Abstract
Introduction
It is generally believed that the restoration or improvement of sagittal spino-pelvic alignment may impact clinical outcomes of surgical treatment of high-grade isthmic spondylolisthesis. Little is known about the impact on low-grade slips. The purpose of the study was to determine whether clinical outcomes are correlated with the restoration or improvement of pelvic balance after surgical correction of low-grade isthmic spondylolisthesis.
Material and Methods
Prospective non-randomized study based on a single-institution series of consecutive patients with isthmic spondylolisthesis during a 10-year period from 2002–2012. 63 adult patients with a low-grade isthmic slip and adequate pre- and postoperative radiograms were available for measurement of spino-pelvic parameters and final assessment of their clinical outcomes. The latter were assessed at least 1 year after the surgery with the use of the Oswestry Disability Index (ODI) and a back pain visual analogue scale. Pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbosacral angle (LSA) and lumbar lordosis were measured on standing lateral view radiograms. We assumed postoperative reduction in pelvic tilt (PT) to reflect improvement in pelvic balance. The Spearman's rank correlation test was used to assess the correlation between the improvement in pelvic balance and the improvement in ODI and back pain. The Mann–Whitney U test was used to identify significant differences in clinical outcomes between patients (i) with a balanced and unbalanced pelvis postoperatively, (ii) who regained and did not regain pelvic balance postoperatively, (iii) who maintained and lost pelvic balance postoperatively, and (iv) with an improved (reduced PT) and worsened (increased PT) pelvic balance postoperatively.
Results
There were no significant differences in clinical outcomes between patients with a balanced and unbalanced pelvis postoperatively regardless of whether they lost, maintained, or regained pelvic balance after the surgery. However, we found a weak (R= -0.3) but statistically significant (p = 0.035) negative correlation between the degree of reduction in pelvic tilt and intensity of postoperative back pain and a weak (R=0.2) but statistically significant (p = 0.034) positive correlation between the degree of reduction in PT and reduction in back pain. No correlation was found between improvement in pelvic balance and quality of life
Conclusions
Postoperative reduction of pelvic tilt may impact improvement of rather back pain than quality of life in low-grade isthmic spondylolisthesis. The latter might be a result of rather neural decompression and stabilization of the affected segment than improvement of pelvic balance.