A knee orthosis comprises an upper leg attachment and a lower leg attachment. In addition, the knee orthosis includes a hinge joint extending between the upper leg attachment and the lower leg attachment. The hinge joint includes an upper arm having a first end fixed to the upper leg attachment and a second end opposite the first end. The second end including a semi-spherical surface. Further, the hinge joint includes a lower arm having a first end fixed to the lower leg attachment and a second end opposite the first end. The second end including a semi-spherical surface that mates with the semi-spherical surface of the second end of the upper arm.