- Discussion:
- as slip progresses, area of contact between L5 & S1 decreases & body of L5 tilts forward on sacrum;
- this is referred to as sagittal rotation, angle of slipping, roll, L5/S1 kyphosis, or gibbus;
- slippage is not present in pts who have mild (
grade-I or II) spondylolisthesis, but is more common
in pts who have a
50 % slip & is always present in pts w/
75 % slip;
-
risk factors for slippage:
- preop slip angle > 35-40 deg;
- slip of more than 50%;
- kyphotic slip angle
- female;
-
dysplastic spondylolisthesis
- back pain;
- abnormal gait;
-
measurement:
- angle that is formed by extending a line along anterior border of body of L5 until it intersects
line that has been drawn along the posterior border of the body of first sacral vertebra;
- slip angle is measured by drawing a line perpendicular to line drawn along posterior aspect of first
sacral vertebral body and measurign angle between that and a line parallel to inferior end plate of L5;
