The incidence rate and risk factors of lumbar retrolisthesis after anterior selective fusion in patients with Lenke 5 adolescent idiopathic scoliosis

English Keywords:Adolescent idiopathic scoliosis  Lenke 5  Anterior selective fusion  Retrolisthesis  Sagittal alignment  Risk factors

English Abstract:

  【Abstract】 Objecctives: To explore the incidence rate and risk factors of lumbar retrolisthesis after anterior selective fusion in patients with Lenke 5 adolescent idiopathic scoliosis(AIS). Methods: From January 2005 to December 2010, a total of 49 patients with Lenke 5 AIS who underwent anterior selective fusion in our hospital were retrospectively reviewed. The following radiographic parameters in standing full spine X-ray films before surgery, at 3-month after surgery and final follow-up were measured: The Cobb angle of thoracolumbar(TL) curve and thoracic(T) curve, lumbar lordosis(LL), thoracic kyphosis(TK), thoracolumbar junctional kyphosis(TJK), sacral slope(SS), pelvic tilt(PT), pelvic incidence(PI), and C7 sagittal vertical axis(SVA). Patients′ demographic data including gender, age, Risser sign, follow-up period, as well as surgical parameters including the number of levels fused and location of lower instrumented vertebra(LIV) were recorded. The Roussouly classification was used to describe the preoperative sagittal alignment. Patients were divided into the retrolisthesis group(R group) and non-retrolisthesis group(NR group) based on the presence of retrolisthesis or not at final follow-up. Within-group or between-group comparisons of parameters at different time points were made statistically. Scoliosis Research Society(SRS)-22 questionnaires were used at the final follow-up to assess the health-related quality of life(HRQoL) of both groups of patients. Logistic regression analysis was performed on the parameters with statistical differences. Results: At the last follow-up, 24 patients(48.9%) developed retrolisthesis(R group), and the other 25 patients did not(NR group). The age, gender, Risser sign, levels fused, distribution of Roussouly classification and LIV location did not differ significantly between the two groups(P>0.05). The follow-up duration was 81.5±16.8 and 78.7±12.3 months for R group and NR group. At all time points, the patients in R group had significantly larger LL(P<0.039) and smaller SVA(P<0.038) than NR group. Compared with NR group, the patients in R group had significantly larger TK before surgery and at final follow-up(P<0.041), and larger SS at final follow-up(P=0.036). The SRS-22 scores including pain and function domains did not differ significantly between the two groups(P>0.05). Logistic regression analysis showed that preoperative SVA[odds ratio(OR)=0.959, 95% confidence interval(CI) 0.925-0.994, P=0.024] and TK(OR=1.158, 95%CI 1.003-1.337, P=0.045) were the risk factors for the occurrence of retrolisthesis after surgery. Conclusions: There is a high incidence rate of retrolisthesis below the fusion levels of patients with Lenke 5 AIS who underwent anterior selective fusion surgery. Smaller preoperative SVA and larger LL are found to be the risk factors for postoperative retrolisthesis, whereas the distribution of preoperative Roussouly classification is not obviously coorelated. The impact of retrolisthesis on the disc degeneration and patients′ HRQoL still requires long-term follow-up for further investigation.