Prior to this paper, no comprehensive classification system existed for cervical spine deformity despite its substantial impact on quality of life. Ames et al. used a modified Delphi approach with 20 expert spinal deformity surgeons to develop and test the reliability of a new CSD classification. The system pairs a deformity descriptor (based on apex location) with five modifiers capturing sagittal alignment, horizontal gaze, myelopathy severity, and global spinopelvic balance.
When you see a patient with cervical kyphosis and myelopathy, two questions shape your surgical plan: where is the deformity apex, and how bad is the global sagittal imbalance? The Ames CSD classification gives you a structured framework to answer both — it links regional cervical pathology to global spinopelvic alignment using parameters that already have HRQOL correlates.
The TS-CL mismatch is the cervical equivalent of PI-LL: just as a high pelvic incidence demands more lumbar lordosis, a steep T1 slope demands more cervical lordosis to keep the head balanced. A TS-CL > 20° flags a patient whose cervical spine is working against the thoracic inlet — important when planning fusion levels and lordosis targets.
The CBVA modifier matters for surgical planning in rigid deformity. Overcorrection (CBVA < -10°) impairs going down stairs and daily function just as much as undercorrection. The target is 1°–10°.
The reliability data tell an honest story: most modifiers are usable (moderate to substantial kappa), but the C7–S1 SVA is unreliable as currently defined — know this as a limitation when applying or interpreting studies that use this classification.
Prior to this paper, no comprehensive classification system existed for cervical spine deformity despite its substantial impact on quality of life. Ames et al. used a modified Delphi approach with 20 expert spinal deformity surgeons to develop and test the reliability of a new CSD classification. The system pairs a deformity descriptor (based on apex location) with five modifiers capturing sagittal alignment, horizontal gaze, myelopathy severity, and global spinopelvic balance.
When you see a patient with cervical kyphosis and myelopathy, two questions shape your surgical plan: where is the deformity apex, and how bad is the global sagittal imbalance? The Ames CSD classification gives you a structured framework to answer both — it links regional cervical pathology to global spinopelvic alignment using parameters that already have HRQOL correlates.
The TS-CL mismatch is the cervical equivalent of PI-LL: just as a high pelvic incidence demands more lumbar lordosis, a steep T1 slope demands more cervical lordosis to keep the head balanced. A TS-CL > 20° flags a patient whose cervical spine is working against the thoracic inlet — important when planning fusion levels and lordosis targets.
The CBVA modifier matters for surgical planning in rigid deformity. Overcorrection (CBVA < -10°) impairs going down stairs and daily function just as much as undercorrection. The target is 1°–10°.
The reliability data tell an honest story: most modifiers are usable (moderate to substantial kappa), but the C7–S1 SVA is unreliable as currently defined — know this as a limitation when applying or interpreting studies that use this classification.