John D. Burrow, DO
Knee Replacement Surgery is a very safe and effective way to treat severe painful arthritis in the knee. About 750,000 Americans underwent knee replacement (arthroplasty) surgery in 2018. As Americans live longer and expect a higher quality of life as they age, the number of knee replacement surgeries will keep growing. As a result, the number of Knee Replacement Revision Surgeries will continue to grow as well. In my practice as a fellowship-trained Orthopaedic Adult Joint Reconstruction Specialist, I do both the initial knee replacement surgeries AND joint revision surgeries of the knee.
Unfortunately, about 7-10% of knee replacements will fail at some point. Failure means patients will continue to have pain, swelling and dysfunction (or all three) soon after the joint is replaced or will have these issues at some point in their lives. This can happen in the first few months after a knee replacement, 20-30 years after a knee has been replaced, or anytime in between. There are several reasons that a joint replacement can fail. In this article, I will discuss the need for knee joint replacement revision surgery due to infection.
Modern surgical preparation involves reducing the risk of infection whenever possible. Patients are asked to scrub with antiseptic wash for three days before joint replacement surgery, and to change their towels, bedtime attire and bed linens daily during this period. The operating room, surgical instruments and all supplies used during surgery are sterilized and the area is kept sterile. Patients must swab the inside of their noses with multiple antibacterial swabs and are bathed in strong antiseptic wash before the first incision is made in their knee. Physicians have to scrub themselves with antibacterial soap before surgery, and wear sterilized gowns and gloves before touching the patient. We also dose our patients with IV antibiotics pre and post operatively and include an IV dose after surgery as well. Patients are asked to take prophylactic antibiotics (for life) just before going to the dentist or for other surgical procedures.
Even with all these precautions and although infection rates are quite low for knee replacement surgery in the United States, infections still can occur. At present, the infection rate for knee replacements is about 1 in 100 patients. Some patients are more at risk for surgical infections than others.
The major risk factors for infection are:
- Poor dental health
- Poor circulation
- HIV or lymphoma
I discuss these factors and encourage patients to help reduce their infection risk by addressing any outstanding issues that can be handled BEFORE surgery.
What symptoms should a post-surgical knee replacement patient look for that may indicate an infection?
- Redness and tenderness around the incision
- Pus or foul smelling liquid draining from the surgical incision
- Fever of over 101.5°F
- Chills and/or sweating
- Pain, stiffness or trouble walking on the affected leg
When an acute infection soon occurs after a knee replacement, I must identify whether it is a superficial infection or a deep joint infection. For either, it is imperative that it be treated quickly and with heavy doses of antibiotics. A sample of the joint fluid will be taken to identify the bacteria that is causing the infection and to determine the most effective antibiotic needed to kill the bug. A blood test may also be performed.
For deeper infections, I will perform a surgical procedure called irrigation and debridement, where the newly implanted prosthesis is left in place, but all contaminated tissue surrounding the implant will be removed and the area around the implant will be thoroughly flushed with antibiotics, changing out any modular components as well. The incision is closed and the patient will be sent home with IV antibiotics for at least a six week period of time.
Infections that occur many months or years after a knee replacement typically are more serious. They may originate in the mouth (remember that earlier reference to the dentist?) or elsewhere in the body where an infection has taken hold and migrated through the bloodstream to the knee implant. I also may order an MRI to visualize the inside of the knee.
These infections are usually treated surgically, often in stages. First, I remove the knee implant, clean out all contaminated tissue, and insert a spacer in the knee. The spacer releases antibiotics into the infected knee and the surrounding tissue. Then the knee is allowed to heal from the infection. IV antibiotics are administered throughout this process, which can take months. When the knee is healed and multiple cultures show no sign of infection, a new implant can be inserted in the patient’s knee. Then the patient can truly begin the process of healing from their knee replacement and enjoying the benefits of a new and pain free knee!
Thankfully, most post-surgical infections from knee replacement can be cured with prompt and aggressive treatment by a skilled orthopaedic surgeon.