REJOINT, an Italy-based medical implant manufacturing company, is leveraging state-of-the-art technologies like GE Additive‘s Electron Beam Melting (EBM) 3D printing and IoT-connected sensorized wearables to offer mass customization and therapy personalization. The offering is specifically targeted at the production of patient-specific knee implants for arthroplasty.

Knee implants are fairly common, and the market is estimated to be around five million implants per year globally. Until very recently, knee arthroplasty relied entirely on the use of standard prosthetic devices, which were limited in terms of available sizes and could cause problems or discomfort to the patient down the line. This means that finding the optimal fit for a knee implant is crucial, especially as knee joints must withstand point loads of over 300 kilograms. An improper implant can result in pain and inflammation and does not have the same feel as natural bone for the patient.

With the proliferation and advancement of 3D printing, however, new opportunities for customized implant solutions are gaining prominence. REJOINT, a Bologna-based company founded in 2015, has recognized this potential and is seeking to transform the knee arthroplasty market with a customized solution driven by additive manufacturing and artificial intelligence.

Today, REJOINT offers the only solution on the market for certified 3D printed knee prostheses made from cobalt-chrome. The implants are made using GE Additive’s Arcam EBM Q10plus system, and are based on patient-specific CT scans, which are analyzed by AI algorithms for optimal fit.

“When it came to additive manufacturing, we were initially undecided about the most suitable solution for personalized cobalt-chrome prosthetics and were evaluating DMLM and EBM,” explained Gian Guido Riva, CEO of REJOINT. “Both modalities, in fact offer a good level of resolution and quality, but we ultimately opted for the GE Additive Arcam EBM Q10plus system. The knowledge and industrialization support that GE was able to provide us and the professional experience of their local team here in Italy also informed our decision.”

At the core of REJOINT’s offering is its AI-driven solution, which compares the anatomy of a patient to several thousand prosthetic dimensions, with many dimensional variables in specific areas of the implant. The software also presents the surgeon with the optimal configuration for the implant’s positioning and enables them to conduct a simulation of the operation using computer-aided surgery tools.

Out-of-machine femoral condyles.

“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,” added Riva. “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.”

REJOINT’s sophisticated offering essentially identifies a series of correlations across the entire arthroplasty process, from preoperative planning to patient rehabilitation. The company’s first implant, which was implanted by Professor Maurilio Marcacci, Head of the Joint Knee Reconstruction Centre at Humanitas Research Hospital in Milan, was a success, with excellent patient satisfaction.

The company is now applying for FDA 510(k) clearance and is expected to receive it in the first half of 2021. Once this is granted, REJOINT will have access to the American market, which represents 62% of the world market for orthopedic devices and over 70% of the global market value for knee implants.

Finished femoral condyles.

In addition to obtaining its FDA clearance, REJOINT is also working closely with GE Additive to reduce the production costs of the powder-based AM process by reducing cycle times and optimizing printing parameters. The company is also developing a single-compartment prosthetic system with minimally invasive design and robotic surgical technology for younger patients.

“The key element is an increasingly close and direct relationship between company and patient,” Riva concluded. “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.”

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