I had a subtotal synovectomy on my knee a year ago, flexion normal, missing few degrees hyperextension, still stiff, pain doing stairs, what is wrong?

Arthritis?: Most patients requiring a synovectomy, especially those 50 years and above, have osteoarthritis. Stairs place a significant load on the knee joints, and many patients with various types of knee problems hurt when going up and down stairs. It would be worthwhile to follow up with your orthopedic doctor for a reassessment and discussion of treatment options. Repeat x-rays could be helpful.