RESUMO
STUDY DESIGN: Open interventional MRI techniques were used to investigate the intervertebral mobility of the lumbar spine in subjects with isthmic and degenerative spondylolisthesis. The findings were compared with those in a published database of subjects with no history of low back pain. OBJECTIVE: To investigate patterns of intervertebral mobility in subjects with spondylolisthesis to determine the level of spinal instability in this population. SUMMARY OF BACKGROUND DATA: Subjects with spondylolisthesis have been considered to present with a special form of spinal instability. Consequently, this condition is frequently managed by spinal fusion. However, confusion exists regarding whether there is excessive motion at the level of the defect. METHODS: For this study, 29 subjects presenting to spinal clinics with spondylolisthesis (15 isthmic and 14 degenerative) were recruited and compared with an existing database of control subjects. The motion characteristics of these subjects in flexed and extended positions were investigated using interventional open MRI of known precision. In all the subjects, the level of resting pain, the grade of slip, and the level of the defect were noted. RESULTS: No mobility differences, in terms of both angular and translational motion, were found between the subjects with spondylolisthesis and those with no history of low back pain, suggesting that subjects with spondylolisthesis do not present with either instability or hypermobility. CONCLUSION: A spondylolytic defect does not lead to detectable instability or hypermobility in the lumbar spine.