Arthritis & Rheumatism, Volume 63,
November 2011 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Chicago, Illinois November 4-9, 2011.


Pressure Pain Threshold and Knee Pain in Osteoarthritis: The Multicenter Osteoarthritis Study.

Neogi1,  Tuhina, Niu1,  Jingbo, Arendt-Nielsen2,  Lars, Scholz3,  Joachim, Frey-Law4,  Laura, Woolf5,  Clifford, Zhang1,  Yuqing

Boston University School of Medicine, Boston, MA
Aalborg University, Aalborg, Denmark
Columbia University, New York, NY
University of Iowa, Iowa City, IA
Children's Hospital, Boston, MA
University of Alabama, Birmingham, AL
University of California-San Francisco, San Francisco, CA

Background/Purpose:

Mechanisms contributing to knee pain in osteoarthritis (OA) are not well understood. Sustained mechanical and inflammatory stimuli in the joint may lead both to changes in the peripheral threshold of nociceptors (peripheral sensitization) and a central amplification of signals in the CNS (central sensitization), resulting in heightened pain sensitivity. We hypothesized findings of sensitization, as assessed by pressure pain threshold, may be associated with symptomatic knee OA (SxOA) and knee pain severity.

Methods:

The Multicenter Osteoarthritis (MOST) Study is cohort study of persons with or at high risk of knee OA. At the 60-month clinic visit, participants underwent knee radiography, answered pain questionnaires, and had pressure pain threshold (PPT) assessed, which is a marker of peripheral +/- central sensitization at sites of disease/inflammation, or of central sensitization when assessed at an otherwise normal area. PPT was assessed with an algometer (1cm2 tip) at the patella (site of pathology: peripheral +/- central sensitization) and wrist (free of pathology: central sensitization) as the point at which the participants indicated that the pressure first changed to slight pain. The average of 3 trials was used to calculate the PPT, which was then categorized into tertiles. Knees were categorized according to presence of SxOA based on KL>=2 and presence of consistent frequent knee pain (answering yes to a question about frequent knee pain at a telephone screen and a subsequent clinic visit within 30 days). Pain severity was categorized as the maximum of none, mild, or at least moderate pain on any of the 5 knee-specific WOMAC pain questions. We evaluated the association of PPT with SxOA and presence of frequent knee pain using logistic regression with GEE, and with knee pain severity using proportional odds logistic regression with GEE, adjusting all analyses for age, sex, BMI, race, clinic site, KL grade, depressive symptoms, catastrophizing, and widespread pain.

Results:

2033 subjects (3823 knees) had all measures performed (mean age 68±8, mean BMI 30.6±5.9, 60% female). The range of PPT at the wrist was 0.38 to >9 kg/cm2 and at the patella was 0.30 to >9 kg/cm2. The lowest tertile of PPT assessed at the wrist (central sensitization) was significantly associated with presence of SxOA, presence of frequent knee pain, and greater knee pain severity, and at the patella (peripheral +/- central sensitization) was significantly associated with frequent knee pain and greater pain severity (Table).

Conclusion:

Low pressure pain threshold was associated with pain in knee OA, as assessed by presence of symptomatic knee OA, frequent knee pain, and greater knee pain severity. These findings support the contribution of both peripheral and central sensitization in the pain experience of knee OA.

To cite this abstract, please use the following information:
Neogi, Tuhina, Niu, Jingbo, Arendt-Nielsen, Lars, Scholz, Joachim, Frey-Law, Laura, Woolf, Clifford, et al; Pressure Pain Threshold and Knee Pain in Osteoarthritis: The Multicenter Osteoarthritis Study. [abstract]. Arthritis Rheum 2011;63 Suppl 10 :1627
DOI:

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