: Injury to the upper part of the calf muscle where it meets the back of the knee.
: A fluid-filled sac that forms behind the knee, often causing a bulge and a feeling of tightness. Pain in the back of my knee – Mr Validity
: Inflammation of the small, deep muscle that helps "unlock" your knee when you start to bend it. : Injury to the upper part of the
: A pull or tear in the muscles at the back of your thigh that attach near the knee joint. : A pull or tear in the muscles
: A sprain or tear of the Posterior Cruciate Ligament, usually caused by a direct blow to the front of the knee. Recommended Recovery Steps Pain Behind Knee (Back of Knee Pain) - Cleveland Clinic
Pain in the back of the knee, often called , can stem from several common issues. If you are specifically looking for Mr Validity (likely referring to the sports injury and wellness brand Validity), they focus on recovery tools and education for athletes. Common Causes of Posterior Knee Pain