A force transducer for a joint prosthesis is disclosed. The transducer includes A f5RUw,V,central body having a plurality of cavities formed therein from a lower surface. Each cavity defines a flexure member. A plate is located on the side opposite the cavities and connect to each flexure member through support posts. The support posts localize three applied to the plate to each flexure member. Force sensing elements attached to each flexure member provide a signal corresponding to the force applied to the flexure member.

A dynamic grip sensor is formed from a unitary block having upper and lower covers. The sensor, being of a size so that it can be gripped by a human hand, comprises two sets of parallel flexure beams connected between outer end blocks and a center block and are loaded by a base plate connected to the outer end block and extending between the end blocks. The flexure beams deflect to respond to hand grip strength. Strain sensors located on the flexure beams and connected in a wheatstone bridge provide indication of gripping strength. The grip sensor may operate apart from a supporting structure or be incorporated into a handle or similar structure.

An apparatus and method for insuring that the evaluation of forces generated from an injured human limb or hand are accurately determined without malingering factors. The apparatus includes a sensor for determining forces generated by a hand which provides an output signal for input into a scaling circuit of a computer. The scaling circuit has a random scale factor randomly selected by a computer's microprocessor. The random scale factor alters presentation of the sensor output signals on a visual display. The visual display provides an indication to the patient of the amount of force that has been generated, but the scale factor modifies the output signals in a manner and amount that is unknown to the patient. The scale factor for example can be such that at a start of a test sequence a standard force can be displayed in approximately the middle of a scale shown on the visual display. In the next test of the sequence, the scale factor modifies a second set of test results so that the patient believes performance has increased. In a third test, the scale factor again modifies a third set of test results so that the patient believes performance has decreased. In this manner the test results can be analyzed and averaged with certainty as to whether or not the test results are valid, or if they are invalid by analyzing the test scores obtained at different scaling factors.

A human hand load sensor is a strain gauge based force measurement instrument that has two platforms or handles that can be moved together with parts of the human hand, for example, a thumb and finger, or the handles can be grasped between the heel of the hand and several fingers. The instrument permits very precise measuring of strength force by supporting a movable handle relative to a base or reference handle through a flexure system which deforms predictably under shear loading as the handles or platforms are moved together. The flexure system is much like a parallel linkages made from a single block of material between a base and a movable block, and having a small deflecting beam sensing element between the base and the movable block that is isolated from influences of bending or rolling movements on the strain level. The strain energy is sensed with strain gauges that provide a signal directly proportional to the shear loading for very accurate measurements. The making of the base and movable block portions from a single block of material eliminates assembly joints, giving a greater repeatability, high linearity, less zero shift during use, less hysteresis, and more stable calibration coefficients. Further, the machining process or manufacturing process is relatively low cost and highly accurate. The one piece body is easy to calibrate. The base or platform size can be modified quite easily for a wide variety of uses.