Classification of degenerative segment disease in adults with deformity of the lumbar or thoracolumbar spine.

BACKGROUND: Lumbar and thoracolumbar deformity in the adult is a condition with impairment of health status that can need surgical treatment. In contrast with adolescent deformity, where magnitude of the curve plays a significant role in surgical indication, the aspects relevant in adult deformity are pain and dysfunction that correlate with segment degeneration and imbalance. Previous classifications of adult deformity have been of little use for surgical planning.
METHODS: Chart review and classification of radiographic and clinical findings. A classification of degenerative disc disease based on distribution of diseased segments and balance status of the spine is presented.
RESULTS: Four main categories are presented: Type I (limited nonapical segment disease), Type II (limited apical segment disease), Type III (extended segment disease--apical and nonapical), Type IV (imbalanced spine: IVa, sagittally imbalanced; IVb, sagittally and coronally imbalanced). DISCUSSION AND
CONCLUSION: Types I and II can be treated by fusion of a selective area of the curve. Type III needs fusion of all the extension of the coronal curve. Type IV usually needs aggressive corrective procedures, frequently including posterior tricolumnar osteotomies. This classification permits interpreting the extension and magnitude of the disease and can help establish a surgical plan regarding selective fusion and methods of sagittal correction. Future research is needed to validate the classification.