knee joint xray in medical settings

3D-printed knee implants made of metal could cut decades of pain

Image credit: Dreamstime

3D-printed metal implants developed by a team at the University of Bath will allow patients going through knee surgery to quickly receive bespoke treatments that fit perfectly to their bodies.

The high tibial osteotomy (HTO) implants are made of titanium alloy, and are designed to reduce discomfort for knee osteoarthritis patients

The ease of 3D printing makes their production relatively simple and could allow for earlier intervention, potentially saving patients decades of pain before surgery becomes viable

The implants are due to be trialled on UK patients, following a virtual ‘in-silico’ trial that demonstrated the technique's safety. Using CT scan data from 28 patients, the trial modelled the stresses that would be exerted on the bespoke plates digitally and showed they would be comparable in safety to the standard treatment.

The process, called TOKA (Tailored Osteotomy for Knee Alignment), is used to realign a patient’s knee, making it more stable, comfortable and better able to bear weight than existing generic plates. The technique also simplifies surgery by making operations quicker and safer.

3d printed knee implant

An illustration of the 3D printed implant

Image credit: university of bath

Professor Richie Gill, one of the researchers on the project, said: “Knee osteoarthritis is a major health, social and economic issue and does not receive as much attention as it should. A quarter of women over 45 have it, and about 15 percent of men, so it’s a significant burden that many live with.

“Knee replacement is only useful for end-stage osteoarthritis, so you can be in pain and have to live with a disability for a long time, potentially decades, before it’s possible. We hope that the new TOKA process we’ve developed will change that.”

Knee osteoarthritis patients undergoing TOKA will first undergo a 3D CT scan of their knee, before a personalised 3D-printed surgical guide and plate, both shaped to their tibia (shin) bone is created. The surgical guide simplifies the surgery, and is designed to improve surgical accuracy.

The process also sees the first implementation of 3D-printed screw threads into the HTO plates, meaning they can be optimally positioned to help secure them against the bone.

When clinical centres return to carrying out elective surgery, expected later this year, the trials will begin.

Hospitals in Bath, Bristol, Exeter and Cardiff will take part in a randomised control trial to compare patient outcomes with an existing generic HTO procedure.

Prof Gill adds: “The HTO surgery has a long clinical history and it has very good results if done accurately. The difficulty surgeons have is achieving high accuracy, which is why we have created the TOKA method, which starts with a CT scan and digital plan.

“3D-printing the custom knee implant and doing the scanning before operating means surgeons will know exactly what they’ll see before operating and where the implant will go.”

Last year, a team from the University of Sheffield developed prototype 3D-printed implants that can link a patient's brain directly to a computer.

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