Knee joint replacement surgery has become a mainstay procedure in the treatment of advanced degenerative arthritis. Because arthritis is painful and debilitating, more and more people are benefiting from knee joint replacement. For all the benefits derived from knee replacement, however, it still has risks and potential complications, some of which can be catastrophic. There are several complications that can arise from this surgery, and prospective patients need to be aware of them.
Infection
Infection is a catastrophic complications of joint replacement of any kind. According to the University of Connecticut Health Center, the incidence of serious, deep infection in post--total knee replacement patients is less than 2 percent. The incidence is relatively low thanks to improvements in sterile technique, air flow in the operating room and better use of prophylactic, or preventative, antibiotics.
When infection does occur in a knee joint replacement, the microorganisms grow rapidly in numbers, multiplying exponentially. Because knee implants are artificial, they have no blood supply to allow for antibiotic penetration. The implants, and any bone cement used, provide barriers to the effectiveness of the antibiotics, thus rendering them mostly ineffective.
In cases of severe infection, the most appropriate treatment is the complete removal of all implanted parts. This procedure is usually followed by the placement of antibiotic-impregnated molds made of bone cement. These act as temporary spacers, shaped like the original implants, and allow for a slow, sustained release of antibiotic into the joint. They also provide the knee compartment with proper support and reasonable function until doctors can safely implant new parts.
Blood Clots
Knee joint replacement carries a risk of blood clot development in the lower portions of the legs, a condition known as deep vein thrombosis. These blood clots have several causes, including tourniquet ischemia during surgery, which is the stoppage of blood flow to the leg by using an inflatable constricting device called a tourniquet; relaxation of the large vessels in the lower portion of the body in response to anesthesia; and postoperative immobility.
Once formed, these clots can dislodge from the vessels in the legs and travel into the heart and lungs, creating a condition known as pulmonary embolism, which is serious and on rare occasions, fatal.
Prosthetic Loosening
One complication that can occur weeks to months after surgery is the loosening of prosthetic implants. Implants can loosen because of improper insertion at the time of surgery and improper balancing of ligaments and soft tissues, which exert abnormal forces on the implants, causing premature loosening, obesity and postoperative trauma, as seen in falls.
Loosening can also occur as a result of infection or substandard bone quality. Examples of poor bone quality include rheumatoid arthritis and osteoporosis. Sometimes implants can loosen for no readily apparent reason.
Implants can loosen even years after surgery, typically as a result of microscopic particles of plastic wearing off the spacer of the tibia, or shin bone. These particles work their way between the bone and the cement, or the bone and implant, creating a scenario of bone resorption, or dissolution.
Implant Breakage
The prosthetic implants used in knee joint replacement are typically made of high-tech metal and plastic. In severely obese patients, as well as in patients in which implantation techniques are substandard, breakage of the plastic spacer can occur. Plastic components can also break if a patient falls directly onto the replaced knee. Broken implant parts must be removed and replaced.
Loss of Motion
Because knee replacement surgery is a major procedure, doctors expect patients to have considerable postoperative inflammation. This inflammation is typically treated with pain medication, cold therapy and physical therapy modalities that reduce inflamed tissues and promote better movement. Persisting joint stiffness can be an aggravating complication of knee replacement surgery. It can occur in the early rehabilitation phase or months after surgery. The technical term for this type of stiffening is arthrofibrosis: arthro, meaning joint, and fibrosis, meaning the formation of fibrous scar.
References
- University of Connecticut Health Center: Total Joint Replacement Conditions and Treatment
- The American Academy of Orthopedic Surgeons: Total Knee Replacement
- Georgetown University Hospital: Complications After Total Hip and Knee Replacement
- eOrthopod: Stiff Knee after Knee Replacement; What's the Best Treatment Approach?
- "Orthopade"; Therapy of Arthrofibrosis after Total Knee Arthroplasty; H. Gollwitzer, R. Burgkart, P. Diehl, R. Gradinger and V. Bühren; February 2006
