novel treatment (new drug/intervention; established drug/procedure in new situation) abrasion arthroplasty resulted in observed pain, functional and structural improvements over a 24-month period of follow-up. The procedure was well tolerated with no serious adverse events recorded. The results suggest that this approach may be a suitable option for the treatment of advanced unicompartmental medial knee osteoarthritis in patients, where due to age or other factors, the patient is not suitable for a total knee replacement. learning points ► Osteoarthritis is a leading cause of pain and disability across the world. ► There is an observed increase in the number of patients undergoing total knee replacement under the age of 65. ► The novel use of high tibial osteotomy, in combination with arthroscopic abrasion arthroplasty and adipose-derived mesenchymal stem cell therapy, may considerably delay the need for total knee replacement.