Summary

Examination of correlation between Central Sensitization and PROMs

Abstract

Objective

Chronic pain associated with knee osteoarthritis (KOA) has been shown to involve not only nociceptive pain but also peripheral and central nerve sensitization. However, there are few reports comparing central sensitization(CS) to the severity of deformity, versus patient-reported outcome measures (PROMs) and we aim to investigate these relationships.

Methods

78 KOA patients (male/female=30/48, mean 63.6±11.8 years, KL2/3/4=29/28/21) who first visited our hospital between June and July 2022 with chronic knee pain refractory to conservative treatment were included in the study, and PROMs and CS were assessed by a self-administered questionnaire (Central Sensitization Inventory[CSI]). The severity levels were divided into the following point categories ; subclinical(0-29 points) ,mild(30-39 points), moderate(40-49 points), severe(50-59 points), and extreme(60-100 points). A CSI score of 30 or higher was defined as having CS. The correlation between CSI score and KL classification, tibiofemoral angle (FTA), % mechanical axis (% MA), Visual Analogue Scale (VAS), Knee injury and Osteoarthritis Outcome Score (KOOS), Japan Knee Osteoarthritis Measure (JKOM) was examined. Statistical analysis was performed using SPSS ver.28 with Spearman's rank correlation coefficient. Comparison among the three groups was performed by one-way ANOVA, followed by post-hoc test using the Tukey-Kramer method. The significance level was set at 5%.

Results

The mean CSI score was 20.1±10.4. CS occurred in 16.7% of patients (CSI score=30), the quantity of subclinical/mild/moderate patients were 11/1/1 respectively. KL2, KL3 and KL4 patients had CS in 3 (10.3%), 5 (17.8%), and 5 (23.8%) patients. There were no significant differences between the groups (p=0.45). FTA and %MA showed no correlation with the CSI score (p=0.74/0.68). VAS, KOOS-ADL, KOOS-QOL, KOOS-pain, JKOM and CSI scores were significantly correlated (r=0.24,p=0.03/r=0.48,p<0.01/r=0.26p=0.02/r=0.31,p=0.007/r=0.41,p<0.01). Only KOOS-symptom did not correlate with the CSI score (p=0.05).
Summary and Discussion
Our findings indicate that there was a correlation between CSI and PROMs, but not with KOA severity or lower limb alignment. 16.7% of KOA patients had CS, but it has been reported that KOA patients with CS often have persisting residual pain after operations such as joint replacement surgery. In conclusion, it is necessary to evaluate not only PROMs but also CSI in patients with chronic pain to determine a correct treatment plan.