Can pain flares in knee OA be predicted?

Knee buckling is a predictor of pain flare in knee osteoarthritis (KOA), say researchers who have identified a combination of risk factors that can be used to predict the likelihood of pain flare (KOAF) in patients with a history of the event.

Asking patients about such episodes could help reduce the likelihood of experiencing the disabling symptom commonly associated with KOA.

Rheumatologist and study investigator Professor David Hunter, told the limbic the study is the first to address the concept of predicting KOAF.

“Buckling is a frequent symptom yet most clinicians don’t ask about it so they don’t find out about these occurrences and it can be a predisposing factor to the disabling symptom of knee pain flare.”

Using a case crossover study design, which allows for within person comparison, investigators were able to compare periods of no pain flare to periods of flare – defined in this study as an increase of ≥ 2 points compared with background pain – in over 300 participants.

The factors that appeared to be most important for triggering pain flare were injury, knee buckling and shoe wear, particularly the use of shoes that had an unstable base or shoes that had a much higher heel of about 2.5-5cm, along with a number of unmodifiable factors including age, BMI and years of OA.

Taken together the model predicted the occurrence of KOAF during the following 30 days, with an area under the curve of 0.73 (95% confidence interval 0.67–0.80).

Professor Hunter said around 70% of patients with knee OA experience flares and for many the acute episode is the most disabling element of knee OA.

“A lot of people when they think about osteoarthritis think, this is a chronic condition – it’s constant pain and it doesn’t change but, for most people, their experience of the disease is one where their pain fluctuates over relatively short intervals.”

He says being aware of the ‘time variant’ triggers – modifiable factors that change over a relatively short period of time that might pre-dispose people to pain flare – could help patients manage exacerbations with short-term prophylactic treatment combined with long-term interventions aimed at preventing knee buckling.

“If a person is having injuries, buckling or wearing shoes that are potentially not favourable for them they’re increasing their likelihood of having these acute episodes. We know that buckling, in particular, will predispose [people] to flares and we should be looking at ways of preventing that.

So prophylactically, or preventively longer term, encourage a person to strengthen their knee muscle and remain active. Over the short term patients can be advised to reduce flare intensity by remaining active, using a neoprene sleeve and considering the use of topical anti inflammatories following knee buckling as a means to alleviate pain from a potential flare, he said.

You can access the study here.

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