Swelling in the leg following hip and knee surgery

Regarding swelling in the leg, this is a common event following a total hip replacement, total knee replacement or a hip resurfacing.

There are a number of reasons why it occurs: 

The most important reason is the bruising and swelling from the surgery.  The surgery on the hip or the knee involves quite a lot of muscle splitting and there is inevitably a fair bit of bleeding.  This is reduced by modern anaesthesia which involves dropping the blood pressure, however in more elderly patients or patients with severe rheumatoid arthritis it is not safe to drop the blood pressure excessively.  

The second confounding factor is that we give the patients anticoagulants or asprin which thin out the blood and tend to stop it from clotting.  The purpose of this is to reduce the risk of a thrombosis in the deep veins of the leg and a pulmonary embolism, so some swelling around the wound is the price that is paid for avoiding these more serious complications.  

It is common to get swelling in the knee following a hip replacement.  This is partly because the knee is twisted a lot whilst the hip is being dislocated and partly because of general swelling in the thigh.  

It is common to get minor degrees of thrombosis in the leg veins or sludging in the leg veins following hip and knee replacement and this exacerbates the tendency to swelling.  

Another key factor in leg swelling is that if the patient sits with their foot on the floor there is a great tendency for fluid to accumulate around the ankle.  This is because, unlike a central heating system, the heart does not pump the blood right around the body.  The blood only gets back into the circulation by the pumping action of the calf muscles.  The right thing to do is therefore to lift the leg up preferably with the ankle above the level of the chest and keep the calf muscles moving.

In more elderly patients any impaired pumping action from the heart tends to exacerbate the problem. 

There is an additional problem in patients who are malnourished as they may have low amounts of albumin protien in the blood, this means that water is more likely to leak from the blood into the tissues.  In extreme cases there may be vitamin deficiencies which affect the pumping action of the heart.

In spite of all these factors the swelling in the leg will normally be improving by one month post-operation.  It can persist for more than three months but it is unusual for it to persist for as long as six months.  The symptom can be helped by leg stockings but leg stockings will actually restrict the leg and overall I do not normally recommend them.