The transacral lumbar interbody fusion (including 1L+ and 2L+) is a minimally invasive technique that uses a transacral approach to achieve fusion at the L5-S1 or L4-L5-S1 spinal levels. The transforaminal lumbar interbody fusion (TLIF) is performed by using a posterior unilateral or bilateral incision in which the lumbar spine is accessed. Both study procedures are approved for use and conform to US regulatory requirements. The study employs these procedures and devices for uses that are consistent with their 510(k), legally cleared, labeling.