Everything You Need To Know About Runner's Knee 1. What it is: Runner's knee refers to a set of symptoms related to the cartilage in the knee and the patella. The patella, more commonly known as the kneecap is a thick bone which articulates with the femur and protects the surface of the knee joint. Runner's knee is caused by contact between the back of the kneecap and the femur - the thigh bone. As the knee is flexed and extended, the patella slides and causes friction. The cartilage of the patella, which is a smooth substance that allows it to slide on the femur, is then irritated and causes pain.2. Symptoms: The following symptoms all relate to knee pain: pain whilst doing sport (running, tennis, cycling), pain whilst taking the stairs, pain when sitting for prolonged periods of time, pain in front of the knee or in the hollow of the knee, sensation of knee blockage or instability, and knees clicking.3. Causes: Although anyone can be affected by patellafemoral pain syndrome, athletes and especially runners are most often affected. There are also several risk factors which can make you more susceptible to this syndrome, such as anatomical abnormalities, muscular dysfunction or a history of trauma or knee surgery. External risk factors, such as the type of sport practiced and the type of surface or footwear used, can also influence the onset and intensity of runner's knee. It should also be noted that runner's knee is more common in women than in men.4. Treatments: The treatment of runner's knee is mainly focused on the muscular rehabilitation of the quadriceps, hamstrings, but also the calves. This must be done carefully and painlessly. Rehabilitation with targeted and personalised physiotherapy is also effective. For athletes, it is advisable to stop exercise, at least until the pain has subsided. Cycling can still be practiced as well as swimming, but breaststroke should be avoided, with front crawl being a better option. Cold applied to the knee can also decrease and relieve pain.