Knee Replacement for Women
Nick London, specialist knee surgeon at Harrogate NHS Trust and the Yorkshire Knee Clinic, explains why women need their own special type of knee replacement
In the early days, knee replacement used to be the last resort for people with severe knee pain and difficulty in walking. However over the last ten years they have become phenomenally successful, thanks to better technology and a better understanding of how the new knee should be fixed in place.
In fact, we do more knee than hip replacements in this country now, and the results are excellent. If patients aren’t sure, I ask them whether things are bad enough to risk a one-in-50 chance that their symptoms could get worse.
Mini-incision surgery (MIS) came in about five years ago; it was a big advance, as it involves much less cutting through muscles to get to the joint. However, we’ll never be able to do keyhole surgery, as any knee replacement involves inserting a lump of metal the size of the patient’s clenched fist into their knee!
MIS has helped to reduce hospital stays from a week to three or four days, with patients able to climb stairs as soon as they get home, and drive after four weeks.
The difference between men and women
Surgeons who were doing lots of replacements started to notice a subtle difference in the results for men and women. Men were doing slightly better on pain scores, and some women complained of pain at the front of the knee – not a lot, but enough to make us want to find out why this was. It turned out that women’s thigh bones (femurs) are a different shape from men’s.
For decades, knee replacements were based on men’s femoral measurements, but we discovered that women’s femurs are slightly narrower from side to side than men’s, and the bone at the front of their knees is subtly different. This means that up to half of women having a standard “unisex” replacement are left with a small overhang that can press on surrounding ligaments and tendons and cause pain.
The Gender Solution’s knee replacement, which was introduced to the UK in May 2007 and which I have been using ever since, was specifically designed to give women a “personalised” implant that gives a better fit and allows more natural movement. We expect that it will reduce post-operative pain even further; the results look good, but it will take years to see all the benefits.
What happens in a knee replacement
Using a general or spinal anaesthetic, the worn-down surfaces at the bottom end of the femur (thigh bone) and the top of the tibia (shin bone) are replaced with metal implants, which are cemented into place. Physiotherapy exercises are started in hospital and continue at home. People are often back at work in a few weeks, but pain can take several months to fully settle.
Ninety per cent of patients can go back to normal activities, such as tennis, golf and even skiing, but not high-impact sports such as football. A further eight per cent may still have some discomfort, but improve enough to get back to more activities.
Who needs a knee replacement?
Osteoarthritis is the main reason for almost all knee replacements. As joint surface cartilage wears out, the bottom of the thigh bone starts rubbing on the top of the shin bone, causing pain and difficulty in walking. More women than men have knee replacements, and most are around retirement age. But the operation is increasingly being offered to younger people who want to carry on being active.
Up to 95 per cent of knee replacements last ten years, and many will last more than 20 years, depending on what activities their owners do. Second or even third replacements are usually successful, but being overweight can make pain worse, and increase the risk of complications.
source: © Woman’s Weekly Magazine