There are many causes of knee pain and its tough to diagnose over the web. You may be experiencing chondromalacia patellae or rubbing of the underside of the kneecap, especially noted when walking up stairs. Or you might have a soft tissue problem such as a bursitits or tendinitis. Quad strenthening may help.
About Alan Matsumoto, M.D.
Part-time Faculty, Division of Rheumatology
Johns Hopkins University