A ligament laxity telemetry system architecture for a knee replacement prosthesis

In this paper the feasibility of a novel instrumented orthopaedic implant for total knee replacement is studied. The system aims at providing an indication on the balance of the lateral ligaments. The measures will be used to estimate the wear out of the polyethylene part of the prosthesis and will also facilitate the patient rehab. The data will be transmitted outside the body through an RF link. Unlike other instrumented implants, the system will be self-powered. Piezo ceramics will be used both as pressure sensors and as power generators. This implies that the measurement system must be ultra low power as the available power is less than 1.8 mW. First simulation results are given for a 0.35 ¿m CMOS process.