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What to expect from a knee replacement

When it comes to knee replacement surgery people’s expectations are wide and varied.

Some people simply want a joint that allows them to get about again, be independent and pain free. Others want to be more active and be able to go walking, running, swimming or cycling for example. For some people, how the knee feels is important. They want a knee that feels normal and not odd or different to their other possibly healthy knee. Most people want to forget about their knee most of the time rather than having to ‘cope’ with it.

How well will it work?

As well as pain relief, one of the factors important to all patients is that their knee feels stable. Instability might affect your confidence. Stepping off a bus or train for example can be unnerving on a knee that feels unstable. Active pursuits are also going to be more difficult with an unstable knee.

Fortunately, this is one aspect of knee replacement designs that can be demonstrated using modern techniques. And published literature is available demonstrating how stable patients’ knees are with some designs. The results can be quite revealing.

Having a high range of motion is useful but not essential for all activities. We all need enough motion to climb stairs, get up from a chair or tie our laces. There aren’t really any knee replacement designs that don’t provide this, but in some cases prior stiffness, difficult surgery, scar tissue or insufficient physiotherapy can lead to a stiff knee. Depending on activity requirements, some of us will expect more than others. Some modern knee replacements claim to allow very high range of motion. What they claim is not what the average patient achieves, but it is good to know that a device won’t inherently prevent what you think you need.

Our natural knees are really the benchmark for our expectations. Our healthy knees are stable and allow as much freedom of movement as we need. Fortunately it is now possible to select a knee that closely mimics the stability and movement of your natural healthy knee and is more likely to meet your expectations.

How long will it last?

We all want a knee to last as long as possible and if possible avoid the need to have repeat surgery. A relatively small number of people have complications, which can be for a number of reasons including infection. Overall just over 4% of patients require further surgery that includes replacing one or more implant components within 10 years. It is difficult to know just how long knee replacements last overall because initiatives like national knee replacement registers have only been running for 15-20 years. But we know that most knee replacements last for over 20 years and for many patients they last for the rest of their life.

When choosing which knee implant to have, you may prefer to have a design that has a long track record and has been used in many operations. Alternatively you may prefer a newer implant that uses the latest technology and promises better movement and stability. It might not have a long proven track record, but some new designs are stepwise evolutions of an earlier model that does and so is likely to at least achieve similar results. But this is not true for all new designs. There may be good evidence that some new designs have not experienced early problems, but radical changes in technology or material will not be proven until they have been in use for a number of years.


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