Osteoarthritis (OA) – what is the latest research. Why do you hurt?
Do you know why you hurt in OA? The real answers may surprise you. I recently attended an online course on the latest research on pain science and one was on osteoarthritis, delivered by researcher Tasha Stanton.
It was previously believed that OA was merely a degenerating joint but now it is known to be a whole body systemic process that involves your nervous system, digestive system, immune system, musculo-skeletal system, your mind- (which means your thoughts, beliefs, emotions), past experiences etc – this sounds a lot like my other posts – because everything is connected. No system in your body works in isolation so it is obsolete mostly to think of working just the musculo-skeletal system or circulatory system etc.
What people feel and what shows on scans is not always aligned and often does not influence our treatment choices. Today, unless another issue, e.g. infection or carcinoma etc is suspected, scans and imaging are not required under the current guidelines. OA can be diagnosed by the symptoms. Often the scans will not change management and often the words used in the report or by the doctor can influence the sensitivity of your system and thus increase your pain. Often changes found on scans are common for the age group. Scans do not tell us what you are capable of or what you can do even if your joint has marked changes. They are a guide only and are also beneficial if treatment is not assisting or the condition is getting worse – Again to rule out more sinister pathology.
Research shows that your beliefs about your OA determines what you will do about it. Research shows many think they have a vulnerable joint because scans show bone on bone wearing, often reinforced by the words from the report and or their doctor. Which often means people think it will get worse over time and that movement should be avoided and often they believe surgery is the only outcome.(Surgery may still be an option for some.) If you believe the joint is degenerated and worn out then you often feel fear exercising or loading the knee as you fear it will lead to more damage and thus these thoughts can determine the amount of pain and limitation.
Thoughts and beliefs can increase pain and dysfunction.
Some interesting research statistics:
*Up to 43% of people without knee pain or injury when MRI’d the scan shows evidence of Osteoarthritis (OA).
*10-34% of people post TKR report long term pain outcomes post surgery. 15% after 5 years is graded as moderate- severe.
OA is now not a ‘wear and tear’ disease of the joint. Seems odd doesn’t but read on…
Cartilage, which lines the end of bones within joints, loves load and it can adapt. It does not have a blood supply but obtains its nutrition from loading and movement. The less you do the thinner the cartilage gets. With appropriate loading- it needs to be appropriate for the condition- Cartilage can wear and repair. For example in marathon runners the knee cartilage is improved and healthier than other non-running knees. With ultra marathon runners the cartilage can adapt during a race of many days duration. Why is this so? Inside every joint is a substance called lubricin, which as it sounds is a great joint lubricator and is always present separating the two bones in a joint…
So why does an OA joint hurt?
The pain in OA is now considered part of a persistent pain condition, or is an over protective pain response (see my other blogs on pain). This means that the entire body is more protective and hypersensitive to stimuli that in non- OA people would provoke a much lower response. What contributes this whole body increase in sensitivity to noxious stimuli? Inflammation…
Increased inflammation increases sensitivity of nociceptors- danger detector cells in the periphery and then on up in the spinal cord, to make the incoming sensory data increased in intensity and at the same time the brain has a 20% decrease in ability to inhibit or decrease the sensitivity of the system. The accelerator of the nervous system is increased by up to 69%- so the amount of pain felt when moving is not an accurate indicator of what is happening in the joint- as the usual nervous system monitoring is altered.
Also how much you weigh does matter- Obesity/fat contributes to the inflammatory component of OA. So the gut micro biome can be a contributor to OA and pain. So high body fat levels are associated with a progression of OA, but high body weight due to higher levels of muscle weight is associated with cartilage health. Extra body fat is associated with increased general body or systemic inflammation.
So you can see food and exercise can influence the inflammation in the body- either up or down.
This is why moving with some pain is ok. But learning to know how much pain can be tolerated before you stop and why a bit of pain is ok is important to learn. We all have a ‘protect by pain’ line which gives us a safety buffer with movement. During normal activity our pain detectors come on way before we reach a damage limit. After an injury or with an exacerbation of OA this protection barrier comes on even earlier. With an overprotective system the safety buffer comes on earlier so exercise is ok if you go a little way into the safety buffer. Pain means ‘pay attention’ not necessarily to stop.
If you push past your limits too much or do too much for your body with exercise it will also increase inflammation and thus increase pain perception. Learning to go just into your buffer zone but not too far is safe. This can be a trial and error effort at first and also there will be times when activity has to modified during a flare up but then it is slowly increased again to suit the joint circumstances. It can be tricky learning to read your body’s signs. But with practice it can be learned.
What other areas influence your pain perception and thus your movement buffer zone?
- Fears, beliefs, what you are thinking, anxiety levels, can increase the pain safety buffer. These can trigger the cortisol in the bloodstream which can help increase inflammation throughout the whole body
- Knowing what is going in the joint etc. Your knowledge of your condition is vital as the more you understand the more it influences how much pain you feel. The safer you feel the less pain you feel.
- The power of prior experience and expectations are important in how much pain you will feel. The brain always is trying to match patterns. The brain is always trying to predict what will happen next and is influenced by these past priors and experiences and thus it changes the adaptations. A movement or activity associated with a painful episode in the past may trigger an increased sensitivity of the system and thus increase pain. Just anticipating the movement may cause pain. The words a clinician uses can be both a danger pain increaser or a safety valve and easer of pain. These can be unconsciously influencing a person’s response and thus pain. Phrases like, ‘Wear and tear’, ‘bone on bone’ are typical common phrases that can increase sensitivity of the system. Words are powerful, so choose empowering safety increasing ones.
We have a dynamic system that constantly updates according to the evidence of danger and safety, and this is a measure of how much pain we are experiencing. So the more safe you feel the better your system can turn down pain intensity.
Your body is resilient and robust. We are bioplastic- which means as long as we are alive we can change our body and adapt. How we change and adapt is determined by how we are using our body and our thoughts etc. We can learn to influence the system consciously.
There are 3 key ingredients: all three are needed together to help minimize OA symptoms.
- Increased Knowledge
- Increasing activity levels
- Decrease inflammation
There two ways to know you have improved your pain:
- Decreased pain experienced
- Increase function and activity levels
Many people go for the first only and feel they are not improving if they still feel pain at all. But having the same amount of pain but being able to do more is actually a reduction in pain, but you also get a better functional outcome and can do more.*latest info above is mostly sourced from a lecture from Tasha Stanton in the Pain Mastersessions from Neuro Orthopaedic Institute in May 2022. www.noigroup.com