removal of OMN

I have found all your info very helpful. I had an IMN inserted in May 2007 after a fall off my horse. I worked hard at rehab and am not limited in any activity I wish to do including back at riding hard! Recently I had a CT of a "lump"above my knee.This has been present and tender since the surgery but has increased in size and is painful at times i.e stairs, direct pressure and it seems inactivity.There is a 7cm seroma present and this is deemed to be impingement of the screw into the muscle. Now I am wondering if it really warrants removal. Your comments would be appreciated.