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Revision operations of hip and knee replacements

Instability hip prosthesis

A hip prosthesis is stabilised by the muscles, the hip capsule and the position of the prosthetic parts. If there is a problem with one of these stabilisers, the hip prosthesis may feel unstable and even dislocate. During the consultation with the orthopedic surgeon, the cause of the instability should be determined. In many cases, replacing the hip socket with an "antiluxation socket" can solve the problem.The procedure can be performed using the muscle-sparing, anterior approach (DAA), even if the hip has previously been operated on from the side or back.This prevents further damage to the hip muscles and allows for easy rehabilitation.

Knee instability

The stability of a knee replacement is extensively tested during the operation. A knee replacement that is too tight causes problems with bending, while a replacement that is too loose leads to complaints of instability. In addition, the function of the thigh muscles, which are attached to the kneecap, is essential for the correct function of the knee replacement. During the physical examination and additional X-rays, the cause of the instability can usually be determined.

Wear and tear of the prosthesis

Both the hip and knee prosthesis consist of titanium and cobalt chrome as well as polyethylene. Polyethylene is plastic and can wear out after 15-25 years. The orthopedic surgeon can detect this on X-rays and decide to replace the component.

Hip or knee replacement loosening

If a prosthesis becomes loose in the bone within a few years, it is always necessary to find out whether a chronic infection is the cause.

However, a prosthesis can also become loose after decades of use or due to an accident. After ruling out an infection, the orthopaedist will draw up a treatment plan. Often only one part of the prosthesis needs to be replaced to solve the problem.

Early infection: within 3 months after insertion of the prosthesis

These infections are usually characterised by long-term wound leakage after surgery, redness and pain. These infections are almost always caused by skin bacteria. If a wound leaks for more than 14 days, it is recommended to rinse the wound and start antibiotics for at least 6 weeks. This is done to prevent the bacteria from attaching to the prosthesis and then being difficult to remove. With this treatment the infection can be controlled in more than 90% of the patients.

Late infection

Patients experience prolonged pain after the prosthesis is fitted, function is limited and sometimes the joint swells. Fortunately, this is rare. The diagnosis is made by means of an anamnesis, physical examination, X-rays, blood tests and a joint puncture, possibly supplemented by an MRI scan and a leucocyte scan.

In these late infections, the prosthesis is always contaminated with bacteria. If the bacteria are known, a one-stage revision can be considered: the old prosthesis is removed, the area is cleaned well and a new prosthesis is placed immediately afterwards.

An alternative is a 'two-stage revision': the old prosthesis is removed with cultures taken, the area is cleaned well and then a temporary prosthesis is placed with antibiotics. After the culture result 2 weeks later, a second operation can be planned to place the definitive prosthesis.

A two-stage revision is therefore done when it is unclear which bacteria caused the infection.

Finally

A recovery operation will be discussed with you well in advance. All pros and cons will be explained and the least invasive treatment will always be chosen. The goal should be that you are pain-free and mobile again in the short term. In general, you will be able to go home within 3 days after a recovery operation.