Ultrasound bone densitometry and dual energy X-ray absorptiometry in patients with spinal cord injury: a cross-sectional study

Abstract

Bone is lost following spinal cord injury (SCI) and in the long-term may become osteopenic and liable to fracture. Two non-invasive techniques, ultrasound bone densitometry (USBD) and dual energy X-ray absorptiometry (DXA), have been applied to monitor bone changes after spinal injury. 31 SCI patients were scanned using an ultrasound bone densitometer, to give measurements of speed of sound (SOS), broadband ultrasound attenuation (BUA) and 'stiffness'. The time since injury of these patients ranged between 5 weeks to 36 years with a mean of 5.87 ± 10.21 years. Ultrasonic properties at the calcaneus of these patients were significantly lower than the healthy reference population, and a rapid decline in ultrasound properties occurred in the first 3 months. The fall continued up to 54 months but at a slower rate. The normal linear relationship between SOS and BUA was not altered by SCI. Eighteen patients had DXA measurements at the lumbar spine and the right proximal femur. Bone mineral density (BMD) at the femoral neck was significantly lower than the normal reference population (P < 0.05). SOS and 'stiffness' correlated significantly with BMD at the lumbar spine, Ward's triangle, the femoral neck, the greater trochanter and the intertrochanteric site (P<0.05). BUA correlated significantly at all these sites with the exception of the trochanter. A negative correlation was found between the ultrasonic properties at the calcaneus and BMD at the lumbar spine which is in contrast to the positive relationship in normal subjects. There was a tendency for BMD to increase at the lumbar spine after the first 12 months after injury, although this trend was not significant overall. The 'stiffness' at the calcaneus and BMD at the femoral neck were lower than the reference population following 12 months since injury. These results show that bone deficit at the calcaneus occurs rapidly and to a severe degree after SCI, and that ultrasound has an important role to play in the assessment of bone status in these patients.

DEXA: a practical and accurate tool to demonstrate total and regional bone loss, lean tissue loss and fat mass gain in paraplegia

“…19,20 This technique has been used in assessment of SCI and appears to be tolerated well by this population. 1,2,21 DEXA provides a precise and accurate measure of body composition, and unlike chemical testing, hydrodensitometry or anthropometry, gives a regional distribution of bone, fat and lean tissue mass. 19,22 The present short study was undertaken to examine bone and soft tissue changes, using DEXA, in a small group of male paraplegics in comparison with age-and height-matched able-bodied controls.…”

Dual-energy X-ray absorptiometry overestimates bone mineral density of the lumbar spine in persons with spinal cord injury

“…[1][2][3][4][5][6] Of note, the literature is replete with reports of cross-sectional studies that have found, contrary to the extremities and other bony structures, that the vertebral column does not seem to lose bone mass after paralysis but, rather, tends to gain bone mass with age and/or longer duration of injury. 1,[7][8][9][10][11] Various mechanisms have been proposed to explain why the vertebral spine does not lose bone mass, and these include continued application of gravity-related forces, the effects of prolonged seated posture and a different mechanical function of the spine than that of the limbs. Two reports have previously challenged the notion that the vertebral bodies are spared from bone loss after paralysis.…”

Sequential Changes of Bone Metabolism in Normal and Delayed Union of the Spine

“…The factors that affect bone metabolism after fracture are the invasiveness of surgery, the period of bed rest, the degree of fracture, immobilization, and the process of fracture healing [7,12,17,26,31]. In our study groups, there were no differences in the period of bed rest and BMD of the femoral neck.…”