Research Fellow NYU Langone Health Paterson, New Jersey, United States
Introduction: Research has been concentrated on cervical deformity realignment thresholds for achieving desired clinical outcomes while decreasing worrisome complications, like distal junctional failure (DJF) and reoperation. The present study aims to establish a hierarchical order for realignment of spinopelvic parameters during ACD surgery.
Methods: Included: Operative CD pts with up to 2-year(2Y) HRQL data. Outcome variables: distal junctional kyphosis(DJK) and failure(DJF), reoperation, and Virk et al Good Clinical Outcome: [Meeting 2 of 3: 1) an NDI>20 or meeting MCID, 2) mJOA >=14), 3) an NRS-Neck<=5 or improved by 2 or more points from baseline]. Optimal Outcome was defined as meeting Good Clinical Outcome without developing DJF or undergoing reoperation. Descriptive analysis identified cohort demographics and radiographic parameters. Using conditional inference tree (CIT) analysis, thresholds for each parameter were derived based on meeting Optimal Outcome. ANCOVA, controlling for age and baseline deformity, assessed outcome rates in patients meeting the hierarchical realignment.
Results: 133 ACD patients (61.8±9.9yrs, 27.6±5.8 kg/m2, CCI: 1.0±1.4, CD-FI: 0.4±0.1) who underwent surgery (7.6±4.0 levels fused, EBL:781±853 mL, op time: 383±218 min, LOS: 5.9±4.4 days) were included. Twenty percent underwent an anterior approach, 46% posterior, 34% combined. After correction, there was a significant difference in meeting Optimal Outcome when correcting C2 Slope below 10° (85%vs.34%,p <.001), along with lower rates of DJF (7%vs.42%,p <.001). Next, after isolating patients above the C2 Slope threshold, correction of T1 Slope below 26° demonstrated lower rates of DJK and higher odds of meeting Optimal Outcome (OR:4.2,p=.011). The best third step was correction of cSVA below 35 mm. This hierarchical approach (11% of cohort) led to significantly lower rates of DJF (0%vs.15%,p <.007), reoperation (8%vs.28%,p <.001), and higher rates of meeting Optimal Outcome (93%vs.36%,p <.001), and maintained significance after controlling for age and baseline deformity.
Conclusion : This ordered realignment of cervical parameters has demonstrated strong correlation to HRQL metrics and complications. Correction of C2 slope should be prioritized during cervical deformity surgery, with subsequent correction of T1 slope and cervical SVA below the derived thresholds. Amongst the numerous radiographic parameters used in cervical deformity, these findings help the surgeon prioritize realignment in certain parameters to achieve successful outcomes.
