5. Patients on anti-coagulants or other blood thinning medications will be eligible for inclusion if they stop taking these medications for at least the time specified below prior to date of surgery: Low molecular weight heparin must stop at least 36 hours prior to surgery. Coumadin must stop at least 5 days prior to surgery. Aspirin, Plavix and NSAIDs must stop at least 7 days prior to surgery.