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Case 11 - Os acromiale

from Section 1 - Shoulder

Published online by Cambridge University Press:  05 July 2013

Edited by
D. Lee Bennett  and
Georges Y. El-Khoury
D. Lee Bennett
Affiliation:
University of Iowa
Georges Y. El-Khoury
Affiliation:
University of Iowa
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Summary

Imaging description

The os acromiale is an accessory bone that is found in 7–15% healthy subjects. This acromial bone is formed when there is a non-union of ossification centers during development. Os acromiale is easy to detect on an axillary view of the shoulder on plain radiographs but is difficult to see on a standard anteroposterior view.

Importance

The os acromiale (Figure 11.1) – optimally seen on axial MR images – is connected to the basiacromion via a diarthrosis or synchondrosis and should not be diagnosed as fracture. The acromion is normally formed by the fusion of several ossification centers, which is generally complete by the age of 25. The discovery of os acromiale on plain radiographs in a symptomatic patient should prompt a search for rotator cuff tendon disease. Its recognition in patients with rotator cuff disease may help the surgeon select an appropriate therapy.

Typical clinical scenario

Presence of os acromiale may be associated with rotator cuff impingement.

Differential diagnosis

The presence of an os acromiale may be confused with a fracture of the acromion distally.

Teaching point

Os acromiale, which can predispose to rotator cuff impingement, can be detected on routine shoulder MR imaging.

Type
Chapter
Information
Pearls and Pitfalls in Musculoskeletal Imaging
Variants and Other Difficult Diagnoses
 , pp. 20 - 21
Publisher: Cambridge University Press
Print publication year: 2013

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References

Morag, Y, Jacobson, JA, Miller, B et al. MR imaging of rotator cuff injury: what the clinician needs to know. Radiographics 2006;26:1045–1065.CrossRefGoogle Scholar
Park, JG, Lee, JK, Phelps, CT.Os acromiale associated with rotator cuff impingement: MR imaging of the shoulder. Radiology 1994;193:255–257.CrossRefGoogle Scholar
Prescher, A.Anatomical basics, variations, and degenerative changes of the shoulder joint and shoulder girdle. Eur J Radiol 2000;35:88–102.CrossRefGoogle ScholarPubMed
Rudez, J, Zanetti, M.Normal anatomy, variants and pitfalls on shoulder MRI. Eur J Radiol 2008;68:25–35.CrossRefGoogle ScholarPubMed
Swain, RA, Wilson, FD, Harsha, DM.The os acromiale: another cause of impingement. Med Sci Sports Exerc 1996;28:1459–1462.CrossRefGoogle ScholarPubMed

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  • Os acromiale
  • Edited by D. Lee Bennett, University of Iowa, Georges Y. El-Khoury, University of Iowa
  • Book: Pearls and Pitfalls in Musculoskeletal Imaging
  • Online publication: 05 July 2013
  • Chapter DOI: https://doi.org/10.1017/CBO9781139031141.013
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  • Os acromiale
  • Edited by D. Lee Bennett, University of Iowa, Georges Y. El-Khoury, University of Iowa
  • Book: Pearls and Pitfalls in Musculoskeletal Imaging
  • Online publication: 05 July 2013
  • Chapter DOI: https://doi.org/10.1017/CBO9781139031141.013
Available formats
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Save book to Google Drive

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.

  • Os acromiale
  • Edited by D. Lee Bennett, University of Iowa, Georges Y. El-Khoury, University of Iowa
  • Book: Pearls and Pitfalls in Musculoskeletal Imaging
  • Online publication: 05 July 2013
  • Chapter DOI: https://doi.org/10.1017/CBO9781139031141.013
Available formats
×