Osteochondromatosis
Osteochondrosis (Juvenile osteochondritis – dyschondroplasia)
Orosinus fistula
Osseous cyst-like lesion (site unspecified)
Ossification of collateral cartilages of foot (Sidebone)
Otitis externa – infective
Otitis externa – meatus and canal only
Otitis externa – pinna only
Otitis interna
Otitis media