Ultrasound of Focal Tears to the Supraspinatus tendon : Does Patient Position affect tear size?

Samantha O'Herlihy, Peterborough Ultrasound Department, North West Anglia Trust


As Ultrasound is now the primary investigation in the assessment of Shoulder rotator cuff tendons, it was decided to see how patient positioning may affect the measurements obtained when assessing a supraspinatus tear.

In the assessment of the Supraspinatus tendon two positions are used - the Crass and Modified crass position. (photo diagram will illustrate this). Looking at Supraspinatus tears using both these positions this study will compare and determine whether there is any significant difference in the measurements obtained.


Thirty -five patients had an ultrasound of their rotator cuff tendons on either the Rt or Lt shoulder. An assessment of the supraspinatus tendon was made using both the Crass and Modified Crass position. If any tears were diagnosed, measurements in both positions were taken in both saggital and transverse planes.


Fifteen patients from the cohort demonstrated either a complete full thickness tear or an incomplete full thickness tear of the supraspinatus tendon.  No significant difference was seen between the size of the tears in the Crass position or the modified Crass position in the transverse plane, however a slight difference was noted between the Crass and modified crass position in the Saggital plane, where the tear was seen to measure larger with the modified Crass position.


Ultrasound reliably detects Supraspinatus tears. Both the Crass and modified Crass positioning are used in the assessment of the tendon but which position used can vary from sonographer to sonographer, although the modified Crass position is deemed as more reproducible. However as measurements of supraspinatus tears are seen to vary between both positions in the saggital plane further studies would be to look at how this may affect the management of a patient and to compare results with surgical findings to decifer which position gives the most accurate result.

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