Question: What is polyosteoarthritis, and how do I choose an ICD-10 code for the condition? Massachusetts Subscriber Answer: Osteoarthritis is a chronic degenerative disorder caused by wear and tear on a joint. Quite simply, polyosteoarthritis occurs when a patient has osteoarthritis in multiple sites. Choose from the following diagnosis codes for polyosteoarthritis: Note: For polyosteoarthritis with bilateral involvement of a single joint, choose a code from the M16.- (Osteoarthritis of hip) through M19.- (Other and unspecified osteoarthritis) code set.