Acromiohumeral interval is a useful and reliable measurement on AP shoulder radiographs and when narrowed is indicative of rotator cuff tear or tendinopathy.
The shortest distance is measured.
- true AP shoulder radiograph
- measure from the cortical bone at the inferior aspect of the acromion to the humeral head 3
- can also be performed on coronal and sagittal oblique T1 MR images
- inferior aspect of the acromion (marked by black line directly above the humeral head) directly inferiorly to the center of the subchondral cortex of the humeral head 3
Measurements of the acromiohumeral interval in the following intervals are suggestive of pathology 1,2:
- >12 mm: shoulder dislocation; inferior subluxation (e.g. from joint effusion)
- 9-10 mm (range 8-12 mm): normal
- 6-7 mm: thinning of supraspinatus tendon
- <6 mm: supraspinatus tear
- 1. Gruber G, Bernhardt GA, Clar H et-al. Measurement of the acromiohumeral interval on standardized anteroposterior radiographs: a prospective study of observer variability. J Shoulder Elbow Surg. 2010;19 (1): 10-3. doi:10.1016/j.jse.2009.04.010 - Pubmed citation
- 2. Davies AM. Imaging of the Shoulder: Techniques and Applications (Medical Radiology / Diagnostic Imaging). Springer. ISBN:B0014DAE8A. Read it at Google Books - Find it at Amazon
- 3. Saupe N, Pfirrmann CW, Schmid MR et-al. Association between rotator cuff abnormalities and reduced acromiohumeral distance. AJR Am J Roentgenol. 2006;187 (2): 376-82. doi:10.2214/AJR.05.0435 - Pubmed citation