"C: CPPD"
"O: osteoarthritis"
"O: osteonecrosis"
"R: rheumatoid arthritis"
"S: synovial-based tumours"
"O: osteoarthritis"
"O: osteonecrosis"
"R: rheumatoid arthritis"
"S: synovial-based tumours"
"Geode (subchondral cyst)"
Expected headings
"Mnemonic"