Not all knee replacements are equal! Many of the most commonly used designs both in the NHS and in Private healthcare are surprisingly old-fashioned and were designed in the 1980s. If you were looking for a new car you would probably not choose one from the 80's! It is perhaps no surprise then that on average about 20% of people are not happy with their knee replacement.
Things have moved on since then and our understanding of how the knee works is not much better. More modern knee replacement designs take this better understanding into account in order to make the knees work better so patients are happier.
Mr Willis-Owen is an unashamed perfectionist and does not think a 20% dissatisfaction rate is acceptable. As a result, he is very interested in high-performance knee replacements and has been investigating these and using them for some time.
If you are due to have a knee replacement you may want to check which type your surgeon plans to use, and do a bit of research.
Part of the solution to getting a better knee is the shape of the knee replacement. The knee is a very complicated shape and so far knee replacements have not come close to mimicking this. Modern research has more accurately defined how the human knee works, and more modern implants come closer to copying the complicated movement patterns.
Mr Willis Owen has been most impressed with a Knee called the Journey BCS which compensates for two of the main ligaments in the knee to make the replaced knee feel more natural. Mr Willis Owen has carried out many of these new replacements and been impressed every time with how natural the knee feels compared to a standard total knee replacement. Patients have typically got off crutches sooner, moved the knee more freely, and enjoyed better function.
Implanting the right shaped knee replacement is only part of the solution. Unless it is put in the perfect position with perfect alignment one cannot expect a perfect result. Patient-specific instruments are a new technology which involves scanning the knee and making a three-dimensional computer model. We then use 3-D printing technology to make a piece of plastic that clips onto the patient's knee during the surgery and allow us to know exactly where to position the new knee having done all the planning on a computer beforehand. This speeds up the surgery, and it allows all of the planning and thinking to take place before the operation has even started. It means that the surgery is less invasive and recovery is more comfortable and quicker. It also reduces the likelihood that the knee is implanted in the wrong position, and therefore should translate into fewer unhappy knees!
Not everybody's knee is the same shape, and in much the same way that an off the peg suit will not fit everybody perfectly, and off the shelf knee replacement is not right for everyone. Custom-made need replacement are like bespoke suits. A special CT scan is taken and from this, a truly bespoke knee replacement is made. This is then implanted with patient-specific instruments to ensure a perfect fit. This technology is in its infancy, but early results have been very promising. Mr Willis Owen has been using a knee called iTotal with excellent results and really happy patients getting back to normal lives.
At the Nuffield Hospital in Bournemouth, we have a Mako robot for robot-assisted partial knee replacement. This allows to take a preoperative CT scan to model the knee, then plan where to put the knee replacement on a computer. We then carry out the surgery using a robot and can make adjustments to the position on the computer to see how the changes will male the knee tighter or looser at various parts of the arc of motion. One we have it perfect we then use the robot to trim away the bone to the nearest millimetre or degree to position the new knee perfectly. This is a well-established technique used over 80,000 times around the world but new to the UK ours in only the fourth robot in the country.