3D printed knee implants on trial to substitute traditional knee replacements

Service Engineering

The new 3D printed medical-grade titanium-alloy knee implant has been engineered at Bath University’s centre for Therapeutic Innovation. The Tailored Osteotomy for Knee Alignment (TOKA) works with the patients existing joint with the aim of relieving knee osteoarthritis sufferers without needing a traditional knee replacement. This can be put in at an earlier stage of arthritis therefore relieving pain much faster.

The treatment is said to be much more stable and comfortable than traditional plates used in the process, as well as simplifying the surgery, thereby achieving a safer, more efficient operative procedure. The preparation makes the actual surgery much less complicated with the potential to reduce the patients time on the operating table down from two hours to approximately half an hour.

“Knee osteoarthritis is a major health, social and economic issue and does not receive as much attention as it should“

TOKA patients initially have a 3D CT scan, then a printed surgical guide and plate is made, customised to the individuals tibia bone. This is the only procedure to use printed screw threads which go into the plates, assisting in affixing them to the bone.

The high-tibial osteotomy (HTO) operation realigns and steadies the knee so that the weight is alleviated from the part of the knee that is suffering. The process involves making a minor incision to the tibia to create a small opening, then secured by a metal plate. The extent of relief is based on how precisely incision and opening was carried out by the surgeon.

Versus Arthritis is the company financing the research and trial in the UK.

Testing has taken place using data from 28 individuals’ CT scans in a computer-based trial. Hospitals across the country including Bristol and Cardiff will trial the process by comparing different patient outcomes with the current HTO operation in a randomised control trial. 25 patients have already received custom HTO plates in Italy during a testing trial in Bologna.

Professor Richie Gill, Co-Vice Chair of the Centre for Therapeutic Innovation, said that “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 per cent 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.”

Professor Gill explained “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.”

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