Swelling on the Side of the Leg Below the Knee

A local bump, strain, or irritated tendon can swell beside the upper shin. Swelling related to the knee may accompany bursitis, a meniscus tear, ACL injury, or osteoarthritis, especially when knee movement is painful or restricted. Gout can cause sudden warmth and tenderness around a joint. Fluid from a Baker's cyst is usually noticed behind the knee but can create fullness lower down. One-sided leg swelling also has causes unrelated to the bones, so the whole leg should be assessed if swelling is new or spreading.

Stop activities that increase swelling, support the leg when resting, and use a wrapped cold pack briefly if it is comfortable. Avoid deep massage or tight compression until a clinician has considered the cause. Keep track of redness, warmth, pain, skin changes, walking ability, and whether the swelling is moving upward or downward. A clinical examination may include the knee, ankle, circulation, and sensation.

Seek urgent medical care for sudden spreading swelling, calf pain with warmth or redness, chest pain, breathlessness, faintness, a cold or pale foot, severe pain, or inability to walk. Prompt review is also appropriate for fever, an infected-looking wound, or swelling that follows significant injury. Do not wait for self-care to work when these warning signs appear.

Ask whether the swelling appears to start at the knee or below it, whether circulation needs checking, and whether imaging or other tests are needed. Ask which activity and compression choices are safe and when follow-up should occur.