A Study Comparing Fusion Rates of Two Lumbar Fusion Procedures

Consecutive subjects who were treated with the transsacral lumbar interbody fusion or TLIF
procedures at least 2 years prior to the date the data is collected will be evaluated.

Inclusion Criteria:

- Adult 18 years of age or older

- Male or female subject that had previously received the transsacral two-level
procedure when used in conjunction with pedicle screw or facet screw fixation or
TLIF two-level procedure with unilateral or bilateral supplemental screw fixation
(e.g. pedicle screws, facet screws at L4-L5-S1 to treat pseudoarthrosis, spinal
stenosis, spondylolisthesis, or degenerative disc disease (DDD)

- Subject that was treated no less than 2 years prior to this evaluation with an
transsacral or TLIF procedure by the participating surgeons

- Subject that had a diagnosis that required a transsacral or TLIF procedure at the
L4-L5-S1 levels and did not require treatment at any other lumbar levels at the time
of surgery

Exclusion Criteria:

- Subject who did not receive the transsacral or TLIF procedure for fusion of L4-L5-S1

- Subject who received lumbar fusion procedures at levels other than L4-L5-S1 at the
time of surgery