I had to extremely modify my weight/resistance training for 4 months, until my PMR was diagnosed and I started prednisone. I am attaching a screenshot of the AI response on Google regarding your question. Maybe modifying your planks by supporting weight on your elbows rather than hands would help. As a retired P.T., I understand the importance of your post op exercises. A therapist may help you find alternative exercises that will accomplish your goals without increasing the inflammation.
God speed as you navigate this life altering disease.