Pain in the hollow of the knee and thigh

The muscles of the thigh are involved in the limitation of the popliteal fossa (see “Biceps tendon tendinosis”). Therefore, diseases, strains and tears of the thigh musculature, especially of the biceps femoris muscle, can cause pain in the hollow of the knee. This pain can radiate into the thigh.

In the outer area of the popliteal fossa, pain usually occurs when the ligament and tendon structures of the knee are irritated or injured, but injuries to the menisci and the joint capsule also cause these complaints when the knee is twisted. Although the outer meniscus does not tear as quickly as the inner meniscus, a wrong rotation can cause pain in the hollow of the knee on the outside due to a tear. The following reasons may be present for pain in the outer popliteal fossa: Both a tear in the inner and outer ligament cause popliteal pain and occur in rotation trauma of the knee, in which the lower leg is excessively twisted against the thigh.

The rupture of the ligaments may be palpable, but above all it causes pain. The tear of the inner ligament is typically associated with a rupture of the anterior cruciate ligament and injury to the inner meniscus, which makes the knee unstable overall. Both ligaments can also be overloaded during sports such as skiing or horseback riding, causing pain in the outer area of the hollow of the knee.

By taking it easy on the knee, the pain caused by overloading improves within days. An injury to the inner or outer meniscus leads to a pressure pain above the joint space of the knee, but it also radiates into the outer hollow of the knee and occurs especially when the knee is bent. Also a degeneration (occurs mainly in old age) or a lesion of the outer meniscus leads to pain in the outer popliteal fossa.

Trauma with an extended leg often results in damage to the outer ligament, the joint capsule and the posterior cruciate ligament. All three structures often result in a mild initial pain in the outer popliteal fossa, which increases and spreads over time.At the muscle – tendon – transition of the ischiocrural musculature, which leads from the back of the thigh to the outer sides of the knee, overloading can occur through extensive training, which then also causes pain in the outer back of the knee. Likewise, the popliteus muscle runs in the hollow of the knee and can cause pain in the outer hollow of the knee in case of overload or injury.

These then occur particularly when running downhill due to the strain on the muscle, whereby the symptoms can partly improve again when resting. It is very important to distinguish between overloading ligaments or muscles and serious injury to structures in the knee in order to avoid consequential damage. If resting, cooling and elevation do not bring about a significant improvement, the cause of the complaints must be clarified.

Another reason for pain in the hollow of the knee on the outside can be a Baker’s cyst (see below: popliteal cyst). This is a symptom of wear and tear that occurs mainly in older patients. The knee swells considerably and stretching it causes pain in the hollow of the knee, whereby the pain is localized either on the outside or inside, depending on the occurrence of the cyst.

If pain occurs in the hollow of the knee, it is possible that the pain radiates into the calf. Conversely, pain can also radiate from the calf into the hollow of the knee. The following possible causes may be present: If the pain radiates from the calf into the hollow of the knee, a thrombosis in the leg may be present.

A thrombosis is a vascular disease with a blood clot in the venous vascular system, especially the deep veins of the leg. The blood clot can be transported to the heart or lungs, where it can cause a life-threatening pulmonary embolism, for example. In a multi-stage thrombosis, vessels are affected that supply blood to the calf, popliteal fossa and thigh.

Accordingly, pain can occur in all the areas mentioned, which also radiates into the surrounding tissues. More frequent, however, is the pain radiating in the direction of the foot, since the blood is backed up here and can no longer flow to the center of the body due to the vessel occlusion. In most cases there is also knee swelling and on one or both calves.

If a thrombosis is suspected, you should therefore urgently consult a doctor. A possible cause of calf pain originating in the hollow of the knee can be a ruptured Baker’s cyst (see below). This is a protuberance at the weakest point of the rear joint capsule of the knee joint.

The cause of a Baker’s cyst is often an injury in the knee joint, which leads to chronic inflammation. The inflammation, in turn, causes fluid to form in the joint, which, due to the resulting pressure, leads to the formation of a Baker’s cyst. If the pressure is too great, the joint capsule ruptures.

The joint fluid empties into the deeper lying calf following the force of gravity. There, the fluid causes swelling and pressure pain, as the compartments of the lower leg are stretched excessively. If pain occurs in the hollow of the knee, the gastrocnemius muscle (which originates in the hollow of the knee and begins in the heel area in the Achilles tendon) may also be overstressed.

Wearing the wrong shoes when walking can also cause pain in the hollow of the knee. Another possible cause of simultaneous pain in the popliteal fossa and calf is an injury or compression of the tibial nerve. This nerve is located on the surface of the popliteal fossa and runs further into the calf to the outer instep.

It can be damaged by a direct injury, but also by a hemorrhage or joint effusion, which leads to nerve irritation through compression. Even when the original injury to the knee joint has healed, the nerve may still be irritated, causing pain in the calf. During very intensive training and when using muscle-building supplements, it is possible that the rapid increase in size of the muscles of the upper and lower leg causes compression of the popliteal artery, which is located in the hollow of the knee. Since this vessel supplies the calf muscles with blood, the squatting of this vessel, for example, can lead to a reduced supply in the calf area and cause a so-called ischemic pain due to the lack of blood.

Thrombosis
Baker cyst
Overloading of the M. gastrocnemius
Wrong footwear when running
Compression/injury of the tibialis nerve
Compression of the A. poplitea