Thoracic vertebral morphology in normal and scoliosis deformity in skeletally immature rabbits: A Longitudinal study

Abstract

Objective: To measure age-related changes in thoracic vertebral body heights (VBH) in skeletally immature normative and scoliotic rabbits to assess how VBH change during growth. To examine the potential link between the moment-arm of the rib tether and vertebral wedging as well as the sum of the curvature angles at the apical level (T7). To assess the correlation between the magnitude of initial spine curve and final spine curve in the scoliotic group. Methods: Eight healthy, skeletally immature normative New Zealand rabbits and ten skeletally immature scoliotic rabbits which underwent unilateral rib tethering were included retrospectively. Each rabbit was scanned at two to four time points (at 7, 11, 14 and 28 weeks). Three dimensional bone models of thoracic vertebrae (T1-T12) were digitally segmented and reconstructed. VBH were calculated using surface landmark points from each thoracic vertebra. Apical level (T7) ± 2 levels in scoliotic rabbits were compared to their corresponding levels and time points in the normative group. The moment-arms between the centroids of 2D projections of T3-T9 vertebral bodies and the line which connects the centroids of the end levels were calculated. Results: Bilateral left-right (L-R) symmetry and anterior-posterior (A-P) asymmetry were observed in normative VBH. Bilateral concave-convex (CC-CX) asymmetry and (A-P) asymmetry were observed in scoliotic VBH. No significant differences in growth rates were found between the normative and scoliotic groups. Vertebral wedging as well as curvature magnitude were positively correlated with the moment-arms. Conclusion: Unilateral rib tether applies compressive forces on both concave and convex sides, whereas compressive forces are lower on the latter. Knowing the

Part 1. Review and meta‐analysis of studies on modulation of longitudinal bone growth and growth plate activity: A macro‐scale perspective

“…An alternative means to induce asymmetric vertebral growth (and scoliosis) is unilateral rib tethering, which provides asymmetric longitudinal compression to vertebrae, altering the stress distribution. Alfraihat et al 20 used unilateral rib tethering in skeletally immature rabbits (age: 7-28 weeks) and reported a 5% reduction of T7…”

“…19 A study on immature rabbits found that T7 vertebral body height averaged 20 microns/day from ages 7 to 28 weeks. 20 In comparison, T1-T12 vertebral body heights in normative pediatric human subjects had considerably slower growth rates, ranging from 1.9 to 3 microns/ day. 21 Caudal vertebral (Cd7) growth plates of late-adolescent rats grow longitudinally at 30 microns/day, while proximal tibial growth plates of earlier-adolescent rabbits grow at a rate of 366 microns/day.…”

“…Data collected from all stress-normalized loading studies, and represented in (A) and (B) as described by the legend22,[31][32][33] [Color figure can be viewed at wileyonlinelibrary.com] normalized static and cyclic lateral loading have not been examined, nor has examination of these loading modes through the range of load magnitude, duration, frequency, amplitude, species, and anatomical location that exists in the longitudinal loading literature to produce a comprehensive comparison between longitudinal and lateral loading. Furthermore, effects of variations in fixation or force application methods may warrant further study; while studies employing external fixation above reported significant alterations in longitudinal growth, force application with rib tethering has been shown not to significantly alter longitudinal growth 20.…”

Predicting curve progression for adolescent idiopathic scoliosis using random forest model

“…Thoracic curves are more likely to progress than lumbar curves because of the inherent stiffness associated with the presence of the rib cage [ 30 , 31 ], and double major curves are more likely to progress than single curves [ 23 , 34 ]. Wedging of the intervertebral disc and adjacent vertebrae are also factors associated with severe spine curvature [ 5 , 24 , 29 , 35 – 37 ]. However, attempts to use each of these features individually as a prognostic factor for curve progression showed inaccurate (i.e., a high number of false positive and false negative) predictions [ 22 ].…”

Evaluation of thoracic vertebrae in healthy White New Zealand rabbit (Oryctolagus Cuniculus): Computed tomographic and morphometric study

“…Studies have also been performed on functional neuroanatomy of the domestic rabbit (Osofsky et al, 2007). Alfraihat et al (2020) studied thoracic vertebral morphology in normal and scoliosis deformity in skeletally immature rabbits: In longitudinal study, they examined changes in the VBH (vertebral body height).…”