Date Approved


Graduate Degree Type


Degree Name

Engineering (M.S.E.)

Degree Program

School of Engineering


Due to the prevalence of work-related musculoskeletal disorders in sonographers, this study evaluated upper extremity kinematics and determined if co-contraction was present during kidney scans. The results provided a greater understanding of joint range of motion and muscular activity, which could be helpful in assessing risk of injury. Four sonographers had reflective markers and surface electromyography electrodes placed on their dominant upper extremity. A Vicon MX motion capture system was used to record the marker positions and electromyography data while the sonographers were scanning a volunteer’s kidneys. The shoulder joint center was determined using the instantaneous helical axis method. The wrist and elbow joint centers were determined by taking the difference between markers located medially and laterally about the joint. Three shoulder angles (flexion/extension, abduction/adduction, and interior/exterior rotation), one elbow angle (flexion/extension), and one wrist angle (flexion-extension) were determined by kinematics. The results indicated that the sonographers were scanning with the shoulder in flexion, abduction, and external rotation. The shoulder abduction was always greater than published acceptable limits. The range of elbow flexion angles during this study was 9.3 to 102.2 degrees. The wrist joint was always in extension except for portions of one scan. The wrist joint angles exceeded acceptable published limits during all scans. The electromyograms indicated that the agonistic muscles in the upper arm and forearm were activated simultaneously with the antagonistic muscles at multiple instances throughout the scans, indicating co-contraction was regularly occurring.