The Journal of Bone and Joint Surgery, Vol 75, Issue 11 1674-1684, Copyright © 1993 by Journal of Bone and Joint Surgery, Inc
A biomechanical analysis of decompression and reconstruction methods in the cervical spine. Emphasis on a carbon-fiber-composite cage
Y Shono, PC McAfee, BW Cunningham and JW Brantigan
Biomechanics Laboratory, Union Memorial Hospital, Baltimore, Maryland 21218.
Biomechanical analysis of three different patterns of instability--that
created by fifth and sixth cervical anterior discectomy, that created by
one-level (fifth cervical) anterior corpectomy, and that created by
two-level (fourth and fifth cervical) corpectomy--was performed in eighteen
calf spines. Three types of anterior reconstruction--anterior iliac strut
bone-grafting, use of an anterior carbon-fiber-composite cage packed with
cancellous bone graft, as well as use of polymethylmethacrylate
anteriorly--were cyclically tested in axial compression, torsion, and
flexion-extension. Each of these types of reconstruction was also tested
with supplemental posterior wire stabilization (the triple-wire technique
of Bohlman). Regardless of the type of anterior instability, the
carbon-fiber-reinforced cage packed with cancellous bone graft was more
rigid than the iliac bone graft alone. The cage resulted in good stiffness
in the axial compression and rotation tests and was the most rigid
construct in the flexion-extension tests. The superior aspect of the
polymethylmethacrylate constructs loosened at the bone-cement interface in
eight of the twelve specimens during flexion-extension testing. The
addition of the supplemental posterior wiring to the anterior constructs
provided additional rigidity in flexion-extension testing.