%0 Journal Article
%@ 0169-8141
%A Koontz, AM
%A Cooper, RA
%A Boninger, ML
%A Souza, AL
%A Fay, BT
%D 2004
%F pittir:15777
%J International Journal of Industrial Ergonomics
%N 3
%P 237 - 248
%T Scapular range of motion in a quasi-wheelchair push
%U http://d-scholarship-dev.library.pitt.edu/15777/
%V 33
%X Descriptions of shoulder kinematics during wheelchair propulsion are limited to motions of the upper arm due to the difficulty of measuring scapular movement in vivo. Using a digitizing stylus, the three-dimensional positions of three anatomical landmarks on the scapula were recorded for 10 manual wheelchair users in six different statically held hand positions (-30°, -15°, 0°, 15°, 30°, 60°) on the pushrim. In each hand position, a motion analysis system recorded the coordinates of infrared markers on the arm and torso. Scapular, humeral, and torso angles were computed using an Euler angle decomposition method for each position relative to the torso. At the beginning of the push, the scapula was rotated slightly upward (1.5°), minimally protracted (15°), and maximally tipped forward (22°). In addition, the humerus was maximally extended, abducted and internally rotated. As subjects moved forward along the pushrim, the protraction angle increased while the forward tipping angle decreased. The humerus became increasingly more flexed as the push progressed with small changes observed in humeral abduction and internal rotation. A stepwise multiple regression analysis procedure (p<0.01) revealed that the torso, humeral flexion/extension and abduction angles are good predictors for estimating forward tipping and upward/downward rotation of the scapula. The regression equations enable researchers to estimate scapular orientation during propulsion which could provide further insight into specific biomechanical factors that lead to shoulder pathology.