Abstract
BACKGROUND CONTEXT Previous studies reported that lumbar spine surgery has a negative effect on bone mineral density (BMD) in the lumbar spine. Dual X-ray absorptiometry (DXA) was generally used for following BMD change in these studie. However, DXA has several limitations for measuring BMD in the vertebrae with morphological changes and metal implants, which are often associated with lumbar spine surgery. Also, it is still unclear if this BMD change is caused by a local mechanical effect or a systemic physiological insult associated with the surgery. PURPOSE To investigate the change of BMDs in multiple adjacent vertebrae utilizing quantitative computed tomography (QCT). STUDY DESIGN/SETTING Retrospective cohort study at a single academic institution. PATIENT SAMPLE Consecutive patients who underwent posterior lumbar spine surgery with instrumentation between 2014-2017 and had both preoperative and secondary postoperative computed tomography of the lumbar spine between 6 to 12 months. OUTCOME MEASURES Regional trabecular vBMDs in the vertebral body by QCT. METHODS Institutional ethics board approval was obtained for this study. Volumetric bone mineral density (vBMD) measurements by QCT were conducted in L1 to S1 vertebral trabecular bone. The change of vBMD in the vertebrae one or two-level above the upper instrumented vertebra (UIV+1, UIV+2) and one level below the lower instrumented vertebra (LIV+1) were analyzed. Statistical analyses were conducted utilizing paired t-test, one-way/repeated-measures ANOVA, and Pearson's correlation test. The statistical significance level was set at p RESULTS A total of 91 patients met our inclusion criteria. Mean age (&± SD [range]) was 61.9 & 11.9; 55.6% of the patients were female. Median interval between the surgery and the secondary CT was 248 (180-364) days. Volumetric BMD (&± SD) in UIV+1 was 113.1 & ± 32.6 mg/cm &>3 & preoperatively and 102.4 & ± 32.2 mg/cm3 (percent change:-10.5 & ± 12.6%) postoperatively (p CONCLUSIONS Posterior lumbar fusion surgery negatively affected the regional vBMDs measured by QCT in adjacent levels. BMDs in UIV+1, UIV+2, and LIV+1 were equally affected by the surgery. Our finding suggests that the postoperative decrease of regional BMDs in the lumbar spine dominantly occurs in the early postoperative phase (within 6 months) and a systemic effect has a greater role, rather than a regional mechanical one, in this postoperative BMD decline. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.
Published Version
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