A wirelessly monitoring system design for Total Hip Replacement surgery

This paper presents a wirelessly monitoring system for Total Hip Replacement (THR) surgery. This system aims to measure and display the attitude and position of femoral head of prosthetic implant during the surgery. The system consists of two parts: the Sensors Array Measuring System (SAMS) and the display part. The SAMS is composed of a sensors array, signal conditioning circuits, a low power Micro Control Unit (MCU), and a low-power transceiver. The SAMS is designed to measure the contact distribution of the sensors array (which is on the surface of the femoral head) between the surface of the femoral head and the acetabulum of the prosthesis. The data is transmitted wirelessly by a low power transceiver. The display part demonstrates the contact distribution and the attitude of the prothesis in-vivo in 3-D images. The two parts of the system communicate with each other on a RF link at the band of 400MHz. The signal conditioning circuits have been designed and fabricated in 0.18μm CMOS process. The tested results show that the resolution of the signal conditioning circuits is 60.1μVpp (1.35g) with ±100mVpp input and the chip can operate under 1.2V to 3.6V voltage supply for single battery application with 116-160μA power current consumption. The system has been validated by experimental results.