Case Study

A bespoke technology package for complex knee surgery will be tested in its first human trial later this year.

The surgical technology, known as ToKa, is a new approach for an operation used on younger patients with osteoarthritis known as high tibial osteotomy (HTO). This involves an incision into the patient’s shin bone (tibia) to realign the knee joint and redistribute weight and forces, often the cause of major pain. A metal plate is then attached to support the bone in the correct position. However, to achieve accurate alignment, the surgical team must rely on x-ray measurement during the operation, requiring a radiologist to be present.

Professor Richie Gill of the University of Bath, who leads the project, explains: “How successful the HTO operation is depends directly on how accurately it is done. If not enough realignment has been done, the result will be poor.” The existing standard off-the-shelf metal plate which is attached to support the bone may also subsequently irritate the patient’s knee tissues, due to poor fit.

Personalised surgery

ToKa uses 3D imaging techniques and software alongside the patient’s own CT scans, allowing surgeons to plan each procedure on an individual basis. The programme prints a 3D personalised surgery guide, or jig, for each patient, as well as a titanium plate implant to fix the shin bone in place. The surgery guide de-risks the procedure, with surgeons easily able to find the optimum angles of cutting and drilling; while the precision-fitting metal implant should greatly reduce the risk of irritation to surrounding knee tissues. Predictions are for the operating time to be cut from two hours around 30 minutes.

Dr Alisdair MacLeod, Design Engineer at 3D Metal Printing, a spin-out company formed to produce ToKa commercially, said: “The whole process will take ten days’ turnaround for the surgeon, from planning to printing, and we believe it will also ultimately be much more successful for the patients.”

Following validation of the technology in a virtual clinical trial involving simulated loading steps on models created from patient CT scans, it is now undergoing regulatory approval to be tested in patients later this year. The blinded randomised trial will compare ToKa with the most commonly used surgical procedure for around 88 patients who need the HTO operation.

Regular oversight

The IKC and Versus Arthritis provided the initial funding to take the technology from an initial idea through to the patenting stage. This was essential in providing a submission for the Medicines and Healthcare Products Regulatory Agency for the technology’s virtual trial, which was also funded by Versus Arthritis.

Professor Gill said: “As well as funding, the input and regular oversight from the IKC’s project management team really kept us on track. Their knowledge and expertise were also very helpful when applying for further investment and their letter of support provided independent validation of what we had achieved.”

Sarah Odoi, IP Development Manager at Versus Arthritis, said: “This kind of personalised approach is set to be the way forward in areas where precision is needed to get the best outcomes. The success of this kind of procedure is especially important for younger patients, to delay the need for joint replacements as long as possible. We’re very excited to see the technology going into a clinical trial and it’s rewarding to know our funding has helped it to get to this stage.”

3D Metal Printing is presently undergoing the UK National Standards (BSI) approval process to be a certified medical device manufacturer. The company employs eight full-time employees working on aspects of the project including the planning software, the surgeons’ web portal, and virtual reality training software.