Does the Presence of Neuropathic Pain Influence the Response to Hyaluronic Acid in Patients with Knee Osteoarthritis?

Neuropathic pain in patients with primary knee osteoarthritis: A cross-sectional study

INTRODUCTION

Neuropathic pain (NP) is believed to be a distinct subtype of pain associated with knee osteoarthritis (KO). This study aimed to determine the prevalence of NP in patients with primary KO and examine its correlation with various factors.

METHODS

A cross-sectional study was conducted on 195 patients with primary KO who did not have the following conditions: knee surgery, infection, rheumatic diseases, peripheral and central neurological diseases, patients who received treatment for neuropathic pain in the past 6 months, diabetes, renal failure, and alcoholism. NP was evaluated using two standardized questionnaires, the Douleur Neuropathique 4 questions (DN4) and the painDETECT questionnaire.

RESULTS

The majority of patients were female (87.5%), with a mean age of 59.15 ± 7.62 years. NP was detected in 55.9% of patients according to the DN4 questionnaire and in 50.7% of patients according to the painDETECT questionnaire. The DN4 score was positively correlated with age (p=0.041; rs=0.145), visual analogue scale (VAS)-pain at rest (p=0.009; rs=0.188), VAS-pain at movement (p=0.017; rs=0.173), Western Ontario and McMaster Osteoarthritis Index (WOMAC) pain score (p=0.030; rs=0.157), WOMAC stiffness score (p=0.000; rs=0.253), physical function WOMAC score (p=0.000; rs=0.271), total WOMAC score (p=0.000; rs=0.305), Lequesne score (p=0.002; rs=0.221), and negatively correlated with quadriceps circumference (p=0.008; rs=-0.210). Whereas, the painDETECT score was positively correlated with VAS-pain at movement (p=0.002; rs=0.220), WOMAC stiffness score (p=0.043; rs=0.147), physical function WOMAC score (p=0.017; rs=0.172), and total WOMAC score (p=0.012; rs=0.182). NP according to the DN4 was associated with quadriceps circumference (p=0.01), while the painDETECT score was associated with VAS- pain at movement scores (p=0.022) and total WOMAC score (P=0.001).

CONCLUSION

This study found that NP is common among patients with primary KO and is associated with more painful pathology and functional impairment. These findings highlight the importance of recognizing and managing NP in this population to improve patient outcomes.

High Prevalence of Pain Sensitization in Knee Osteoarthritis: A Meta-Analysis with Meta-Regression

OBJECTIVE

The aim of this meta-analysis was to study the evidence on pain sensitization in knee osteoarthritis (OA), providing a quantitative synthesis of its prevalence and impact. Factors associated with pain sensitization were also investigated.

METHODS

Meta-analysis; PubMed (MEDLINE), Cochrane Central Register (CENTRAL), and Web of Science were searched on February 2021. Level I to level IV studies evaluating the presence of pain sensitization in patients with symptomatic knee OA, documented through a validated method (questionnaires or quantitative sensory testing), were included. The primary outcome was the prevalence of pain sensitization. Factors influencing the prevalence were also evaluated, as well as differences in terms of pain thresholds between knee OA patients and healthy controls.

RESULTS

Fifty-three articles including 7,117 patients were included. The meta-analysis of proportion documented a prevalence of pain sensitization of 20% (95% confidence interval [CI] = 16%-26%) with a significant heterogeneity of results (I² = 89%, P < 0.001). The diagnostic tool used was the main factor influencing the documented prevalence of pain sensitization (P = 0.01). Knee OA patients presented higher pain sensitivity compared with healthy controls, both in terms of local pressure pain threshold (standardized mean difference [SMD] = -1.00, 95% CI = -1.67 to -0.32, P = 0.007) and distant pressure pain threshold (SMD = -0.54, 95% CI = -0.76 to -0.31, P < 0.001).

CONCLUSIONS

Knee OA pain presents features that are consistent with a significant degree of pain sensitization. There is a high heterogeneity in the reported results, mainly based on the diagnostic tool used. The identification of the best methods to detect pain sensitization is warranted to correctly evaluate and manage symptoms of patients affected by knee OA.

REGISTRATION

PROSPERO CRD42019123347.