Differences in self-reported signs related to central sensitization and pressure pain threshold related to knee osteoarthritis and sarcopenia

AimThis study investigates differences in self-reported signs of central sensitization and pressure pain threshold in individuals with knee osteoarthritis and sarcopenia.FindingsPatients with knee osteoarthritis had significantly increased central sensitization inventory-9 scores compared with those with sarcopenia, but there was no significant difference in pressure pain threshold between patients with knee osteoarthritis and patients with sarcopenia. In addition, comparing sarcopenia and non-sarcopenia in community-based older-age participants, pressure pain threshold was significantly lower in those with sarcopenia, but there was no significant difference in central sensitization inventory-9.MessageThe interpretation of the Central Sensitization Inventory-9 (CSI-9) and Pressure Pain Threshold (PPT) may differ in the context of knee osteoarthritis and sarcopenia, potentially affecting the assessment of central sensitization and Central Sensitization Syndrome (CSS), with the responsiveness of these measures varying according to the specific disease condition. PurposeNeuroinflammation, which occurs in knee osteoarthritis and sarcopenia, has attracted attention as a mechanism of central sensitization, but the relationship between central sensitization and these conditions has not been widely studied. This study investigates differences in self-reported signs of central sensitization and pressure pain threshold in individuals with knee osteoarthritis and sarcopenia.MethodsWe examined 340 patients (mean age +/- standard deviation: 76 +/- 5.9, women were 86.9%) with knee osteoarthritis scheduled to undergo total knee arthroplasty. For comparison, 129 community-dwelling older people (mean age +/- standard deviation: 76 +/- 5.5, women were 68.9%) individuals without a history of knee osteoarthritis or any other diagnosed illnesses were matched for age and sex. We assessed central sensitization inventory-9, pressure pain threshold, pain-related factors, skeletal muscle mass index, and hand grip strength. ANCOVA using 2 (patients with knee osteoarthritis and community older people without knee osteoarthritis) x 2 (sarcopenia and robust) was performed to assess outcome measurements.ResultsThe prevalence of sarcopenia among patients with knee osteoarthritis was 50.3%. ANCOVA revealed an interaction effect for the central sensitization inventory-9. For the main effect of knee osteoarthritis, there was a significant difference in central sensitization inventory-9, and for the main effect of sarcopenia, there was a significant difference in pressure pain threshold.ConclusionsDiscrepancies in the evaluation of central sensitization were identified between knee osteoarthritis and sarcopenia. Individuals with knee osteoarthritis had elevated score of self-reported indications of central sensitization, whereas sarcopenic patients had reduced pressure pain thresholds.