I have had knee problems since the mid 1990's. I have gone to a few doctors, and they found zip. I went to the Serotta Factory for a fit with Mr. McGlen several years ago, and he diagnosed all sorts of problems, while reminding me he is not a doc. ITB tight, substantial leg length difference, right leg more muscular than left, and outer thigh way more developed than inner. It all made sense after meeting with him.