REJOINT Uses EBM, Sensors & IoT Data for Patient-Specific Knee Surgery

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REJOINT is an Italy-based medical device company specializing in Total Knee Arthroplasty operations that received 3 million Euro in EU Horizon 2030 funding in 2019. The firm is seeking US Food & Drug Administration, FDA 510(k) clearance for a new data-driven mass customization approach to patient-specific implants.

In total knee arthroplasty procedures, usually arthritic, knees have their surfaces completely replaced by implants. Total knee arthroplasty is becoming more prevalent as more people enter more advanced ages. More of those people also want to live active lifestyles compared to years ago, when more sedentary lifestyles were the norm. Increasingly people from developing and middle-income countries can also now have these procedures made available to them and younger patients (below 65) are increasingly getting them.

At the same time, these kinds of operations may become more prevalent due to increased obesity. Obesity affects over 1.9 billion adults and over 600 million are clinically obese which in turn can exacerbate osteoarthritis. For “every 5 kg increase in weight, the risk (of the development of knee osteoarthritis) increases by 30%.” Around 45% of TKA patients may have diabetes as well, which is a steadily rising condition in and of itself.

In the US alone, some estimate that the prevalence of the procedure will increase by 143% by 2050, while, as of 2015, 7 million adults have had the procedure. In 2010, the prevalence was “1.52%….Prevalence was higher among women than among men and increased with age, reaching…10.38% for total knee replacement at eighty years. These estimates corresponded …. 4.7 million individuals (3.0 million women and 1.7 million men) with total knee replacement in 2010.” Other estimates predict 673% growth in the US until 2030 or even growth of 855%. In the US 790,000 procedures are performed annually, while even a small country as the Netherlands has over 28,000 procedures per year.

REJOINT’s approach puts the firm in the middle of several converging megatrends and the firm is also taking a very trendy approach to improving total knee arthroplasty. By extensively using data, IoT sensors, artificial intelligence, and 3D printing the company hopes to create better mass-customized implants for patients.

REJOINT uses GE’s Arcam EBM technology to make patient-specific implants. On the whole, we would expect that patient-specific implants would hasten procedures and perhaps shorten recovery time because the implants fit the patient better, reducing the length of the procedure and requiring less pushing and shoving by the doctors to make the implant fit.

Pushing and shoving is not used facetiously here. Orthopedic surgeries are a lot less delicate than one may assume. So patient-specific seems like a very logical choice that may be quite beneficial to the patient. Most studies on patient-specific implants have, however, been carried out at the behest of the manufacturers of these implants.

What we do know is that we can get good osseointegration through EBM implants and this is partially why the procedure has grown in popularity in recent years. EBM medical devices can also be comparatively easier to develop through making more iterations possible and are lower cost than conventionally manufactured implants.

Higher specificity of designs and more patient-specific options have been something that the medical device industry has been flirting with for quite a while now, but what should guide patient-specific designs? Can we create specific textures for osseointegration for specific patients or groups of patients? How many sizes of implants are optimal, and do we really need individualized implants? There are no hard and fast answers to these questions at the moment.

What REJOINT has done however is to look further at new data sources that could input implant design and individualization. The company maintains that, “For the patient, over- or under-sizing means constant awareness of the presence of an artificial joint, as well as leading to muscle and ligament decay.” The company also notes, “Patient feedback after an implant can sometimes reflect these issues and indicates that dissatisfaction can be felt by one in five patients and sometimes even to levels of one in four. Dissatisfaction is often largely related to the suboptimal sizing of the implanted prosthesis.

“To produce the additively manufactured prosthesis, REJOINT starts by 3D modelling the patient’s CT scan. Sophisticated Artificial Intelligence (AI) algorithms are then used to analyze the images and identify the most suitable size for each specific case.

AI is used to compare the unique anatomy of a patient on several thousand prosthetic dimensions, each with as many dimensional variables in specific areas of the implant.

The surgeon is then offered the optimal configuration, for positioning both the prosthetic components and for simulating the operation. This analysis forms the basis for the production of the prosthesis and for patient-specific tools for the planning of the intervention – which is carried out with the support of computer-aided surgery tools.”

In 3D printing for in-the-ear hearing aids, such configuration and placement decisions are still guided by the choice of the operator. By making the configuration step software-guided, the company is making it easier for surgeons to order and receive the right implants for the patient. The risk of choosing the right-sized implant is now also partially offloaded from the surgeon’s shoulders to the device manufacturer. This may reduce some hesitation to go patient-specific by some surgeons and administrators to a certain extent.

The fit system is based in part on Enhatch, a startup that was started by some of Rejoint’s founders. The implants are 3D printed on GE Additive Arcam EBM Q10plus systems in cobalt chrome. In modular hip systems specifically, designers are increasingly opting for cobalt chrome over titanium because, in some cases, the femoral neck portion of some total hip arthroplasty implants has fractured in titanium implants; however, in some very isolated cases, Co-Cr femoral necks have also reportedly failed. Having said that, the jury isn’t out on when which material delivers better results for patients.

Besides just 3D printing, Rejoint data-driven mass customization approach uses web-enabled sensors to provide feedback data to the company which will help it improve its products.

REJOINT CEO, Gian Guido Riva, said of the announcement:

“Having all this data made us realize that we could link it to the information recorded during the operation. And in turn, this data could still be further improved upon if we could collect through the use of wearable devices (such as sensorized headbands and socks), both pre- and post-operative measurements, on how the patient loads their limb or bends their knee, until post-operative evaluation questionnaires have been completed,”

“By 2022, we will have the complete data of thousands of cases available. This will provide us with an unparalleled wealth of application information, in terms of completeness, in the sector. Despite the sale of millions of pieces, there is little or no information on what happens post-sale.”

A real genius element of this is that, “The key element, is an increasingly close and direct relationship between company and patient. This will further increase the degree of post-operative satisfaction. We are at the beginning of a revolution in the field of knee implants. REJOINT’s work in adopting additive technology will allow for more personalized procedures and higher levels of long-term patient satisfaction.”

If REJOINT can strengthen its relationship with the patient and listen intently during the feedback phase, then better implants could result. What will of course most probably be the case is that the soliciting of direct feedback and the closer relationship with the patient that the company is seeking will result in better patient satisfaction. If patients feel more of a connection with the device manufacturer and feel listened to, we would expect them to have a better self-reported feeling towards this procedure and the company. Indeed, the company is now working on a host of mobile apps and web tools to connect it with doctors and patients. Actual listening to patients coupled with a data-driven approach to implant design could very well cause REJOINT to produce better and better-rated implants.

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