200. Development and validation of a radiographic classification of lumbar lateral listhesis for predicting radicular leg pain in adult scoliosis

BACKGROUND CONTEXT Lumbar lateral listhesis has been found to be associated with radicular leg pain in adult scoliosis. This relationship, however, has yet to be specified by making a simple grading/classification system of lateral listhesis that stratifies the risk of leg pain. Such a classification could better alert surgeons of potential involvement of nerve impingement early in the evaluation, especially in such emerging settings as “telehealth" wherein history inquiry and image review may take place separately. PURPOSE To develop and validate a radiographic classification system of lumbar lateral listhesis that stratifies the probability of having radicular leg pain in adult scoliosis. STUDY DESIGN/SETTING Derivation and validation of a risk-based classification system, at a tertiary university hospital. PATIENT SAMPLE A total of 294 consecutive adult scoliosis patients enrolled in a retrospective derivation cohort (189 patients) and a prospective validation cohort (105 patients). OUTCOME MEASURES Odds ratio of the radiological parameters of lumbar lateral listhesis in predicting leg pain, and the percentage of patients with leg pain in each type of lateral listhesis. METHODS A radiographic classification of lumbar lateral listhesis was developed using a derivation (retrospective) cohort of consecutive adult scoliosis patients diagnosed at our clinic in 2011-2015. Four radiographic factors of lateral listhesis were put into multivariable logistic regression to identify two most influential predictors of radicular leg pain:(1) L4 lateral listhesis, (2) Nash-and-Moe grade of vertebral rotation at the lowest slipped segment, (3) the number of slipped segments, and (4) the presence of another listhesis superiorly at the thoracolumbar junction contralateral to the main listhesis below. . These four factors were selected based on research evidence and clinical experience, and odds ratio was used to assess their strength of association with the presence of radicular leg pain. The classification was thus made based on the two most influential factors of the four and, then, validated in a prospective cohort of consecutive patients diagnosed in 2016-2018. RESULTS In the derivation cohort of 189 patients, vertebral rotation ≥ grade 2 (OR=9.5, 95% CI: 3.8-24.6) and the presence of L4 lateral listhesis (OR=4.5, 95% CI: 1.8-12.1) were found to be most strongly associated with the presence of radicular leg pain. The classification of lumbar lateral listhesis was thereby made based on the presence of these two factors: Type 1 (neither of the two factors present), Type 2 (one of two factors present), and Type 3 (both factors present). Additionally, Type 0 was used to describe scoliosis without any lateral listhesis. The prevalence of leg pain varied significantly among the four types: 0% (0/49), 6% (3/47), 34% (25/74), and 68% (13/19) in Type 0, 1, 2, and 3, respectively (P CONCLUSIONS This classification system of lumbar lateral listhesis can effectively stratify the probability of radicular leg pain in adult scoliosis. Type 2 and Type 3 lateral listhesis should alert physicians of potential nerve impingement early in the evaluation. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.