, Volume 470, Issue 6, pp 1540-1544
Date: 14 Dec 2011

Reliability of Scapular Classification in Examination of Professional Baseball Players

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Clinically evaluating the scapulothoracic joint is challenging. To identify scapular dyskinesis, clinicians typically observe scapular motion and congruence during self-directed upper extremity movements. However, it is unclear whether this method is reliable.


We therefore determined the interrater reliability of a scapular classification system in the examination of professional baseball players.


Seventy-one healthy uninjured professional baseball players between the ages of 18 and 32 years volunteered to participate. We used a digital video camera to film five repetitions of scapular plane elevation while holding a 2-pound weight. Four examiners then independently classified the motions on video into one of four types. Interrater reliability analysis using the kappa (k) statistic was performed for: (1) classifying each scapula into one of the four types; (2) classifying each scapula as being abnormal (Types I–III) or normal (Type IV); and (3) classifying both scapula as both being symmetric (both normal or both abnormal) or asymmetric (one normal, one abnormal).


We found low reliability for all analyses. In classifying each scapula as one of the four types, reliability was k = 0.245 for the left limb and k = 0.186 for the right limb. When considering the dichotomous classifications (abnormal versus normal), reliability was k = 0.264 for left and k = 0.157 for right. For bilateral symmetry/asymmetric, reliability was k = 0.084.


We found low reliability of visual observation and classification of scapular movement.

Clinical Relevance

Current evaluation strategies for evaluating subtle scapular abnormalities are limited.

Level of Evidence

Level III, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.

Each author certifies that he or she, or a member of their immediate family, has no commercial associations (eg, consultancies, stock ownership, equity interest, patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article.
All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research editors and board members are on file with the publication and can be viewed on request.
Each author certifies that his or her institution approved the human protocol for this investigation, that all investigations were conducted in conformity with ethical principles of research, and that informed consent for participation in the study was obtained.
This work was performed at Physiotherapy Associates Scottsdale Sports Clinic, Scottsdale, AZ, USA.