Unilateral primary osteoarthritis, unspecified knee

This code signifies a degenerative joint disease affecting one knee, where the underlying cause is not secondary to another condition. It indicates the gradual breakdown of cartilage and bone within a single knee joint, leading to pain, stiffness, and reduced mobility. The specific knee (left or right) is not documented or specified.

Apply this code when documentation clearly states "unilateral primary osteoarthritis of the knee" without specifying laterality. This is appropriate when the physician's notes indicate osteoarthritis in only one knee, but the medical record does not differentiate between the right or left knee.

• Avoid using this code if laterality (right or left knee) is documented; instead, choose the more specific M17.11 (right) or M17.12 (left).
• Ensure the documentation specifies "primary" osteoarthritis to differentiate from secondary forms (e.g., post-traumatic).
• This code should be used when the documentation is insufficient to assign a more specific laterality code.