University of Bath

TOKA®: A High Precision, Patient Specific, High Tibial Osteotomy Procedure

TOKA® is a novel High Tibial Osteotomy (HTO) treatment for relieving pain of early knee osteoarthritis whilst preserving the natural joint.

Dr. Alisdair MacLeod and Professor Richie Gill believe that by exploiting advances in imaging techniques and 3D printing they can offer an accessible, alternative surgery to treat early stage knee osteoarthritis.

Arthritis of the knee is extremely common. In the UK, 14% of the population over 40 suffer from diagnosed knee arthritis (4.5 million people). And there is a similar prevalence in most European countries and the United States.

Professor Gill says: "We should not underestimate the urgent clinical need for innovative solutions to treat knee osteoarthritis. We see a growing number of younger people in pain with early stage knee osteoarthritis who we can’t offer effective treatment. A third of people who have received a knee replacement recorded in the National Joint Registry are under 65.”

Overcoming surgical barriers

High tibial osteotomy (HTO) is a surgical procedure suitable for patients who have osteoarthritis on one side of the knee and healthy cartilage on the other side. Knee osteoarthritis often starts in the inside of the knee. This means one side of the leg starts wearing out and the leg becomes bowed. HTO surgery realigns the knee joint by reorienting the tibia (shin bone), using a metal plate to support the bone while it heals. This allows the load to transfer from the worn to the unworn side of the knee.

It is a proven treatment, but there are barriers we need to overcome to make it a viable option for more people. At the moment, it's complicated to achieve the desired correction in the tibia. The surgical team relies on x-rays during the operation to take measurements and check positioning. This requires a large number of staff in theatre along with surgeons. And it makes the surgery lengthy and expensive to perform. We also see many patients complaining of irritation caused by the metal plate. This can mean further surgery is needed, adding time to the patient’s recovery and expense to the NHS.

Developing a more cost-effective, accurate procedure

Working with Professor Andrew Toms from the Royal Exeter and Devon Hospital, the ToKa team believe they have a solution to address both issues. They are devising a product that will improve the accuracy of the surgery, reduce the cost and resources involved and achieve better outcomes for the patient. They have developed a new procedure that uses 3D imaging techniques and software to design and 3D print a personalised medical grade titanium implant tailored to each patient’s bones.

Professor Gill explains: "The level of precision we can achieve through 3D planning and metal printing, generating a plate contoured to the patient’s anatomy, removes the need for inter-operative radiology.”

"This should dramatically reduce both the length of the operation and the number of professionals involved. The customised plate will also reduce the risk of soft tissue irritation and the need for plate removal surgery. So as well as being cost-effective for the NHS, it will be better for the patient. A large part of the project is pre-clinical testing to make sure that the new device will function properly.

Dr MacLeod says: “We are conducting the UK’s first orthopaedic virtual clinical trial to prove the safety of the new TOKA® device compared to existing treatments. This involves simulating a large number of virtual patients and examining what will happen to the implant during different activities such as walking, running, sitting down or going up stairs.

“Engineers already use simulations to ensure the safety of commercial aircraft or nuclear power plants. But we’re only now applying it to the human body.”

If successful, the team hope clinical trials will lead to their innovation becoming widely available by 2022.

What causes knee osteoarthritis?