Spinal motion and intradiscal pressure measurements before and after lumbar spine instrumentation with titanium or PEEK rods

Spinal instrumentation and fusion have been incriminated as contributing to adjacent Segment degeneration (ASD). It has been suggested that ASD results from increased range of motion and intradiscal pressure (IDP) adjacent to instrumentation. Posterior dynamic stabilization with polyetheretherketone (PEEK) rods has been proposed as potentially advantageous compared to, rigid instrumentation with titanium (Ti) rods in reducing the incidence of ASD. We evaluated segmental motions' in the cadaveric Vim instrumented with PEEK or Ti rods from L3 to S1, as well as the adjacent segment motions and IDP at L1-2 and L2-3. Human cadaveric spines were potted at T12-L1 and S1-2. Spinal instrumentation: from L3-S1 was accomplished using pedicle screws with either PEEK or Ti rods. Specimens were subjected to. displacement controlled testing: 15 degrees flexion; 15 degrees extension, 10 degrees lateral bending, and 5 degrees right axial: rotation using the MTS machine (MTS, Minneapolis; MN; USA): Intradiscal pressure was measured: by placing pressure transducers into the intervertebral disc at L1-2 and L2-3. Spinal motion of L2 relative to L3, and L3 relative to S1 Was tracked using a three dimensional motion analysis system. Instrumentation with PEEK. and Ti rods was associated with a decrease in L3-S1 motion compared to the intact state that was significant in flexion (p = 0.002) and extension was significant in flexion (p = 0.0028. Instrumentation with either PEEK or Ti rods resulted in decreased motion at the instrumented levels while increasirig IDP at the adjacent level. Published by Elsevier Ltd.