THE ACCURATE DESCRIPTION OF SHOULDER MOVEMENTS

Aim: To describe accurately the contributions of glenohumeral (GH) and scapulothoracic (ST) joints in shoulder movements in normal male adult subjects, aged 20–30 years.Methods: We recorded data with a Polhemus magnetic tracking device (Kaiser Aerospace and Electronics Co., Vermont). Receivers were taped on landmarks, over the sternum, scapula and humerus. The movements that were studied were elevation in the sagittal plane, abduction in the scapular plane and lowering the arm from these positions. We collected data from 26 male subjects (52 shoulders), aged 20–30 years, with no history of shoulder problems. Repeatability data were obtained in 16 subjects.The data can be expressed in a number of ways, including plotting the ratio of GH/ST movement versus overall shoulder movement. Polynomial equations to fit these curves describe movement patterns. We have developed software to calculate cumulative averaging of data.Results: Both GH and ST movements contribute to shoulder movement throughout the ranges st...