Newly developed antibiotic spacers successfully eradicated infection in more than 90 percent of patients with total knee and hip replacements, and allowed them to be successfully re-implanted, according to a study published in the online edition of the Journal of Arthroplasty.
The study showed that antibiotic spacers, which prevent total bed rest and allow patients to move during the six or more weeks of antibiotic treatment, also facilitate complex revision surgery that is needed once the infection is gone,
“If the bacteria get in or on the metal or plastic (parts of a hip replacement), then the hip replacement should be removed and the area has to be thoroughly cleaned so the body can heal itself,” said Dr. Stephen Incavo, an orthopedic surgeon at The Methodist Hospital and the study’s lead investigator. “When you do this, the patient is left without a hip joint and has limited mobility for an extended period of time.”
Antibiotic spacers are made out of traditional bone cement, the same material used to attach knee and hip replacements. The cement is filled with a high dose of powder antibiotics; the antibiotics then leach out of the spacer over a six week period, delivering a high dose to the infected area. This not only fills the gap and heals the problem, but it also gives surgeons more space and soft tissue to work with later on. Additional antibiotics are also given intravenously to maximally treat the infection.
The spacers are left in for about six weeks during which time patients can use a walker or wheelchair to get around. In some cases, depending on the severity of the problem, a second spacer might need to be put in to completely rid the area of infection.
“Once the infection has been eradicated, we can go back in with new implants and once again replace the hip,” Incavo said. “In this study, no knee patients had a recurrence of infection and all were successfully re-implanted. There were also no reports of spacer breakage during the time they had them in place.”
With any operation, there can be complications and patients can develop an infection. This can happen shortly after surgery or over an extended period of time. Infections that occur right after surgery are easier to treat. Sometimes, however, the infection doesn’t show up until one or two years after surgery.
Symptoms of an infected knee or hip replacement include:
• Feeling feverish or having the chills.
• Reddish incision or swelling around the incision.
"Patients will have some pain with the spacers in place, but unfortunately that is what is required to fix the problem,” Incavo said. “Having the spacers in is not as comfortable as a true hip replacement, but it is better than strict bed rest or even being in traction.”
From start to finish, the process of fixing a diseased hip with the spacers takes about a year and will allow people to get back to performing the activities of daily living, pain-free.