The AMA released a new category III code for subchondroplasy the code is 0707T - Injection(s), bone substitute material (eg, calcium phosphate) into subchondral bone defect (ie, bone marrow lesion, bone bruise, stress injury, microtrabecular fracture), including imaging guidance and arthroscopic assistance for joint visualization
Includes parenthetical notes:
(Do not report 0707T in conjunction with 29805, 29860, 29870, 77002)
(For aspiration and injection of bone cysts, use 20615)
https://www.ama-assn.org/system/files/cpt-category3-codes-long-descriptors.pdf
Remeber that as of Nov 2019 CPT Assistant gave an updated official opinion in that assistant that subchondroplasty is reported with 29999 - there is NO other code that can be used.