Some causes of pain behind the knee and calf are deep vein thrombosis, tendinitis, muscle cramp and a Baker's cyst. Although these are common conditions that may cause pain symptoms, there can be other medical issues that lead to pain in these leg regions, such as an infection or knee sprain, as noted by WebMD.
Deep vein thrombosis (DVT) can occur if a blood clot forms in a vein located in the calf area. This can cause symptoms, such as pain and inflammation in this region, as stated by Mayo Clinic. A blood clot in the lower extremities can travel to the lungs, causing a pulmonary embolism, a complication of DVT.
Knee sprains, knee infections, tendinitis and muscle cramps are different types of conditions that can cause pain at the back of the calf or knee area. For example, tendinitis, an inflammation of the tendons, can affect the calf muscles. A treatment option for tendinitis is prescribed anti-inflammatory medications, according to WebMD.
A Baker's cyst is a pocket or collection of synovial fluid that forms at the back of the knee. Although some patients may experience pain, others do not. However, if the cyst ruptures, it can lead to inflammation and bruising at the back of the knee and calf regions. Some causes, which can lead to a cyst formation in this area, are arthritis and a knee cartilage tear, as stated by the National Institutes of Health's MedlinePlus.