Knee joint replacement surgery has, over the years, become a mainstay procedure in the treatment of advanced degenerative arthritis. Because of the painful and debilitating nature of arthritis, more and more people are benefiting from knee joint replacement.
For all the benefits derived from knee replacement, it doesn't come without its own set of risks and potential complications, some of which can be catastrophic. There are several different complications that could potentially arise from this surgery, and prospective patients need to be aware of them.
Infection
Infection is one the most, if not the most, catastrophic complications of joint replacement of any kind. Of all joints replaced in the United States, the knee is the most frequently replaced.
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. This is a relatively low percentage, thanks to improvements in sterile technique, air flow in the operating rooms, and better use of prophylactic, or preventative, antibiotics.
When infection does occur in a knee joint replacement, the microorganisms begin to grow rapidly in numbers, multiplying exponentially. Because the implants are artificial, they possess no blood supply to allow for antibiotic penetration. The implants, and bone cement if used, provide barriers to the effectiveness of the antibiotics, thus rendering them all but useless.
In cases of severe infection, the most appropriate treatment is the complete removal of all the implanted parts. This is usually followed by placement of antibiotic-impregnated molds made of bone cement. These act as temporary spacers, shaped like the original implants, and allow for slow, sustained release of antibiotic into the joint as well as providing the knee compartment with proper support and reasonable function until such time as it is safe to re-implant new parts.
Blood Clots
Knee joint replacements carry a risk of the development of blood clots in the lower portions of the legs, known as deep vein thrombosis. These blood clots develop from several causative factors, including tourniquet ischemia during surgery or stoppage of blood flow to the leg by using a pneumatic inflatable constricting device called a tourniquet; relaxation of the large vessels in the lower portion of the body secondary to anesthesia; and postoperative immobility.
Once formed, these clots carry with them the potential for dislodging from the vessels in the legs and traveling into the heart and lungs, creating a condition known as pulmonary embolism, which can be very serious and on rare occasions, fatal.
Prosthetic Loosening
One complication that typically occurs weeks to months after surgery is loosening of the prosthetic implants. This can occur from a variety of reasons, including improper insertion of the implants at the time of surgery and improper balancing of ligaments and soft tissues, creating abnormal forces to be exerted 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 quality of the host bone. Examples of poor bone quality can include rheumatoid arthritis and osteoporosis. Sometimes implants can loosen for no readily apparent reason.
Implants can loosen years after surgery. This typically happens as a result of years worth of microscopic particles of plastic wearing off the spacer of the tibia or shin bone. These microparticles of plastic work their way between the bone and cement, or the bone and implant, creating a scenario of bone resorption or dissolution.
Implant Breakage
Knee joint replacements are accomplished by using prosthetic implants. They are typically made of high tech metal and plastic. In severely obese patients, as well as in patients where implantation techniques are substandard, breakage of the plastic spacer, or articular surface, can occur.
Plastic tibial articular components can also break from falling directly onto the knee. In any case, the broken plastic tibial component must be removed and replaced.
Loss of Motion
Joint stiffness can be an aggravating complication of knee replacement surgery. It can occur in the early rehabilitation phase or months down the road from surgery. The technical term for this type of stiffening is arthrofibrosis: arthro--meaning joint and fibrosis--meaning formation of fibrous scar.
Because knee replacement surgery is a major procedure, there is the expectation of a fair amount of postoperative inflammation. This inflammation is typically treated with pain medication, cold therapy and physical therapy modalities designed to reduce inflamed tissues and promote better movement.
References
- University of Connecticut Health Center: Total Joint Replacement Conditions and Treatments
- The American Academy of Orthopedic Surgeons: Total Knee Replacement
- Georgetown University Hospital: Complications After Total Hip and Knee Replacement
- eOrthopod.com: Stiff Knee after Knee Replacement; What's the Best Treatment Approach?
- PubMed.gov: Therapy of Arthrofibrosis after Total Knee Arthroplasty
