Misconceptions about Osteoarthritis

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PT Inquest, my favourite physio podcast, recently discussed this paper:

Misconceptions and the Acceptance of Evidence-based Nonsurgical Interventions for Knee Osteoarthritis. A Qualitative Study

The abstract summarises:

In contrast to best practice guidelines for knee osteoarthritis (OA), findings from several different healthcare settings have identified that nonsurgical treatments are underused and Total Knee Replacement surgery is overused. Empirical evidence and qualitative observations suggest that patients’ willingness to accept nonsurgical interventions for knee OA is low.

Participants’ beliefs about knee OA and its treatment were identified. Beliefs were grouped into five belief dimensions:

• identity beliefs (what knee OA is),
• causal beliefs (what causes knee OA),
• consequence beliefs (what the consequences of knee OA are),
• timeline beliefs (how long knee OA lasts),
• treatment beliefs (how knee OA can be controlled).

The participants' beliefs are what I would guess, based on what I hear from patients everyday:

• All participants believed that their knee OA was “bone on bone” (identity beliefs).
• Most believed it was caused by “wear and tear” (causal beliefs).
• Most believed that loading the knee could further damage their “vulnerable” joint (consequence beliefs).
• All believed that their pain would deteriorate over time (timeline beliefs).
• Many believed that physiotherapy and exercise interventions would increase pain and could not replace lost knee cartilage (treatment beliefs).
• They preferred experimental and surgical treatments which they believed would replace lost cartilage and cure their knee pain (treatment beliefs).

The authors conclude: 

Common misconceptions about knee OA appear to influence patients’ acceptance of nonsurgical, evidence-based treatments such as exercise and weight loss.

Once the participants in this study had been “diagnosed” with “bone-on-bone” changes, many disregarded exercise-based interventions which they believed would damage their joint, in favor of alternative and experimental treatments, which they believed would regenerate lost knee cartilage.

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These misconceptions do feel like commonsense and, as such, are widely held by the general public. Some of them may be true at the very end stage of osteoarthritic disease, but they are definitely not true for all patients with osteoarthritis, and as such, the misconceptions are harmful because patients disregard beneficial conservative treatments like weight loss and exercise, and rush towards surgical options.

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"BONE ON BONE" is a metaphor that is commonly used, even by physios and knee surgeons.

"Bone on bone" creates a very dramatic image of what's going on in the knee, and undermines the possibility of osteoarthritis being pain free. Using words like "bone on bone" can cause harm because it sounds like it is definitive and painful, when in reality it's only a metaphor.

The reality could be explained more like: "the joint reinforces and repairs the damaged area by laying down new tissue". Or, "the joint wants to make itself even stronger than cartilage, so it lays down stronger building blocks - bone cells".

​Not everyone with osteoarthritis has "bone on bone", and the perception of "bone on bone" as what's happening in the knee can make patients less likely to stick with evidence-based conservative treatment options.

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​The concept of "WEAR AND TEAR" makes sense if you imagine the joint as mechanical. A cupboard's metal hinge can be opened and closed a certain number of cycles before it breaks. Metal and plastic fatigues and fails. Mechanical joints "wear out". But our joints aren't made of metal and plastic. Knees are not mechanical joints. They are biologically active joints, that adapt to what we do. 

If we do a million bicep curls, we don't expect our biceps to "wear out" - we expect to end up with bigger, stronger biceps. Similarly, the bones, cartilage, ligaments and muscles in our knees are biologically adaptive, they have regenerative ability, and adapt to what we do. Our joints get stronger with use.

Rather than "wear and tear", the more appropriate phrase should be: "use it or lose it".

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DOESN'T RUNNING "WEAR OUT" KNEES?

Another common misconception is that running "wears out" knees.

Doctors and knee surgeons see patients complaining they have sore knees when they run. The X-ray shows some arthritis, so it's very easy to make the assumption that running causes arthritis. But we know that distance runners don't "wear out" their knees. Runners have better knees than non-runners. ​

This 2017 research comparing 2,637 runners to non-runners (matched for age, weight, mileage, injury, and other variables) concludes: There is no increased risk of symptomatic knee OA among runners compared with non-runners. In those without OA, running is not detrimental to the knees. 

This 2008 research concludes: Long-distance running among healthy older individuals was not associated with accelerated radiographic OA, and long-distance running or other routine vigorous activities should not be discouraged among healthy older adults out of concern for progression of knee OA.

This 2004 research concludes: The results of this literature review strongly suggest that regular mild-moderate impact exercise does not increase the risk of OA, and that there is some evidence that it does not increase symptoms in patients with mild-moderate OA. And: Regular running increases joint space width.

So:

• Running does not cause osteoarthritis.
• Osteoarthritis is not caused by "wear and tear".
• Most osteoarthritis should not be considered "bone on bone".
• Research supports the conservative treatment of osteoarthritis with weight loss and exercise.

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