The risk factor analysis of kyphosis reccurrence in single level thoracolumbar burst fracture after short-segment instrumentation in fractured vertebra

English Keywords:Thoracolumbar fracture  Burst fracture  Internal fixation  Kyphosis reccurrence  Risk factor

English Abstract:

  【Abstract】 Objectives: To analyze the risk factors of kyphosis reccurrence in thoracolumbar burst fracture before or after implant removal after short-segment instrumentation in fractured vertebra. Methods: From January 2014 to January 2016, patients with thoracolumbar burst fracture who underwent posterior short-segment pedicle screw instrumentation in the cooperation units were carefully reviewed. The followings were obtained: age, Cobb angle of the fractured segment(CA), regional angle(RA), vertebral wedge angle(VWA), anterior vertebra height ratio(AVH), posterior vertebra height ratio(PVH), anteroposterior ratio(A/P), upper intervertebral angle(UIVA), lower intervertebral angle(LIVA), body mass index(BMI), visual analogue scale(VAS), thoracolumbar injury classification and severity score(TLICS), load-sharing classification(LSC), history of diabetes. Posterior kyphosis reccurrence was defined as posterior correction loss >10°. The patients were divided into kyphosis recurrence(KR) group and none kyphosis recurrence(NKR) group. The parameters were analyzed according to before or after implant removal. Logistic regression was used to analyze the risk factors. The threshold value was calculated by ROC curve analysis. Results: A total of 196 patients from 5 cooperation units were included in this study. When KR group was compared with NKR group before implant removal, age(P<0.001) and BMI(P<0.001) were risk factors of kyphosis reccurrence; age >58.5 years[area under curve(AUC)=0.885], BMI >29.1kg/m2(AUC=0.962) were the thresholds. When KR group was compared with NKR group after implant removal, female(P<0.001), age(P<0.001), BMI(P<0.001), L1 fracture(P<0.001), AO classification of A3.3(P=0.001), preoperative UIVA(P=0.014) were the risk factors of kyphosis reccurrence after implant removal; T12 fracture(P＜0.001), AO classification of A3.1(P<0.001), preoperative AVH(P＜0.001) were the protective factors; age >50.5 years(AUC=0.789), BMI >26.6kg/m2(AUC=0.740), preoperative UIVA >-4.2°(AUC=0.650), preoperative AVH >60.5% were the thresholds. Conclusions: Before implant removal, age >58.5 years and BMI >29.1kg/m2 are the risk factors of kyphosis reoccurrence in single level thoracolumbar burst fracture after short-segment instrumentation. After implant removal, age >50.5 years(AUC=0.789), BMI >26.6kg/m2(AUC=0.740), preoperative UIVA >-4.2°(AUC=0.650), L1 fracture, AO classification of A3.3 are the risk factors of kyphosis reoccurrence; T12 fracture, AO classification of A3.1 and preoperative AVH >60.5% are the protective factors of kyphosis reccurrence.