Coronal Imbalance in Adult Spinal Deformity Following Posterior Spinal Fusion With Instrument: A Related Parameters Analysis.

STUDY DESIGN: A retrospective radiographic study.

OBJECTIVE: To explore the radiological parameters which correlated to postoperative immediately coronal imbalance in adult spinal deformity (ASD) and to determine whether preoperative coronal imbalance affects postoperative coronal imbalance following posterior multi-level fusion with instruments and osteotomy operation.

SUMMARY OF BACKGROUND DATA: There was paucity of literature paying attention to the postoperative immediately coronal imbalance after operation.

METHODS: The study included 67 consecutive patients with ASD who underwent posterior multi-level fusion with instruments and osteotomy operation. The radiological parameters, measured on the pre- and postoperative anteroposterior and lateral radiographs, were compared and analyzed. Patients were divided into three groups (group A, B, and C) according to preoperative coronal balance distance (pre-CBD) and the relation of cervical 7 plumb line (C7PL), and the convex of curvature. To analyze the radiological parameters of the three groups.

RESULT: Differences of the radiological parameters between pre- and postoperation concerning Cobb angles, degree of apical vertebra rotation, thoracic kyphosis (TK), thoracic lumber kyphosis (TLK), lumber lordosis (LL), sacral slope (SS), pelvic tilt (PT), and sagittal vertical axis (SVA), were significant (P < 0.05). Pelvic incidence (PI), pre-CBD, and postoperative coronal balance distance (post-CBD) had no change (P > 0.05). The ratio of coronal imbalance in pre- and postoperation was 31.34% (21/67) and 40.30% (27/67), respectively, which had significant difference (P = 0.02). Significant correlations were observed among post-CBD, pre-CBD (P < 0.001), and d-Cobb (pre-Cobb - post-Cobb) (P = 0.002), post-CBD = -2.737 - 0.924*d-Cobb + 0.356*pre-CBD. The ratio of postoperative immediately coronal imbalance of the group C was much higher than other two groups (P = 0.01).

CONCLUSION: The sagittal alignments in ASD patients would be improved effectively after posterior multi-level fusion with instruments and osteotomy operation. There were significant correlations among post-CBD, pre-CBD, and d-Cobb. Patients in group C may be at greater risk for immediate postoperative coronal imbalance after operation.

LEVEL OF EVIDENCE: 3.