The Relation between Scapular Dyskinesis and the Upper Quarter Y-Balance Test

The shoulder is a complex mechanical system. Alterations in the position and/or orientation of its joints may interfere with optimal shoulder coordination. Scapular dyskinesis (SDK) is defined as mal-positioning or mal-movement of the scapula along the thoracic wall. It is not well established the role of scapular dyskinesis as the cause or the effect of shoulder pathologies. The Upper-Quarter Y-Balance test (UQYBT) has been suggested as a return-to-play tool for athletes with upper extremity injuries. The objective of this study was to quantify the relation between the UQYBT and SDK. Six males and five females participated in the study, age 18-30 years old. All participants' shoulders were evaluated by a certified athletic trainer using Kibler Scapular Dyskinesis Test (SDT) as having dyskinesis or not. Each participant performed three of the SDT and three of the UQYBT. The outcomes of the UQYBT were the highest score for each direction SuperiorLateral Reach (SLR), Inferior-Lateral Reach (ILR), and Medial Reach (MR) and the Composite score. An independent t-test with unequal variances was performed to determine statistical differences between normal and SDK shoulders during the UQYBT. Results indicate significant differences between the normal and SDK shoulders in the Composite score (p=.048). No significance was found during the ILR, SLR, and MR. In conclusions, when the SDK shoulder was stabilizing during the UQYBT higher scores were seen in every direction compared to the normal shoulder. These suggest that SDK may affect the scores of UQYBT.