Abstract
Introduction
A deformity in the sacrum has been reported in patients with spondylolysthesis (Antoniades, Spine 2000)
Hypothesis
Besides sagittal profile, the sacrum in itself is deformed, probably due to a fixed point in the sacoiliac joints acting as fulcrum and deforming force from ventral displacement of gravity line.
Matherial and Methods
A control group (group C), matchable for age and gender, was compared with a series of 83 patients with L5 istmic lythis spondylolysthesis (group A), which was later subdivided in low grade (Meyerding types I and II, group A1, n = 67) and high grade (Meyerding III or IV, group A2, n = 16)
Variable
Proximal sacral kyphosis measured by the angle formed by the S1 posterior wall and the S2 posterior wall, if S1 was kyphotic on S2 then it was considered a positive angle, other wise being negative.
Statistics
SPSS 21.0, working with means or medians and appropriate tests after studying whether the variable showed a normal distribution.
Results
Group C lordosis -2° (minimum -8°; maximum +7°). Group A kyphosis +10° (minimum -11°; maximum +30°). And then: Group A1 kyphosis +10° (minimum -11°; maximum +30°). Group A2 kyphosis +15° (minimum +5°; maximum +26°). There were statistically relevant differences between group C and group A and also between groups A1 and A2.
Conclusion
Besides spinopelvic balance issues, there is an intrinsic deformity in the sacrum of patients with L5 istmic lythic spondylolysthesis, even more in high grade lysthesis.