Evaluation of Clinical Assessment Methods for Scapular Dyskinesis
Received 19 September 2008; accepted 10 June 2009.
Purpose
The purposes of this study were to (1) assess the inter-rater reliability and validity of 2 clinical assessment methods of categorizing scapular dyskinesis and (2) quantify the frequency of asymmetry of bilateral scapular motion in injured and uninjured shoulders by use of 3-dimensional (3D) kinematic analysis.
Methods
We evaluated 56 subjects, 35 with shoulder injury and 21 with no symptoms. Two blinded evaluators categorized the scapular motion of all subjects to determine inter-rater reliability using 2 observational methods (“yes/no” and “4 type”) to evaluate scapular dyskinesis. Subjects were also instrumented with electromagnetic receivers to assess bilateral 3D scapular kinematics to determine the presence of dyskinesis and establish criterion validity of the 2 methods.
Results
The inter-rater percent agreement and the degree of this agreement as measured by κ statistic showed that the yes/no method produced a higher inter-rater percent agreement (79%, κ = 0.40) than the 4-type method (61%, κ = 0.44). The yes/no method had a higher sensitivity (76%) and positive predictive value (74%) when compared with the 3D criterion. A χ2 analysis found significantly more multiple-plane asymmetries in symptomatic subjects (54%) in flexion compared with asymptomatic subjects (14%) (P = .002).
Conclusions
The yes/no method allows multiple-plane asymmetries to be considered in clinical assessment and therefore renders this a good screening tool for the presence of scapular dyskinesis. Kinematic analysis shows that asymmetries are common in symptomatic and asymptomatic populations. Testing in flexion showed a higher frequency of multiple-plane scapular asymmetries in the symptomatic group.
Clinical Relevance
Identification of scapular dyskinesis is a key component of the shoulder examination. The clinician's ability to establish the presence or absence of scapular dyskinesis by observation is enhanced using a simple yes/no method especially when testing subjects in shoulder forward flexion. Although scapular asymmetries appear to be a prevalent finding, dyskinesis in the presence of shoulder symptoms should be considered a potential factor contributing to the dysfunction in the presence of shoulder symptoms should be considered a potential factor contributing to the dysfunction.
aDivision of Athletic Training, University of Kentucky, Lexington, Kentucky, U.S.A.
bShoulder Center of Kentucky, Lexington, Kentucky, U.S.A.
cGreenville Hospital System, Greenville, South Carolina, U.S.A.
dDepartment of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida, U.S.A.
Address correspondence and reprint requests to Tim L. Uhl, Ph.D., P.T., A.T.C., Division of Athletic Training, University of Kentucky, 206 Charles T. Wethington Bldg, 900 S Limestone, Lexington, KY 40536, U.S.A.
Supported by the American Shoulder and Elbow Surgeons. The authors report no conflict of interest.
ABSTRACT