Revision Total Knee Replacement Surgery

Revision total knee replacement is the surgical procedure to replace the components of a prior knee replacement. Primary total knee replacement is one of the most common surgeries performed by orthopaedic surgeons. Common indications for a knee replacement include arthritis caused by primary osteoarthritis, rheumatoid arthritis, psoriatic arthritis, and secondary arthritis.

Total knee replacement offers excellent pain relief and restores prior mobility. Total knee replacement is one of the most successful surgeries of the twentieth century in the history of modern medicine.

 

On average, a knee replacement surgery may last for 15-20 years or even more. However, due to various biological and mechanical reasons, the parts may fail. Failure requires surgery which involves removal of the prosthesis and it’s replacement with a new prosthesis.

Revision knee replacement surgery is usually far more complex surgery than a primary total knee replacement. Revision surgeries require extensive planning and may require special implants and tools. The operating surgeon requires mastery of his/her technique to conquer the difficulties encountered in revision surgery.

 

Removed articulating cement spacer and reamers.

The ultimate goal of the revision surgery remains the same as that of the primary replacement. The aim is to provide pain-free mobility so that the patients can return to the activities they enjoy.

Causes of failure

Both mechanical and biological factors play a role in the failure of the surgery. The primary knee replacement may fail over the years or due to sudden injury/infection.

• The infection of the artificial knee joint is one of the commonest causes of early failure. The metallic and plastic parts may serve as growth surfaces for infectious agents. The surfaces are inaccessible for the body’s immune system.
• Aseptic loosening is the most common cause of failure of components many years after the surgery. There is micromotion between the interface of bone cement, bone surface, and the metallic component which causes loosening of the parts.
• There may be a generation of wear particles due to micromotion. The body’s defense system tries to get rid of the wear and tear particles. But in the process, the cells may also destroy the normal bone and cause loosening of the implant known as osteolysis.
• Fractures of the bones in the region of the implant may require revision of the implant. The type of surgery depends upon the location of the fracture.
• Instability of the artificial joint may be due to inadequate fixation of the implants or improper positioning of the implants. There may be laxity of the ligaments on the inner or outer side of the knee causing instability.
• Hypersensitivity to the metal parts may require revision with patient-friendly implants.
• Scar tissue may form on the undersurface of the quadriceps tendon causing a clunk on straightening the knee.
• Certain patient factors play a role in implant failure. Young patients with an active lifestyle may require revision earlier than the older age groups. Obese patients and patients with a history of prior knee surgery have a greater risk of infection.

Symptoms

The symptoms of implant failure may be knee pain or swelling in the knee. The pain may be more pronounced on weight-bearing in case of mechanical failure. The pain may be associated with fever and malaise in case of joint infection.

There may be associated stiffness of the knee joint. The patient may walk with a limp secondary to pain or instability. The skin overlying the joint may be warm and red in case of joint infection.

Diagnosis of failure

The patients with implant failure require a thorough investigation of the cause of failure. The physician may acquire a detailed history regarding the symptoms. The physician will also test the joint in various ranges of motion and examine the gait of the patient. The physician will look for any signs of infection and instability.

Radiological examination is done in the form of an X-ray to look for the component position, loosening, and alignment. CT scan may provide a detailed view regarding the femoral rotation and the component position. MRI studies may be helpful to detect bone loss. Bone scans are helpful to detect loosening and infection.

Aspiration of the knee joint is done to investigate the source of infection or rule out the infection. Blood investigations may also be done to look for markers of infection.

Surgery

The surgery is planned preoperatively according to the condition of the implant and the bone. The exposure and the surgery time is usually longer than the primary knee replacement surgery.

In the case of infection, the type of surgery depends upon the severity and time of onset of the infection. The surgery may be divided into two steps or done in a single step.

Revision knee replacement implant (semi – constrained with a long stem).

In a two-step approach, during the first surgery, the infected implants are removed. The joint is thoroughly washed and debrided. A prosthesis made of bone cement is inserted with antibiotics.

The patient is given intravenous antibiotics and after a period of a few weeks, definite fixation is undertaken. The joint aspiration is repeated before the definite surgery.

In the case of recent onset infection, the joint is washed thoroughly and only the plastic parts are replaced. In some cases, the infected prosthesis is removed and replaced with a new one in the same setting.

Periprosthetic fractures may require the use of special long stem implants. The type of surgery depends upon the level of the fracture.

In case of failure of the plastic component, only the plastic component may require revision. The revision surgery may require bone grafts or special cones to account for bone loss during the extraction.

Cementing of the femoral component.

The above images show modular femoral and tibial components. The modular components allow the surgeon to make intraoperative adjustments to achieve greater stability. There are provisions to attach stems to the components as well as adding bone augments to account for bone loss encountered during surgery.

Constrained polyethylene inserts in the images above utilize a tall and wide tibial post to provide side to side and rotational stability. These inserts are usually used with femoral and tibial components with stems. The stems dissipate the additional stress arising from the constrained construct.

A bone graft may be taken from the patient from a different location or may be taken from a bone bank. Metallic cones and metaphyseal sleeves may be used to compensate for bone loss. Specialized implants with a long stem or constrained tibial implants may be used to reduce instability and provide better fixation.

Metallic cones.

Metaphyseal sleeves.

Complications

The risk of complications is slightly more in knee revision surgery than the primary procedure. They may be potential complications such as heart attack, stroke, or pneumonia. There may be intraoperative complications such as fractures, shortening, instability, nerve, or blood vessel damage.

During the few weeks after the surgery, there is an increased risk of blood clots in the leg, infection, or dislocation.

Success

The vast majority of the revision knee replacements are done without any complications. A few may complain of residual knee pain, which can be managed with medications and physical therapy. With the increasing effectiveness of the implant materials and surgical techniques, revision surgeries are being done successfully.