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New hips could put a silver spring in your step
Replacement joints with added nanoparticles – could these be the hips of the future?
It’s amazing what science can do. Not so long ago, when our hips or knees gave up on us we would have just had to resign ourselves to the immobility and pain killers that came hand in hand with crumbling joints. These days many of us can have a new hip or knee joint when ours wear out – in 2009 146,307 knee and hip replacement operations were carried out in England and Wales. They’re operations that have brought pain relief and a return to mobility for thousands of us. Now researchers have found a way to potentially improve them even more.
In the future, your orthopaedic surgeon may ask if you’d like silver nanoparticles with your new joint. Scientists at North Carolina State University have used their expertise in biomedical engineering to develop a 'smart coating' for surgical implants. When we have knee, hip or dental implants there’s a risk that our bodies will reject the implant. The smart coating aims to reduce that risk by encouraging bone growth into the implant.
This is how the coating works. The outer layer of the coating, the area that is in contact with bone, dissolves over time, releasing calcium and phosphate that encourage bone growth. "The bone grows into the coating as the amorphous layer dissolves, resulting in improved bonding, or osseointegration," says Dr Afsaneh Rabiei, NC State associate professor of mechanical and aerospace engineering, associate faculty member of biomedical engineering and co-author of a paper describing the research. The bonding also helps to ensure that bone and implant do a better job of sharing the load.
"We call it a smart coating because we can tailor the rate at which the amorphous layer dissolves to match the bone growth of each patient," Dr Rabiei explains. This is an important step because we don’t all have the same rate of bone growth. Not surprisingly, young people’s bones tend to grow faster than those of their parents and grandparents.
This new development also holds a precious secret. Silver nanoparticles are incorporated into the coating. It may sound rather space age, but they have an important job. At the moment anyone having an implant is given an intense course of antibiotics, to help prevent an infection following their surgery. The area around the implant will always be vulnerable to infection, but the silver nanoparticles can help to fight it off.
The silver particles are antimicrobial agents that are released as the outer layer of the coating dissolves. The silver is released more quickly immediately after the implant surgery – the time when risk of infection is at its highest – and slows down with time. The nanoparticles should give some protection against infection around the implant for as long as the implant lasts. And these miniscule particles of silver should also reduce the amount of antibiotics we need after surgery. “That is another reason why we call it smart coating,” says Dr Rabiei.
If you’re feeling pain in your hip or knee, and wondering whether you might be in need of a new joint, your GP is the person to talk to. You can, however, get an idea of your chances of needing an op by heading for the internet. Go to the Hip and Knee Network – link shown below – and click on the Patient Support Tool on the menu at the left hand side of the page. When the new page comes up, click on Score Your Joint. Filling in the questionnaire takes about 10 minutes and may give you a clearer idea of what to expect at your GP’s surgery.
Useful websites
British Orthopaedic Association: www.boa.ac.uk
Hip and Knee Network: www.hipandkneenetwork.co.uk/pages/patient-zone
The Royal College of Surgeons: www.rcseng.ac.uk
Useful links
- Hip replacement options
- Hip replacement FAQs
- Shoes aggravate arthritic knees
- What works for arthritis?
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First published February 5, 2010
Information on this site is for interest only and is not a substitute for professional medical advice. You should consult your own doctor about any specific health concerns.
