Hi,
I would code that as M19.019 Primary Osteoarthritis, unspecified shoulder.
Using ICD 10 CM book, i searched Osteoarthritis > Shoulder > directs me to M19.01- (Primary Osteoarthritis of other joints) > then chose shoulder M19.019.
When I used 3M, it also directs me to M19.019 when i chose unspecified type and laterality of OA.