In the past, surgeons selected “off-the-shelf” knee implants from a range of prefabricated, standard, fixed models. Now, few things epitomise the wonders of modern surgery like customised knee implants, created using 3D printing. Are you considering knee replacement surgery – are you aware of your options?
One size fits all…or does it?
When opting for prefabricated knee implants, surgeons chose the best fit, based on the patient’s individual size, shape and stature, and then adjusted the implant during surgery.
This approach has several disadvantages. Because the prefabricated knees are standard sizes, surgeons may have to make compromises in terms of fit. While these may be extremely minor they may lead to loss in improvement in symptoms after surgery. Pain can be caused by implant overhang, where the replacement knee hangs over the bone, or implant underhang, where the bone is left exposed and uncovered because the implant is too small. There can also be discomfort because the implant is not aligned properly.
Advantages of patient-specific implants
With patient-specific implants, the replacement knee is designed to fit the patient, rather than patients having to fit around the size and style of the implant. It is an important difference.
The advantages of having an implant that is individually made for you include:
- a reduced risk of residual pain after surgery
- a more natural feeling knee as the implant follows the precise shape and contour of your real knee
- the opportunity to preserve as much of your existing bone as possible
How does it work?
The technology used to create these implants is state of the art. Patients undergo a CT scan which enables surgeons to create a three dimensional image of the joint that has been damaged. This information is then used by the computer software to design a custom-made implant, taking into account both the patient’s size and stature but also any underlying arthritic abnormalities, such as bone spurs, cysts or flattening of the joint. The knee implant is then printed using 3D printing technology to create an exact fit with the patient’s own body.
This technology also allows surgeons to rehearse the operation beforehand, planning where to make incisions and how to realign the bone using the 3D model. It is better for patients if these decisions can be made before they are on the operating table as it reduces the amount of time they need to be anaesthetised and may speed recovery times.
There are also significant cost-savings for hospitals, which no longer have to maintain a full stock of hip and knee replacements and keep all of the implants sterilised in case they are needed during surgery.
Who could benefit?
Customised knee implants are suitable for people with painful joint disease due to:
- Osteoarthritis
- Traumatic arthritis
- Rheumatoid arthritis, or
- Osteonecrosis of the knee
3D printing has the potential to transform healthcare. Already we have seen a surgeon use this technology to create a new pelvis for a man who had lost his to cancer.
With around 200,000 hip and knee replacements in England and Wales each year, there are a lot of patients who could benefit from individualised implants now and in the future.
