Instrumented Hip Implant: A Review

About 20% of people older than forty years old face more bone degenerative diseases. The older population is increasing quite rapidly than before which increases the need for knee or hip implants tremendously. One of the major problems of the current implants is their short lifetime and their impact on the surrounding human tissue. The short life can be attributed to implant wear, loosening, and misalignment, which often cause pain and discomfort to the patient. Functional failure of the implant may be followed by a revision surgery, which is often painful and has a relatively low success rate. Moreover, to avoid unexpected failure and unnoticed deterioration of the implant, it is important to make provision for monitoring implants' performance. Instrumented implants can provide accurate monitoring of the loosening state of the implant, which can delay the revision surgeries and its consequences. This study provides a comprehensive review of the technological development of instrumented hip implants to monitor the status of the implants. The main requirements for the implants are highlighted by reviewing different aspects of the instrumented hip implant systems. In-vivo studies reported in the literature were summarized. Vibration and Acoustic Emission (AE) measurement based loosening detection were found to be the most common methods for in-vitro studies. A comprehensive review of power supply and communication modules was presented. Despite the advancement in this field, current systems are not yet able to provide effective monitoring of the implant's status during the daily activities of patients.