Anatomical distribution of vertebral fractures: comparison of pediatric and adult spines

Abstract

Summary: We compared the distribution of vertebral fractures in adults and children and found that fractures occurred in different locations in the two age groups. This likely relates to the different shape of the immature spine.

Introduction: We hypothesized that the anatomical distribution of vertebral fractures (VF) would be different in children compared to adults.

Methods: We compared the distribution of VF defined using the Genant semi-quantitative method (GSQ method) in adults (N = 221; 545 fractures) and in children early in the course of glucocorticoid therapy (N = 44; 94 fractures).

Results: The average age in the adult cohort was 62.9 years (standard deviation (SD), 13.4 years), 26% was male, the mean lumbar spine Z-score was -1.0 (SD, 1.5), and the corresponding T-score was -2.4 (SD, 1.4). The pediatric cohort median age was 7.7 years (range, 2.1-16.6 years), the mean lumbar spine Z-score was -1.7 (SD, 1.5), 52% was male, and disease categories were acute lymphoblastic leukemia (66%), rheumatological conditions (21%), and nephrotic syndrome (14%). The VF distribution was biphasic in both populations, but the peaks differed in location. In adults, the peaks were at T7/T8 and at T12/L1. In children, the focus was higher in the thoracic spine, at T6/T7, and lower in the lumbar spine, at L1/L2. When children were assessed in two age-defined sub-groups, a biphasic VF distribution was seen in both, but the upward shift of the thoracic focus to T6 was observed only in the older group, with the highest rates of fracture present between ages 7 and 10 years.

Conclusions: These results suggest that the anatomical distribution of VF differs between children and adults, perhaps relating to the different shape of the immature spine, notably the changing ratio of kyphosis to lordosis.

Fig. 1

Vertebral fracture distribution in children (solid circles) and adults (open circles). Peak locations are shown by solid arrows for children and dashed arrows for adults.

Fig. 2

Spinunculus. The probability ratio for the risk of fracture at each vertebra from T4 to L4 is expressed by the relative anteroposterior diameter of the schematic vertebral body in the sagittal plane. (a) Adults. (b) Children. (c) Young children (median age, 4.1 years; range, 2.1 to 6.4 years). (d) Older children (median age, 10.8 years; range, 7.2 to 16.6 years)

Fig. 3

Vertebral fracture distribution in relation to age. (a) Young children (solid circles; median age, 4.1 years; range, 2.1 to 6.4 years) compared to Older children (open circles; median age, 10.8 years; range, 7.2 to 16.6 years). (b) Proportion of children at each age having fractures at T6 (circles). For comparison is shown the kyphosis/lordosis ratio at different ages derived from the publication of Cil et al. (squares) [5]

Fig. 4

Forces on the vertebral body. (a) Body mass generates a torque with an anteriorly-directed component and a downward component centered on the vertebral body. This is countered by the paraspinal muscles that produce a posteriorly-directed force and a downward force. (b) The anteriorly- and posteriorly-directed forces cancel while the downward forces sum to create a net downward compressive force on the vertebral body.

Fig. 5

Comparison of our pediatric results with published data. Our pediatric data (solid circles) are compared to VF distributions of two published studies that used similar morphometric criteria: Nakhla et al. (solid triangles) [31] and Varonos et al. (open circles) [32].