AO Spine Clinical Practice Recommendations: Sagittal Alignment Assessment and Planning in Adult Spinal Deformity Surgery

Study DesignLiterature review with clinical recommendation.ObjectivesTo provide the readers with a concise curation of the relevant spine literature regarding patient-specific alignment planning in patients with adult spinal deformity (ASD) and set out recommendations for how the practicing clinician should interpret and make use of this evidence.MethodsKey articles on patient-specific alignment planning for ASD were reviewed to develop clinical recommendations by consensus. Recommendations are graded as strong or conditional, based on methodological quality and expert opinion.ResultsFour articles were selected by the AO Spine Knowledge Forum Deformity and each evaluated for the strength of methodology and scientific evidence.ConclusionsThe 4 reviewed publications illustrate the progression from descriptive to proportional and finally continuous alignment concepts in adult spinal deformity surgery. The Roussouly morphotypes help clinicians understand native sagittal shape and compensatory patterns, the SRS-Schwab classification remains useful for standardized description and communication, the GAP Score introduces pelvic-incidence-based proportionality, the T4-L1-Hip axis offers continuous, directly modifiable angular targets. Used together, these models offer complementary perspectives that enhance preoperative planning and postoperative evaluation. Integrating their strengths, while considering patient-specific factors such as bone quality, physiologic reserve, and surgical goals, supports more individualized and durable alignment strategies.