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About 1% of patients will develop a complication after surgery. Some of the most common complications are outlined in this explainer:



Mr Lawrence, to date, has a 0.25% deep infection rate following total knee replacement at Parkway Hospital.

A bug can get into the knee replacement via several routes. On occasion, the bug can be transferred into the joint from the patient's skin or from the air in the theatre at the time of surgery. In about 1/3 of cases, the bug is transferred by the patients' circulation (blood-borne contamination) and this may result in the joint becoming infected years after the operation.

In order to prevent infection, Mr Lawrence takes certain precautions. Intra-venous antibiotics are given, the surgery is done in a specially ventilated theatre;

If an infection develops in the joint, 2 or three operations will be required to put things right. In the first instance, the knee joint may be opened up and irrigated to remove the infection. This is followed by a period of 6 weeks of intravenous antibiotics. The infection can be treated by these simple measures in about 25% of cases.

In most cases, the knee replacement will be removed for a minimum period of  6-8 weeks. During this time, the patient will require crutches or a frame to walk. Once the infection has been treated (90%) of cases, a new knee joint is inserted. Regrettably, there cannot be any guarantee of success with the second operation and recurrence of infection may occur in 5-10% of patients. The key to success is avoiding infection in the first place by being vigilant and by using good surgical techniques.

On occasion, the thigh bone or the shin bone may become damaged by the infection and complex reconstruction is required. In Mr Lawrence's practice at Parkway Hospital, the deep infection rate to date is as low as 0.25%  over 18 years.



On very rare occasions the peroneal nerve, which runs close to the knee joint, may be damaged or stretched following surgery resulting in a foot drop. Recovery is variable.



Over a period of years, the implants may loosen from the bones and this will result in pain. The rate of loosening varies according to the type of implants used and the skill of the surgeon. In Mr Lawrence's experience, the weight of the patient, their level of activity, and the thickness of their bones do not affect rates of loosening.

In Mr Lawrence's practice at Parkway Hospital, the loosening rate over a 12 year period of time is  0%.



In the event of a fall after the knee replacement, the bone around the knee replacement may break. This is a rare complication and usually requires further surgery to treat it.

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There is a risk to your general health following any major operation.  Patients with poor blood supplies to their hearts or brain are at increased risk of heart attacks and strokes resulting from the stress of the surgery. Fit, healthy, active patients are at less risk. An attempt is made to assess your fitness for the surgery before the operation by looking at your heart tracing and blood results in conjunction with your previous medical history. Unfortunately, none of these investigations is 100% accurate, and as a result, some unexpected events may occur.

Medical complications that may be encountered include:



Any operation will increase the risk of blood clot formation in the limbs because the blood becomes a little thicker and stickier following an operation. Sometimes the blood clot can travel to the lungs which may be life-threatening. The risk of this complication is about 1-3 in 1000 patients. Every attempt is made to minimise this risk including the use of leg pump devices, heparin, and aspirin.  Getting up out of bed and walking after the surgery is also very important to encourage a good blood flow through the legs.



These complications are completely unpredictable.   Some patients may have an unrecognised heart condition that only comes to light under the stress of surgery.



The risk of developing a stroke after an operation depends on the quality of the pre-existing blood supply to the brain. It is unlikely that a fit and active patient will develop this complication whereas a patient with high blood pressure, who smokes heavily and has furred up arteries would be at greater risk.



Because patients undergoing surgery are less mobile than they are normally and their breathing pattern may be slightly different than normal, they are at greater risk of developing a chest infection. This is, however, a surprisingly rare occurrence and can be easily treated with physiotherapy and antibiotics.



Men are particularly prone to develop retention of urine following knee surgery.  The risk is greatest in patients that have enlarged prostate glands. A combination of decreased mobility, pain from the knee joint surgery and a spinal anaesthetic is often enough to upset the waterworks. If you cannot pass urine for about 6 hours or so, a tube will be inserted into the bladder and your urine may be collected in a bag. Usually, this is a short-lived problem but on occasion, some patients may require prostate surgery at a later date.