The heat

In hot weather the body tries to regulate its own heat by dilating the blood vessels. The principle behind this measure is to be able to release more heat to the outside by increasing the surface area of the vessels. This usually works very well, since many vessels are superficial.

If the vessels are excessively dilated, however, the circulation of blood is impaired and as a result the blood accumulates in the vessels. With increasing filling, the vessel wall becomes more permeable and fluid escapes, which can be observed as swelling. According to the force of gravity, this occurs mainly on the legs.

The thrombosis

A thrombosis is a blood clot that closes a vessel. Due to the occlusion, blood congestion occurs in the affected vessel and the vessel wall is stretched by the volume. As the degree of stretching increases, the vessel wall becomes “more porous” and fluid escapes into the surrounding tissue. If a vessel in the lower leg is blocked, however, in addition to swelling in the ankle area, there is also swelling in the lower leg area. This is typically accompanied by overheating and redness of the affected leg.

The inflammation

An inflammation in the ankle joint can certainly cause a swelling in the ankle area. It does not matter from which structures the inflammation originates – both an irritation of the ligaments and an overstrained joint surface can cause the classic inflammatory symptoms of “swelling, pain, redness and functional impairment”. An inflammatory reaction of the body leads to a permeability of vessels and to a sensitization of the nerves.

For this reason, fluid can leak from the vessels and collect outside. Overstraining only causes temporary swelling. If the joint partners are incorrectly positioned, the swelling is permanent – as a result, every movement or strain produces a new inflammatory stimulus. In this case orthopedic treatment is required.

The insect bite

For a swelling of the ankle to occur in the event of an insect bite, the ankle must be close to the bite. Swelling above the ankle is primarily a localized symptom in response to insect venom or saliva. As part of the body’s own defence against the insect bite, an inflammation is triggered in the directly surrounding tissue, which manifests itself as swelling, redness and overheating. However, depending on the sensitivity of the person affected to the insect venom, the swelling can spread further in the course of the infection and be accompanied by other symptoms.