A Clinical Method for Identifying Scapular Dyskinesis, Part 2: Validity

Abstract

Abstract Context: Although clinical methods for detecting scapular dyskinesis have been described, evidence supporting the validity of these methods is lacking. Objective: To determine the validity of the scapular dyskinesis test, a visually based method of identifying abnormal scapular motion. A secondary purpose was to explore the relationship between scapular dyskinesis and shoulder symptoms. Design: Validation study comparing 3-dimensional measures of scapular motion among participants clinically judged as having either normal motion or scapular dyskinesis. Setting: University athletic training facilities. Patients or Other Participants: A sample of 142 collegiate athletes (National Collegiate Athletic Association Division I and Division III) participating in sports requiring overhead use of the arm was rated, and 66 of these underwent 3-dimensional testing. Intervention(s): Volunteers were viewed by 2 raters while performing weighted shoulder flexion and abduction. The right and left sides were rated independently as normal, subtle dyskinesis, or obvious dyskinesis using the scapular dyskinesis test. Symptoms were assessed using the Penn Shoulder Score. Main Outcome Measure(s): Athletes judged as having either normal motion or obvious dyskinesis underwent 3-dimensional electromagnetic kinematic testing while performing the same movements. The kinematic data from both groups were compared via multifactor analysis of variance with post hoc testing using the least significant difference procedure. The relationship between symptoms and scapular dyskinesis was evaluated by odds ratios. Results: Differences were found between the normal and obvious dyskinesis groups. Participants with obvious dyskinesis showed less scapular upward rotation (P < .001), less clavicular elevation (P < .001), and greater clavicular protraction (P  =  .044). The presence of shoulder symptoms was not different between the normal and obvious dyskinesis volunteers (odds ratio  =  0.79, 95% confidence interval  =  0.33, 1.89). Conclusions: Shoulders visually judged as having dyskinesis showed distinct alterations in 3-dimensional scapular motion. However, the presence of scapular dyskinesis was not related to shoulder symptoms in athletes engaged in overhead sports.