It usually develops slowly and gradually gets worse.
In time, the pain, stiffness and swelling of the joint is diagnosed as osteoarthritis. Or just plain arthritis, as most of us call it.
Early detection – before symptoms appear – could have made a considerable difference to the 30 million US adults suffering with this condition, but right now there’s no reliable test to find arthritis early.
This may soon change however, as separate research groups in the UK and US believe they have come up with an answer. In both cases the diagnosis involves the difference in the sounds that healthy and unhealthy joints make when they move.
Aerospace Sensors Detect Unusual Noise
The UK research team at Cardiff University is in the process of developing a thin, disposable, electronic, “smart” patch that the patient wears over a joint. It would only cost around 10 pence (13 cents).
The idea was adapted from sensors used in the wings of jet aircraft to detect structural damage.
Mechanical engineer Davide Crivelli, PhD, explained how it works in humans:
“The acoustic sensor listens for cracking or rubbing sounds your joint makes. If you have early stage osteoarthritis, you may have cartilage damage which will have a specific sound signature. These sounds are at high frequencies which we can’t hear, hence the use of specialized acoustic emission sensors.”
The procedure could take place at a doctor’s office, or people could purchase a patch, stick it to the joint to be tested, and then link it to a self-monitoring smartphone app before recording basic movements like walking or climbing stairs.
Stick-Slip Friction
Meanwhile, over at the University of California, Santa Barbara, scientists are developing their own low-cost, non-invasive method of early detection.
They discovered that – contrary to what most doctors think — it’s not the amount of force created between joint surfaces that leads to wear and tear. Instead, it’s a type of friction called “stiction” in its early phase and stick-slip friction as the problem develops.
Stick-slip can cause vehicles to break down, computer hard drives to crash and doors to squeak. This new discovery shows that it affects human joints as well.
Normal joint surfaces slide smoothly over each other. But in the very first stages of osteoarthritis, before the patient is aware of a problem, the joint surfaces stick.
With increasing movement, the joint surfaces slide, only to stick and slide again. This is repeated as an ongoing process. The stick-slip phenomenon causes microscopic damage that can build over many years before symptoms appear.
In This Case, You Want to Be a Flat-Liner
To measure the adhesion and friction forces between the joint surfaces, the scientists use an ultra-sensitive, high-resolution instrument called a Surface Forces Apparatus device.
Pads containing acoustic sensors are placed around the joint. The sensors give a signal according to the type of friction they hear. In a healthy joint, the signal appears on a screen as a constant line. If there’s damage – and depending on how much damage – the signal appears as different degrees of jagged line.
Both the UK and US teams need to improve and fine-tune the procedures before human trials can begin.
If successful, these early detection methods could be in regular use in the not too distant future.
I share the inventors’ hopes that this approach will help catch arthritis in its early stages, but I’m a bit skeptical. The best evidence we’ve seen here at Green Valley is that bone surfaces rubbing on one another is not the source of the disease. The cause is systemic inflammation in which the immune system assaults the joints (and probably other body parts too, like the heart and brain).
Tame inflammation with healthy habits, and chances are you won’t need to go looking for joint damage.
Perhaps the test will be helpful in another way. If people are told their joint damage is detectable, they might be motivated to do something about their chronic inflammation.
