Session Title: Rehabilitation Sciences
Session Type: Abstract Submissions (ARHP)
Background/Purpose: Exercise has beneficial effects on pain in patients with knee osteoarthritis (OA), yet the underlying analgesic mechanisms are ambiguous. A deeper understanding of the analgesic mechanisms of exercises in knee OA is imperative to optimize the exercise paradigm in clinical management of OA. The purpose of this study was to investigate the effects of a 12 week therapeutic exercise program on pressure pain sensitivity in patients with knee OA.
Methods: This was a randomized trial with blinded outcome assessors (NCT01545258). Participants were randomly assigned (1:1) to 12 weeks of facility-based neuromuscular exercise therapy (ET), 3 sessions per week supervised by trained physical therapists, or a no attention control group (CG). To assess pressure pain sensitivity, we used cuff pressure algometry, with an inflatable tourniquet cuff mounted on the calf of the most symptomatic leg. The co-primary outcomes were pressure pain thresholds (PPT unit: kPa) and temporal summation (TS) of pressure pain. TS was assessed by continuous recordings of pain (100 mm electronic visual analog scale (VAS)) during sustained (6 minutes) noxious pressure stimulation at PPT+25%. TS was quantified as the area under the time-VAS curve (unit: mm*s). Higher PPT and lower TS, respectively, represent less pressure pain sensitivity. Secondary outcomes included patient reported pain using the KOOS questionnaire, with higher scores representing less pain. According to the protocol, the analyses were based on the ‘Per-Protocol’ population (defined as participants following the protocol). Analysis of covariance adjusting for the level at baseline was used to determine differences between groups (95% confidence intervals) in the changes from baseline at week 13.
Results: 60 participants were randomized to ET (n= 31) or CG (n=29). In the ET group, six participants were lost to follow-up; in the CG five were lost and one violated the protocol (exercise outside study). Thus per protocol population included 48 participants (25 ET/23 CG). At baseline, the average PPTs were; ET: 18.1 kPa (SD 6.1), and CG: 19.1 kPa (6.8). At follow-up the PPT increased in the ET group by 1.94 kPa corresponding to a group difference in the change from baseline of 3.06 kPa (95% CI: 0.17 to 5.95; P=0.04) favoring ET. Accordingly, the ET group was stimulated at higher pressure levels in the sustained noxious pressure experiment at follow-up. The TS decreased in the ET group by 1,641 mm*s, giving a group differences in TS change of 2,608 mm*s (95%CI: 458 to 4,758; P= 0.019) favoring ET. After 12 weeks exercise, there was a statistically significant difference between groups in regard to KOOS pain of 6.8 points (95% CI 1.2 to 12.4; P= 0.0179) in favor of ET (corresponding to an effect size of 0.71).
Conclusion: A 12-week supervised neuromuscular exercise program reduces the pressure pain sensitivity, seen as a higher PPT and lower TS at follow-up in the ET group, in adjunct to a clinically relevant effect on pain estimated by KOOS. These results indicate that neuromuscular exercise therapy has beneficial effects on basic pain mechanisms, and further exploration of this effect may provide basis for optimized treatment.
T. S. Joergensen,
Abbott, Axellus A/S, Bristol-Myers Squibb, Cambridge Weight Plan, Norpharma, Pfizer, and Roche,
Axellus A/S, Cambridge Weight Plan, Mundipharma, and Roche,
Abbott, Axellus, Bayer HealthCare Pharmaceuticals, Biogen Idec, Bristol-Myers Squibb, Cambridge Weight Plan, Ipsen, Laboratoires Expanscience, MSD, Mundipharma, Norpharma, Pfizer, Roche, and Wyeth,
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/exercise-therapy-reduces-pain-sensitivity-in-patients-with-knee-osteoarthritis-a-randomized-controlled-trial/