From the Texas Back Institute in Plano, Texas.
BONE QUALITY
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A Comparative Review of Lumbar Bone Density Measurement Techniques and Additional Applications The evaluation of vertebral bone density prior to spinal instrumentation is a critical component of the preoperative assessment. Instrumentation of osteoporotic bone can result in complications such as pedicle screw pullout, device subsidence, or device migration.1-5 A growing area of research focuses on screening lumbar bone prior to spinal surgery and may yield great benefits to patients in reducing instrumentation complications. Dual-energy x-ray absorptiometry (DEXA) has been the gold standard for assessing lumbar bone densit y and classifies bone as either normal, osteopenic, or osteoporotic.6,7 In light of potential shortcomings in DEXA’s lumbar composite values, alternative imaging for bone density measurements have been investigated, such as computed tomography (CT) Hounsfield units (HU), quantitative computed tomog raphy (QCT), and mag net ic resonance imaging (MRI) vertebral bone quality (VBQ). 8,9 In a prev ious issue of Vertebral Columns,10 we explained how to acquire and inter pret t hese lumbar bone density measurements. In the
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present article, we discuss the literature comparing lumbar bone density measurement techniques and present additional applications of these measurements for spinal surger y. A considerable number of studies have provided evidence that indicate promising alternatives to DEX A for measuring lumbar bone quality.
CT HU and QCT Lumbar Measurements Multiple studies have tested CT HU as a measure of bone density in comparison to DEXA bone mineral density (BMD) values. Viswanathan et al reported a significant correlation between CT HU and DEXA T-scores at the upper lumbar levels (L1-L3) in patients who underwent 1-2 level lumbar fusions.11 The opportunistic availability of CT measurements may provide reasonable identification of osteoporosis, but not all studies agree. Kohan et al found a low to moderate correlation between CT HU measurements and femoral neck DEX A BMD values in patients with adult spinal deformities.12,13 In addition, the cutoffs for defining osteoporotic versus osteopenic or normal
Emily C. Courtois, MS
Mary P. Rogers-LaVanne, PhD
Peter B. Derman, MD, MBA
Alexander M. Satin, MD
Vertebral Columns
Fall 2023
