Knee joint replacement has become a life-altering surgical procedure for those who suffer from chronic, painful end-stage arthritis of the knee. The replacement procedures have had profound effects upon the quality of life that most arthritis sufferers have lost over years of joint degeneration. That being said, knee joint replacements are not without risks and the potential for problems.
Infection
The various component implants that make up a knee joint replacement are typically constructed of a high-tech metal, such as cobalt, chrome and titanium, together with parts made from a high-density plastic called ultra high molecular weight polyethylene.
Because these are artificial components, they do not possess any blood supply, therefore making it extremely difficult to fight any infection that may occur in the knee around these implants. Similarly, the widespread use of bone cement for implantation of the components has the same problem of no blood supply to deliver important antibiotic therapy in the event of an infection.
Infections in joint replacements can be a recipe for disaster, which is why so much care is taken with patient selection, sterility and proper antibiotic coverage before, during and after surgery.
Loosening of Implants
Although a patient's host bone is prepared in such a way as to accept the fitting of the prosthetic components with very tight tolerances, the mere reality of bone meeting cement and bone meeting metal can set the stage for loosening of the different interfaces. While the risk of prosthetic loosening can rise over the lifespan of these implants, improper implant placement and inadequate balancing of soft tissues such a ligaments during the insertion of the prostheses during surgery can initiate unwanted loosening at a very early stage.
Breakage of implants
The metallic components of a knee replacement carry an extremely low risk of metal failure and breakage, mainly due to the metals used. This cannot be said as emphatically about the plastic components, which are more susceptible to wearing, thinning an ultimate breakage.
When the plastic spacers used in knee replacements come under excessive pressure due to improper placement or postoperative abuse of the knee, premature wear, thinning and possible breakage of the plastic is possible. If breakage does occur, the original spacer must be removed, the entire knee joint inspected for other damage and, at the very least, a new spacer inserted. In some severe cases, complete removal of the components may be necessary and new ones inserted.
Loss of Motion
Stiffness and loss of motion are preventable problems after knee replacement. Early activation of physical therapy helps break the cycle of pain, thus allowing for increased range of motion. Moving an extremity after surgery is no easy task, but it is crucial to the overall success of the procedure. Avoiding stiffness early on will increase the success potential for the joint.
