Introduction: Lumbar PSO (LPSO) is frequently used to correct sagittal spino-pelvic malalignment (SSM), however, proximal junctional kyphosis (PJK) and unfavorable reciprocal changes in the unfused thoracic spine may lead to poor postoperative sagittal alignment and loss of correction. Purpose: evaluate maintenance of sagittal spino-pelvic correction following LPSO based upon UIV in UT vs. TL regions.
Methods: Inclusion criteria: LPSO for SSM and distal fusion to the pelvis. Radiographic and HRQOL evaluation time points: preoperative and 6 week, 3 month, 6 month, 1 year and 2 year postoperative. Subjects stratified by UIV (UT vs TL). Sagittal alignment correction and correction maintenance evaluated and correlated with HRQOL values and sub-analysis performed for correction maintenance for patients with very high SVA >15 cm.
Results: 328 ASD patients met inclusion criteria. UT and TL had similar preoperative SVA and pelvic incidence/lumbar lordosis (PI/LL) mismatch. UT had greater preop pelvic tilt (PT; 33.4; p=.048). UT had lower SVA than TL at 6 week postop (11mm vs. 54mm; p<0.05), however beyond 6 week postop, all sagittal radiographic parameters were similar UT vs TL. UT and TL maintained similar sagittal correction through 2 years. UT and TL initially maintained threshold criteria good sagittal alignment (SVA<5cm, PT<25, PI-LL <11) however mean TL SVA was > 5cm at 1 year (5.3cm). HRQOL values were similar for UT vs TL for all time points except SRS-22 at 6 weeks (3.4 vs 2.6) and VAS at 1 year (5.2 vs 3.1).
Conclusions: Analysis of UIV location for LPSO procedures demonstrated UT and TL achieve and maintain acceptable sagittal correction, however, UT maintained better SVA correction (<5cm) than TL at 2 year postop. Both groups demonstrated loss of initial PT correction at 2 years postop. Long term evaluation will determine if these differences impact HRQOL values, complication and revision rates.
Patient Care: This research improves patient care by providing assessment of radiographic outcomes following two different surgical plans for correction of adult spinal deformity. These data may prove useful for surgical planning.
Learning Objectives: By the conclusion of this presentation, participants should: 1) understand that UIV in upper thoracic spine (UT; T2-T5) had better early sagittal alignment, better maintenance of sagittal correction and better maintenance of sagittal vertical axis <5cm than patients with UIV in the thoracolumbar (TL; T9-L1) region at 2 year follow up and 2) be aware that HRQOL scores were the same between UIV in upper thoracic spine and UIV in the thoracolumbar.