As synovial fluid alpha-defensin showed a cross-reactivity in the presence of crystal deposits (53, 77) and abrasive wear (52), we wanted to investigate if the C9 immunostaining in the tissue showed similar cross-reactivity with other inflammatory joint conditions such as chondrocalcinosis (CC), rheumatoid arthritis (RA) and wear particles. Here, C9 is linked to chondrocalcinosis.