3D Printed Knee Implants Could Cut Surgery Times & Improve Arthritis Treatment

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A New Treatment has Been Developed Using Personalised, 3D Printed Implants to Help Improve the Lives of Thousands of Arthritis Sufferers.

Engineers from the University of Bath’s Centre for Therapeutic Innovation have developed the personalised early knee osteoarthritis treatment, which uses state-of-the-art 3D metal printing technology to make personalised medical-grade titanium-alloy plates to perfectly fit every patient.

Following a virtual ‘in-silico’ trial to demonstrate its safety, the treatment has been given the go ahead to be trialled in UK patients. The findings from the trial have been published in Communications Medicine.

Personalised HTO Plates

Known as Tailored Osteotomy for Knee Alignment (TOKA), the treatment improves the operative procedure and fit of high-tibial osteotomy (HTO) plates used to realign a patient’s knee, making them more stable, comfortable, and better able to bear weight than existing generic plates. The technique also simplifies HTO surgery, making operations quicker and therefore safer.

The virtual trial tested the HTO plates using CT scan data from 28 patients. The in-silico clinical trial, the first in the world to demonstrate the safety of an orthopaedic device, modelled the stresses that would be exerted on the bespoke plates and showed that they would be equally as safe as the standard treatment.

Professor Richie Gill, from the Centre for Therapeutic Innovation, 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% 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.”

Simplifying Surgery & Improving Accuracy

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

3D printed screw threads will also be implanted into the HTO plates, meaning they can be optimally positioned to help secure them against the bone.

The trials using real patients will begin as soon as clinical centres return to carrying out elective surgery, which is expected later this year. 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.

Tests of the TOKA technique have already begun in Italy, where so far 25 patients received new personalised HTO plates as part of a trial at the Rizzoli Institute in Bologna.

High Tibial Osteotomy (HTO) surgery realigns the knee joint by making a cut to the tibia (shin bone) and opening a small gap, which needs to be stabilised by a metal plate. This realignment moves the loading to a less ‘worn’ part of the knee. Patient outcomes depend on how accurately the cut is made and the gap opened.

Professor Gill added: “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.

“In addition to a surgeon being able to precisely plan an operation, a surgical guide (or jig) and a plate implant, each personalised to the patient, can be 3D printed automatically based on the scanning data.

“Importantly, this type of treatment relieves the symptoms of knee osteoarthritis while preserving the natural joint.”

The pre-planning element of the treatment could reduce time on the operating table from two hours to around 30 minutes.

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