TLIF at L5 to S1 + PS + DDS, and AxialITR at L5 to S1 + PS + DDS. Specimens were destabilized by performing a complete denucleation at L5 to S1 and sectioning 2/3 of the annulus' width from anterior to posterior. The S1 PSs were instrumented with strain gauges to measure screw-be...