The use of tapers in orthopaedic applications for the fixation of one implant component to another is well documented, such as in femoral head fixation to a hip stem. By providing sufficient interference between the two components, hoop stresses and friction forces are generated which hold the assembly together. Under normal physiological conditions, the spine is subjected to a variety of loading regimes, including tension, compression, torsion, bending, and combinations of all four. With the addition of instrumentation, these spinal loads are shared with the fixation device. The resulting construct must be strong enough to maintain correction of the spinal deformity during healing. To examine the strength of a spinal instrumentation system which includes the new locking mechanism of tapers, several tests were utilized, including flexion-extension, axial rod gripping capacity, torsional rod gripping capacity, anterior-posterior pull, and fatigue flexion-extension tests.