Fig. 3.
A schematic illustration shows the custom, biaxial testing apparatus used to measure RSA stability. A compressive force (FN: 66 N, 110 N, 155 N, or 200 N) is applied in the Y direction to the glenosphere, which is attached to the bottom of a movable sled. The amount of force it takes to dislocate the glenosphere from the humerosocket FS is measured by a load cell attached to a metal fixture resting on a bed of bearings. The load cell, metal fixture, and bearings all rest on a movable sled that moves in the X direction at a constant 5 cm/minute. LVDT = linear voltage displacement transducer used to measure movement of the sleds.