Integrating sensors into total hip replacements

Total hip replacement (THR) is a successful intervention for late stage osteoarthritis. The NJR reported in 2022, that 100,000 total hip replacement (THR) surgeries were performed in England, Wales and N.Ireland . Use of THR is increasing and younger patients are receiving THRs. Implants need to be reliable, have good survivorship, be cost effective and enable surgeons to provide a high level of patient care to reduce the growing burden on clinicians, healthcare providers and the economy. Instrumented implants capable of in-vivo sensing would allow for the continuous monitoring of patients post operatively. Data collected from the implant could provide insight into the function of the implant in-vivo and track the recovery of the patients. Previous work on integrating sensing systems into THRs has focused on measuring joint reaction forces and component loosening. Tracking joint kinematics would allow the collection of metrics such as joint range of motion and step count which are commonly used to track post operative recovery. Furthermore, measuring the components relative position and orientation could enable the detection of adverse events and so give early indications of component damage or the need for clinical intervention. The aim of this thesis was to develop a sensing system for use within a THR to measure the relative kinematics of the components. This thesis has resulted in a validated engineering prototype. With further development this sensing method could feature within an instrumented THR implant and be used to measure the kinematics of the components in vivo. Metrics such as joint range of motion, step count and risk of component impingement or impingement driven subluxation could be extracted and used to guide post operative care.