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Knee Replacement Surgery Risks

Knee replacement risks overall are minor and there is a 96% probability than you will have your operation very successfully and without suffering any important complication. Overall, total knee replacement is an astonishingly successful operation, with its very high increases in quality of life enjoyed by over 65,000 people in the UK every year. The three most serious risks are discussed here.

Blood Clots or DVT – the most common complication

Infection – the most serious complication

Loosening of the components – the most important long term problem


Blood Clots in the Legs

This is the most common complication and indeed is common for any kind of surgical operation and in people who may be in hospital for medical reasons. Anyone who is very inactive for an extended period of time suffers this risk. A deep vein thrombosis of DVT is a clot in the veins of the calf and is easily treated with blood thinning drugs.

Sometimes a piece of the clot can detach itself (it is then called an embolus) and travel via the blood stream to the lungs where it is known as a pulmonary embolus or PE. It is possible to die from a PE although this is rare with the drug treatments available. Compression pumps for the calves are used and physiotherapists encourage early exercises and mobility to limit inactivity. This complication might delay discharge by a day or two but not much longer.


This is the most serious risk after a joint replacement of any kind. The overall infection rate is estimated at 0.5% at present and strenuous efforts are made to limit the chances of infection. Sterile operating rooms and special suits are used and antibiotic cover administered prior to, during and after the operation is completed.

Increased infection risk occurs in people with diabetes or rheumatoid arthritis and if anyone has an infection anywhere else in the body it can travel to the new joint. This method of infection via the blood can occur at any time in the life of the artificial joint so special care needs to be taken with infections and dental work.

Infections can be treated with antibiotics but in some cases the new joint needs to be removed for a period of weeks or months before a new set of components can be inserted.


This is the most important risk in the long term and depends on the strength of the bond between the metal and the bone or the cement and the bone in cemented joints. The effectiveness of the surgical technique is the primary factor here and an experienced surgeon is a vital asset for any patient. The bone quality can also influence the bond over time and being overactive, i.e. subjecting the joint to repeated high physical stresses can also limit the life of the joint by loosening the components.

Partial knee replacement or unicompartmental knee arthroplasty is one of the types of knee replacement surgery performed for specific purposes, in this case to treat arthritis confined to one side of the knee joint. This type of joint is claimed to be more suitable for younger people and people who wish to be more active with their joint, but it is not yet clear whether this carries increased risks of loosening.

If the joint needs to be revised due to loosening this procedure is more complex than an primary knee replacement and has an increased degree of risk of occurrence of one of the knee replacement complications.

Being aware of the potential risks and complications allows you to understand what might happen and how it might be treated so you can cooperate best to manage your new joint with the physiotherapist. The best way to prepare for knee replacement surgery is to have good knee replacement surgery information and also to watch videos of the operations concerned such as a partial knee replacement surgery video.


Further useful information about knee replacement and its risks can be found at MedicineNet and on Wikipedia's knee replacement page.

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