The common causes of sore calves and knee pain are strain on the knee and calf area, or lesions in the structures within the knee. The former is commonly caused by prolonged weight-bearing walking and exercise, resulting in wear and tear of the joint structures and strain on the calf muscles, which may lead to knee pain and calf discomfort. The latter is due to structural lesions within the joint, such as wear and tear of the cartilage, meniscal tears, popliteal cysts behind the popliteal fossa, and damage to the cartilage and cruciate ligaments, all of which can cause knee pain and pain involving the back of the calf. Some older adults with osteoarthritis due to joint degeneration may experience knee pain as well as calf pain due to contracture of the joint capsule at the back of the joint.