The Effect of Neck Flexion on Measurement of Spinal Bone Mineral Density and the Need to Apply Head Positioners During Dual-Energy X-Ray Absorptiometry.

Abstract

Our purpose was to investigate any potential effect of neck flexion on measurement of spinal bone mineral density (BMD) through further reduction of spinal lordosis and whether it is necessary to apply a head positioner, in addition to a leg positioner, during dual-energy x-ray absorptiometry. Methods: Fifty-nine patients with no significant history of spinal disorders were recruited. A bone densitometry scan of the spine was obtained for all patients using a standard leg positioner in the supine position. Then, another scan of the spine was conducted using a small subnuchal cushion to flex the neck and, thus, straighten and minimize the lumbar lordosis. Parameters including the area, bone mineral content, BMD, and T and z scores for each lumbar vertebra (L1-L4) and for the total spine were extracted from the 2 scans and compared. Results: The mean age of the patients was 55.53 y (±11.86 y); 53 (89.83%) were female and 6 (10.17%) male. A statistically significant difference was found between corresponding values for area, BMD in L4, and total spine. The percentage change from a scan without a cushion to one with a cushion was 1.20% for L4 and 0.58% for the total spine. The percentage BMD change was -0.64% for L4 and -0.34% for the total spine. A change in diagnosis-from normal to osteopenia-occurred for only 1 patient. Conclusion: Use of a head positioner to flex the neck and thus minimize lumbar lordosis in dual-energy x-ray absorptiometry does not significantly affect the diagnosis or densitometric measurements from a clinical standpoint.