WHAT MAKES THAT SOUND?
Crepitus is a cracking or popping sound produced by a joint during movement. It's believed that this is due to a reduction in pressure in the synovial fluid the joint where gases and water are contained.
It's a normal human experience that is often present in the complete absence of any joint pathology.(1)
DOES IT MATTER?
It can be present in addition to osteoarthritis but crepitus doesn't infer a pathology is always present.
In a study of 584 people presenting with crepitus and knee pain in addition to another risk factor for osteoarthritis there were no differences in knee function or strength between the knees with crepitus and the ones without. and compared to the control group without crepitus.
However, self-reported function was lower in the people and limbs with crepitus compared to those without, in addition to higher self-reported pain compared to those without. Their subjective perception of their knees was the main difference.
WHAT HAVE YOU HEARD ABOUT CREPITUS?
Fear and anxiety around these noises seems to be further enhanced by inaccurate information found on the internet. Leading to self diagnosis, worry and trips to the GP.
A quick google pulls up: 'The grating sensation felt when a joint affected by arthritis is moved and dry or damaged joint surfaces rub together.'(2) Oof.
A study by Robertson et al. (4) looked at people's beliefs about the meaning of crepitus in knee pain and their influence on their behaviour.
They found people had beliefs about what their interpretation of the meaning of the noise was, such as:
'Inside the bone is rubbing because there is a noise, you could imagine it's the bone grinding on the bone.'
'I think it means my knee is wearing away.'
It symbolised ageing for them:
'It should not be happening at my age'
'My grinding knees make me feel old.'
Some had an emotional response to the noise that made them want to avoid movement:
'I am always a little bit scared when I stretch my leg out because I am thinking, am I going to hear that noise?.'
For some this meant no longer engaging in meaningful, health promoting behaviours out of fear of embarrassment:
'When I used to do yoga everybody in the place could hear them. I really did feel embarrassed. I couldn't stand it so I stopped.'
Comments from friends and familiy were further reinforncing their negative belief system:
'If I was with my Mum … every time it makes the noise, she sort of winces.'
'My mother will say, ah your knees are not so good'
Some mentioned others had voiced concerns upon hearing the noise:
'Most people say you need to get that checked out.'
Some felt they were not heard when they mentioned it to their healthcare professional: 'Nobody said anything about it even when they asked about the symptoms. I was just completely glossed over and ignored'
These factors fuelled a negative cycle of fearing 'wear and tear' , reducing activity, and fearing and avoiding certain movements through inaccurate beliefs.
Can you think of any examples of these scenarios you have thought, heard or seen?
In cases involving pain, fear avoidance (avoidant behavior based on pain-related fear) and catastrophising (viewing a situation as considerably worse than it actually is) are consistently associated with worsened outcomes.(5,6)
These things matter.
Education and reassurance are vital to help reframe interpretations of crepitus and encourage continued physical activity. Words matter, choose them wisely when conversing with other humans.
Robertson, C. J. (2010). Joint crepitus - are we failing our patients? Physiotherapy Research International, 15(4), 185– 188. (2)https://medicaldictionary.thefreedictionary.com/crepitus
Robertson, C. J., Hurley, M., & Jones, F. (2017). People’s beliefs about the meaning of crepitus in patellofemoral pain and the impact of these beliefs on their behaviour: A qualitative study. Musculoskeletal Science and Practice, 28, 59–64.
Robertson, C. J., Hurley, M., & Jones, F. (2017). People’s beliefs about the meaning of crepitus in patellofemoral pain and the impact of these beliefs on their behaviour: A qualitative study. Musculoskeletal Science and Practice, 28, 59–64.
Vlaeyen, J. W. S., & Linton, S. J. (2000). Fear-avoidance and its consequences in chronic musculoskeletal pain: a state of the art. Pain, 85(3), 317–332.
Rosenbloom, B., Khan, S., McCartney, C. and Katz, J. (2013). Systematic review of persistent pain and psychological outcomes following traumatic musculoskeletal injury. Journal of Pain Research, p.39.
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