Abstract
Introduction
Degenerative spondylolysthesis results from anteroposterior instability, giving rise to a facet remodeling, generally at the L4L5 level. For istmic lythihc spondylolydsthesis an intrinsic sacral deformity has been described (Antoniades Spine 2000, Díez-Ulloa Proc Geer 2007). This sacral kyphosis, if present could contribute to a disbalance scenario that would render L4 more prone to olysthesis.
Hypothesis
A sacral kyphosis S1S2 could be a contributing factor to degenerative spondylolysthesis at L4L5.
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 D). 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 D kyphosis +2° (minimum -14°; maximum +22°). There were statistically relevant differences between group C and group D.
Conclusion
An intrinsic sacral deformity might be a contributing factor to L4 degenerative spondylolysthesis in a degenerative environment.