Hello, Thanks for your query. You might be suffering from patellar tendinitis or chondromalacia patellae, which causes pain in your knee when you try to climb the stairs. This type of knee pain related to overuse. Visit your doctor, get yourself examined. Your doctor will advice you to go for a xray. Generally physiotherapy for your quadriceps muscle with straight leg raising and knee mobilisation will improve your muscle strength and will decrease the progression of arthritis. Life style modifications like avoiding stairs, squatting, sitting cross legged & cycling will also help in reducing your symptoms. Reducing weight is of prime importance if you are overweight. If the pain is severe, you can take few doses of NSAID s or physiotherapic modalities like IFT to relieve your pain. I do hope that you have found something helpful and I will be glad to answer any further query. Take care