OBJECTIVE: The aim of this study was to determine if there was a difference in the sacral base angle in females with spondylolysis compared with females without spondylolysis. This is a follow-up study to an earlier pilot program, in which the female sample size was too small.

DESIGN: Retrospective study utilizing upright neutral lateral lumbar radiographs of females with evidence of pars defects (test group) and upright neutral lateral radiographs of females with no evidence of pars defects (control group). The control group was age matched to the test group.

SETTING: Chiropractic college clinic.

INTERVENTIONS: None.

MAIN OUTCOME MEASURES: The sacral base angle was measured on each radiograph.

RESULTS: The mean sacral base angle was found to be 52.7 +/- 6.8 degrees (mean +/- SD) (n = 22) and 38.6 +/- 7.6 degrees (mean +/- SD) (n = 47) in the test and control groups respectively. This difference was found to be statistically significant (p < .001).

CONCLUSIONS: The study has determined that females with spondylolysis have a steeper sacral base angle than females without spondylolysis. It does not, however, indicate whether a larger sacral base angle is a cause or an effect of the spondylolysis. This study also suggests that there is virtually no difference in the sacral base angles between males and females with and without pars defects.

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