VOL. 126 | NO. 102 | Wednesday, May 25, 2011
Orthopedic Infection Growing Concern
By Aisling Maki
Dealing with infection is a complex problem facing orthopedic surgeons, and a growing concern as the first of the baby boomer generation turns 65 – increasing the number of artificial hips, knees and other orthopedic devices implanted in patients.
Infections can be painful, devastating and even deadly.
“We put devices in people who have wounds,” said Richard Smith, assistant professor at the University of Tennessee Health Science Center-Campbell Clinic Department of Orthopedic Surgery, who served as moderator at a Monday, May 23, night panel on infections.
“These wounds disrupt the blood supply and the blood supply can no longer be adequate to fight infections. Bacteria and other organisms love to adhere to plastic materials and metals and things that we put in. So, infections tend to be a pretty big area for folks in research.”
It was mostly students involved in research that turned out for the Orthopedic Research Panel on Infections at the Memphis Bioworks Foundation, 20 S. Dudley St. in the city’s Medical District.
Sponsored by Memphis Bioworks Business Association, InMotion Orthopaedic Research Center, University of Memphis and UTHSC, the event’s featured speakers were Dr. George W. Wood II, associate professor at UTHSC-Campbell Clinic Department of Orthopedic Surgery and lead orthopedist at White Service and the Regional Medical Center at Memphis; and Warren Haggard, chair of excellence and professor at the University of Memphis Department of Biomedical Engineering.
To offer an industry perspective on orthopedic infections, the panel also included Mary Anthony, group director of technology development research at Smith & Nephew Inc., the global medical device maker whose orthopedic reconstruction and trauma headquarters is based at 1450 Brooks Road in Memphis.
Wood discussed the three types of infection orthopedists deal with: post-traumatic, postoperative and blood and local.
Each type of infection behaves differently and must be dealt with differently.
Post-traumatic wounds, for example, are open wounds, and the degree of contamination and tissue damage is extremely important in determining a treatment system. As with all infections, it’s a race against time, and to minimize infection in post-traumatic wounds, it’s recommended antibiotics be administered within two hours of a patient’s admittance to the emergency room.
Postoperative wounds are clean wounds, but infection can occur anywhere from one day to many years later, and most commonly occurs 10 days after surgery.
Methods for dealing with infection include irrigation, stabilization, antibiotic beads and bead pouches, and covering wounds so “they are bathed in a sea of antibiotics,” Wood said.
The Centers for Disease Control and Prevention recommends treating any remote infections before elective surgery, and not shaving the operative site – a formerly common practice that created skin nicks and increasing the possibility of infection.
Other precautions Wood described include administering antibiotics an hour before making an incision; improved wound space oxygenation; removing a patient’s urinary catheter within one to two days; controlling glucose levels in diabetics; improving patients’ nutrition; requiring patients to cease tobacco use 30 days prior to surgery; and keeping hospital stays to a minimum.
In the future, Wood said he anticipates improved patient selection and preparation, less invasive surgeries, better post-operative conditions, implant design changes and new antibiotics.
Haggard said his research at the University of Memphis is focused on reducing bacterial contamination in wounds and lessening and eliminating bacterial rebound after irrigation and debridement.
Once bacteria adhere to a surface such as that of an implanted device, they can form colonies with a protective covering, making them immune to both human immune systems and to antibiotics.
Part of the funding for his department’s research comes from the U.S. Department of Defense, with hopes the research will provide insight into tackling contaminated battlefield injuries.
Haggard is looking into the local delivery of antibiotics and antimicrobials using a chitosan sponge, as well as “Trojan horse” method that delivers a local antibiotic in the form of a biofilm messenger.
Anthony said not only are infections catastrophic and time consuming, typically doubling hospital stays, but they’re extremely costly; up to $100,000 per infected joint, totaling about $800 million a year in health care costs in the U.S. alone.
She said orthopedic device industry researchers are looking at advanced dressings to protect wound sites post-infection, device coatings that would protect implants from bacterial colonization, and a stand-alone product that could release an anti-infective agent into the area at risk for infection.