Analysis Of The Risk Factors Of Proximal Junctional Kyphosis After Posterior Surgery Of Long-segmental Internal Fixation And Fusion In Patients With Lumbar Degenerative Disease

Purpose Proximal junctional kyphosis is a common complication after correction of spinal deformity,which can lead to nerve compression and spinal cord injury and affecting the quality of patients’ life;At present,there is no clear conclusion about the pathogenesis and risk factors of PJK,and Previous studies had focused on the occurrence of post-surgery PJK in adolescent idiopathic spinal deformity and adult spinal deformity.There is no report on the occurrence of PJK in patients with lumbar degenerative disease who have had posterior Long-segmental Internal Fixation and Fusion,This study was designed to follow up the patients with lumbar degenerative disease who have had long segmental fixation and to investigate the incidence and risk factors of PJK.Methods A retrospective analyze of 118 degenerative lumbar disease patients who were treated with posterior long segmental fusion surgery during October 2012 to July 2014 in the Beijing Army General Hospital,with a follow-up at least 1.5 years.According to the inclusion criteria and exclusion criteria,with a mean follow-up of 3.2years,66 patients With complete data were classified into PJK group(12 patients)and Non-PJK group(54 patients)according to whether one has a PJK.In order to investigate the risk factors of PJK,we analyzed the three kinds of factors.(1)General data of patients: the patients’ sex,age,body mass index(BMI),bone mineral density(BMD);(2)Surgical factors: upper instrumented vertebrae(UIV),lower instrumented vertebrae(LIV),the number of fixed segments;(3)radiographic variables: lumbar lordosis(LL),proximal junctional kyphosis angle(PJKA).To assess the severity of symptoms in the two groups,we performed a statistical analysis of preoperative and final ODI.Result During the follow-up(of which the mean was 3.2year),66 patients With complete data were classified into PJK group(12 patients)and Non-PJK group(54 patients)according to whether one has a PJK.In this study,the incidence of PJK was 18.18%.There is no statistical significance in age and sex between the groups.A statistical significance was noted in BMI,bone density and the last follow-up ODI scores(P <0.05).a statistical significance was noted when UIV was located in the thoracolumbar segment(T11~L1),while the lower instrumented vertebrae(LIV)located in S1 and the length of fused segment shows no significant difference(P >0.05).The PJKA of the PJK group(11.25±3.44)is much larger than the Non-PJK group(6.74±3.70),and the difference between the groups is statistical significant(P <0.05).A significance was noted in post-surgery and last follow-up PJKA(P <0.05).Both the pre-and post-surgery lumbar lordosis between the two groups shows no significance(P>0.05).A binary logistic regression analyze shows that osteoporosis,UIV located in the thoracolumbar segment(T11~L1)and a pre-surgery PJKA>10°are the independent risk factors of PJK.Conclusion A pre-surgery PJKA>10°,UIV located in the thoracolumbar segment(T11~L1)and osteoporosis are risk factors of PJK after Posterior Long-segment Internal Fixation and Fusion in Patients with Lumbar Degenerative Disease.