💪 Shoulder Measurements (Acromiohumeral Interval / Critical Shoulder Angle / Acromion Index)
UseShoulder imaging: true AP, Y view and 3D CT — rotator cuff disease and instability reporting and procedure se…
SourceMoor BK, et al. Is there an association between the individual anatomy of the scapula and the devel…
This-shift next steps
After scoring: open the scene pack, peer scores, and the matching pathway. Local reference — no HIS write.
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Methodology · worked example, guidelines & full notes
True AP (Grashey) view tangential to the glenohumeral joint.
When to use
Shoulder imaging: true AP, Y view and 3D CT — rotator cuff disease and instability reporting and procedure selection.
How it works
Acromiohumeral interval < 7 mm: suggests massive / full-thickness cuff tear (supra- and infraspinatus) Acromiohumeral interval 7–14 mm: normal Acromiohumeral interval > 14 mm: widened (effusion, inferior subluxation, etc.) Critical shoulder angle < 30°: associated with glenohumeral osteoarthritis Critical shoulder angle 30–35°: normal Critical shoulder angle > 35°: associated with degenerative cuff tear Acromion index < 0.7: normal (~0.6) Acromion index ≥ 0.7: large lateral extension, associated with cuff tear
Key points
- True AP (Grashey) view tangential to the glenohumeral joint.
- Each value is graded against published reference ranges.
- Measurement technique and positioning change the numbers — compare like with like on follow-up.
- Part of the YuanDoctor MSK measurement topic.
References
- Moor BK, et al. Is there an association between the individual anatomy of the scapula and the development of rotator cuff tears or osteoarthritis of the glenohumeral joint? Bone Joint J 2013;95-B:935-941
- Saupe N, et al. Association between rotator cuff abnormalities and reduced acromiohumeral distance. AJR 2006;187:376-382
- Nyffeler RW, et al. Association of a large lateral extension of the acromion with rotator cuff tears. J Bone Joint Surg Am 2006;88:800-805
Worked calculation
The values below come from this tool's own example placeholders and are computed server-side with the formula shown on this page, so the arithmetic can be checked quickly. It demonstrates how to substitute values only — it is not clinical advice and not a real case.
| AI: glenoid plane → lateral acromion | 32 mm |
|---|---|
| AI: glenoid plane → lateral humeral head | 48 mm |
| Bigliani acromion type (Y view) | Type II: curved |
| Acromiohumeral interval | 8 mm |
| Critical shoulder angle | 34 ° |
→Acromiohumeral interval8mm
- Acromiohumeral interval：8 mm → 7–14 mm: normal
- Critical shoulder angle：34 ° → 30–35°: normal
- Acromion index：0.67 → < 0.7: normal (~0.6)
Verification & sources · governance
FAQ
Frequently asked questions
- What are the limits and cautions when using Shoulder Measurements (Acromiohumeral Interval / Critical Shoulder Angle / Acromion Index)?
- For licensed clinicians and clinical researchers. Interpret results with history, investigations and local protocols; not a diagnosis or prescription, and not a substitute for multidisciplinary decision-making or local guidelines.
- Does Shoulder Measurements (Acromiohumeral Interval / Critical Shoulder Angle / Acromion Index) upload patient data? Where is it calculated?
- Calculation runs locally in the browser; inputs and results are not uploaded. For licensed clinicians only; interpret with history, investigations and local protocols — not a diagnosis or prescription.
- How is Shoulder Measurements (Acromiohumeral Interval / Critical Shoulder Angle / Acromion Index) calculated in practice? Can you show a worked example?
- Inputs: AI: glenoid plane → lateral acromion 32 mm, AI: glenoid plane → lateral humeral head 48 mm, Bigliani acromion type (Y view) Type II: curved, Acromiohumeral interval 8 mm, Critical shoulder angle 34 ° → Result: Acromiohumeral interval 8 mm（Acromiohumeral interval: 8 mm → 7–14 mm: normal, Critical shoulder angle: 34 ° → 30–35°: normal, Acromion index: 0.67 → < 0.7: normal (~0.6)）