ISAKOS Congress 2021

2021 ISAKOS Biennial Congress Paper


Interrater Reliability of Novice Sonographers Performing Ultrasonographic Measurements of Subacromial Structures in Patients With Subacromial Pain.

Karen Mikkelsen, MD, Copenhagen DENMARK
Adam Witten, MD, Copenhagen DENMARK
Birgitte Hougs Kjær, PT, PhD, Copenhagen DENMARK
Per Hölmich, DMSc, Prof., Copenhagen DENMARK
Kristoffer W. Barfod, MD, PhD, VIRUM DENMARK

Sports Orthopedic Research Center – Copenhagen (SORC-C), Copenhagen, DENMARK

FDA Status Not Applicable


Ultrasonographic measurements of subacromial structures in patients with subacromial pain demonstrate fair to good interrater reliability when performed by novice sonographers.



Ultrasonographic measurements of the subacromial structures are reliable in the hands of experienced sonographers, but it is unknown if inexperienced sonographers can achieve a satisfactory level of reliability.


To investigate if standardized subacromial ultrasonographic measurements are reliable in the hands of novice sonographers.


Two novice sonographers, a medical student with no prior ultrasonographic experience and a junior orthopedic resident with limited shoulder ultrasonographic experience, completed a training phase with an experienced sonographer. The two novice sonographers subsequently performed standardized ultrasonographic measurements on patients, diagnosed with subacromial pain, recruited consecutively from an orthopedic outpatient clinic. The measurements were: supraspinatus tendon thickness, subacromial bursa thickness, acromio-humeral distance and an assessment of dynamic impingement (visual impingement of the supraspinatus tendon and the subacromial bursa between the humeral head and the anterolateral aspect of acromion). Intraclass correlation coefficients (ICC(2,1)), standard error of measurement (SEM), minimal detectable change (MDC), 95% Limits of Agreement (LOA) and Cohen’s unweighted kappa were used to evaluate reliability and agreement.


Twenty-eight patients (mean age: 52 years; mean BMI: 27,5) were included (28 symptomatic and 20 asymptomatic shoulders). ICC-values of supraspinatus tendon thickness ranged from 0.73 to 0.77 (SEM 0.4–0.5 mm; MDC 1.2-1.4 mm). Subacromial bursa thickness ICC ranged from 0.41 to 0.88 (SEM 0.2–0.4 mm; MDC 0.4-1.0 mm) and acromio-humeral distance ICC ranged from 0.68 to 0.72 (SEM 0.9 mm; MDC 2.5-2.6 mm). Kappa of mechanical impingement in symptomatic shoulders was 0.29 and was driven by a discrepancy of positive findings between the raters (43% vs 18%).


Novice sonographers achieved good reliability for ultrasonographic measurements of supraspinatus tendon thickness and acromio-humeral distance. The reliability of subacromial bursa thickness ranged from fair to good, while the evaluation of mechanical impingement only resulted in fair reliability.

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