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

Objectives Up to 50% of patients with symptomatic knee osteoarthritis (OA) present with neuropathic pain (NP) features. We assessed the impact of NP according to DN4 (Douleurs Neuropathiques 4 questions) score on the response to intra-articular (IA) hyaluronic acid (HA) injections and the effects of HA injections on NP. Materials and Methods We conducted apost hocanalysis from a multicenter, randomized, double-blind, noninferiority trial comparing the efficacy of 2 HA in symptomatic knee OA at 24 weeks. At baseline, demographic, anthropometric, radiologic data, and symptoms were recorded. The symptomatic effect of HA was assessed by VAS pain, patient global assessment (PGA), WOMAC, DN4, and OMERACT-OARSI response. Results A total of 187 patients were included. NP according to DN4 score was present in 20 patients (10.7%) at baseline. Most common positive DN4 items were tingling (36.9%) and burning (36.4%). NP was associated with WOMAC pain score (P= 0.02). The presence of NP at baseline did not affect the symptomatic improvement after HA injections according to the VAS pain (P= 0.71), PGA (P= 050), WOMAC pain (P= 0.89), WOMAC function (P= 0.52), and rate of OMERACT-OARSI responders (P= 0.21). The prevalence of patients with NP decreased by 50% (n= 10) at 24 weeks after HA injections. Most improved DN4 items were itching (90%), hypoesthesia to pinprick (88%), and burning (50%). Conclusion In our study, NP was associated with pain severity, but did not influence the response to IA HA. On the other hand, HA injections reduced some NP features, especially itching, sting hypoesthesia, and burning.