Biomechanical evaluation of posterior thoracic transpedicular discectomy.
OBJECTIVE
The authors investigated the biomechanical properties of transpedicular discectomy in the thoracic spine and compared the effects on spinal stability of a partial and total facetectomy.


METHODS
Human thoracic specimens were tested while intact, after a transpedicular discectomy with partial facetectomy, and after an additional total facetectomy was incorporated. Nonconstraining pure moments were applied under load control (maximum 7.5 Nm) to induce flexion, extension, lateral bending, and axial rotation while spinal motion was measured at T8-9 optoelectronically. The range of motion (ROM) and lax zone were determined in each specimen and compared among conditions.


RESULTS
Transpedicular discectomy with and without a total facetectomy significantly increased the ROM and lax zone in all directions of loading compared with the intact spine (p < 0.008). The segmental increase in ROM observed with the transpedicular discectomy was 25%. The additional total facetectomy created an insignificant 3% further increase in ROM compared with medial facetectomy (p > 0.2).


CONCLUSIONS
Transpedicular discectomy can be performed in the thoracic spine with a modest decrease in stability expected. Because the biomechanical behavior of a total facetectomy is equivalent to that of a medial facetectomy, the additional facet removal may be incorporated without further biomechanical consequences.
Deniz
Fatih Ersay
FE
Faculty of Medicine, Department of Neurosurgery, Gaziosmanpasa University, Tokat, Turkey.
Brasiliense
Leonardo B C
LB
Lazaro
Bruno C R
BC
Reyes
Phillip M
PM
Sawa
Anna G U
AG
Sonntag
Volker K H
VK
Crawford
Neil R
NR
D015502:Absorptiometry, Photon; D000328:Adult; D001696:Biomechanical Phenomena; D015519:Bone Density; D002102:Cadaver; D017586:Diskectomy / Q000379:methods*; D005260:Female; D006801:Humans; D007403:Intervertebral Disc / Q000502:physiology* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D016059:Range of Motion, Articular; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000502:physiology* / Q000601:surgery*; D016474:Weight-Bearing