the postoperative JOA score were recorded at this time.The prognosis of patients with cervical OPLL after double-opening surgery was evaluated comprehensively.After statistical analysis,the postoperative NDI score obtained from the follow-up questionnaire was used as the basis to obtain the median score(13.5),and the 50 cervical OPLL patients who underwent double-opening surgery were divided into a good prognosis group and a poor prognosis group,with 25 patients in each group,in which the postoperative NDI score was <13.5 in the good prognosis group and >13.5in the poor prognosis group.score.The statistical methods were used to investigate whether there were significant differences in the preoperative cervical spine indexes,postoperative kyphosis,preoperative JOA score,postoperative JOA score and postoperative JOA score recovery rate between the good prognosis group and the poor prognosis group,and then to investigate whether the preoperative cervical spine indexes that were significantly different between the two groups were correlated with the postoperative NDI score by linear correlation and linear regression.Finally,multiple linear regression was used to investigate the degree of influence of these preoperative cervical spine indices on postoperative NDI scores.RESULTS:All 50 patients with cervical OPLL treated by double-door laminoplasty showed some degree of improvement in neurological symptoms.There was a significant difference between the good prognosis group and the poor prognosis group in CGH-C7SVA(17.20±6.36 mm vs 31.16±8.85 mm),C2-C7SVA(17.44±5.35 mm vs 27.96±4.50 mm),T1 slope(20.88±2.77° vs 27.64±2.60°);there was no difference in CL(18.44±2.16° VS 18.36±2.81°);there was no difference in the change of cervical lordosis(0 VS 0).Also,there was a significant difference between the good prognosis group and the poor prognosis group in the postoperative JOA score(12.96 ± 1.93 vs.10.52 ± 3.28)and the recovery rate of the postoperative JOA score(57.8% ± 12.5% vs.32.9% ± 21.8%),while there was no difference in the preoperative JOA score(7.72 ± 2.72 vs.7.96 ± 2.73).The postoperative NDI score was strongly linearly correlated with the 3 preoperative CGH-C7 SVA,C2-C7 SVA,and T1 slope parameters(r=0.943,P<0.01;r=0.943,P<0.01;r=0.899,P<0.01),while each 2 of these 4 parameters were strongly linearly correlated with each other.Using preoperative CGH-C7 SVA,C2-C7 SVA,and T1 slope as independent variables and postoperative NDI score as the dependent variable,the multiple linear regression equation could be derived: Y=0.314X1+0.361X2+0.506X3-14.369(Y=postoperative NDI score;X1=CGH-C7SVA;X2=C2-C7 SVA.X3=T1 slope;R2=0.939),and the absolute values of the standardized coefficients Beta for CGH-C7 SVA,C2-C7 SVA,and T1 slope were 0.408,0.327,and 0.274,respectively,in decreasing order.In addition,using the postoperative NDI score as the independent variable and the preoperative CGH-C7 SVA as the dependent variable,a linear regression equation could be derived: Y = 1.225 X + 7.71(Y = CGH-C7SVA;X = postoperative NDI score;R2 = 0.889),and bringing the postoperative NDI score = 25 points into the equation to find CGH-C7 SVA = 38.34 mm.CONCLUSIONS:1.The preoperative cervical sagittal balance parameters CGH-C7 SVA,C2-C7 SVA,and T1 slope were correlated with the clinical prognosis of patients with cervical OPLL treated with the double-door laminoplasty.The higher the values of these three indicators,the higher the postoperative NDI scores of patients and the worse the clinical prognosis,and the influence on the prognosis of double-opening surgery gradually becomes weaker.2.The preoperative CGH-C7 SVA,C2-C7 SVA,and T1 slope were positively correlated between each of the three indicators,and there was a positive relationship.Therefore,CGH-C7 SVA can replace C2-C7 SVA and T1 slope,and thus play a guiding significance in the selection of preoperative surgery and the prediction of clinical prognosis.3.When the postoperative NDI score > 25,preoperative CGH-C7 SVA > 38.34 mm indicates a poor prognosis.Therefore,cervical OPLL patients with a larger preoperative CGH-C7 SVA are more likely to have cervical sagittal imbalance and poor clinical prognosis after treatment with the double-door laminoplasty.4.The preoperative CGH-C7 SVA was not predictive of the occurrence of cervical lordosis during the short-term postoperative follow-up period in patients with cervical OPLL treated with the double-door surgery. |
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