A Validated Score for Evaluating Spinal Instability to Assess Surgical Candidacy in Active Spinal Tuberculosis—An Evidence Based Approach and Multinational Expert Consensus Study

STUDY DESIGN: Modified Delphi Consensus and Observational Study. OBJECTIVE: Instability in spinal tuberculosis (STB) leads to disabling spinal deformity and neurodeficit. Identifying and estimating instability remains subjective, mainly based on experience. This study aims to develop an objective scoring system to determine instability in STB. MATERIALS AND METHODS: The study included 4 phases. (1) A panel of 10 experienced spine surgeons developed a questionnaire based on literature. (2) 68 spine surgeons from 12 countries opined on the importance of each factor in a survey. Five factors deemed important by >70% of participants were further analyzed (3) 60 representative cases of STB were analyzed for instability. A preliminary scoring system was developed, a threshold score for determining instability was derived, and (4) Results were validated. RESULTS: All the 5 factors (“Spine at risk” signs, severity of vertebral body loss, Cervicothoracic/Thoracolumbar junction involvement, age ≤15, and kyphotic deformity ≥30°) considered important by >70% of participants were associated with instability and included in scoring: age ≤15 years (P-value, 0.05), cervicothoracic/thoracolumbar junction involvement (P-value, 0.028), sagittal deformity angle ratio (DAR) ≥ 15° (P-value, <.001), vertebral body loss-segmental ratio ≥.5 (P-value, <.001), and presence of spine at risk signs (P-value, <.001). A total score of ≥3/09 indicated definite instability with good sensitivity (77%) and excellent specificity (100%). Repeatability assessment showed a good agreement (.9625), and Cohen’s kappa coefficient was strong (.809). CONCLUSION: A simple objective scoring system for predicting instability in STB has been developed using 5 main factors; young age, junctional involvement, severity of the deformity, vertebral body loss, and presence of spine at risk signs.