Correlation between Scapular Dyskinesia and Endurance of Rotator-Cuff Muscles in Non-Symptomatic Individuals with Scapular Dyskinesia in Ahmedabad, Gujarat - An Observational Study

The position and motion of the scapula are closely interrelated with motion of the arm to accomplish most of the shoulder function. The scapula plays many roles in normal shoulder function which requires control of static and dynamic position of scapula. For maintaining the good kinematics of the scapula and the surrounding structures, the movement of the scapula must be synchronized. The dynamic muscle function is the major method by which the scapula is stabilized and purposefully moved to accomplish its role. Alteration of normal positioning of the scapula can lead to altered biomechanics of the shoulder as well. When there is weakness in scapulae musculature, the normal scapular position and mechanics gets altered leading to scapular dyskinesis. Scapular dyskinesis can also reduce rotator cuff strength and increase the rotator cuff strain. The study was carried out to find the correlation between scapular dyskinesis and endurance of the rotator cuff muscles in non-symptomatic individuals with scapular dyskinesia. Around 900 non-symptomatic subjects aged 18 to 25 years of both the genders from different colleges and hostels from Ahmedabad were assessed for the presence of scapular dyskinesia. Out of these about 402 subjects were found to have scapular dyskinesis. Those non symptomatic young adults were scanned for the presence of the scapular dyskinesis with the help of Modified Lateral Scapular Slide Test (MLSST). The subjects with scapular dyskinesis were included in the study, the type of dyskinesia was also ruled out. The subjects were than assessed for the strength of the rotator cuff muscles by using hand held dynamometer. The 25% weight of the best of three reading of strength of external rotation was given to assess the endurance of the rotator cuff in modified base position. The time holding an isometric contraction in modified base position was recorded in seconds. The correlation between the scapular dyskinesia and the endurance of the rotator cuff was analysed. The results suggest that amongst 402 subjects, there is significant but weak correlation between scapular dyskinesis and endurance of rotator cuff muscle in both dominant and the non-dominant arm.

Key words: Scapular dyskinesis, Endurance, Rotator cuff Muscles, External Rotation .