Predictive Value of Pain Sensitization Associated with Response to Exercise Therapy in Patients with Knee Osteoarthritis: A Prospective Cohort Study

Abstract

Knee osteoarthritis (KOA) is a degenerative disease with inflammation, becoming persistent as it progresses, resulting in reduced quality of life. Exercise is the recommended treatment for KOA; however, the extent of pain reduction with exercise is heterogeneous and the prognostic implications of baseline factors in patients undergoing exercise are still unknown. This study examined the association between the response to exercise therapy and clinical outcomes, radiologic severity, and pain sensitization, and investigated the optimal predictive value for the effectiveness of exercise. Patients and Methods: Demographics, radiologic severity, pressure pain threshold (PPT), and temporal summation of pain (TSP) at the knee, tibia, and forearm were assessed at baseline. The pain numeric rating scale (NRS) was assessed before and after 12 weeks of exercise. Patients were divided into responder/non-responder groups according to recommended criteria: responder, ≥30% reduction in pain; non-responder, <30% reduction in pain, and each variable was compared between the groups. The area under the curve (AUC) and cutoff points were determined by receiver operating characteristic curve analysis. Results: Sixty-five patients were categorized as responders and 26 as non-responders. In the non-responder group, baseline NRS (P<0.01), pain duration (P<0.01), and TSP at the knee (P<0.001) and tibia (P<0.05) were significantly higher, and PPT at the knee (P<0.001), tibia (P<0.001), and forearm (P<0.001) were significantly lower, than those in the responder group; however, no significant differences between groups were found in other demographics and radiologic severity. The variables that showed moderate or better predictive ability (AUC≥0.7) were PPT at the knee (cutoff points: 241.5 kPa), tibia (307.5 kPa), forearm (318.5 kPa), and TSP at the knee (15.5 mm). Conclusion: Our findings suggest that pain sensitization is associated with the response to exercise therapy. Furthermore, we provide clinically predictive values for PPT and TSP in predicting the outcome to exercise in KOA.

Exercise induced hypoalgesia during different intensities of a dynamic resistance exercise: A randomized controlled trial

“…In examining baseline pain sensitivity factors that may be associated with response to each intervention, significant correlations were not observed with the exception of a significant, positive moderate association with baseline heat pain threshold applied over the trapezius (r = 0.61, p<0.01) and temporal summation (r = 0.46, p = 0.04) with EIH during low intensity exercise. Temporal summation has been previously associated with response to exercise[ 7 , 8 ]. However, our study demonstrated this measure is also associated with response to low intensity dynamic resistance exercise in healthy individuals which contributes to the literature in a novel way and expands our broader understanding.…”

“…It remains unclear why certain individuals demonstrate hyperalgesia in response to exercise; [ 1 , 2 ] however, pain sensitization may be a contributing factor. Significantly higher temporal summation and lower pressure pain threshold at multiple locations have been demonstrated in individuals who are considered ‘non-responders’ to a twelve week aerobic and strength training in patients with knee osteoarthritis [ 7 ] . Temporal summation is also predictive of individuals who display an increase in clinical pain during exercise [ 8 ] .…”

Pathology of knee osteoarthritis pain: contribution of joint structural changes and pain sensitization to movement-evoked pain in knee osteoarthritis

“…2) 22 . The PPT at the knee was de ned as the lowest PPT at the four sites 23 . The mean of the two measurements was used for the analysis.…”

“…Subsequently, ten sequential stimuli were applied to the same site in 1-second intervals, and the patients reported the pain intensity for the last stimulation on the VAS. The TSP value was calculated as the difference between the 10th VAS score and the rst VAS score 23 . The pressure intensity of the sequential stimuli was equal to the PPT level.…”

Pathology of knee osteoarthritis pain: contribution of joint structural changes and pain sensitization to movement-evoked pain in knee osteoarthritis

“…3,11,43 Pain sensitization is a factor that decreases treatment response to exercise therapy and pharmacotherapy. 10,15,16 Moreover, alterations in the central nervous system may cause various symptoms, such as fatigue and poor sleep, which are called central sensitization-related symptoms and affect KOA pain symptoms. 2,15 Thus, factors contributing to pain symptoms are varied, but which ones are strongly associated with MEP in KOA remains unclear.…”