Experiencing Painful Osteoarthritis: What Have We Learned From Listening?

Gillian A Hawker

Disclosures

Curr Opin Rheumatol. 2009;21(5):507-512. 

In This Article

What can We Learn about Osteoarthritis Pain Mechanisms from Pain Descriptors?

A growing body of evidence supports the occurrence of sensitization of the central pain pathways, termed central sensitization, in chronic painful osteoarthritis.[31–35] Among these is a study by Imamura et al.,[36••] who evaluated 62 female knee replacement candidates and 22 age-matched healthy, pain-free controls for differences in pressure pain thresholds (PPTs) over various muscle groups. Knee osteoarthritis patients had significantly lower PPT than controls, indicating hyperalgesia consistent with central pain sensitization. Lower PPTs were associated with greater pain intensity, greater arthritis disability and lower quality of life.

Central sensitization is characterized by changes in sensitivity to heat, cold, touch, and pressure as well as changes in the quality of the pain itself, including radiating pain and symptoms such as numbness and tingling, burning pain, deep bone pain, and electric shock like pain.[37,38] Thus, greater attention to the words people use to describe their osteoarthritis pain may provide clues to the cause of, and thus best treatment for, osteoarthritis pain. Indeed, some of the words people use to describe their osteoarthritis pain are those typically associated with central sensitization. Pasqual Marquez et al.[39] administered a Portuguese version of the short-form McGill Pain Questionnaire, MPQ-SF[40] to individuals with osteoarthritis, fibromyalgia, and low back pain to compare their pain experiences. Osteoarthritis participants were 22 physiotherapy clinic outpatients (21 out of 22 participants were female) with a mean age of 64 years. The MPQ-SF comprises a list of 78 pain descriptors, clustered in 20 subgroups within four domains: sensory (e.g. throbbing or pricking), affective (e.g. sickening, exhausting), evaluative (e.g. annoying or troublesome), and miscellaneous. Respondents are asked to indicate the word that best describes their pain, or pick none, within each descriptor subgroup. The authors found that fibromyalgia patients chose many more descriptors, particularly in the 'affective' domain, than did those with osteoarthritis or low back pain. The descriptors osteoarthritis participants used most to describe their pain were throbbing (65%), jumping (56%), tiring (82%), sickening (69%), troublesome (59%), and pricking (52%), the latter being a term often considered suggestive of neuropathic pain.

Research is currently underway to evaluate the ability of symptom profile on questionnaire to identify individuals with osteoarthritis who have findings on physical examination consistent with central sensitization.[41] This research is important as it is the critical next step toward identifying subsets of patients with osteoarthritis pain who may benefit from different pain strategies. For example, many effective therapies exist for the treatment of neuropathic pain, but most have not been assessed for use in osteoarthritis. Future research will need to examine whether treatment response differs systematically according to symptom profile (the pain experience), thus supporting a more tailored approach to pain management in osteoarthritis.

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