Characteristics of the DXA Measurements in Patients Undergoing Lumbar Fusion for Lumbar Degenerative Diseases: A Retrospective Analysis of Over 1000 Patients

Abstract

To explore the characteristics and reliability of dual-energy x-ray absorptiometry (DXA) measurements in patients undergoing lumbar fusion for lumbar degenerative diseases (LDD). Patients and Methods: A total of 1041 patients aged ≥50 years undergoing lumbar fusion for LDD were reviewed. The BMDs and T-scores of DXA were retrospectively analysed. The diagnosis of osteoporosis was in accordance with World Health Organization (WHO) criteria. Based on the guidelines of International Society for Clinical Densitometry (ISCD), an abnormal lumbar segment is identified as having unreliable T-scores when there is more than a 1.0 T-score difference between two adjacent vertebrae. Results: The prevalence of osteoporosis diagnosed on DXA was 42.3%, and it was higher in women than in men (50.2% vs 31.8%, P < 0.001). Increasing age resulted in higher prevalence of osteoporosis in females. The prevalence of osteoporosis significantly declined with increasing BMI. The lowest lumbar T-score was mostly found at L1. Unreliable T-scores were mostly seen in the lower lumbar segment (L3-L4) and were the least common in L1-L2. The average amount of abnormal lumbar segments increased with age (P = 0.003) and BMI (P = 0.021). Furthermore, those with degenerative lumbar scoliosis had more abnormal segments (P < 0.001). Of the 95 patients with at least one fractured vertebra, 39 (41.1%) were not diagnosed as having osteoporosis on lumbar DXA. Conclusion: Female, older age and low BMI are the risk factors for osteoporosis in patients undergoing lumbar fusion for LDD. Lower lumbar segments, such as L3-L4, are more likely to have unreliable T-scores. Patients with older age, higher BMI or degenerative scoliosis have more abnormal segments with unreliable T-scores. Lumbar DXA measurements are not sensitive enough to identify patients with vertebral fracture.

Opportunistic CT-Based Hounsfield Units Strongly Correlate with Biomechanical CT Measurements in the Thoracolumbar Spine

“…In addition, DXA-based measures of BMD are known to be less accurate in certain populations, such as obese patients or those with severe degenerative changes in the spine. 18,19,31,32 To address these limitations, newer methodologies have been developed to assess vertebral strength, including BCT analysis, 21,26,33 an FDA-approved diagnostic modality for osteoporosis testing. There has been increasing literature demonstrating that opportunistic BCT of the lumbar spine is more predictive of future spine fractures than DXA and might actually be superior in making this diagnosis in certain patient populations.…”

“…determine due to severe degenerative changes, prior instrumentation, deformity, 17 and even aortic calcification, all common in the degenerative spine population. 18,19 Biomechanical computed tomography (BCT) analysis, which involves constructing a finite element model of bone from calibrated CT data to measure vertebral strength and trabecular BMD, has recently emerged as a new Food and Drug Administration (FDA)-approved modality for assessing bone strength and fracture risk and was endorsed by the International Society for Clinical Densitometry in their 2019 guidelines. 20 Opportunistic CT-based Hounsfield units (HUs) have gained increasing attention as another tool for providing BMD estimates in the spine.…”

Evaluation and analysis of surgical treatment for single-level or multi-level lumbar degenerative disease based on radiography

“…With the aging of the population, the incidence of lumbar degenerative disease (LDD) is increasing ( 1 ). Transforaminal lumbar interbody fusion (TLIF) and posterior lumbar interbody fusion (PLIF) have become the standard and widely accepted treatments for patients with LDD, which includes spinal stenosis, lumbar spondylolisthesis, lumbar disc herniation, and degenerative scoliosis ( 2 , 3 ) when conservative measures have failed for at least six months ( 4 ). Many researchers have identified risk factors affecting surgical treatment, including old age, obesity, and anatomical structure, but no consensus has been reached ( 5 ).…”

Skeletal Status in Patients Scheduled for Elective Lumbar Spine Surgery: Comparison of Discectomy, Decompression, Fusion, and Revision

“…The frequency of osteoporosis in patients undergoing spine surgery ranges from 9.6 % to 42.3 % [8][9][10][11][12] , with heterogenous findings primarily attributable to risk profiles, sex and geographic factors. Nonetheless, it remains unclear whether differences in the frequency of low bone density as well as abnormalities in laboratory bone metabolism occur between different spinal conditions and surgical treatments.…”