However, knee replacement dissatisfaction rates needn't be this great - one size and one shape definitely do not fit all, and that's where 3D-printed patient-specific implants fit in.
These days, people are much more active, which is great, but this is placing much greater strain on joints, especially the knees, and it's taking its toll, meaning we're operating on younger and younger patients. People's expectations for the feel and function of their knee replacement are much higher nowadays too, and rightly so.
With a traditional knee replacement, various size options are available but they are all the same shape. The problem with knees is that they're very complex and each individual has not only different sized knees, but different shapes and contours. Patients want the best knee for them, that's going to give them the best function and that's going to feel as close as possible to a normal natural knee, and patient-specific custom-made prostheses with 3D planning and 3D printing are the best way of achieving this.
The 3D-printed prosthesis is designed to fit the exact contours and shape of each patient's knee perfectly, based on a CT scan providing the patient's exact anatomy. With a standard prosthesis, you end up cutting the patient's bone to fit the prosthesis, often having to take away more bone than one would like. With a 3D-printed patient-specific implant, the implant fits the patient's bones with millimetre precision, which means that the bone cuts are much smaller, which is beneficial on a number of levels: first, there's more bone left should the patient potentially end up needing revision surgery later in life; and second, less bone removal means a larger surface area for the fixation of the prosthesis, and hence a stronger and better fixation between the bone and the implant. The blood lost during the procedure is also reduced with a custom knee because you can be less invasive, there are less exposed raw bleeding bone surfaces left in the knee (because of the better fit), and the procedure is actually slightly faster.
The most important outcome for me is patient satisfaction, and with a custom 3D-printed knee patient satisfaction rates are about 95%. Now, the way to look at that is not just a 10 to 15% increase in happy patients from 80% with a standard off-the-shelf knee to 95% with a custom-made prosthesis; that's actually a two-thirds reduction (from 15% down to just 5%) in unhappy patients, which is massive.
I have been using custom-made knee replacements from Conformis for 5 years now, since I implanted the UK's first Conformis G2 custom-made replacement back in 2012. Virtually all of my knee replacements are now done using custom-made prosthesis, because I want nothing but the best for each and every one of my patients. Every patient is different, every knee is different and I'm absolutely convinced that 3D-printing and custom-made prostheses are the best possible way forward in top-of-the-range knee replacement surgery.
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