A clinical study exploring hip and knee osteoarthritis pain transmission using cerebrospinal fluid

Abstract

Background: Osteoarthritis affects approximately 40% of older adults but molecular mediation of OA pain in the dorsal horn is unexplored clinically. This study explored amino acids and cytokines related to pain signalling and sensitisation to determine whether significant differences existed in their concentration in comparison with pain-free controls after adjustment for age, gender and psychological distress.
Method: After ethical approval people having primary hip or knee arthroplasty (OA group) or urological surgery (pain-free controls) were recruited. Pain at rest, (PAR), pain on movement (POM) (0-10 numerical rating scale), and HADS data was collected before aspiration of 2ml sample of CSF. HPLC and multiplex bead array assay was conducted and data explored using ANCOVA and logistic regression.
Results: Data from 21 control (75% male) and 59 OA (46% male) participants revealed that HADS, serine, leucine, valine, and TNFα were significantly higher and IL-12 was significantly lower in the OA group. IFNγ was significantly lower in the PAR group.
Discussion: This study suggests central sensitisation is involved in OA. Psychological distress is an integral part of the OA experience. Amino acid and cytokine involvement in pain transmission is complex; further work exploring human CSF in painful conditions with clinical follow up is recommended.