ICD-10-CM > M00-M99 > M15-M19 > M18 > M18.5 M18.5 Other unilateral secondary osteoarthritis of first carpometacarpal joint Non-Billable/Non-Specific Applicable To Secondary osteoarthritis of first carpometacarpal joint NOS Codes M18.50Other unilateral secondary osteoarthritis of first carpometacarpal joint, unspecified handM18.51Other unilateral secondary osteoarthritis of first carpometacarpal joint, right handM18.52Other unilateral secondary osteoarthritis of first carpometacarpal joint, left hand