Her knee OA is really grade-4 but isolated medial compartment osteoarthritis. Try intrarticular steroid injections , although they are most likely to fail but still give it a try. She can be benefitted by High tibial osteotomy .  It is a procedure that can delay TKA or uni-replacement by 10-20 years by offloading the medial compartment.

She is having a medial joint arthritis. U can also get Partial knee replacement done. Better results than total knee replacement