Lumbar segmental motion patterns in patients with degenerative spondylolisthesis were detected with digital videofluoroscopic videos and distortion compensated Roentgen Analysis System

Abstract

Introduction. Assessment of lumbar segmental instability (LSI) in patients with degenerative spondylolisthesis using functional radiographs is controversial. With newly developed image analysis system using enhanced digital videofluoroscopic videos and distortion compensated roentgen analysis, different motion patterns in normal subjects and patients with LSI were noted. Methods. 100 normal subjects and 91 patients with diagnosis of degenerative spondylolisthesis were recruited. Dynamic segmental motion were captured and analyzed in every frame intervals during flexion/extension. The angular displacements of each vertebral level were automatically calculated. The slopes of angular displacement curve were calculated using Linear Regression. Multiple Regression Analysis was conducted to determine the most parsimonious set of independent variables able to predict the distinguish patterns in patients group. Results. A linear-liked motion pattern was found in different genders and age groups in various vertebral levels in normal group. The mean slope of angular displacement of L4/5 was 0.72 0.11. 91 patients were divided into different groups according to their slopes of L4/5 angular displacement curves with reference to the norm. Four major mobility patterns namely, hyper-mobility(n39), normal(n13), hypo-mobility(n27) and total immobility(n12) were detected. Excessive compensatory angular displacements were found in the adjunct levels in patients with hypomobility and total immobility. The standard regression coefficients ( ) showed that age followed by grade of slippage were significant predictors of the mobility patterns. Younger patients with grade I L4/5 degenerative spondylolisthesis predicted hyper-mobility pattern, 0.488, p0.05 whereas elder patients with grade II or above predicted hypomobility pattern, 0.571, p0.05. Discussion. Different lumbar segmental motion patterns could be found in patients with LSI. Corresponding treatments should be specifically given accordingly. Younger patients with grade I L4/5 degenerative spondylolisthesis predicted hyper-mobility pattern whereas elder patients with grade II or above predicted hypo-mobility pattern. These results correlated well with the pathomechanism and the natural history of degenerative spondylolisthesis.