Orthopedic Coding Alert

Question: How should I code a diagnosis of arthritis if an underlying cause is indicated (in my case, chondrocalcinosis of the shoulder) on the surgeon's notes?


Illinois Subscriber


Answer: The Arthritis Foundation reports that there are more than 100 forms of arthritis and related diseases, so coding for specific diagnoses with underlying causes can be tricky. In your case, you would list both diagnoses, with the underlying diagnosis indicated first.

For your patient, you would use one of the codes for disorders of calcium metabolism, which are in the 275.4x series. In addition, you would have to indicate a fifth digit for the underlying disease, as follows:

- 275.40 -- Unspecified disorder of calcium  metabolism

- 275.41 -- Hypocalcemia

- 275.42 -- Hypercalcemia

- 275.49 -- Other disorders of calcium metabolism.

You would then indicate the code identifying crystal-induced arthritis, which is in the 712.3x series, requiring a fifth digit to report the site. In your case, it would be 712.31, for the shoulder.

You will see a notation following 712.3x that states, -code first underlying disease [275.4],- which is why 712.31 should be the secondary diagnosis code.