What explains osteoarthritis pain physiology?

Nearly 3 out of every 4 patients with osteoarthritis (OA) report that their pain is constant or chronic.1 There is, however, only a weak correlation between radiographic evidence for OA progression and the extent of OA-related pain: for example, the range of people who do have radiographic OA of the knee and who also report knee pain is relatively wide (from 15 to 81%).2

Chronic vs acute pain

How does chronic pain differ from acute pain – and how do patients get sensitised to pain?

The pain pathway involves the transmission of a pain signal from the periphery (where the pain occurs) to the central nervous system (CNS). When injury or inflammation occurs, cells at the site of pain release a variety of biochemical mediators,3–5 which bind to, and activate, sensory nerves in the periphery.3–5

The two types of pain experienced by patients – chronic or acute – differ in their physiology.3,6 Most people experience acute pain, a body’s natural response to painful stimuli; acute pain typically resolves after the cause of pain is resolved. However, for 1 in 5 people, pain becomes chronic.7,8 In chronic pain (lasting more than 3 months), the experience of consistent pain changes the way in which the brain processes pain signals; in turn, this results in a heightened response to pain – a process called 'sensitisation'.7,9,10

As OA progresses, peripheral sensitisation develops into central sensitisation.11 In response to injury or inflammation, nociceptors in the periphery can become more sensitive to painful stimuli,
a process called ‘peripheral sensitisation’. These sensitised nociceptors then send additional pain signals to the CNS, which can lead to the overstimulation of the CNS.11 This results in central sensitisation, which increases the perception of pain. As such, central sensitisation leads to the perpetuation of pain.11

Peripheral and central sensitisation

Understand peripheral and central sensitisation in chronic pain – and the sustained pain response to stimuli

What can I do now?

Support patients and healthcare professionals to better understand the difference between acute and chronic pain, and the link between peripheral and central sensitisation.

1. Conaghan PG, Porcheret M, Kingsbury SR, Gammon A, Soni A, Hurley M, Rayman MP, Barlow J, Hull RG, Cumming J, Llewelyn K, Moscogiuri F, Lyons F, Birrell F. Impact and therapy of osteoarthritis: the Arthritis Care OA Nation 2012 survey. Clin Rheumatol. 2015;34:1581-1588. 2. Bedson J, Croft PR. The discordance between clinical and radiographic knee osteoarthritis: A systematic search and summary of the literature. BMC Musculoskelet Disord. 2008;9:116. 3. McGreevy K, Bottros MM, Raja SN. Preventing chronic pain following acute pain: risk factors, preventive strategies, and their efficacy. Eur J Pain. 2011;5(suppl):365-372. 4. Mantyh PW, Koltzenburg M, Mendell LM, Tive L, Shelton DL. Antagonism of nerve growth factor-TrkA signaling and the relief of pain. Anesthesiology. 2011;115:189-204. 5. National Pharmaceutical Council. Pain: current understanding of assessment, management, and treatments. December 2001. https://www.npcnow.org/system/files/research/download/Pain-Current-Understanding-of-Assessment-Management-and-Treatments.pdf. Accessed March 29, 2018.
6. Johannes CB, Le TK, Zhou X, Johnston JA, Dworkin RH. The prevalence of chronic pain in United States adults: results of an Internet-based survey. J Pain. 2010;11:1230-1239. 7. IOM. Relieving pain in America: a blueprint for transforming prevention, care, education, and research. 2011 https://www.uspainfoundation.org/wp-content/uploads/2016/01/IOM-Full-Report.pdf. Accessed August 3, 2020. 8. Dahlhamer J, Lucas J, Zelaya C, Nahin R, Mackey S, DeBar L, Kerns R, Von Korff M, Porter L, Helmick C. Prevalence of chronic pain and high-impact chronic pain among adults - United States, 2016. MMWR Morb Mortal Wkly Rep. 2018;67(36):1001-1006. 9. Neogi T. The epidemiology and impact of pain in osteoarthritis. Osteoarthritis Cartilage. 2013;21:1145-1153. 10. International Association for the Study of Pain. (IASP). IASP terminology. December 2017. http://www.iasp-pain.org/Education/Content.aspx?ItemNumber=1698. Accessed June 20, 2018. 11. Rice D, McNair P, Huysmans E, Letzen J, Finan P. Best evidence rehabilitation for chronic pain part 5: osteoarthritis. Journal of Clinical Medicine. 2019;8:1769.

Nearly 3 out of every 4 patients with OA report that their pain is constant or chronic1

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Further reading
Impact on the patient
Many patients with osteoarthritis (OA) suffer from inadequate relief for their OA-related chronic pain but what is the impact of this?1 Chronic pain can have a real domino effect on the patient with OA: pain reduces movement, which lowers exercise capacity, which can…
Does osteoarthritis have more impact than you think?
The individual suffering from osteoarthritis (OA)-related pain is not the only person affected; the domino effects of chronic pain on a patient’s function and daily life also impact on relationships with family, friends and colleagues. In particular, when family and friends take on…

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PP-INT-GBR-0207 February 2021