Revision Hip Surgery
Revision Hip Surgery is required when the original implant becomes loose, breaks or becomes infected. This can occur due to a multitude of reasons. The most common cause is due to aseptic (uninfected) loosening. When the prosthesis becomes loose, it can cause pain, and this usually manifests as “start up pain”. Start up pain occurs when you first start using the limb, and bearing weight through it. This occurs in the hip when the prosthesis is loose, and is wobbling around inside the bone. This micro movement causes pain, especially during the first few steps. Once the prosthesis has stopped moving, due to its impaction in the bone from walking, it stops being as painful.
Revision hip replacement for infection is a large operation. If caught early, in some cases the original prosthesis can be kept. In the very least, the easily exchangeable parts of the hip replacement, such as the metal head and the plastic insert (if they are modular components) can be changed over to reduce the bacterial load in the hip joint. Some bacteria can cause a biofilm. A biofilm is created by the bacteria to protect itself from the body’s natural response to infection – to kill it. Once a biofilm has been produced, it is extremely hard to kill the bacteria with antibiotics alone. Antibiotics alone are usually unsuccessful in eradicating the bacteria once it has come in contact with the prosthesis. If the infection has been present for more than 3 weeks, often all the prosthesis needs to be removed. This is a large operation, and sometimes requires cuts to be made in the bone to remove a well fixed implant. Once the implant is out, a spacer is usually inserted. This spacer is made out of a special antibiotic coating which has a high concentration of antibiotics in it. Because it is distributing the antibiotics in the local environment, it is usually more successful than antibiotics alone.
Revision hip replacements can also occur when the prosthesis has worn out. This is more common in older designs where the polyethylene (plastic insert) wears out, just like any other bearing, due to wear and tear. This requires removal and reinsertion. It is important to find out the correct prosthesis prior to surgery so the correct replacement part can be inserted. Often the newer part is an improved version of the old one. If the wear and tear has caused damage to the surrounding bone, then it is usually better to replacement prosthesis if it is easily removable.
Dr Chien-Wen Liew performs revision surgery in 2 main ways. For hips that have had a previous anterior approach, then Dr Liew performs revision hip surgery through the anterior approach. Because the muscles have not been detached and soft tissue has been preserved, then this approach is not usually technically as demanding as other approaches. For hip revision surgery where a different approach has been performed, Dr Liew will normally perform the surgery through the original approach. This minimises further damage to tissue, as the original approach has usually already damaged the tissue. In general, a direct anterior approach is best for primary operations or simple revision where the original operation was also performed through a direct anterior approach. Complex revisions are best performed through a posterior approach or whatever approach was initially used.
Hip revision surgery is a highly specific skill, requiring a thoughtful and considered process to enable the best outcome for the patient. All cases are different and should not get treated in the same way. It is important to speak to your surgeon prior to having revision hip surgery about all of the options, and possibilities.
For appointments with Dr Chien-Wen Liew please contact (08) 7099 0188