RecruitingDevice studyTreatment of Post Traumatic Knee Osteoarthritis With Extracorporeal Shockwave TherapyThis study is recruiting current or former athletes who had ACL reconstruction surgery over a year ago and have been diagnosed with knee osteoarthritis (OA). We are doing the research to investigate the effects of extracorporeal shockwave therapy (ESWT) on pain, function, biomechanics, knee range of motion and strength, inflammation, and joint structure and integrity of the knee.