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. Author manuscript; available in PMC: 2016 Jan 21.
Published in final edited form as: J Biomech. 2014 Dec 9;48(2):383–387. doi: 10.1016/j.jbiomech.2014.11.046

Fig. 1.

Fig. 1

Our previous study showed that chronic stroke survivors with severe hand impairment gripped with their paretic digit force directed further away from the normal/perpendicular direction compared to age-matched persons without stroke (control) (Seo et al., 2010). The mean angular deviation of digit force is illustrated as the width of the cone for each of the paretic and control hands. The paretic cone is shorter than the control cone, since the paretic hand is substantially weaker than the control hand, and thus produces less grip force. In addition to the mean values, ±1 standard error is shown as the shade around each cone. When the digit force deviation angle reaches the slip threshold (42° for rubber finish), the finger slips against the object surface (Fikes et al., 1994; MacKenzie and Iberall, 1994). The paretic digit force deviation angle is closer to the slip threshold compared to control, indicating greater likelihood of finger-object slippage, grip loss, and object drop.