Predicting Mechanical Failure Following Cervical Deformity Surgery: A Composite Score Integrating Age-Adjusted...

Area of Science:

• Spine surgery
• Orthopedic surgery
• Radiographic analysis

Background:

• Cervical deformity (CD) surgery aims to correct sagittal malalignment.
• Distal junctional kyphosis (DJK) is a common complication following CD surgery.
• Predictive tools for mechanical failure are needed to improve patient outcomes.

Purpose of the Study:

• To develop and validate a composite alignment score to assess the relationship between alignment proportionality and the risk of DJK.
• To identify early radiographic predictors of mechanical failure after CD surgery.

Main Methods:

• Retrospective cohort study of 84 patients with CD and minimum 1-year follow-up.
• A 'Cervical Score' was created using offsets from age-adjusted normative values for sagittal vertical axis (SVA), T1 Slope (TS), and TS minus cervical lordosis (CL).
• Logistical regression analysis assessed associations between early radiographic alignment and 1-year mechanical failure rates (DJK revision or severe DJK).

Main Results:

• The overall mechanical failure rate was 21.4%, with 10.7% requiring revision.
• Early radiographic parameters (3-month TS, TS-CL, SVA) were independent predictors of 1-year failure.
• Patients with a Cervical Score ≥3 had a significantly higher failure rate (71.4%) compared to those with a score <3 (P < .001).
• The Cervical Score demonstrated strong predictive capability (Nagelkerke r² = .524, P < .001).

Conclusions:

• A novel composite alignment score, the Cervical Score, effectively predicts mechanical failures in CD surgery.
• A Cervical Score of 3 or higher at 3 months post-surgery is associated with a substantially increased risk of mechanical failure.
• The Cervical Score can aid in analyzing sagittal alignment and guiding realignment objectives to mitigate mechanical failure risk.