Influence of pain quality on physical performance in subjects with osteoarthritis of knee

Objectives: Neuropathic pain features are frequently observed in subjects with knee osteoarthritis, which reduces their physical performance. This study was done to compare the physical performance between the subjects with neuropathic and nociceptive pain features. In addition, to assess the relationship between pain quality and physical performance in subjects with osteoarthritis of the knee. Methods: Eighty subjects, ranging from 40-70 years of both genders with symptomatic and radiologically verified unilateral knee osteoarthritis (OA) were included for the study. Before having them in the study, all the subjects completed baseline interviews and demographic data. The subjects were categorized under neuropathic and nociceptive groups using Pain Detect Questionnaire (PDQ). One-time measurement of pain intensity, isometric strength of Quadriceps & hamstrings, and knee joint range of motion were assessed in both groups. Physical performance was measured using Osteoarthritis Research Society International recommended physical performance tests for knee osteoarthritis (40m Fast Paced Walk Test, 6 min walk test, 30s chair stand test, Timed up and Go Test, Stair Climb Test) and OA knee-related disability using Knee injury and Osteoarthritis Outcome Score (KOOS) questionnaire. Results: Of the eighty subjects, forty subjects were included in the neuropathic group (44%), forty in the nociceptive group based on PDQ. Physical performance (p < 0.05) was significantly reduced in the neuropathic group. There existed a weak negative correlation between pain quality and variables measured (p < 0.05). Conclusion: Physical performance was significantly reduced in OA knee subjects with neuropathic pain features. There is a negative correlation between pain quality and most of the physical performance variables.