The knee is a complex system of bones, cartilage, ligaments, tendons, and muscles responsible for weight-bearing and movement. Anything that causes stress, inflammation, or injury to the knee can result in sharp knee pain.Most people experience knee pain at some point in their lives. Older people may get knee pain and discomfort from multiple age-related conditions. Younger people may experience similar symptoms but the cause is more likely from playing sports or doing other physical activities.Whatever the cause, sharp knee pain symptoms are often a sign of serious knee injury, and you should have it checked by a medical provider right away.