To evaluate the biomechanical
characteristics of polyetheretherketone (PEEK) rods of 3.2 mm in
diameter for cervical spine by comparing with the traditional titanium
Six fresh cadaveric sheep
cervical spines (C3~C4) were used for this study. After intact specimens
had been tested, partial facetectomy was performed on the spine to
create a destabilized model. Subsequently, the destabilized spines were
instrumented with PEEK rods or Titanium alloy rods randomly.
Nondestructive biomechanical testing was conducted on each specimen to
evaluate the axial displacement, axial rigidity, micro-strain of
anterior vertebral body and intervertebral range of motion (ROM) in
flexion, extension as well as lateral bending.
ROMs in both the PEEK group and titanium group were significantly less
than that of the intact group (P<0.05) , while the ROM in the PEEK
group was greater than the titanium groups in lateral bending
(P<0.05) . In addition, the axial compression rigidity of the PEEK
group and titanium group was significantly higher than that of the
intact group (P<0.05) ,whereas the rigidity of the PEEK group was
significantly less than that of the titanium group (P<0.05) . In term
of micro-strain in C3, the PEEK group and the intact group were
significantly superior to the titanium group (P<0.05) , despite the
fact that no significant difference was noted between the PEEK group and
the intact group (P>0.05) .
The PEEK rod of 3.2mm in diameter does provide enough biomechanical stability for sheep cervical spine, associated with increased intervertebral compression stress over the titanium rod, which has potential to promote intervertebral fusion.