Pseudoarthrosis after thoracolumbar fusion in patients with Parkinson's disease.

Background: Pseudoarthrosis is the most common indication for revision in spinal deformity surgery. Parkinson's disease (PD) is associated with postural instability and sagittal and coronal plane deformities. Spinal fusion in PD has a high rate of complications. The risk factors for pseudoarthrosis in PD cases are yet to be elucidated. This study identifies operative and patient factors associated with pseudoarthrosis after thoracolumbar (TL) fusion in patients with PD. Methods: In this retrospective case-control study, adult PD patients who underwent posterior TL fusion at an academic center between 2017 and 2022 were retrospectively identified. Comorbidities, functional status, PD metrics, bone and muscle quality, indications, and construct-related factors were extracted. Fusion status was assessed via continuous osseous bridging on 1-year postoperative computer-aided tomography (CT) scan. Univariate analysis compared preoperative and intraoperative variables based on fusion status. Results: Fifty-nine patients were analyzed (27% pseudoarthrosis rate). Pseudoarthrosis was associated with screw loosening (53% vs. 16%, P=0.01) and mortality (90-day: 13% P=0.05; 1-year: 31% P=0.001). Tremor (87% vs. 54%, P=0.049), lower Hounsfield units (HU: 97 vs. 138, P=0.03), wheelchair use (25% vs. 5%, P=0.01), and trauma indications (38% vs. 5%, P=0.003) showed elevated risk of pseudoarthrosis. There were no differences in fusion rates based on PD duration, PD medications, psoas muscle area, non-traumatic indications (spondylolisthesis, deformity), interbody utilization, construct length, and bone morphogenic protein usage (P>0.05). Conclusions: PD remains a major risk factor for poor outcomes after TL spinal fusion. Wheelchair use, lower HU, essential tremor, and trauma patients increased pseudoarthrosis rate. Pseudoarthrosis was associated with increased mortality.