Biomechanical examination of the thoracic spine—the axial rotation moment and vertical loading capacity of the transverse process

Abstract

Our objective was to examine the load-bearing capacity of the transverse processes of human cadaveric thoracic vertebrae to vertical loads and axial rotation moments (i.e., moment applied in the transverse plane). A secondary objective was to examine the effect of the attached rib stumps. We wanted to demonstrate that the transverse process is durable enough to support the CAB hook-a complementary hook to the CD system-and can handle the vertical load or axial rotation moment during correction of scoliosis. We used 107 thoracic vertebrae removed from 10 cadavers. They were prepared in vertebral pairs, and were fixed into a material testing apparatus. Superoinferior vertical loads and axial rotation moments were applied to the transverse process using the CAB hooks at a rate of 30 mm/min and 8.58/s respectively until it fractured. We recorded 142 measurements, 99 were for vertical load and 43 for axial rotation moment. The average ultimate vertical load was 338 (SD ¼ 128) N and the average ultimate axial rotation moment was 14.4 (SD ¼ 4.52) Nm. The ultimate axial rotation moment for specimens with rib stumps attached was significantly greater than for specimens without rib stumps 15.9 (SD ¼ 4.1) Nm versus 12.5 (SD ¼ 4.4) Nm. Our results showed that both the vertical and axial rotation loading capability of the transverse process are large enough to withstand significant correctional forces, without fracture, through the CAB hooks. ß

Adolescent idiopathic scoliosis correction achieved by posteromedial translation using polyester bands: A comparative study of subtransverse process versus sublaminar fixation

“…Patients with preoperative kyphosis < 20 • gained 12.7 • ± 10.5 • and 15.8 • ± 7.1 • in groups 1 and 2, respectively. This indicates that the thoracic transverse process is resistant enough to pull back the spine as reported by Csernatony in a biomechanical cadaveric study [27]. The greater leverage provided by the transverse process probably may explain why similar correction was achieved despite the fact that fewer bands were used in group 2.…”

Finite Element Analysis of an Improved Correction System for Spinal Deformity

“…In view of the above problems, a new concept of dynamic spinal internal fixation has been proposed. Recently, we designed a new improved spinal correction system (ISCS) (1) based on the Corhet à Appui Bilatéral (CAB) system invented by Csernátony et al (2)(3)(4). The advantages of ISCS over PSRS are that its surgical operations are simple, convenient, and safe, because only transverse processes or lamina in ISCS need to be exposed.…”

Intradiscal cement leakage (ICL) increases the stress on adjacent vertebrae after kyphoplasty for osteoporotic vertebra compression fracture (OVCF): a finite-element study

“…The load was applied as a uniform compressive pressure of 0.3 MPa on the superior endplate of T10. The standard load cases flexion–extension, axial rotation and lateral bending of the upper body were simulated by 15 Nm moment load on the finite element models 31 – 33 . Boundary conditions included constraining the base of the lower vertebral body (L2) in all degrees of freedom (U1 = U2 = U3 = UR1 = UR2 = UR3 = 0).…”