Objectives

Ageing, sedentary behavior, and obesity are predictors of osteoarthritis, and the combination of arthritis and obesity causes an undue stress on joints, and when conservative treatments no longer yield a satisfactory response, joint replacement becomes necessary. Despite the standardized procedures, a significant share of total joint replacements fail because the prosthesis becomes loose or because of osteolysis, and the prosthesis must be replaced. Bone loosening is usually diagnosed by radiography and clinical symptoms, but pre-operative radiographic diagnosis of loosening has a sensitivity of 80%, and a considerable number of revision surgeries is not necessary because loosening of the total joint replacement was diagnosed false positively. Currently clinically applied methods of assessing implant fixation and implant loosening are of sub-optimal precision, leading to unsecure indication of revision surgery and late recognition of bone defects. To solve this technology gap, the SMART-HIP goal is to develop a new intelligent hip prosthesis, enabling timely and accurately diagnosis of bone loosening, thus allowing for a fast and reliable support to the orthopaedists while deciding upon revision surgery of joint replacements. The final SMART-HIP system will be composed of two fundamental sub-systems:

A) The Intelligent Prosthesis, whose basic component will be the Oscillator Unit consisting of a magnetic or magnetisable body which is fixed on a flat steel spring, which will enable to perform an acoustic-mechanical analysis of the variation of the resonance frequencies of total joint replacements, correlating them with the loosening status of the bone.

B) The Diagnostic Device, which is placed outside the patient’s body and used during the clinical test to excite the oscillator. This excitation within the implant bending modes leads to a sound emission to the surrounding bone and soft tissue, which can be detected by a vibration sensor, which is applied outside the patient.