Risks of Knee Replacement Surgery
Knee Replacement Complications
Adverse events after surgery include:
- Infection is important to note. Areas in the wound or around the new joint may get infected. Infections can happen during the surgery, after the surgery while still in the hospital, or long after the surgery is completed. Minor infections in the wound are usually treated with drugs. Deep infections may need a second operation to treat the infection or replace the joint (see Revision Surgery).
- Organs close to the surgical area may become damaged in the process including the arteries and veins in the leg.
- Patellar tracking problems can occur where the knee cap does not properly move along the groove in the femur as designed.
- Ligamentous Instability can occur if the ligaments of the knee become unbalanced, stretched, cut, or injured due to the nature of the knee as a joint.
- Nerves going to the leg may become damaged in the process decreasing sensitivity and cause weakness in the limb.
- Mechanical failure. The replaced joint may become loose or detached from the adjoining bone or, if there is a mobile bearing, the prosthesis may become dislocated from the socket.
- A “bow-legged” appearance is a difference in leg length that may occur due to the prosthesis or angular deformity.
- Stiffness in the joint area that may feel abnormal.
- Bone fracture of the femur or tibia
- Bone loss (osteolysis)
There is an increase in the likelihood of blood clot formation in the lungs (Pulmonary Embolus or PE) and the lower leg and thighs (Deep Vein Thrombosis or DVT). The doctor may suggest drugs to make your blood thin or special stockings, exercises, or devices such as venous foot pumps or compression devices. 3 If swelling, redness, or pain occurs in your leg after you leave the hospital, contact your doctor right away.
Knee Revision Surgery
Despite the success rate of so many knee replacements a year, some knee replacements eventually fail for multiple reasons and may require additional surgery to be replaced called “revision”. The length of time your current replacement lasts depends on multiple factors as well. The longevity and performance of a knee replacement depends on several factors, including your activity level, weight, and general health.
Revision surgery may require special components. Typically they will have longer stems which fit into the femur and tibia. They may also have attached metal pieces called augments which substitute for missing bone. Revision components often have a cam in the center of the knee similar to a posterior stabilized component. In revision components, though, the cam is larger to give the knee more stability. In cases where the knee is very unstable and a large amount of bone is missing, it may be necessary to join the femur and tibia with a metal “hinge” in the center.
Knee Revision Study
A study published in 2010 reviewed the data in the U.S. for all total knee arthroplasty revisions performed between October 2005 to December 2006. 4 The published data was based on 60,355 revision surgeries and included the type of procedure (whether it was all component revision or if revision focused on a particular component) and the diagnosis of the cause of failure of the device that led to revision.
The causes included:
- Mechanical loosening
- Implant failure/breakage
- Periprosthetic fracture
- Periprosthetic osteolysis
- Bearing surface wear
- Other mechanical complication of prosthetic joint implant
- Other mechanical complication of other internal orthopedic device implant or graft
The greater portion of these revisions were “all component” revisions where each piece of the prosthesis was replaced followed by complete removal of the prosthesis. Male patients were more likely to have revision surgery than woman with the most common causes of revision were infection, mechanical loosening, or implant failure or breakage. 5