Biomechanical stability of lower cervical spine immediately after discectomy with grafting.
OBJECTIVE
Anterior cervical discectomy is commonly used to treat radiculopathy and myelopathy. Although the size of the implanted graft may influence the clinical outcome of anterior reconstruction of the cervical spine, the ideal graft height remains arguable. The objective of the current study was to study the interrelations of graft height and immediate biomechanical stability in an anterior cervical discectomy model.


METHODS
Six fresh-frozen human cadaver cervical spines (C1-T1) were tested in five sequential states. The first state tested was the "normal" state (specimens with intact discs). The other four states were tested after C5-C6 discectomy by the Smith-Robinson graft technique, using graft thicknesses of 100%, 120%, 140%, and 160% of the baseline height. The baseline height was defined as the intervertebral disc height of C5-C6 at the intact stage. Intervertebral segment flexion, extension, bending and rotation of C5-C6 were recorded using a 3D laser scanner and analyzed using Geomagic Studio 5.0 software.


RESULTS
Bone grafting at 100% baseline height after discectomy provided the least stability and the greatest movement range. With increasing height of grafts, the movement range of the cervical spine declined. Immediate stability of the operated segments was significantly increased by grafting with 140% and 160% baseline heights compared to the baseline height condition.


CONCLUSIONS
Strut-graft with appropriate distraction after Smith-Robinson anterior cervical discectomy plays an important role in the whole immediate biomechanical stability of the lower cervical spine. A graft height of 40% greater than baseline may be ideal after single discectomy in clinical practice.
Department of Orthopaedic Surgery, Weihai Municipal Hospital, China.
De-zhen
DZ
Yin
Xiao-tang
XT
Xin
Rui
R
Yang
Yu-peng
YP
Shi
Hui-yong
HY
Shen
D000328:Adult; D016025:Bone Transplantation / Q000379:methods*; D002102:Cadaver; D002574:Cervical Vertebrae / Q000502:physiology* / Q000601:surgery; D017586:Diskectomy / Q000379:methods*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008875:Middle Aged; D016059:Range of Motion, Articular / Q000502:physiology; D013123:Spinal Fusion / Q000379:methods; D016896:Treatment Outcome