By Chris Ricard, DPT · Explore Physical Therapy · North Kingstown, RI My R Knee After a Cartilage Surgery for Chronic PFPS Well, the front of your knee hurts. That much you know. But trail runners with knee pain make one of two very different mistakes depending on which condition they actually have, and treating the wrong one keeps you sidelined far longer than necessary. Patellofemoral pain syndrome and patellar tendinopathy both show up as anterior knee pain in runners, the