Delineation of Alignment Goals for Adult Cervical Deformity Correction for Optimal Clinical and Functional Outcomes

Introduction: Surgical correction of cervical deformity (CD) can restore alignment and function but carries higher risk of complications and subsequent failure. It remains unclear which baseline and postoperative radiographic parameters correlate with improved HRQL metrics and minimized complications.

Methods: Operative CD patients with a UIV above C7 and with pre-(BL) and at least 2-year (2Y) postoperative radiographic/HRQL data were included. CD defined as ≥1 of: C2-C7 lordosis<-15°, TS-CL>35°, segmental cervical kyphosis>15° across any three vertebrae between C2-T1, C2-C7 SVA>4 cm, McGregor’s slope>20°, or CBVA>25°. An optimal outcome defined as no DJF and meeting Virk et al.’s criteria for good clinical outcome [≥2 of NDI < 20 or meeting MCID, mild myelopathy (mJOA≥14), NRS-Neck≤5 or improved by ≥2 points from BL]. Regression analysis and Chi-squared Automatic Interaction Detector (CHAID) identified BL and 3-month postoperative radiographic thresholds predictive of an optimal outcome.

Results: 340 patients met inclusion criteria (Age=57.5±10.8 years, 48% F, BMI=29.1±6.6 kg/m2, CCI=0.81±1.2) and underwent surgery (levels fused=5.0±3.6, EBL=496 mL, OR time=277 min). Mean BL radiographic parameters: SS=35.5°, PT=18.5°, PI-LL=-0.3°, SVA=0.1 mm, T2-T12 kyphosis=-37.3°, T1S=29.2°, C2-C7 lordosis=-6.1°, TS-CL=29.4°, C2S=30.7°, cSVA=29.0 mm, C2-T3=-10.6°, and C2-T3 SVA=53.5 mm. Mean BL HRQLs: NRS back=6.0, NRS neck=7.3, NDI=56.3, mJOA=12.9, and EQ5D=5.8. At 1Y, 79 patients (23.2%) met optimal outcome criteria, and 55 (16.2%) met criteria at 2-3Y. Regression analysis with CHAID identified these radiographic thresholds predictive of an optimal outcome: BL T1S≤18.3º (OR=3.2, 95%CI [1.63-6.27], p<.001), 3M T1S≤31º (OR=16.3, 95%CI [1.94-145.95], p = 0.012), and 3M C7-S1 SVA≤ 38º (OR=44.4, 95%CI [4.55-432.22], p = 0.001).

Conclusion : This study suggests novel baseline radiographic thresholds and postoperative realignment goals associated with favorable functional/clinical outcomes in patients undergoing surgery for CD.