XXXX and alignment in spondylolisthesis.

@entity1 @entity1515 @entity530
STUDY DESIGN AND OBJECTIVES: Pelvic morphology and @entity1515 were measured on standing radiographs of 75 @entity1 with greater than 10% L5-S1 spondylolytic spondylolisthesis. The findings were compared with those of 75 volunteers to determine significant differences between the two groups. SUMMARY OF BACKGROUND DATA: Etiology of isthmic (lytic) spondylolisthesis remains uncertain. Causation appears to be multifactorial. The relationship between pelvic morphology and spondylolisthesis deserves additional study. METHODS: Both groups had a standing lateral radiograph of the thoracolumbar spine and pelvis taken that included both hips. Three radiographic angles for pelvic morphology (pelvisacral, pelvic incidence, and @entity530 ) were measured by two observers. Each offered similar reliability. Measurement of the @entity530 angle by the pelvic radius technique required fewer steps. It also allowed calculation of the combined angles comprising both the pelvic morphology component for @entity1515 (the constant @entity530 angle) and the @entity1515 in the lumbar spine (the variable @entity1515 from T12-S1) that should complement the fixed @entity530 (the @entity1515 ). Mean values and statistical correlations were then computed for each group and compared. RESULTS: The mean slippage for @entity1 was 30% (range, 11-85%), with 34 @entity1 (45%) having Grade I slips, 32 (43%) having Grade II slips, and nine (12%) having Grade III and IV slips. The mean measurements between @entity1 and volunteers were significantly different (P < 0.01) for @entity1515 , @entity530 , and @entity1515 . Subgroups of @entity1 with increasingly larger slips (Grade I-III) had significantly smaller mean angles for @entity530 . CONCLUSIONS: The pelvic and lumbopelvic parameters studied were different in @entity1 compared with controls. The contribution of the pelvis to @entity1515 was significantly smaller in the subgroups of @entity1 with increasingly larger grades of spondylolisthesis. Pelvic morphology may play a role in the development of spondylolisthesis. Measurement of the combined lumbar and pelvic (lumbopelvic) @entity1515 on standing radiographs is important.
