An experimental model of adult-onset slip progression in isthmic spondylolisthesis

摘要

Spondylolisthesis is defined as a slippage of a vertebral body on the one below. Isthmic spondylolisthesis, caused by stress fracture or a developmental anomaly at the pars interarticularis, is the most common type of lumbar spondylolisthesis with a 6% incidence in adults. Isthmic lumbar spondylolisthesis is a frequent cause of disabling low-back and leg pain. The goal of this study is to improve the quality of treatment of these patients. Progressive spondylolisthesis in adults with a chronic isthmic spondylolysis has been observed. To date, a laboratory model of adult-onset slip progression in isthmic spondylolisthesis does not exist. Previous studies showed that bilateral pars disruption alone failed to produce anterior slip at the affected segment. Disruption of the iliolumbar ligament also did not contribute to the s1ip at L5-S1. Studies in the literature suggest the progression of anterior slip in adults with L5-S1 isthmic spondylolisthesis would be influenced by: (i) the extent of load-bearing deficiency of the intervertebral disc caused by degenerative changes, and (ii) the magnitude of the shear/compressive force ratio at the lumbosacral joint. However, biomechanical studies investigating the combined effects of these factors on slip progression have not been carried out. The purpose of this study was to quantify the combined effects of (i) the load-bearing deficiency of the intervertebral disc and (ii) loading conditions in causing progressive anterior slip of the LS vertebra on sacrum in an isthmic spondylolisthesis.