Glenohumeral translations during range-of-motion movements, activities of daily living, and sports activities in healthy participants

• Assessment of normal glenohumeral translations is limited to a few movements.
• Translation during range-of-motion, activities of daily living, and sport activities
• Upward translation was minimized during arm elevations with internal rotation.
• Range of translations during sports activities and range-of-motion were comparable.
• Fast movements, but also movements of large amplitude cause large translations.

BackgroundGlenohumeral translations have been mainly investigated during static poses while shoulder rehabilitation exercises, activities of daily living, and sports activities are dynamic. Our objective was to assess glenohumeral translations during shoulder rehabilitation exercises, activities of daily living, and sports activities to provide a preliminary analysis of glenohumeral arthrokinematics in a broad range of dynamic tasks.MethodsGlenohumeral translations were computed from trajectories of markers fitted to intracortical pins inserted into the scapula and the humerus. Two participants (P1 and P2) performed full range-of-motion movements including maximum arm elevations and internal–external rotations rehabilitation exercises, six activities of daily living, and five sports activities.FindingsDuring range-of-motion movements, maximum upward translation was 7.5 mm (P1) and 4.7 mm (P2). Upward translation during elevations was smaller with the arm internally (3.6 mm (P1) and 2.9 mm (P2)) than neutrally (4.2 mm (P1) and 3.7 mm (P2)) and externally rotated (4.3 mm (P1) and 4.3 mm (P2)). For activities of daily living and sports activities, only anterior translation during reach axilla for P1 and upward translation during ball throwing for P2 were larger than the translation measured during range-of-motion movements (108% and 114%, respectively).InterpretationWhile previous electromyography-based studies recommended external rotation during arm elevation to minimize upward translation, measures of glenohumeral translations suggest that internal rotation may be better. Similar amplitude of translation during ROM movement and sports activities suggests that large excursions of the humeral head may be caused not only by fast movements, but also by large amplitude movements.