The impact of a corrective tether on a scoliosis porcine model: a detailed 3D analysis with a 20 weeks follow-up

Abstract

Purpose Non-fusion treatment for adolescent idiopathic scoliosis generates interest due to the potential for growth preservation and mobility. Using an established porcine scoliotic model, this study aims to evaluate the global alignment and the morphology of the spine with and without application of a non-fusion corrective tether. Methods At 12 weeks of age, 21 immature Yorkshire pigs had an induction of scoliosis. Once a 50°Cobb angle was obtained; animals were placed into one of the following groups: a scoliosis model group (SM, n = 11) where animals were euthanized, tether release group (TR, n = 5) where the inducing tether was removed, and an anterior correction group (AC, n = 5) where the inducing tether was removed and non-fusion corrective tether was applied. TR and AC were observed for a further 20 weeks and then euthanized. Post-mortem CT scans were used to create 3D spinal reconstructions to obtain global and morphologic parameters. Results Maximal Cobb angle of the scoliotic deformity was significantly lower for AC (27.9°± 12.0°) than for the two other groups (TR 52.7°± 10.0°, SM 48.3°± 7.6°). AC experienced an increase in kyphosis (24.2°± 15.9°) compared to TR (7.1°± 6.4°). Correction in the axial plane was also observed in AC versus TR. Correction of vertebral wedging was found for AC compared to SM and TR in the three apical vertebrae.Conclusions 3D realignment of scoliotic curves was observed with application of the corrective tether. The correction was the product of both mechanical action and growth modulation. These findings are encouraging for future development of a non-fusion device for the treatment of immature scoliotic curves.

Utility of an allograft tendon for scoliosis correction via the costo‐transverse foreman

“…With regard to the establishment of scoliosis and natural progression, our results agreed with the previous studies . However, the rib fusion mass of the concave side resulted in a rigid spinal deformity similar to that encountered in congenital scoliosis; this fact compromised the tether correction in the scoliotic plane.…”

“…However, the rib fusion mass of the concave side resulted in a rigid spinal deformity similar to that encountered in congenital scoliosis; this fact compromised the tether correction in the scoliotic plane. Similar effects were also reported in the latest treatment study of the same animal model, in which the curves within the fusion mass were very stiff. This limitation helps to explain the limited correction obtained in this study.…”

“…After the first surgery, a modest spinal deformity on both the coronal and sagittal planes was confirmed as created by the initial surgery as expected. [17][18][19] Prior to the second surgery, a significant spinal deformity was established on both the coronal and sagittal planes ( Fig. 4C and G).…”

“…With regard to the establishment of scoliosis and natural progression, our results agreed with the previous studies. [17][18][19] However, the rib fusion mass of the concave side resulted in a rigid spinal deformity similar to that encountered in congenital scoliosis; this fact compromised the tether correction in the scoliotic plane. Similar effects were also reported in the latest treatment study 18 of the same animal model, in which the curves within the fusion mass were very stiff.…”

Recent Advances in the Management of Early Onset Scoliosis

“…73 Recent animal studies using anterolateral spinal tethering have been encouraging, showing that tethering may be a nonfusion option for larger curves that promotes correction to 3D alignment. 74,75 This technique is experimental and will require rigorous testing to determine specific indications and applicable patient populations. No testing has been completed in the EOS population.…”