Original ArticleInfluence of Lumbar Lordosis on the Outcome of Decompression Surgery for Lumbar Canal Stenosis
Introduction
Sagittal spinal balance significantly affects the postoperative quality of life (QOL) of patients with spinal deformity.1, 2, 3, 4 Parameters such as sagittal vertical axis, lumbar lordosis, pelvic tilt, and spinopelvic harmony were shown to be correlated to postoperative QOL of patients with spinal deformity.1, 2, 3, 4, 5, 6 As sagittal spinal balance is such an important factor in lumbar surgery, it is quite probable that it also affects the outcome of decompression surgery.
In this respect, the question in the current study was whether sagittal spinal balance influences the outcome of decompression surgery for lumbar canal stenosis. The knowledge of such relationships, if present, would affect not only daily practice but also future clinical studies. So far, the literature has provided conflicting results. On one hand, some authors found a weak correlation between some sagittal parameters and preoperative status of patients.7 Some found a slight improvement of alignment correlated with improvement of QOL after decompression surgery.8 On the other hand, other authors found no relationship between preoperative sagittal vertical axis and outcome after decompression surgery.9, 10
One reason for this discrepancy may be that, in contrast to spinal deformity, overall sagittal spinal balance may be compensated in patients with lumbar canal stenosis.1, 6 For example, sagittal vertical axis was shown to underestimate the underlying problem in patients with lumbar canal stenosis.6 Based on this consideration, lumbar lordosis was chosen as the indicator of sagittal spinal balance in the present study. This parameter directly reflects the local alignment of the lumbar spine and is not influenced by compensation in other parts of the spine. Thus, the objective of the present study was to investigate the possible relationships between lumbar lordosis and outcome of decompression surgery in patients with lumbar canal stenosis. It was hypothesized that decreased lumbar lordosis before surgery would negatively affect the outcome of patients.
Section snippets
Materials and Methods
This was a prospective cohort study that was conducted with institutional review board approval. QOL was evaluated of patients undergoing decompression surgery for lumbar canal stenosis at a single institution during the period 2007–2011. All operations were performed with microsurgical unilateral laminotomy for bilateral decompression. Patient QOL was evaluated with the 36-item short form health survey (SF-36) questionnaire administered before surgery and at 3 time points (6 months, 1 year,
Results
During the study period, 85 patients underwent the above-described surgical procedure (Table 1). SF-36 data were available in 70 (82%) patients before surgery, 80 (94%) patients at 6 months after surgery, 73 (86%) patients at 1 year after surgery, and 57 (67%) patients at 2 years after surgery. Standing lumbar x-rays obtained before surgery and 6 months after surgery were available in all 85 patients.
Mean preoperative lumbar lordosis was 42.1° (SD = 16). It increased to 44.8° (SD = 17) at 6
Discussion
This study showed that a clear correlation exists between preoperative lumbar lordosis and postoperative QOL of patients with lumbar canal stenosis undergoing decompression surgery. The size of the slope of this correlation was large enough to be clinically significant; a 10° increase of lumbar lordosis was associated with about a 5-point increase in the average physical score and a 4-point increase in the bodily pain score, both in the better direction. The range of lumbar lordosis in the
Conclusions
This study of patients with lumbar canal stenosis undergoing decompression surgery showed that preoperative lumbar lordosis had a significant correlation with patients' postoperative QOL. Using some measures to improve lumbar lordosis may have a beneficial effect on these patients. This needs to be addressed in future studies.
Acknowledgments
The author thanks Shinsuke Yoshida, M.D., and Tomokazu Takahashi, B.A., for their assistance in data collection.
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Conflict of interest statement: The author declares that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.