AO Spine staging systems and referral tools
A staging tool is a structured clinical aid designed to categorize disease severity or risk based on key clinical findings. Rather than replacing clinical judgment, staging tools support decision-making by translating complex medical information into clear, actionable pathways.
In spine care, staging tools help clinicians stratify severity by identifying which patients are stable versus those at risk of rapid deterioration. They standardize communication by providing a common clinical language across specialties, guide urgency by clarifying when immediate referral or intervention is required and reduce variability by supporting consistent decision-making across providers and settings.
AO Spinal Metastasis Staging (SMS) referral tool
The AO Spinal Metastasis Staging (SMS) referral tool is a practical, stage-based tool for non-spine clinicians to recognize disease severity in patients with spinal metastases and guide referral urgency.
Using the front-page flowchart, clinicians answer simple yes/no questions on neurological deficits, spinal cord compression, mechanical pain, and spinal instability to assign SMS I–IV, each linked to a clear action:
- SMS IV—immediate contact with a spinal specialist (emergency)
- SMS III—same-day contact with a spinal specialist
- SMS II—consider consulting radiotherapy
- SMS I—ongoing monitoring with alertness for new symptoms
The reverse side provides concise reference for ASIA, Bilsky, and SINS, while a QR code links to short educational resources and case examples. The digital version can be locally adapted with regional pathways and contact details to ensure rapid access to definitive care when it matters most.
Why staging is particularly important in spinal metastases
Patients with spinal metastases can deteriorate rapidly. Delays in recognition or referral may result in irreversible neurological deficits, loss of mobility, or severe pain. This staging-based framework from AO Spine Knowledge Forum Tumor helps clinicians distinguish between conditions requiring emergency specialist involvement, situations needing urgent consultation, cases appropriate for planned oncologic management, and patients suitable for monitoring.
By linking each stage to a specific action, the SMS system reduces uncertainty and supports timely escalation of care.
Evidence base
The AO Spinal Metastasis Staging (SMS) system and referral tool are grounded in established concepts of neurological assessment, epidural spinal cord compression grading, and spinal stability evaluation.
Clinical pocket map
For rapid bedside use, the AO Spine SMS Referral Tool is also available as a compact pocket reference featuring a flowchart and grading information to support decision making.