Revision knee replacement surgery involves replacing part or all of your previous knee prosthesis with a new prosthesis. Although total knee replacement surgery is successful, sometimes the procedure can fail due to various reasons and require a second revision surgery.
The knee joints are lined by soft articular cartilage that cushion the joints and aid in smooth movement of the joint bones. Degeneration of the cartilage due to wear and tear leads to arthritis, which is characterized by severe pain.
During total knee replacement, the damaged cartilage and bone is removed from the knee joint and replaced with artificial components. Artificial knee joints are usually made of metal, ceramic or plastic and consist of the femoral component and the tibial component.
Revision knee replacement surgery may be advised to patients if they have one or more of the following conditions:
Revision knee replacement surgery may involve the replacement of one or all of the components.
The surgery is performed under general anesthesia. Your surgeon makes an incision over the knee to expose the knee joint. The kneecap along with its ligament may be moved aside so that there is enough room to perform the operation. Then the old femoral component of the knee prosthesis is removed. The femur is prepared to receive the new component. In some cases the damaged bone is removed and bone graft or a metal wedge may be used to make up for the lost bone.
Next the tibial component along with the old plastic liner is removed. The damaged bone is cut and the tibia is prepared to receive the new component. Similar to the femur, the lost bone is replaced either by a metal wedge or bone graft. Then, a new tibial component is secured to the end of the bone using bone cement. A new plastic liner will be placed on the top of the tibial component. If the patella (kneecap) has been damaged, your surgeon will resurface and attach a plastic component. The tibial and femoral components of the prosthesis are then brought together to form the new knee joint, and the knee muscles and tendons are reattached. Surgical drains are placed for the excess blood to drain out and the incision is closed.
Following revision knee replacement surgery, a Continuous passive motion (CPM) machine may be used to allow the knee joint to slowly move. The machine is attached to the treated leg which slowly moves the joint through a controlled range of motion, while you relax.
You can walk with crutches or a walker. You will be sent for rehabilitation within a couple days of surgery. A physical therapist will teach you specific exercises to strengthen your leg and restore range of motion to the knee. Your physical therapist will also provide you with a home exercise program to strengthen thigh and calf muscles.
Knee immobilizers are used when performing physical therapy, walking and while sleeping in order to keep the knee stabilized.
As with any major surgical procedure, there may be certain risks and complications involved with revision knee replacement surgery. The possible complications after revision knee replacement include:
A knee revision procedure involves removing and replacing a partial or total knee implant with a new implant. It can be a complex surgical procedure that may require extensive preoperative planning, specialized implants and tools, and a skilled surgeon experienced in difficult surgical techniques.
The decision to perform a revision surgery is based on several factors. After partial knee replacement osteoarthritis may have advanced to other compartments of the knee. After total knee replacement the implant may have become loose, worn or infected. As the implant fails the patient may experience a limp, stiffness, or instability. X-rays or computer imaging may show a change in the position or condition of the implant components. Assessment of these indicators will help determine when knee revision surgery is needed.2 It’s estimated that over 50% of knee revision procedures will be performed within two years of the initial knee replacement.
Loosening: Cemented implants can become loose because the cement-bone interface has failed. This is usually due to bone die back, meaning the tiny projections of bone that the cement initially attaches to have either broken off in weight bearing or simply deteriorated due to infection or weak bone (osteoporosis). Non-cemented implants can loosen for much the same reason except it is the implant-bone interface that fails. However, current state-of-the-art materials and techniques have improved the quality of implant fixation to bone which had historically been a weak link that created a potential site of failure.
Wear: The plastic parts of knee replacements are softer than the metal and are more prone towards wear during use. Usually this happens after a long period of time as modern plastics (ultra high molecular weight polyethylene or UHMWPE) are very durable and can withstand a considerable amount of wear and impact. Generally speaking, plastic parts are more likely to wear because the accompanying metal parts are not properly aligned, the plastic itself is misaligned, there is a presence of infection, or because they are very old.
It is known that wear actually begins from day one after surgery but the implants can cope with the early stages of wear very well. Implant manufacturers have significantly decreased the amount of wear particles that are created by friction on joint surfaces. However, after several years there may be a build-up of worn off particles which can cause problems in nearby tissues as microscopic fragments get absorbed into the cells and create inflammatory conditions causing pain.
Infection:Infection: With modern surgical techniques the risk of infection from total knee replacement is very low at about 0.5%.2 If infection does occur, it usually arises due to a substance on the devices called bio-film. This organic material is a microscopic layer of fungal material containing microbes living in a state of hibernation. All implanted devices have this phenomena including items such as stents and pacemakers. Infection arises when the microbes become active and multiply. It is not yet known what provokes this sudden change, but it is known that a series of changes occur allowing the microbes reach a state of maturity and become more susceptible to eradication with antibiotic treatment.
Fractures: Although rare, trauma to the knee may result in a fracture that disrupts the stability of the implant and fixation to bone which may require surgery to repair.
Patient-related factors: Rarely do age, activity level, health or being overweight contribute to implant failure. Most knee replacement patients are over 50 years of age and older individuals tend to put lower demands on their implants.
A revision procedure is typically more complex than the initial knee replacement surgery because your surgeon must remove the original implant. The surgery also takes longer to perform than an initial knee replacement. Revision knee replacement usually does not provide the same expected lifespan as an initial replacement. Surgical trauma, scar tissue, and mechanical weakening of components tend to reduce performance of a revised implant.
Care after knee revision surgery is similar to the care you’d receive after total knee replacement. This includes a combination of light physical therapy and pain medications as needed. Blood thinning medication will also be given to prevent blood clots. A walker or crutches will be used early in the recovery period, and you will progress to a cane or walking without any assistance as your condition improves.
Although pain relief and increased stability are expected outcomes, complete pain relief and restoration of function is not always possible. Up to 20% of patients may still experience some pain following knee revision surgery. This may persist for several years after the procedure. More than 90% of patients who undergo revision procedures can expect to have good to excellent results.
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