1205 The Coronal Plane Matters: An Evaluation of Primary Coronal Cobb Correction for Adult Spinal Deformity using Pre-Bent Sagittal Contoured Rods

INTRODUCTION: Patient specific rods (PSRs) are pre-bent to post-spinal fusion sagittal alignment goals. Adult idiopathic and degenerative scoliosis cause large and rigid coronal deformities. Whether a sagittaly-derived PSR detracts from coronal correction is unknown. METHODS: Patients > 18 years-old with idiopathic/degenerative scoliosis receiving posterior instrumented fusion from a single surgeon/single institution were reviewed. Prior fusions > 2 levels were excluded; fusion >6 levels using PSRs with a UIV/LIV greater than T1/L1 were included. All patients had at least one coronal Cobb angle > 20°. Demographics, operative/inpatient variables were recorded. Post- versus pre-operative primary Cobb angle and sagittal alignment were compared. Restoration of primary coronal Cobb was evaluated in multivariable regression model with scoliosis type, +/- apex PCOs, and end-sagittal alignment deviation from the plan. RESULTS: 33 patients were included; average age was 61.1±16.7; 25 were female (25/33, 75.8%). BMI averaged 26.5 ± 4.3kg/m2. Degenerative scoliosis was more common than idiopathic (22/33, 66.7%). Average pre-op PI, lumbar lordosis (LL), and pelvic tilt (PT) were 56.0 ± 13.7°, -48.1 ± 16.0°, and 21.6 ± 9.5°, respectively. T5-T12 kyphosis was 33.3 ± 17.0°. Most frequent primary Cobb angles were thoracolumbar (38.1 ± 10.5°, 30/33, 90.9%.). 9.7 ± 3.1 levels were fused/case; coronal apex PCOs were performed in 29/33 cases (87.8%). Primary Cobb angle reduced 58.8± 27.7% to 15.0 ± 9.7° post-op. Final LL was less than planned (mean 4.3°, 95% CI[.91 -7.7], p = 0.01); PT and T5-T12 kyphosis were similar to the plan (mean 4.9°, 95% CI[-.95 -10.7], p = 0.9; mean 2.5°, 95% CI[-1.0-6.0], p = 0.16). On multivariable analysis, primary Cobb change was significantly correlated with the initial Cobb angle (r2 = .48, p = .01). PCO location/number and end-sagittal alignmetn deviatino from the plan were not significant. CONCLUSIONS: Significant primary coronal Cobb restoration from PSRs is achieved in tandem with sagittal realignment.