Do the newly proposed realignment targets for C2 and T1 slope bridge the gap between radiographic and clinical success in corrective surgery for adult cervical deformity?

Lara Passfall; Tyler K Williamson; Oscar Krol; Jordan Lebovic; Bailey Imbo; Rachel Joujon-Roche; Peter Tretiakov; Katerina Dangas; Stephane Owusu-Sarpong; Heiko Koller; Andrew J Schoenfeld; Bassel G Diebo; Shaleen Vira; Renaud Lafage; Virginie Lafage; Peter G Passias

doi:10.3171/2022.2.SPINE211576

Do the newly proposed realignment targets for C2 and T1 slope bridge the gap between radiographic and clinical success in corrective surgery for adult cervical deformity?

J Neurosurg Spine. 2022 Apr 15;37(3):368-375. doi: 10.3171/2022.2.SPINE211576. Print 2022 Sep 1.

Authors

Lara Passfall^{1

2}, Tyler K Williamson^{1

2}, Oscar Krol^{1

2}, Jordan Lebovic^{1

2}, Bailey Imbo^{1

2}, Rachel Joujon-Roche^{1

2}, Peter Tretiakov^{1

2}, Katerina Dangas³, Stephane Owusu-Sarpong^{1

2}, Heiko Koller⁴, Andrew J Schoenfeld⁵, Bassel G Diebo⁶, Shaleen Vira⁷, Renaud Lafage⁸, Virginie Lafage⁹, Peter G Passias^{1

2}

Affiliations

¹ 1Departments of Orthopaedic and Neurologic Surgery, NYU Langone Orthopedic Hospital, New York, New York.
² 2New York Spine Institute, New York, New York.
³ 3University of Oxford, United Kingdom.
⁴ 4Department of Neurosurgery, Technical University of Munich, Klinikum rechts der Isar, Munich, Germany.
⁵ 5Department of Orthopaedic Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
⁶ 6Department of Orthopedics, SUNY Downstate, Brooklyn, New York.
⁷ 7Department of Orthopaedic Surgery, University of Texas Southwestern Medical Center, Dallas, Texas.
⁸ 8Department of Orthopedics, Hospital for Special Surgery, New York, New York; and.
⁹ 9Department of Orthopedics, Lenox Hill Hospital, Northwell Health, New York, New York.

PMID: 35426823
DOI: 10.3171/2022.2.SPINE211576

Abstract

Objective: Surgical correction of cervical deformity (CD) has been associated with superior alignment and functional outcomes. It has not yet been determined whether baseline or postoperative T1 slope (T1S) and C2 slope (C2S) correlate with health-related quality-of-life (HRQoL) metrics and radiographic complications, such as distal junctional kyphosis (DJK) and distal junctional failure (DJF). The objective of this study was to determine the impact of T1S and C2S deformity severity on HRQoL metrics and DJF development in patients with CD who underwent a cervical fusion procedure.

Methods: All operative CD patients with upper instrumented vertebra above C7 and preoperative (baseline) and up to 2-year postoperative radiographic and HRQoL data were included. CD was defined as meeting at least one of the following radiographic parameters: C2-7 lordosis < -15°, TS1-cervical lordosis mismatch > 35°, segmental cervical kyphosis > 15° across any 3 vertebrae between C2 and T1, C2-7 sagittal vertical axis > 4 cm, McGregor's slope > 20°, or chin-brow vertical angle > 25°. Spearman's rank-order correlation and linear regression analysis assessed the impact of T1S and C2S on HRQoL metrics (Neck Disability Index [NDI], modified Japanese Orthopaedic Association [mJOA] scale, EuroQOL 5-Dimension Questionnaire [EQ-5D] visual analog scale [VAS] score, and numeric rating scale [NRS]-neck) and complications (DJK, DJF, reoperation). Logistic regression and a conditional inference tree (CIT) were used to determine radiographic thresholds for achieving optimal clinical outcome, defined as meeting good clinical outcome criteria (≥ 2 of the following: NDI < 20 or meeting minimal clinically important difference, mild myelopathy [mJOA score ≥ 14], and NRS-neck ≤ 5 or improved by ≥ 2 points), not undergoing reoperation, or developing DJF or mechanical complication by 2 years.

Results: One hundred five patients with CD met inclusion criteria. By surgical approach, 14.7% underwent an anterior-only approach, 46.1% a posterior-only approach, and 39.2% combined anterior and posterior approaches. The mean baseline radiographic parameters were T1S 28.3° ± 14.5° and C2S 25.9° ± 17.5°. Significant associations were found between 3-month C2S and mJOA score (r = -0.248, p = 0.034), NDI (r = 0.399, p = 0.001), EQ-5D VAS (r = -0.532, p < 0.001), NRS-neck (r = 0.239, p = 0.040), and NRS-back (r = 0.264, p = 0.021), while significant correlation was also found between 3-month T1S and mJOA score (r = -0.314, p = 0.026), NDI (r = 0.445, p = 0.001), EQ-5D VAS (r = -0.347, p = 0.018), and NRS-neck (r = 0.269, p = 0.049). A significant correlation was also found between development of DJF and 3-month C2S (odds ratio [OR] 1.1, 95% confidence interval [CI] 1.01-1.1, p = 0.015) as well as for T1S (OR 1.1, 95% CI 1.01-1.1, p = 0.023). Logistic regression with CIT identified thresholds for optimal outcome by 2 years: optimal 3-month T1S < 26° (OR 5.6) and C2S < 10° (OR 10.4), severe 3-month T1S < 45.5° (OR 0.2) and C2S < 38.0° (no patient above this threshold achieved optimal outcome; all p < 0.05). Patients below both optimal thresholds achieved rates of 0% for DJK and DJF, and 100% met optimal outcome.

Conclusions: The severity of CD, defined by T1S and C2S at baseline and especially at 3 months, can be predictive of postoperative functional improvement and occurrence of worrisome complications in patients with CD, necessitating the use of thresholds in surgical planning to achieve optimal outcomes.

Keywords: C2 slope; DJF; DJK; T1 slope; cervical deformity; clinical outcomes; reoperation; spine.