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Knee revision surgery differs from total knee replacement surgery. With revision surgery, some or all of the existing prosthetics that were placed there during the original surgery will be replaced, which makes the procedure more complex than the first. The end goal of the procedure is the same as the original surgery, which is to improve overall function and reduce or relieve pain.
Reasons for revision knee replacement surgery
When someone experiences knee replacement failure, they are understandably disappointed. They are likely to experience ongoing and increasing levels of instability in the joint, pain, and loss of mobility. There is no one reason for a knee joint to fail; instead, the range of reasons includes:
Implants may become loose if the interface between the cement and the bone fails. This can happen if the tiny pieces of bone to which the cement is attached break or deteriorate. If an implant is not cemented, the interface between the implant and the bone can fail in a similar way. Weight-bearing, infection and weakened bone due to osteoporosis can all cause this. The quality of the materials and techniques used are improving all the time, meaning that the likelihood of this happening is less than previously. High-impact activities are likely to increase the chances of loosening.
The implants used for knee replacement have a lifespan, with wear beginning straight after surgery. The modern materials used for implants are extremely hardwearing; however, after several years, there is likely to be wear caused by friction to the surfaces of the joint. This friction can cause associated problems with inflammation and pain.
Ligaments around the knee can become damaged. Implants are generally designed to work with the patient’s ligaments as they exist at the time of the original surgery. If there are changes to the ligaments subsequently, this could prevent the implant from working as expected. The patient may feel that the knee is not supportive. Non-surgical intervention such as braces or physical therapy may be attempted initially; however, if these don’t work, instability may mean revision surgery is needed.
Although rare, there is a risk of infection with any surgery; however, the incidence of infection is extremely low. An artificial joint that becomes infected is likely to become painful and stiff. How long the joint has been infected and the level of infection will have a bearing on how the revision will need to be undertaken.
If the knee experiences trauma, a fracture may result that disrupts the implant and causes stability issues. This type of fracture is known as a periprosthetic fracture and can be the result of a fall. Again, although possible, the likelihood of this happening is low.
Occasionally, a total knee replacement may not provide the expected range of motion required to undertake everyday activities. This can be due to the build-up of excessive scar tissue. If this cannot be improved through manipulation techniques, it may be determined that knee revision surgery is required.
Although age in itself is not likely to be a reason for revision surgery, younger patients are more likely to outlive their original implants, even with good care. They are therefore at higher risk of ultimately having to undergo a revision knee replacement.
Determining whether knee replacement surgery is required
The consultant will discuss the symptoms, including pain, stiffness and loss of mobility, with the patient. Commonly, an x-ray will be ordered; less commonly, other tests may be carried out. These could include a nuclear medicine bone scan, a magnetic resonance imaging scan (MRI), or a computed tomography scan (CT). Blood tests may also be carried out for suspected infections.
How revision knee replacement differs from total replacement
As the revision procedure involves removing the original implants and additional preparation of the area receiving the new implant, the procedure is usually more complex than the original operation. For this reason, it will usually take longer than the original operation.
A revision replacement is not usually expected to last as long as an original replacement, as there will already have been surgical trauma to the joint and a build-up of scar tissue.
Before knee replacement surgery is considered, the consultant will discuss the reasons why a revision surgery is being considered with the patient. This will include the possibilities and potential benefits that the patient may expect.
About the procedure
The surgeon will follow the line of the original surgical incision and may need to extend the original incision to allow for the removal of the old implants. The surgeon will then move the kneecap to access the knee joint.
An examination will be made of the soft tissues in the knee to ensure their health, then an assessment will be made of the original implants to determine the requirements. Parts may have become worn, loosened or shifted from their original position.
The original implant will be removed with great care to ensure that as much bone is preserved as possible. If cement was used, this will also be removed, adding to the duration of the operation.
Once the original implant has been removed, the bone surfaces will be prepared for the new implant. Any significant bone loss will be compensated for by adding to the main components to ensure good stability in the new joint.
As with any surgery, there is the possibility of unexpected complications arising from the procedure. Fortunately, these are relatively rare; however, the following may be experienced:
- Nerve damage
- Blood clots
- Infection of the wound
- Stiffness and pain in the knee
- A reduced motion range in the knee
Recovery in hospital
A hospital stay of several days is likely to be required. Recovery is generally slower than from the original surgery, but the type of care and process to be followed is similar.
The hospital staff will work to manage the pain experienced as part of the healing process. Treatments offered can include local anaesthetics, opioids and non-steroidal anti-inflammatory drugs, also known as NSAIDs. Steps will also be taken to reduce the likelihood of blood clots whilst motion is limited.
A physiotherapist will advise on specific exercises suitable for both the individual and the surgery. The exercises will be designed to help strengthen the leg and the joint and to restore a range of motion that enables the patient to walk and complete other normal activities as soon as possible.
A continuous passive motion machine (CPM) may also be used. This moves the joint through a range of motions whilst the patient rests in bed and helps to reduce the stiffness and swelling.
Recovery at home
The patient is likely to need to use crutches, a cane or a walker for anything from a few days to a few weeks. How long this is required will depend on the individual, the complexity of the operation, and how well the individual heals. Support from a friend or family member at home may be required for several days to support the individual when they are undertaking everyday tasks.
The patient will need to care for the wound appropriately to avoid potential infection and avoid soaking it in water until it is sufficiently healed. The hospital staff will advise on the likely duration and actions required for the removal of stitches. The patient’s doctor will also be able to help and provide advice.
The patient must continue the regime of physical exercises laid out by the physiotherapist, as these will go a long way towards helping the patient to recover well and ensure a good range of motion is achieved. Exercises are likely to include activities to target good levels of straightening, bending, strengthening and mobility. If stairs must be used in the home, the individual should be advised by the physiotherapist on the most appropriate way to tackle going upstairs and downstairs to ensure the joint does not have too much pressure placed on it while recovering.
Knee immobilisers may be helpful for stabilisation during exercise and could also help whilst walking and sleeping. The physiotherapist will be able to advise on their appropriate usage.
It should be remembered that revision surgery is a more complex procedure and recovery is likely to take longer than from the original surgery. A primary operation can take 12 months to recover from. The recovery period from a revision operation can be between two and three years before there is full recovery. It can take months before the individual can walk without experiencing pain, and the swelling may last for several months.
Increased stability and pain relief are expected; however, complete relief from pain and the restoration of all levels of function are not always achieved. A minority of patients are likely to still experience a level of pain following the revision surgery. This may continue for several years, although physical therapy and medication can go a long way towards helping with this. The majority of individuals undergoing revision surgery can expect good results.