1.Patellofemoral pain syndrome.

Patellofemoral pain syndrome, also known as runner’s knee, is a common cause of knee pain among runners. Patellofemoral pain syndrome is caused by vigorous physical activities that put repeated stress on the knee—such as jogging, squatting, and climbing stairs.it can also be caused by a sudden change in physical activity. Symptoms of this syndrome may include pain behind or around the kneecap (patella), pain while bending the knee, pain that worsens when walking downstairs or downhill, knee swelling, or popping or grinding sensations in the knee.

Patellofemoral pain syndrome can affect one or both knees. It can be caused by overuse (repetitive bending, high stress exercises, or overstretched tendons), direct trauma (fall or blow), misalignment of the kneecap or other leg bones, problems with the feet (hypermobility, fallen arches, or flat feet), and weakness in the thigh muscles or other muscle imbalance. Treatment of the syndrome may include rest, ice, compression, elevation, anti-inflammatory medications, stretching and strengthening exercises, especially for your quadriceps muscles and arch supports or shoe orthotics.