Cutaneous temperature and pressure pain threshold in individuals with knee osteoarthritis

Abstract

Introduction: Osteoarthritis is a common disease in which skin temperature may be included among the pathophysiological factors. Thermography allows the mapping of cutaneous temperature and may be employed in the investigation of osteoarthritis. Objectives: To evaluate cutaneous temperature of the lower limbs, as well as to verify its association with pressure pain thresholds in individuals with knee osteoarthritis. Material and methods: This case series study was conducted with individuals of both genders aged 48–77 years with unilateral knee osteoarthritis. Volunteers underwent thermographic evaluation by an infrared sensor (FLIR T650SC). The anterior region of the thigh and leg and the knee area were evaluated. Pressure pain thresholds (PPT) were evaluated by algometry (Pain Diagnostics, Great Neck, USA) at the vastus medialis, vastus lateralis, rectus femoris, and patellar tendon. Data analysis was conducted with the statistical package SPSS v.24 for Windows. Comparisons between affected and unaffected sides were made by paired Student’s ttest or the MannWhitney U test, and associations between variables were assessed by Pearson or Spearman’s correlation coefficient. In all cases, the significance level was set at p ≤ 0.05. Results: Eleven volunteers (63.1 ±9.5 years) participated in this study. When comparing cutaneous temperature, only the region of the knee showed a significant difference between sides (p = 0.02). There were no differences between affected and unaffected knees regarding pain tolerance (PPT) at all sites evaluated. There were also no significant associations between the study variables. Conclusions: Individuals with knee osteoarthritis presented a higher temperature of the affected knee, but this was not associated with pressure pain thresholds.