Author(s): LIANG, Z., WANG, J.B., Institution: TONGJI UNIVERSITY, Country: CHINA, Abstract-ID: 646

INTRODUCTION:
Knee Osteoarthritis (KOA) is a common degenerative osteoarthritis that frequently leads to chronic pain and progressive joint dysfunction. Patients generally report heightened sensitivity to temperature fluctuations, with some even claiming an ability to predict weather changes based on their symptoms.Our objective is to investigate potential alterations in thermoceptive thresholds among patients with KOA and to examine the modulating effects of two thermoceptive receptor agonists, capsaicin and menthol, on these thresholds.
METHODS:
In this study, a cross-sectional observational design was used to recruit patients with KOA aged 40-80 years (n=5) and age-matched healthy controls. Thermoceptive thresholds for warmth, coolness, heat nociception, and cold nociception were measured in the forearm, medial knee joint, and lateral knee joint of both groups using the Q-Sense Thermal Sensations Analyzer.
Subsequently, the four thresholds were re-measured after capsaicin was applied on the medial side and menthol on the lateral side of the knee. Data were statistically analyzed using paired samples t-tests to compare pre-and post-agonist measurements within each group and independent samples t-tests to assess differences between groups.
RESULTS:
The thresholds for warmth and heat nociception were significantly higher in the knee than in the forearm, whereas coolness thresholds were significantly lower in the knee than in the forearm (p < 0.05).In the healthy group, the application of capsaicin resulted in a significant reduction in the coolness threshold, [from 27.98 ± 0.53°C to 25.26 ± 0.95°C (p < 0.05)] while in the KOA group, menthol application significantly reduced the coolness threshold [from 27.48±2.14°C to 23.85±1.67°C (p<0.05)]. Before administering the agonist, patients with KOA exhibited higher warmth thresholds and lower coolness thresholds compared to the healthy control group. However, these differences were not statistically significant.
CONCLUSION:
This study found that temperature sensation thresholds at the knee joint differed between healthy individuals and patients with KOA. The application of capsaicin increased the gap between the patients and the healthy controls, whereas the application of menthol reduced it.