Pain sensitization in people with knee osteoarthritis: a systematic review and meta-analysis.
OBJECTIVE
Emerging evidence suggests that pain sensitization plays an important role in pain associated with knee osteoarthritis (OA). This systematic review and meta-analysis examined the evidence for pain sensitization in people with knee OA and the relationship between pain sensitization and symptom severity.


METHODS
A search of electronic databases and reference lists was carried out. All full text observational studies published between 2000 and 2014 with the aim of investigating pain sensitization in humans with knee OA using quantitative sensory testing (QST) measures of hyperalgesia and central hyperexcitability were eligible for inclusion. Meta-analysis of data was carried out using a random effects model, which included results comparing knee OA participants to controls, and results comparing high symptom severity to low symptom severity.


RESULTS
Fifteen studies were identified following screening and quality appraisal. For the meta-analysis, pressure pain threshold (PPT) and heat pain threshold (HPT) means and standard deviations were pooled using random effects models. The point estimate was large for differences in PPTs between knee OA participants and controls [-0.85; confidence interval (CI): -1.1 to -0.6], and moderate for PPT differences between knee OA participants with high symptom severity vs those with low symptom severity (0.51; CI: -0.73 to -0.30). A small point estimate was found for differences in HPTs between knee OA participants and controls (-0.42; CI: -0.87 to 0.02).


CONCLUSIONS
Evidence from this systematic review and meta-analysis suggests that pain sensitization is present in people with knee OA and may be associated with knee OA symptom severity.
School of Public Health, Physiotherapy and Population Science, University College Dublin, Dublin, Ireland. Electronic address: caitriona.fingleton@ucdconnect.ie.
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C
Fingleton
St. Vincent's University Hospital, Dublin, Ireland.
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K
Smart
Department of Physiotherapy, Faculty of Health Sciences, University of Sydney, Sydney, Australia.
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N
Moloney
School of Public Health, Physiotherapy and Population Science, University College Dublin, Dublin, Ireland.
B M
BM
Fullen
School of Public Health, Physiotherapy and Population Science, University College Dublin, Dublin, Ireland.
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C
Doody
D006801:Humans; D006930:Hyperalgesia / Q000209:etiology; D020370:Osteoarthritis, Knee / Q000150:complications*; D010146:Pain / Q000209:etiology*; D010147:Pain Measurement / Q000379:methods; D017288:Pain Threshold / Q000502:physiology
Central hyperexcitability; Knee osteoarthritis; Pain processing; Sensitization