Effect of intervertebral height index recovery on radiographic degeneration of adjacent segments after posterior L4/5 single-level fusion

English Keywords:Intervertebral height index  Radiographic adjacent segment degeneration  Single segment  Transforaminal lumbar interbody fusion

English Abstract:

  【Abstract】 Objectives: To investigate the effect of recovered intervertebral height index on radiographic adjacent segment degeneration(rASD) during posterior L4/5 single-level fusion. Methods: A total of 354 patients who underwent L4/5 transforaminal lumbar interbody fusion(TLIF) surgery in our hospital from March 2008 to March 2014 were collected. According to the inclusion and exclusion criteria, a total of 58 patients were enrolled, and they were divided into youth group(20-40 years old, 16 cases, group A) and middle-aged group(41-60 years old, 42 cases, group B) according to age. Visual analogue scale(VAS) score, Oswestry disability index(ODI), and lumbar Japanese Orthopaedic Association(JOA) score were recorded before surgery and at final follow-up. L4/5 intervertebral height index(IHI) and spine-pelvis parameters[lumbar lordosis(LL), pelvic incidence(PI), sacral slope(SS), pelvic tilt(PT)] were measured before and after surgery and at final follow-up, and the incidence and risk factors of rASD were analyzed, Logistic regression analysis was performed. According to whether the intervertebral height index was restored to the normal range during operation, patients were further divided into the intervertebral height index recovery group(youth group and middle-aged group were A1 and B1, respectively) and the non-recovery group(youth group and middle-aged group were A2 and B2, respectively), the incidence of rASD in each group was compared. Results: The mean postoperative follow-up was 59.36 months, and the postoperative clinical efficacy(VAS, ODI and JOA) was significantly improved in both groups(P<0.01). rASD occurred in 23 patients(39.7%) at final follow-up. No rASD occurred in A1 group(0/6), and 1 case(1/10, 10%) occurred in A2 group. There were 5 cases(5/16, 31.25%) in B1 group and 17 cases(17/26, 65.4%) in B2 group, with a statistically significant difference in incidence between the two groups(P=0.031). The risk factors for rASD were age, follow-up time, postoperative L4/5 IHI and postoperative LL, Logistic regression analysis showed that postoperative L4/5 IHI was a significant risk factor(OR=17.1, P<0.001). Conclusions: In patients aged 40-60 years, intraoperative restoration of the IHI to the normal reference range after posterior L4/5 single-level fusion may reduce the incidence of rASD.