Abstract
Background
Reliable measurements of shoulder strength are important in assessing rotator cuff integrity.
Aim
To determine whether a fixed strength assessment device is more reliable than a handheld dynamometer (HHD) when measuring the strength of five shoulder movements (internal rotation, external rotation, abduction, lift-off and adduction).
Methods
We tested 12 asymptomatic and 11 symptomatic shoulders in the intra-rater reliability assessment. For each shoulder tested, the strength of five shoulder movements were recorded three times using HHD and three times using the fixed device by the same examiner. We tested 11 asymptomatic shoulders and 10 symptomatic shoulders in the inter-rater reliability assessment. Each of three examiners tested the shoulder strength of each subjectl once using HHD and once using the fixed device. Intra-class correlation coefficients (ICCs) were calculated to assess reliability of measurements.
Results
Both HHD and the fixed device showed excellent (ICC > 0.80) intra-rater and inter-rater reliability for all movements. The inter-rater reliability of HHD began to decrease as the subject strength increased when testing abduction in the plane of the scapula.
Discussion
HHD is a reliable method of measuring shoulder strength in the clinical setting. However, when several examiners are testing strength of stronger subjects in abduction of the scapular plane, stabilizing the dynamometer provides more reliable results.
Keywords
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