Development of optimized instrumentation for total hip replacement – OrthAncil

Total Hip Replacement (THR) is considered as the “surgery of the century”. The main cause is osteoarthritis (93%) which is prevalent in 11% of women and 9% of men. Moreover, age is one of the most important risk factors for osteoarthritis. In France, THR is the most common surgery with around 150 000 patients treated per year. Even if THR provides excellent technical outcomes with a 10-year survival exceeding 95%, the increase of life duration of the population, the fact that 20% of surgical procedures are for patients over 60 years old and the demand of the same patients to keep a physical activity will lead to increase the lifetime of patients with their implants. The most common and serious complications in THR surgery are the risk of aseptic loosening, depending on the primary stability of cementless implants; and the risk of intraoperative bone fractures (30% in revision surgeries). To overcome these issues, we aim at developing a non-invasive tool allowing to define the precise impact energy necessary for the implant insertion to minimize intraoperative bone fracture and to assess the primary implant stability to decrease the risks of aseptic loosening.
Moreover, the instrumentation used so far to perform THR is reusable which leads to different risks associated to infection, sterilization, storage, and traceability. In this context, the development of single-use (SU) instrumentation in orthopedic surgery will simplify the surgical procedure, reduce the contamination of instruments, improve the operating room efficiency, and decrease the overall costs.
OrthAncil aims at improving THR surgery by developing and validating a market-ready innovative instrumentation based on the coupling of SU ancillaries and a decision support system consisting in an instrumented hammer based on a computational model. The main goals are to develop i) a SU instrumentation, which requires to determine the most suitable material for each component according their specifications, the regulatory and the manufacturing constraints; ii) an instrumented hammer able to assess the stability and the insertion endpoint of the implant in the host bone; iii) a reliable numerical and decisional model, necessary to mimic the surgical conditions to better understand the mechanisms involved in terms of impact, adhesion, and friction phenomena in the dynamic context; and iv) a market-ready prototype including the SU ancillary, the instrumented hammer, the reamer and the impactor. We want to manufacture prototypes ready for the CE marking and to test them under various conditions (in silico, in vitro, ex vivo and in anatomical subjects).
Based on feasibility studies performed on acetabular cup implants and on the femoral stem, the originality of OrthAncil is to bring this technology into the medical field by adjusting the approach to the problem considered. Our technology presents the following advantages: i) the direct integration of the device in the operating room; ii) the device is not directly in contact with the implant, minimizing infection risks; iii) there are no modification of the surgical procedure, which makes it ready-to-use. Moreover, the OrthAncil instrumentation can be used in both conventional and robotic orthopedic system. The combination of both systems will allow to secure the insertion of implants in bones, decrease the cost of surgery, and make more accessible robotic systems to the hospitals. Despite all these advantages, concerns over increased waste may lead to the perception that SU instrumentation is less environmentally friendly than traditional systems. However, several studies proved that the carbon footprint of the SU plastic instrumentation is neutral compared to the average CO2 equivalent annual emission of conventional re-usable metal instrumentation. On the longer term, findings obtained in OrthAncil will be used to develop new medical devices for other applications such as other arthroplasty or osteotomy.