| Objectives: To observe whether a causal relationship exists between an L5/S1 isthmic spondylolisthesis and the symptoms of back pain. This study aimed at demonstrating that the pain from an L5/S1 isthmic spondylolisthesis occurs as a consequence of an alteration in the associated lumbosacral biomechanics rather than directly arising from the presence of the spondylolisthesis. Design. Cross-sectional survey of the patient records and radiological files in subjects who presented with spondylolisthesis and a grade one isthmic listing at L5/S1 . Setting.. X-rays were collected from Macquarie University outpatient clinics and private practice. Intervention.. Subjects were allocated to group 1 (n = 63) non-spondylolisthesis, group 2 (n = 57) symptomatic, and group 3 (n = 29) asymptomatic spondylolisthesis. Radiological measurements were made from x-rays using a standard protractor to measure the intervertebral disc (IVD) and the sacral base angles (SBA) . Results: A difference (p < 0.01) was observed between the mean SBA for the spondylolisthesis patients and the non-spondylolisthesis patients (ANOVA). The average SBA for the symptomatic and asymptomatic groups was significantly higher (p < 0:01) than the SBA for the non-spondylolisthesis group. The Iumbosacral or 1-5 disc angle for the spondylolisthesis patients was significantly smaller (p < 0.02) compared with non-spondylolisthesis patients. At L4, 88% of the symptomatic patients had hyperextension (+5.97, p < 0.02) compared WITH 66% in asymptomatic patients. Conclusions: There was a significantly greater incidence of hyperextension at L4/5 in symptomatic spondylolisthesis patients (88%), and the 1-5 disc angle in symptomatic subjects was significantly smaller than the other two groups, which is inconsistent with the trend currently described in the literature. This prevalence of facet hyperextension at L4/5 may represent another model for the symptoms experienced by spondylolisthesis patients. This abstract is reproduced with the permission of the publisher; full text by (print only) subscription.
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