While joint arthroplasty has become impressively advanced over the past few decades, the essence of the procedure still ultimately boils down to trial and error. Using pre-operative X-rays and intra-operative sizing guides, joint surgeons pick from a pre-set list of joint replacement “sizes.” Then, once the bone cuts have been made, temporary implants called “trials” are used to see how the fit is, and the best fit is selected. Rarely are these pre-determined sizes a perfect fit, but they are usually more than sufficient and function quite well.
However, in the quest for perfection, patient-matched custom implants are beginning to increase in popularity. Stanmore Implants just announced the launch of their custom matched unicondylar knee replacement system dubbed “Savile Row,” after the famous Tailoring destination. Unicondylar knee replacements are used in patients with isolated arthritis in one part of their knee and only replace the damaged portion.
The procedure begins with Stanmore using patient CT data to create a custom implant aligned and sized to optimize fit in the patient’s knee. It is then subsequently implanted following cuts made by the company’s proprietary robotic system. Ideally this gives the patients a more functional and longer lasting implant while also leaving them with more bone stock for possible future revisions (assuming less cuts are made than traditional methods). While not explicitly stated, this method most likely is significantly more expensive than the current standard that is used by the majority of the world. Early studies are showing some promise in terms of better aligned knees and improved patient outcomes. Whether it has a major impact on long term outcomes and justifies a higher cost remains to be seen.
More from the press release:
This approach to knee surgery focuses on careful patient selection and uses CT scan data to enable Stanmore to design a personalised and optimised knee implant exactly matched to the patient. This type of knee design is called a unicondylar knee as only one part of the worn knee joint is replaced, leaving healthy, functional tissue in place. By using this approach, minimal bone is removed offering both faster recovery and improved function compared with more invasive traditional techniques, which remove both worn and healthy bone.
Surgeons can directly review and approve each implant using the Company’s online design service; a technology-led video conferencing and electronic communication tool. Once the design has been approved, Stanmore uses computer assisted manufacturing techniques to produce personalised implants in a cost effective manner with great accuracy.
The same knee design is loaded into Stanmore’s Sculptor intra-operative system, which uses a robot arm to ensure that the surgeon accurately prepares the bone surface to match the implant precisely. This high technology approach offers significantly enhanced precision in comparison with the conventional use of hand held saws and metal jigs, which is the current standard method for bone preparation in knee surgery.