A spacer is used in infected knee replacements because it contains antibiotics to eliminate the infection, states OrthoInfo. The spacer is made of antibiotic-loaded bone cement and works to maintain normal joint space and alignment. Antibiotics gradually flow to the infected areas to eliminate the infection over time.
Knee infections may develop after the initial knee replacement surgery, but only about one out of every 100 patients develop an infection, according to OrthoInfo. Surgeons normally use antibiotic-loaded spacers for deep knee infections that are present for longer periods of time in a process called staged surgery. To treat skin or soft tissue infections around the knee, commonly known as superficial infections, doctors may only need to use intravenous or oral antibiotics.