Analysis of anatomical risk factors for postoperative proximal junctional kyphosis in elderly spinal patients

WANG Wei; DING Jun-zhe; KONG Chao; ZHU Wei-guo; LI Xiang-yu; LU Shi-bao

doi:10.3969/j.issn.2095-252X.2025.04.004

Abstract：Objective To analyze the incidence and related risk factors of proximal junctional kyphosis(PJK)in elderly patients undergoing long-segment spinal fusion surgery.Methods From January 2016 to March 2020,95 elderly patients with long-segment fixation and fusion surgery in the Department of Spine Surgery,Xuanwu Hospital,Capital Medical University were screened,the patients were divided into PJK group and non-PJK group.Demographic data were collected.Imaging parameters,including spinal pelvic parameters,cross sectional area of paraverteral muscle(CSA),fat infiltration(FI),and vertebral CT values of the upper instrumented vertebra(UIV)were measured.The risk factors of postoperative PJK were analyzed by inter-group comparison and logistic regression.Results The average follow-up time of the patients was(24.6±5.4)months.34 patients developed PJK after surgery,with an incidence rate of 35.8%.According to the occurrence of PJK after surgery,BMI in PJK group was significantly higher than that in non-PJK group(P=0.005),and there was no significant difference in age,sex ratio and smoking history between the two groups.The average number of fixation segments in PJK group(6.6±1.4)was significantly higher than that in non-PJK group(5.6±1.2)(P=0.001).There was no significant difference in LL,PI,PT,PI-LL,SS,SVA and UIV between the two groups.Both ES and MF-rCSA in PJK patients were significantly lower than those in non-PJK group(P<0.001).ES-Fi was significantly higher than that in non-PJK group(P=0.001),and UIV vertebral CT values in PJK group were significantly lower than those in non-PJK group.Binary logistic regression results showed that more internal fixation segments(OR=1.486,95%CI=1.035-2.135,P=0.032),less MF-rCSA segments(OR=0.451,95%CI=0.269-0.756,P=0.003)and lower UIV CT value(OR=0.957,95%CI=0.931-0.984,P=0.002)were independent risk factors for PJK in elderly patients after long-segment spinal fixation.Conclusions PJK is a common complication of internal fixation in elderly patients after spinal fusion.More internal fixation segments,less multi-fidus rCSA and lower UIV vertebral CT value are independent risk factors for postoperative PJK in elderly patients with long-segment internal fixation.