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Citation:
Weerakkody Y, Luong D, Murphy A, Acromion index. Reference article, Radiopaedia.org (Accessed on 21 Mar 2025) https://doi.org/10.53347/rID-90426
The acromion index (AI) is a parameter that can be measured on the AP radiograph (or sometimes on coronal CT or MR images) to assess predisposition to rotator cuff pathology.
It is taken as the ratio between
GA: distance from the plane of the glenoid cavity to the lateral edge of the acromion and
GU: distance from the plane of the glenoid cavity to the lateral edge of the humeral head.
Acromion index (AI) = GA / GU
A high AI has been suggested as one of the associated factors for progression to large-to-massive rotator cuff tears in rotator cuff disease but only in some populations 3.
Research by some authors suggest that an acromion index over 0.7 being symptomatic in some populations 4.
See also
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1. Miyazaki AN, Fregoneze M, Santos PD, Da Silva LA, Menegassi Martel É, Debom LG, Andrade ML, Checchia SL. RADIOGRAPHIC STUDY ON THE ACROMION INDEX AND ITS RELATIONSHIP WITH ROTATOR CUFF TEARS. (2010) Revista brasileira de ortopedia. 45 (2): 151-4. doi:10.1016/S2255-4971(15)30285-8 - Pubmed
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3. Kim JR, Ryu KJ, Hong IT, Kim BK, Kim JH. Can a high acromion index predict rotator cuff tears?. (2012) International orthopaedics. 36 (5): 1019-24. doi:10.1007/s00264-012-1499-4 - Pubmed
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3. Miyazaki AN, Itoi E, Sano H, Fregoneze M, Santos PD, da Silva LA, Sella Gdo V, Martel EM, Debom LG, Andrade ML, Checchia SL. Comparison between the acromion index and rotator cuff tears in the Brazilian and Japanese populations. (2011) Journal of shoulder and elbow surgery. 20 (7): 1082-6. doi:10.1016/j.jse.2011.04.028 - Pubmed
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4. Hanciau FA, da Silva MA, Martins FS, Ogliari A. ASSOCIATION CLINICAL-RADIOGRAPHIC OF THE ACROMION ÍNDEX AND THE LATERAL ACROMION ANGLE. (2012) Revista brasileira de ortopedia. 47 (6): 730-5. doi:10.1016/S2255-4971(15)30030-6 - Pubmed
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