A Meta-analysis Of The Incidence And Risk Factors Of Proximal Junctional Kyphosis After Correction Surgery For Scheuermann’ Disease

Background context:Orthopaedic surgery for Scheuermann’s disease is a challenge,Current procedures include combined anterior-posterior and simple posterior approaches.However,there is a growing debate about the complications associated with these procedures.One of the notable complications is postoperative proximal junctional kyphosis（PJK）.Several factors exist that influence proximal junctional kyphosis,but how this relates to the risk of PJK in Scheuermann’s disease is not known.Objectives:To investigate the incidence and associated risk factors of proximal junctional zone kyphosis（PJK）after correction surgery for Scheuermann’s disease.Methods:PubMed,Embase,Cochrane Library,China Knowledge Network and Wanfang database were searched from the beginning to November 2021 for studies related to the occurrence of PJK in patients with Scheuermann’s disease after surgery.The Newcastle-Ottawa Scale（NOS）was used to evaluate the quality of the included studies,and the outcome indicators of the included studies were extracted,including the incidence of PJK,age and gender;the surgical procedure,the proximal instrumented vertebra（PIV）compared to the proximal steered vertebra(The position of the proximal end vertebra（PIV）compared to the proximal end vertebra（PEV）,the position of the proximal fixed vertebra,the amount of kyphosis correction,the pelvic incidence（PI）,pre-and post-operative lumbar lordosis（LL）,pre-and post-operative pelvic tilt（PT）,pre-and Sacral slope（SS）,Thoracic kyphosis（TK）,Pelvic incidence-Lumbar lordosis（PI-LL）,corrected loss,and TK correction rate.Statistical analyses were performed using Revman 5.3 software.A fixed or random effects model was used with risk difference（RD）for individual rates,dominance ratio（Odds ratios,OR）for dichotomous variables and weighted mean difference（WMD）for continuous variables,and confidence intervals(Confidence interval（CI）was 95%.Results:A total of 17 studies were included in this meta-analysis,all of which were high quality cohort studies.A total of 784 patients we re included,of which 213 patients with Scheuermann’s disease devel oped PJK after corrective surgery.Among them,213 cases in PJK g roup and 571 cases in non-PJK group,The follow-up time was 35.72 ± 14.16 months.Meta-analysis showed that the overall incidence of PJK was 23%（RD 0.23,95% CI,0.13-0.33,p <0.00001）,proximal p osition of the fixed vertebrae（OR 0.37,95%CI 0.16-0.85,P=0.02）,and the amount of correction of kyphosis（OR 4.52,95%CI 1.72-11.90,P=0.002）,with statistically significant differences between the two grou ps for these two outcome indicators,with a significantly higher incid ence of PJK when the fixed position of the upper end vertebrae wa s between T5 and T8.The incidence of PJK also increased signific antly when the amount of kyphosis correction was>50%;whereas PI（WMD-1.51,95% CI-4.75-1.73,P=0.36）,age（WMD 0.15,95% CI-1.80-2.09,P=0.88）,sex（OR 1.08,95% CI 0.39-2.97,P= 0.88）,surgical pr ocedure（OR 1.2,95%CI 0.65-2.22,P=0.55）,location of PIV compared t o PEV（OR 0.6,95%CI 0.32-1.14,P=0.12）,preoperative LL（WMD-1.22,95%CI-5.86-3.41,P=0.60）,postoperative LL（WMD-1.43,95%CI-6.02-3.16,P=0.54）,preoperative PT（WMD 0.63,95%CI-1.82-3.08,P=0.62）,postoperative PT（WMD 4.03,95%CI-1.71-9.78,P=0.17）,preoperativ e SS（WMD-0.10,95%CI-3.40-3.19,P=0.95）,postoperative SS（WM D-1.15,95%CI-3.95-1.67,P=0.42）,preoperative TK（WMD 1.38,95%CI-1.21-3.98,P=0.30）,postoperative TK（WMD 3.13,95%CI-0.56-6.817,P=0.10）,（PI-LL）（WMD-2.40,95%CI-6.92-2.12,P=0.30）,corrected loss（WMD-0.49,95%CI-2.92-1.93,P=0.69）,and corrected TK（WM D-4.22,95%CI-12.63-4.18,P=0.32）,no statistical differences.Conclusions:The incidence of PJK after correction surgery in patients with Scheuermann’s disease was 25%,and the incidence of PJK rise significantly when the fixation position of the proximal end vertebrae was between T5-T8.The incidence of PJK also increased significantly when the amount of curve correction was >50%.