The present disclosure provides an orthosis for flexing tissue about an arm joint of a wearer. The orthosis includes a first arm member configured to couple to a first arm portion of the wearer, a second arm member pivotably coupled to the first arm member, the second arm member configured to couple to a second arm portion of the wearer, and a drive assembly coupled to the first and second arm members and configured to move the first arm member in an arcuate path.