Your knee cartilage is composed of two separate wedges called menisci. Each meniscus acts as a cushion for your knee joint, and tears in a meniscus can cause significant pain and decrease your overall knee stability.

Knee pain is a common complaint for anyone who participates in a running program or attempts to run without being prepared. Running in the cold weather can add to knee pain or make it more difficult to run at your normal pace.

The knee has more structures than any other joint, making it very vulnerable to injury and pain. It doesn’t help matters that it’s also a weight-bearing joint. Factors that contribute to knee pain include overuse, an unusual motion, abnormal joint structure or a degenerative condition such as arthritis.

Running is an exercise that benefits almost every system in your body -- it helps you lose or maintain body weight, strengthens your leg muscles and improves your cardiovascular fitness.

According to the textbook "Sports Medicine A Comprehensive Approach" knee injuries are one of the most often injured joints in the body during sport activities. In children doctors often see ankle sprains as a result of rough play and other contact sports.

Testicular pain does not strike most men in the same way as pain in other locations. The testicles are a highly sensitive spot on the body and one that is associated with several important roles, including sexual reproduction and as a symbol of masculinity.

Knee pain can significantly affect your ability to move around, particularly when you need to climb stairs. Pain in the front of your knee is typically related to your patellofemoral joint, where your kneecap sits in front of your thigh bone. Stair climbing increases compression at this joint. "

Knee clicking is a common symptom and does not always indicate cause for concern. A complex interworking of ligaments, tendons and muscles support your knee joint. These must support your body weight during normal activities and added force when you exercise, particularly for high-impact activities like running.

The hamstring is a muscle in the back of the thigh. It straightens and rotates the leg and bends the knee. A pulled or strained hamstring can cause some discomfort when straightening the leg, and if severe enough, can make it painful to walk.

Cysts that form on the back of your knees and legs are known as Baker's cysts. According to the University of Maryland Medical Center, Baker's cysts form when the fluid from your joints builds up, causing your skin to protrude and mild to moderate pain.

The knee joint is the largest synovial, or movable, joint in the body, according to The Pain Clinic. This means the knee has many moving parts that can become damaged due to injury or wear and tear over time.

Running routines sometimes bring more than just the benefits of a good workout and an endorphin rush. They may also bring knee pain, especially when you run downhill. It’s likely one of two common knee conditions. Don’t wait until the pain is so bad that you can’t run anymore. Seek treatment as soon as possible.