ABC Classification (Posterior Shoulder Instability)
Derives the ABC type of posterior shoulder instability: A for a first event within 3 months, B for recurrent dynamic instability, and C for static decentering.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Pattern of posterior instability
- Recurrent dynamic instability
- If recurrent
- Structural: posterior Bankart, glenoid bone loss, or reverse Hill-Sachs
Result: ABC type B2: recurrent dynamic instability from structural damage (posterior Bankart, glenoid bone loss or reverse Hill-Sachs).
The tool opens with these values already filled in. Replace them with your own.
What you enter
- Pattern of posterior instability
- If a first event: subluxation or dislocation
- If recurrent: functional or structural
- If static: constitutional or acquired
How this is calculated
Citation
Moroder P et al. SECEC Didier Patte Prize 2023: the ABC classification of posterior shoulder instability. J Shoulder Elbow Surg. 2024;33. Definitions as given in Paksoy A et al. EFORT Open Rev. 2024;9(5):403-412. Read the sources: Moroder 2024 ↗, Paksoy 2024 ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.