REVISION KNEE REPLACEMENT
WHAT IS THE PROBLEM?
A knee replacement comprises different components and with time, the rubbing between the different parts can result in wear, especially of the polyethene (plastic) insert between the femoral and tibial implants. Extreme wear can result in abnormal contact between the implants and may also cause resorption of the bone in contact with the prosthesis and thus the loosening of the implant (disassociation of the implant and the bone), which causes pain when moving and weight-bearing. The implants need to be replaced.
CHANGE OF KNEE PROSTHESIS
Knee replacement, also called total knee replacement, is a surgical procedure performed when the existing knee prosthesis has complications or problems that require correction. Here are some important points to consider regarding this procedure:
- Indications : Changing the knee prosthesis is generally indicated in cases of deterioration of the existing prosthesis due to causes such as component wear, instability, infection, fracture or loosening of the prosthetic components.
- Surgical procedure : The procedure involves the removal of the existing knee prosthesis, followed by replacement of the defective components with new implants. The surgery may be more complex than the initial prosthesis placement due to anatomical changes, bone loss, and scarring resulting from the initial procedure.
- Preoperative Assessment : Before surgery, a comprehensive assessment is performed to determine the cause of complications and plan the best surgical approach. This may include imaging tests such as X-rays, CT scans, or MRIs to assess the condition of the bone and surrounding soft tissues.
- Recovery and rehabilitation : Recovery after a knee replacement can be longer and more demanding than the first surgery, as there may be loss of bone tissue and a reduction in joint stability. Patients may require a period of rehabilitation supervised by a physical therapist to restore muscle strength, range of motion, and joint function of the knee.
- Risks and Complications : As with any surgical procedure, there are risks associated with changing a knee prosthesis, including infection, persistent pain, joint stiffness, separation of prosthetic components, and recurrence of complications.
Changing a knee prosthesis is a necessary surgical procedure in cases where the existing prosthesis presents complications or problems that compromise joint function. Thorough evaluation, careful surgical planning, and postoperative rehabilitation are essential to ensure optimal results and successful recovery.
BEFORE THE OPERATION
A revision knee replacement requires an operation. The implant best suited to the patient is chosen during the pre-surgical consultations. Before the operation, a pre-anaesthesia consultation and a preoperative assessment are conducted to check the patient is physically apt to undergo the operation and minimise the risk of postoperative complications, especially infections. This assessment generally includes a blood test, a cardiovascular check-up, as well as a dental check-up and a urine test to ensure there are no infections and thus avoid any microbial contamination of the implant.
REVISION OF DIFFERENT KNEE REPLACEMENTS
A total knee replacement (TKR) is always replaced with a new prosthesis.
A revision partial knee replacement (PKR) is more complex. If only the polyethene insert between the tibia and the femur is worn, only the insert is replaced. However, if the prosthesis is loose or if the knee is painful because osteoarthritis has developed in the other part of the knee, a TKR is necessary.
Loosening of a partial knee replacement with sinking and tilting of the tibial implant
After replacement with a total knee prosthesis
A tibial tuberosity osteotomy (partial opening of the tibia) may be required to correctly expose and remove the old implant. In this case, the tibia must be reduced and held in place with metal wires or screws.
The deterioration of the bone in contact with the implants may require bone grafts to replace significant bone loss that will be incorporated in the recipient bone. The bone is taken from the femoral heads of selected patients (after questioning and serological tests) who have had a total hip replacement. This bone is then treated to inactivate any residual microbes or viruses and is frozen until use. Contrary to an organ transplant, a bone graft does not require antirejection medication.
Revision knee prosthesis
THE OPERATION
The operation takes place in an operating theatre in compliance with strict standards of cleanliness and safety. The patient is placed supine on an operating table and a tourniquet is placed around the thigh.
The duration of the procedure varies according to the type of prosthesis to be changed and the bone wear. It generally lasts between 1 and 2 hours but can sometimes be longer. This operation can be carried out under general or spinal anaesthesia. The latter is a regional anaesthetic anaesthetising the lower part of the body (as with an epidural). The anaesthetist will decide on the most suitable anaesthetic together with the patient.
From a technical point of view, the surgeon will follow the incision made for the primary knee replacement. It may need to be extended to carry out the procedure.
AFTER THE OPERATION
After the procedure, the knee is partially numbed with a nerve block to help improve postoperative pain management. The effect lasts approximately 18 hours after the operation but can be extended with the insertion of a catheter in the thigh if the anaesthetist considers it necessary. Medication and ice on the knee also provide effective postoperative pain management.
Rehabilitation begins the day after the operation with the help of physiotherapists. Resumption of weight-bearing is often allowed immediately, sometimes with a rigid knee brace. Rarely, in the case of considerable bone reconstruction, resumption of weight-bearing is delayed for several weeks. Crutches are used to start with but are gradually abandoned
The stay in hospital is between 3 and 6 days. When leaving the clinic, the patient can return home as long as it is not too difficult to access and someone can help with daily activities (shopping, meals…). Otherwise, a stay of approximately 1 month in a rehabilitation centre is generally preferable.
When the patient is discharged from the clinic, a consultation with follow-up x-rays of the implant is scheduled with the surgeon generally 4 to 6 weeks after the operation to ensure satisfactory progress. Subsequently, the frequency of the checkups will be determined by the surgeon. Once recovery is satisfactory, x-rays to monitor the replacement are recommended, generally every 2 years, to check there is no wear of the different components or the surrounding bone.
