Lumbar Scoliosis Induction in Juvenile Dogs by Three-dimensional Modulation of Spinal Growth Using Nickel-Titanium Coil Springs.

BACKGROUND: Current treatments for scoliosis have some defects and complications. To study spinal deformities and test novel scoliosis treatments, many animal models of scoliosis have been developed. These models applied a single load to the spine and could not precisely modulate the spinal growth in different dimensions. In this study, we applied posterior tethering in various directions with the application of nickel-titanium (NT) coil springs in dog's spine to modulate spinal growth in the coronal, sagittal, and transverse planes and create a scoliosis model possess curves that mimic adolescent idiopathic scoliosis (AIS) three dimensionally. METHODS: Scoliosis was surgically induced in eight 8-week-old female dogs (weight: 1.95-2.30 kg) using bone screws and NT coil springs. The deformity was induced through the placement of posterior NT coil springs that tethered the spine by bone screw fixation. All dogs were monitored with serial radiographs to document changes in deformities. RESULTS: All experimental animals developed scoliotic curves convex to the left in the lumbar segment. The mean coronal Cobb angle was 18.0° immediately postoperatively and 54.5° at 22 weeks. The mean lordosis increased from 6.2° postoperatively to 35.0° at final follow-up. Apical axial rotation increased from 4.5° postoperatively to 31.2° at 22 weeks. CONCLUSIONS: With the application of NT springs in dogs that allowed posterior tethering in various directions, lumbar spinal deformity was achieved in three planes: coronal, sagittal, and transverse planes. Notably, the lumbar spine in surgically treated dogs developed lordoscoliosis with obvious rotation and the curves mimic AIS three dimensionally well. This method allows lumbar scoliosis to develop without deep dissection of muscle and maintains the essential anatomical elements along the spinal curve. Moreover, the spinal growth modulation technique could yield information that would provide a basis for developing novel early-stage treatments for children with scoliosis.

[Study of rat lumbar vertebral endplate via micro computed tomography].

OBJECTIVE: To reconstruct the 3-dimensional (3D) models of vertebral endplate and internal canal structure based upon the micro computed tomography (MicroCT) scanning data and clarify the structural characteristics and changes of bone, canals and lumbar vertebral endplates with advancing age in SD rats. METHODS: Lumbar spines from male SD rats aged 3, 9 and 16 months (n = 15 each) were subjected to MicroCT scan. Mimics software was used to reconstruct the 3D models of lumbar vertebral endplate and internal canal structure. The bone volume fraction (BV/TV) of endplate was measured by CTAn software. RESULTS: The rebuilt 3D models of vertebral endplate showed that lumbar endplate was a thin layer of bone and the canals within vertebral endplate formed a ring-shaped canal network after reconstruction. Communicating branches existed between the adjacent canals. Every ring-shaped canal connected with trunk canals lying in the ventral and dorsal portions of endplate. The BV/TV of endplate in the ventral portion was lower than that in dorsal portion (ventral side: 79.9% ± 7.3%; dorsal side: 90.6% ± 6.2%, P < 0.05) and BV/TV increased with advancing age. CONCLUSION: The canals within rat lumbar vertebral endplate are not haphazard, but regularly arrayed to form a ring-shaped network of many circular canals, communicating branches and ventral and dorsal trunk canals. This canal network provides channels for blood vessels within endplate. The ratio of older rat canals decreases in endplate.