Swelling in the leg; or is it a clot?


Administrative Staff
Jun 11, 2013
United States United States
By: Josephine (Josephine, Nurse Emeritus)
Updated December 4, 2021 (Jamie)

Many times people get anxious because their leg is swollen. They may expect some swelling around the knee but to see almost the entire leg swollen can be extremely disconcerting and possibly very painful. People immediately begin to fear blood clots and infection.

Reasons for post-op swelling

1. The surgery itself. Having tissues cut, handled, and pulled around can make fluid build up in the hours after your procedure. The swelling can stay constant (or increase), but it also may ebb and flow for days or weeks.

2. Increased blood and lymph flow. Following joint replacement surgery, healing occurs because there is increased circulation bringing plentiful blood cells, plasma, and lymph into the area to supply nutrition and oxygen - all needed for the creation of necessary scar tissue as well as new normal tissue.

3. Tourniquet. During upper and lower limb surgery, surgeons will sometimes use a high pressure tourniquet on the upper part of the limb. For a knee replacement, placement of the tourniquet would normally be in the middle of the thigh as shown in the photo below:


Before the pressure is applied, an inflated roller is pushed up over the leg to remove most of the free circulating blood from the vessels. Then the tourniquet cuff is then inflated. Pressures used are generally around 500mgs mercury (blood pressure is usually about 120 or above).

Benefits of a tourniquet
  • Gives the surgeon a blood free area in which to operate
  • Makes surgery easier and faster
  • Anatomical points are much easier to spot
  • Minimizes blood loss. This is of great benefit to the patient since these operations would otherwise can have a moderately high blood loss.

Disadvantages of a tourniquet
  • Can cause post-operative swelling
  • Swelling can result in discomfort, pain, and difficulty with mobility
  • A collection of blood either inside the joint or within the incision and the soft tissue layers nearby (hematoma) can form
When surgery is complete and the tourniquet is removed, blood and lymph quickly flood back into the leg and a rebound swelling occurs. This rebound is also why a patient can experience bleeding in the first 48 hours or so following a joint replacement.

To help prevent the formation of a hematoma, vacuum drains are often inserted into the wound. A compression dressing of wool and crepe is applied that covers the leg and elevation is encouraged. While in the hospital, the pulse in your foot is monitored to make sure any excessive swelling isn't compromising the circulation - an event described as "compartment syndrome."

Swelling can continue for 2-3 weeks after surgery and can result or worsen by spending too much time standing or with your feet on the floor when sitting.

The swelling can create a mechanical obstruction to flexion of the knee. It's not at all uncommon for patients to get depressed or frustrated when it seems as if they are going backwards. But knowing about and remembering the effects of post-surgical swelling should reassure that this will eventually pass.

Blood clots or deep vein thrombosis (DVT)

There is always the risk of blood clots following surgery. Blood clots can be a life threatening event as portions of the clot can break loose and travel to your lungs. Symptoms that can indicate the presence of a blood clot include:
  • Swelling of the surgical leg
  • Pain and tenderness in the surgical leg
  • Difficulty standing with full weight on the surgical leg
  • A change in the color of the skin on the surgical leg, usually increased redness
  • Skin that feels warm or hot to the touch
If you experience any of these symptoms, contact your surgeon immediately or go directly to an Emergency Room.

A good test you can try for yourself is to place your open hand over the fullness of the calf and squeeze firmly but gently. If you are unable to do this because it is too painful or doing it causes more pain, then you should seek medical advice at once.

This website has some excellent detail about DVT.
Deep vein thrombosis fact sheet
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