The objective of this study is to compare the status and functioning of the nociceptive and antinociceptive systems between patients with and without chronic postsurgical pain following total knee arthroplasty.
This observational case-control study included 117 patients who underwent total knee arthroplasty for primary osteoarthritis, with pain being the primary indication for surgery. Cases were defined as patients with persistent postoperative pain, evaluated using a Visual Analog Scale (VAS) score of ≥30/100 at 3 months post-surgery. Pressure pain thresholds were measured with algometry at eight periarticular sites around the knee, as well as distant locations, including both tibias and forearms. The Cold Pressor Test was also employed to assess conditioned pain modulation. Data from both groups were compared using the Mann-Whitney U test.
Among the 117 participants, 45.3% (n=53) experienced chronic postsurgical pain, while 54.7% (n=64) reported no pain. Comparisons between the two cohorts revealed that individuals with chronic postsurgical pain had significantly lower pressure pain thresholds at all eight periarticular assessment sites (p0.001), both tibial assessment points (p0.05), and the ipsilateral forearm (p=0.026). Additionally, conditioned pain modulation was reduced in the chronic postsurgical pain group, both locally (p=0.002) and globally, as observed in the contralateral forearm (p=0.016).
The results suggest that individuals with chronic postsurgical pain exhibit signs of dysfunction in both nociceptive and antinociceptive systems.
This indicates that the persistence of pain may be influenced by central sensitization mechanisms, which could guide physiotherapists and orthopedic surgeons in optimizing strategies for managing persistent pain in patients following total knee arthroplasty.
chronic postsurgical pain
conditioned pain modulation
