424 Facet Arthroplasty Composite Outcomes Remain Superior to Fusion in a Medicare-Eligible Cohort >65-Years Old

INTRODUCTION: Despite proven superiority in patient-reported outcomes and lumbopelvic parameters following total facet arthroplasty (TFA) in comparison to fusion for patients with lumbar spinal stenosis with grade I spondylolisthesis, criteria for adequate patient selection has remained under scrutiny for these devices. METHODS: 206 patients receiving TFA and 93 patients receiving TLIF were assessed at 24 months for overall composite clinical success using 5 domains: 1) reoperation/ the need for subsequent lumbar injections 2) major adverse events (e.g. device breakage, disassembly, screw loosening, or increase in spondylolisthesis grade) 3) reduction in ODI =15 points 4) new or worsening neurological deficits 5) fusion success. Groups were compared using both Fisher's exact test (for categorical age), and simple logistic regression (for continuous age) to evaluate the association of age and overall composite clinical success. RESULTS: Patients <65yo and =65yo did not have significantly different rates of overall composite clinical success following TFA (78.3% vs 67.9%, respectively, p = 0.286) or fusion (19.0% vs 30.8%, respectively, p=0.505); however, both populations attained higher rates of success with TFA compared to fusion (73.5% vs 23.5%, p<0.0001). The primary reason for failure in TFA patients =65yo was an adverse event due to screw loosening, device breakage, or disassembly (12%), versus 1.8% in patients <65 (p=0.052). The primary reason for failure of patients =65 was fusion failure (54.5%) which was consistently poor across age strata. CONCLUSIONS: TFA demonstrates superior composite clinical outcomes over fusion for single-level degenerative grade I spondylolisthesis regardless of age. Poor bone health is a crucial consideration for Medicare-age patients being evaluated for TFA and represents a common source of failure that should be considered in patients receiving both TFA and fusion.