Evidence of generalised mechanical hyperalgesia in patients with advanced knee osteoarthritis undergoing total knee arthroplasty

Background and objective: Persistent pain is reported in up to 34% of patients following total knee arthroplasty (TKA) for management of knee osteoarthritis (KOA). Persistent pain in this group is thought to be at least partly reflective of pain sensory hypersensitivity. The objective of this study was to evaluate sensory hypersensitivity, using mechanical and thermal quantitative sensory testing, in patients about to undergo TKA. Design and methods: Pressure pain thresholds (PPT) and cold pain thresholds (CPT) were recorded from 30 participants prior to their TKA, and compared with recordings taken from 30 healthy control participants of similar age and gender. Thresholds were recorded locally and remotely (other knee, deltoid) to the operative knee. Group comparisons (KOA, control, groups) were made using a general linear mixed models approach with age, gender, and body mass index (BMI) included as covariates. Pairwise comparisons were conducted with Bonferonni correction for multiple comparisons. Results: Significantly lower PPTs were at all measured sites in the KOA group compared to the control group (P < 0.001 at all sites, except the deltoid P = 0.004). Males demonstrated higher pain threshold compared to females, averaged over all sites, P = 0.02. There were no observed between-group differences in CPT (P = 0.122). Conclusions: This study suggested that some individuals about to undergo TKA for their advanced KOA demonstrated widespread mechanical sensory hypersensitivity. These findings have potentially important clinical implications regarding perioperative and longer-term pain management in these patients. (C) 2018 Elsevier B.V. All rights reserved.