Abstract: The novel temperature gradient compensation circuit is designed to overcome temperature gradient problems in inductive or capacitive circuits, such as, differential variable reluctance transducers. The system comprises, in one embodiment, the use of an inductive or alternating current bridge which sends its output to a low pass filter in order to remove the alternating current component of the bridge output. The output of the low pass filter is fed into an instrumentation amplifier whose gain can be adjusted. The output of this instrumentation amplifier is a signal that is proportional to the temperature gradient experienced by the alternating current bridge. The output of the alternating current bridge is also fed to a high pass filter and then sent to a demodulator and amplifier. By subtracting the direct current output from the alternating current output, the effects of temperature do not have an effect upon the result.

Abstract: The novel ligament tension measuring device has a looped prosthetic ligament or sutures that surround a receptacle. The receptacle contains a positioning hole that allows a fixation pin to be inserted to obtain the optimum position for the desired process. The receptacle also has measuring devices, such as strain gauges or magnets and hall effect sensors. The method includes the steps of: preparing to attach the ligament to the bone; placing the device into the loop of the ligament at the tibia; adjusting the tension on the measuring device; temporarily attaching the ligament at the desired position; pinning the device in place; moving the knee through the entire range of motion; repositioning the device as necessary for the optimum position; removing the device, while leaving the pin in position; and proceeding with the permanent attachment of the ligament.

Abstract: This device is adapted for replacable implantation in soft body tissue for the measurement of the mechanical behavior of the soft tissues of the body. The device consists of an hall-effect strain transducer that detects the linear motion of a magnetic core. A barb force transducer uses a barbed probe that is inserted into the soft tissue. The barb force transducer has pressure sensors located within the body of the probe that detect the squeezing of the tissue fibers against the sides of the transducer. The combination of the hall-effect strain transducer and the barb force transducer allows the operator to simultaneously measure the strain and force on a specific soft tissue.