High levels of substance P and CGRP in pseudosynovial fluid from patients with aseptic loosening of their hip prosthesis

Background Aseptic loosening is the most important complication after total hip arthroplasty (THA). The nervous system has been implicated in the etiology and pathogenesis of joint diseases.

Methods We compared levels of substance P (SP) and calcitonin gene‐related peptide (CGRP) in pseudosynovial fluid from patients with aseptic loosening after THA with those in synovial fluid from patients undergoing primary THA for osteoarthritis, who served as controls. Levels of SP and CGRP were measured using an enzyme immunoassay.

Results We found that SP and CGRP levels were significantly higher in the pseudosynovial fluid of loose artificial joints than in the synovial fluid of controls.

Interpretation SP and CGRP may have a role in aseptic loosening.