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DOS Kongressen 2016 ·
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The Critical shoulder angle show excellent reliability
Arnar Oskar Bjarnison, Thomas Juul Sørensen, Thomas Kallemose,
Kristoffer W. Barfod
Department of Orthopedics, Zealand University Hospital; Department of
Orthopedics, Zealand University Hospital; Department of Orthopaedic sur-
gery, Clinical Orthopaedic Research Hvidovre, Copenhagen University Hospital
Hvidovre ; Department of Orthopedics, Zealand University Hospital
Background:
In 2013 Moor et al introduced the concept of the critical shoul-
der angle (CSA) and suggested that an abnormal CSA was a leading factor in de-
velopment of Rotator Cuff Tear (RCT) and Osteoarthritis of the shoulder (OA).
Purpose / Aim of Study:
The purpose of the study was to test inter- and in-
tra- rater reliability of the CSA in a population suffering from RCT or OA.
Materials and Methods:
The study was performed as a retrospective reliabil-
ity study. 97 patients with RCT and 87 patients with OA constituted the study
population. The CSA was measured as described by Moor et al in 2013 by two
independent raters and repeated by rater 1 after 4 weeks. Data were evaluated
using the Inter/intra Correlation Coefficient (ICC), calculated by mixed effect
models, and the Minimal Detectable Change (MDC).
Findings / Results:
Intra-rater reliability showed a non-significant system-
atic difference in CSA of 0.05° for RCT and 0.08 ° for OA between test days
(p=0.71 and 0.52). For RCT the ICC value was 0.92, MDC 0.4°; for OA the ICC
was 0.95, MDC 0.4 and 0.3. Inter-rater reliability showed a systematic differ-
ence between raters of 0.8° for RCT and 0.7° for OA (p<0.001 for both). For
RCT the ICC value was 0.95, MDC 0.3°; for OA the ICC was 0.93, MDC 0.4.
Conclusions:
The CSA measurement showed excellent reliability for use be-
tween raters and at repeated measurements by the same rater. Differences of
more than 0.4° can be detected which is sufficient to distinguish between a
normal and an abnormal CSA.
No conflicts of interest reported
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