RISKS LINKED TO THE OPERATION
Unfortunately, zero risk does not exist in surgery. Any operation has its risks and limitations, which you must accept or not undergo the operation. However, if an operation is proposed, the surgeon and the anaesthetist consider that the expected benefits far outweigh the risk incurred.
Some risks, such as microbial infections of the surgical site, are common to all types of surgery. Fortunately, this complication is rare but when it occurs requires another operation and a course of antibiotics. Some infections may require the implants to be replaced. Bruising can also appear around the surgical site. This is usually prevented or reduced with a suction drain inserted at the end of the operation and removed in the days following the operation. However, in the case of severe bleeding during or following the operation, another operation to stop the haemorrhage or a blood transfusion may be required.
Knee surgery also increases the risk of phlebitis, which can lead to a pulmonary embolism. To minimise this risk, blood thinners (in the form of daily injections or tablets) are prescribed for the entire month following the operation.
In rare cases, the knee remains stiff, hot, and painful for several months after the operation. This complication, known as algodystrophy or Chronic Regional Pain Syndrome (CRPS), is unpredictable and sometimes takes a long time to heal.
Finally, rarer complications can also occur. A fracture can occur when removing the implants and will require osteosynthesis (bone fixation). Blood vessels (arteries, veins) can be accidentally damaged and will require vascular surgery (bypass). Nerves can also be damaged accidentally during the operation with a risk of paralysis or loss of feeling in the limb operated on, which can be transitory or permanent.
If you have any concerns about the operation, do not hesitate to talk to your surgeon or the anaesthetist and they will answer any questions you may have.
A FEW QUESTIONS ABOUT REVISION KNEE REPLACEMENTS
What is the expected outcome of a revision knee replacement?
A revision knee replacement is required when the prosthesis in place no longer provides satisfactory results and possibly causes pain or discomfort when walking. The operation aims to improve function and therefore provide the most satisfactory quality of life possible. However, the result is not always as satisfactory as with a primary knee replacement due to the complexity of this type of operation.
What is the lifespan of the new knee prosthesis?
It is not possible to give an accurate lifespan for the new prosthesis, as too many factors are involved such as the quality of the bone around the prosthesis, or the weight and physical activity of the patient.
All we can say is that, generally speaking, the lifespan of the new prosthesis is often shorter than that of the previous prosthesis.
Do I need to make any changes at home after a revision knee replacement?
No, it is not necessary. However, ground-floor accommodation would be more comfortable in the first few weeks after the operation.
Where will the scar be?
The previous incision will be used but is sometimes slightly longer to facilitate the operation.
Can I put weight on the knee straight after the operation?
Yes, but it is sometimes necessary to wear a rigid brace for a few weeks if a tibial tuberosity osteotomy was carried out during the operation.
Do I have to have a general anaesthetic for the operation?
No, this operation can be performed under regional anaesthesia if there are no contra-indications.
How long is the stay in hospital?
The stay in hospital is generally 3 to 6 days.
When can I drive after the operation? Can I travel by car?
It depends on the type of revision. Before driving again, you must be fully fit and capable of doing an emergency stop. A minimum of 4 weeks is necessary before driving again, but most of the time it is better to wait 2 months. As a car passenger, there are no specific restrictions as long as you are sat comfortably and can stretch your leg.
How long will I be off work after the operation?
It depends on your profession and the level of physical activity required but generally varies between 2 and 3 months.
Can I do any sport after a revision knee replacement?
Yes, but only sports that have a low impact on the knee. Swimming and cycling are therefore best. You generally have to wait until the 3rd month after the operation before resuming sport.
What are the risks linked to revision knee replacement surgery?
Unfortunately, zero risk does not exist in surgery. Any operation has its risks and limitations, which you must accept or not undergo the operation. However, if an operation is proposed, the surgeon and the anaesthetist consider that the expected benefits far outweigh the risk incurred.
Some risks, such as microbial infections of the surgical site, are common to all types of surgery. Fortunately, this complication is rare but when it occurs requires another operation and a course of antibiotics. Some infections may require the implants to be replaced. Bruising can also appear around the surgical site. This is usually prevented or reduced with a suction drain inserted at the end of the operation and removed in the days following the operation. However, in the case of severe bleeding during or following the operation, another operation to stop the haemorrhage or a blood transfusion may be required.
Knee surgery also increases the risk of phlebitis, which can lead to a pulmonary embolism. To minimise this risk, blood thinners (in the form of daily injections or tablets) are prescribed for the entire month following the operation.
In rare cases, the knee remains stiff, hot, and painful for several months after the operation. This complication, known as algodystrophy or Chronic Regional Pain Syndrome (CRPS), is unpredictable and sometimes takes a long time to heal.
Finally, rarer complications can also occur. A fracture can occur when removing the implants and will require osteosynthesis (bone fixation). Blood vessels (arteries, veins) can be accidentally damaged and will require vascular surgery (bypass). Nerves can also be damaged accidentally during the operation with a risk of paralysis or loss of feeling in the limb operated on, which can be transitory or permanent.
If you have any concerns about the operation, do not hesitate to talk to your surgeon or the anaesthetist and they will answer any questions you may have.
