Knee pain can be caused by a sudden injury, an overuse injury, or by an underlying condition, such as arthritis. Treatment will vary depending on the cause. Symptoms of knee injury can include pain, swelling, and stiffness. Knee pain is a common complaint that affects people of all ages. Ligament damage often happens from a sports injury. A torn ligament severely limits knee movement. This results in the inability to pivot, turn, or twist the leg. Surgery is a choice to repair a torn ligament if other medical treatment is not effective.