Figure 2.

(a) Schematic drawing of a synovial joint highlighting the important anatomic features. (b) Simplified picture of the squeeze flow in a synovial joint undergoing a compressive deformation (such as occurs in the knees during locomotion). The black arrows indicate the flow of the synovial fluid being squeezed outwards orthogonal to the compression axis, resulting in a biaxial extensional flow at the mid-plane between joint surfaces and a stagnation point at the center of symmetry (marked by the red “x”).