Types of deformity and surgical plans
Deformity Type | Regional Deformity | Compensatory Mechanisms | Correction | Fusion Levels |
Normal sagittal alignment | None | None | None | None |
Cervical kyphosis | Cervical kyphosis | Lumbar hyperlordosis Thoracic lordosis Pelvic tilt (if global kyphosis) | Cervical osteotomy in rigid deformity. Multilevel anterior release and posterior fixation. | ㅤ |
Thoracic kyphosis | Thoracic kyphosis | Cervical hyperlordosis Lumbar hyperlordosis Pelvic tilt (if global kyphosis) | Correction of kyphosis to predicted value | T2 to sagittal stable vertebra |
Thoracolumbar kyphosis | Thoracolumbar kyphosis | Lower Lumbar hyperlordosis Pelvic retroversion (if global kyphosis) | Correction to neutral T11–L2 | If the deformity is segmental, the minimum needed for stability. If regional, all the thoracolumbar junction. In some cases with kyphosis of more discs in the thoracolumbar junction associated to thoracic hyperkyphosis, after correction the levels to be fused are as in the thoracic kyphosis pattern |
Lumbar kyphosis | Lumbar kyphosis | Pelvic retroversion (flexed knees) Upper lumbar hyperlordosis Thoracic Lordosis | Correction to predicted lordosis value | If segmental, short fusion, only involving the diseased levels. If regional, extend cranially to L2 or T10 |
Lower lumbar kyphosis | Lower lumbar kyphosis | Upper lumbar hyperlordosis Pelvic retroversion | Correction to predicted lordosis value | L4–S1 with restoration of L4–S1 lordosis. Otherwise, longer, as needed to restore lumbar lordosis |
Global kyphosis | Lumbar kyphosis normal or increased thoracic kyphosis | Thoracic lordosis Increased pelvic tilt Flexed knees | Correction of thoracic kyphosis and lumbar lordosis to predicted values | T2–Ilium |
Pelvic kyphosis | Increased SVA with normal spine or minor regional kyphosis | No compensatory mechanisms. Normal pelvic tilt | Rule out hip disease or neurological disease | ㅤ |
Principle of the classification
- For a given patient, an ideal sagittal alignment can be predicted
- Sagittal appearance of the standing spine and pelvis is the result of the combination of regional deformity (or deformities) and its interaction with compensatory mechanisms.
- This combination determines the presentation of sagittal deformity patterns
- Surgical treatment addresses
- Correction of regional deformity and/ or
- Eliminates the need for active muscle contraction to compensate regional deformity
- The presence of compensatory mechanisms can help estimate the ability of the spine to maintain correct alignment of segments left mobile after correction of the deformity
- The absence of compensatory mechanisms can determine the need to extend correction to segments not involved in the primary sagittal deformity
- Eventually, some patterns of imbalance in the absence of expected compensatory mechanisms can be explained by the presence of abnormal schemes of neurological motor activation
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