INTRODUCTION
Patients with lumbar spinal disorders (LSDs) often have several comorbidities. Among them, metabolic syndrome has been reported as a potentially implicated disease of lumbar spinal canal stenosis. It is speculated that reduced physical activity due to lumbar spinal canal stenosis mediates the development of metabolic syndrome. Lumbar spine surgery for patients with LSDs has been shown to benefit pain, motor function, social life, psychological well-being, and healthy life expectancy. However, it is still unclear how lumbar spinal surgery affects the lipid metabolism of patients with LSDs. The present study aimed to assess the impact of lumbar spinal surgery on lipid metabolism in patients with LSDs and clarify the factors associated with changes in visceral fat (VF) accumulation before and after lumbar spinal surgery.
METHODS
Consecutive patients with lumbar spinal surgery for LSDs were prospectively included. Abdominal computed tomography images, blood examination of the participants and clinical outcome assessments were evaluated before surgery and at 6 months and 1 year after surgery. The cross-sectional VF area (VFA) was measured at the level of the navel using computed tomography images. Patients were divided into four groups according to whether they had an increased or decreased VFA one year after surgery and whether their preoperative VFA was ⩾ or < 100 cm2. Blood examination items included triglycerides and high-density lipoprotein (HDL). The Zurich Claudication Questionnaire (ZCQ) and the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) were used for clinical outcome assessment.
RESULTS
The study enrolled a total of 138 patients. The correlation coefficient between participants preoperative VFA and preoperative BMI was 0.62, indicating a moderate correlation.Overall, patients with LSDs tended to have increased VFA and increased triglyceride and decreased HDL levels on blood examination after lumbar spinal surgery. Female patients with LSDs had significantly increased VFA and serum triglyceride levels after lumbar spinal surgery. No significant changes were seen in men. There were no significant differences among the four groups in the preoperative scores for each domain of the JOABPEQ or in the frequency of effective cases of surgical treatment in each domain of the JOABPEQ. On multivariable analysis, the group with > 100 cm2 of preoperative VFA and a postoperative decrease in VFA had a significantly worse preoperative walking ability based on JOABPEQ (relative risk 2.1; 95% confidence intervals 1.1–4.1).
DISCUSSION
The present study demonstrated that patients with LSDs did not necessarily improve their lipid metabolism after lumbar spinal surgery. Instead, female patients with LSDs had significantly deteriorated lipid metabolism after lumbar spinal surgery. Finally, a worse preoperative walking ability was associated with the improvement in excess VF accumulation after lumbar spinal surgery.