Subjects with Knee Osteoarthritis Exhibit Widespread Hyperalgesia to Pressure and Cold.

Penny Moss,Emma Knight,Anthony Wright,Arvind Chopra

doi:10.1371/journal.pone.0147526

Abstract

Hyperalgesia to mechanical and thermal stimuli are characteristics of a range of disorders such as tennis elbow, whiplash and fibromyalgia. This study evaluated the presence of local and widespread mechanical and thermal hyperalgesia in individuals with knee osteoarthritis, compared to healthy control subjects. Twenty-three subjects with knee osteoarthritis and 23 healthy controls, matched for age, gender and body mass index, were recruited for the study. Volunteers with any additional chronic pain conditions were excluded. Pain thresholds to pressure, cold and heat were tested at the knee, ipsilateral heel and ipsilateral elbow, in randomized order, using standardised methodology. Significant between-groups differences for pressure pain and cold pain thresholds were found with osteoarthritic subjects demonstrating significantly increased sensitivity to both pressure (p = .018) and cold (p = .003) stimuli, compared with controls. A similar pattern of results extended to the pain-free ipsilateral ankle and elbow indicating widespread pressure and cold hyperalgesia. No significant differences were found between groups for heat pain threshold, although correlations showed that subjects with greater sensitivity to pressure pain were also likely to be more sensitive to both cold pain and heat pain. This study found widespread elevated pain thresholds in subjects with painful knee osteoarthritis, suggesting that altered nociceptive system processing may play a role in ongoing arthritic pain for some patients.

Highlights

Studies utilizing quantitative sensory testing (QST) data suggest that widespread pressure and cold hyperalgesia are present in a number of musculoskeletal pain disorders such as tennis elbow [1,2,3], back pain [4, 5], fibromyalgia [6, 7] and whiplash associated disorder (WAD) [8, 9]
It has been suggested that there is an association between pain severity and chronicity, and the presence of cold hyperalgesia in the immediate period post whiplash injury [10] and based on the findings of a systematic review, the presence of cold hyperalgesia has been identified as an important prognostic factor for long term pain and disability in WAD [11] and tennis elbow [12]
Given the potential prognostic importance of evaluating cold hyperalgesia, the current study aimed to investigate the extent to which widespread pressure and cold hyperalgesia is experienced by subjects with knee OA compared to matched, healthy controls

Summary

Introduction

Studies utilizing quantitative sensory testing (QST) data suggest that widespread pressure and cold hyperalgesia are present in a number of musculoskeletal pain disorders such as tennis elbow [1,2,3], back pain [4, 5], fibromyalgia [6, 7] and whiplash associated disorder (WAD) [8, 9]. Osteoarthritis is one of the most prevalent musculoskeletal disorders affecting Western society and is associated with joint pain, tenderness and decreased function. It is often anecdotally associated with exacerbations during cold weather conditions. Studies have evaluated pressure pain thresholds and reported widespread mechanical hyperalgesia in subjects with OA of the knee [16, 20]. A number of studies have reported reduced PPT in the upper limb of subjects with knee OA compared with matched controls [13,14,15]

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Discussion

Conclusion