Associations between three-dimensional measurements of the spinal deformity and preoperative SRS-22 scores in patients undergoing surgery for major thoracic adolescent idiopathic scoliosis

Study design: Retrospective study. Objective: To analyze the relationships between three-dimensional (3D) measurements of spinal deformity and Scoliosis Research Society-22 (SRS-22) scores in preoperative patients with major thoracic adolescent idiopathic scoliosis (AIS). Summary and background data: Previous studies reported 2D measurements were not or only weakly correlated with preoperative SRS-22 scores. However, 2D measures do not always accurately represent the 3D deformity. Methods: A multicenter prospective registry of surgically treated AIS patients was reviewed for patients with right major thoracic AIS (Lenke type 1–4) who underwent biplanar radiography and completed the SRS-22 questionnaire preoperatively. For the 3D measurements, two reference frames were utilized: global (gravity/patient-based) and local (vertebra/disc-based). To obtain regional measurements, the individual segments in the appropriate reference plane were summed between the levels of interest. Patients were divided into two groups for each SRS-22 domain according to their scores: low (< 4) and high (≥ 4) score groups. Group differences and correlations with SRS-22 scores were analyzed with p < 0.01 as the threshold for significance. Results: There were 405 eligible patients (mean age, 14.4 years). The mean 3D thoracic curve was 59° (45°–115°). The only significant group difference of 3D measurements occurred in the local lumbar lordosis (LL) with a small mean difference (− 3.4°, p = 0.008) in the mental health domain. In the correlation analyses, global and local thoracic kyphosis (TK) and TK/LL ratio demonstrated significant, but weak, correlations with function and total scores (|r|< 0.2, p < 0.01). Conclusion: 3D measurements of scoliosis severity have only weak associations with preoperative SRS-22 scores, which might indicate a limit to the discriminative capacity of the SRS-22 within surgical range major thoracic AIS curves. Interestingly, the sagittal plane was the principle 3D plane in which significant correlations existed. Level of evidence: II, prognostic.