Risk factors for proximal junctional kyphosis after posterior long-segment internal fixation of chronic symptomatic osteoporotic thoracolumbar fracture in the elderly / 中华创伤杂志

ABSTRACT

Objective:To investigate the risk factors associated with the occurrence of proximal junctional kyphosis (PJK) after posterior long-segment internal fixation for type IV chronic symptomatic osteoporotic thoracolumbar fracture (CSOTLF) in the elderly.Methods:A case-control study was used to analyze the clinical data of 95 elderly patients with type IV CSOTLF treated in Honghui Hospital affiliated to Xi′an Jiaotong University from January 2013 to June 2018, including 32 males and 63 females, aged from 60 to 85 years［(67.4±6.5) years］. Injured segments were T 11 in 17 patients, T 12 in 37, L 1 in 30 and L 2 in 11. All patients were treated with posterior long-segment internal fixation and divided into PJK group ( n=30) and non-PJK group ( n=65) according to whether PJK occurred after surgery. Univariate analysis was performed for the correlation of the following indices with the incidence of postoperative PJK, including general information such as gender, age, body mass index (BMI), bone mineral density (BMD), history of smoking, cause of injury, comorbidities, injury segments, American Spinal Injury Association (ASIA) classification and time from injury to surgery, preoperative imaging data such as posterior junctional angle (PJA), sagittal vertical axis (SVA), pelvic incidence-lumbar lordosis difference (PI-LL), pelvic tilt (PT) and sacral slope (SS), basic surgical data such as posterior ligament complex (PLC) injury, location of upper instrumented vertebrae (UIV), location of lower instrumented vertebrae (LIV) and number of fixed segments. Multifactorial Logistic regression analysis was used to measure the independent risk factors associated with the occurrence of postoperative PJK. Results:Univariate analysis showed that the incidence of postoperative PJK was correlated with age, BMI, BMD, preoperative PJA, preoperative SVA, preoperative PI-LL, PLC injury, location of UIV, location of LIV and number of fixed segments (all P<0.05), rather than gender, history of smoking, cause of injury, comorbidities, injury segments, ASIA classification, time from injury to surgery, preoperative PT and preoperative SS (all P>0.05). Multifactorial Logistic regression analysis showed that age ≥70 years ( OR=32.28, 95% CI 3.83-272.29, P<0.01), BMI>28.0 kg/m 2 ( OR=7.88, 95% CI 1.63-37.99, P<0.01), BMD T value<-3.5 SD ( OR=20.84, 95% CI 2.36-183.93, P<0.01), preoperative PI-LL>20° ( OR=13.30, 95% CI 1.54-113.87, P<0.05) and PLC injury ( OR=13.98, 95% CI 1.37-142.34, P<0.05) were significantly associated with the occurrence of postoperative PJK. Conclusions:Age≥70 years, BMI>28 kg/m 2, BMD T value<-3.5 SD, preoperative PI-LL>20° and PLC injury are independent risk factors for the incidence of PJK after posterior long-segment internal fixation in elderly patients with type IV CSOTLF. Attention should be paid to soft tissue protection and sagittal balance restoration of the spine intraoperatively and weight control and anti-osteoporosis treatment postoperatively.