Infection and Joint Replacement
Infection is the most common and the most serious complication following joint replacement surgery. Infection is simply understood as an abnormal growth of microorganisms (most commonly bacteria) within previously microorganism-free tissue. Joint infection is the most common reason for revision joint replacement surgery.
Why is infection a risk in replaced hip and knee joints?
Hip and knee joints are relatively infection-free when in their natural state. Whenever these joints are replaced they are prone to get infected. The risk of infection is more than any other surgery being performed. There are several reasons for this:
- Prosthesis. Whenever a prosthesis is placed, the prosthesis surface provides a medium or surface for the bacteria to grow. The bacteria grow easily along the surface of the prosthesis and small blood clots present after the surgery provide a favorable medium for the bacteria to grow. When bacteria grow substantially they form a defensive layer, called Biofilm. Antibiotics cannot enter Biofilm and so the antibiotics don’t work after there is an infection in the replaced joint.
- Age: joint replacement surgery is commonly performed in older age groups since osteoarthritis is common in the elderly. Elderly are more prone to infection not only at the replaced joint but also at other body organs. The bacteria can seed into the joint after spreading from other organs like the lungs or urinary tract.
- Immunosuppressed state. Infections are common whenever there are medical comorbidities like diabetes, thyroid disorders, etc. With increasing, age comorbidities increase too and so do the chances of getting joint infection after replacement surgery.
How do I know I have developed a joint infection?
There are obvious signs of infection like
- Persistent Hip/Knee pain that is not improving.
- Difficulty moving the joint.
- Red and inflamed joint which is tender to touch.
- Persistent discharge from the wound.
These signs are more obvious when the infection is early (within days to weeks). However, these features are not present or are subtle when the infection is late (infection occurring after 6weeks).
Whenever you develop these signs and symptoms you should immediately follow up with your doctor. Your doctor will perform radiographs, a thorough exam, and labs. Blood workup might show increased WBC counts, Erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP). Blood could also be cultured for some cases.
Your x-rays might indirectly show the infection like lucent shadows surrounding the prosthesis, implant loosening, etc.
If the diagnosis of joint infection is still not clear, then the joint is aspirated and analyzed for cell counts and cultured for microorganisms. Sometimes your joint might have to be surgically opened and tissue obtained for biopsy and culture.
How is the infection treated?
Joint infections need prompt medical and surgical interventions. The microorganisms causing infection forms the biofilm over the implant surface to hide from the immune cells of the body as well as from the antibiotics. Oral and Intravenous antibiotics might be tried but are more likely to fail and ultimately surgery needed.
Your surgeon might perform joint wash out (joint debridement) and exchange of modular pieces when the infection is early and mild. Mild joint pain, no discharge from the wound, or fever are the ideal candidates for joint wash-out surgery. This is usually followed by culture guided antibiotic therapy.
However, if there are frank signs of infections like severe joint pain, joint stiffness, difficulty moving the joint, discharge from the wound, fever, etc. then simple washing of the joint (joint debridement) is not enough. Your surgeon will advise you to surgically open the joint, remove all the implants and place a spacer made up of bone cement (with or without antibiotics) for 6weeks to allow the joint to heal from the infection.
Once the joint is made free from infection your surgeon will place a new set of prostheses over the joint surface. This is called a Two-Stage Revision. Some surgeons exchange the prosthesis in the same setting (Single Stage Revision surgery) if the joint looks ok after debridement of the joint although this carries a bit more risk of re-infection.
How to decrease the chances of joint infection after joint replacement surgery?
As joint infection is one of the dreaded and most common complications of joint replacement surgery every precaution has to be followed to prevent it. The preventive steps are begun before the surgery itself and are continued during and after the surgery.
Before the surgery, every risk factor for infection is evaluated. Diabetes is checked and controlled. Medicines suppressing the immune system like medicines for rheumatoid arthritis are stopped. You should avoid smoking and should focus on weight loss and a healthy protein-rich diet. The skin overlying the surgery is washed and any foci of infection like lungs infection, tooth decay, urinary tract infections are adequately treated.
On the day of surgery, antibiotics are started. The surgical site (hip or knee) is thoroughly washed and every step is taken with care to avoid contamination of the surgical area. Bleeding is controlled during the surgery. The wound is dressed with a sterile dressing keeping all bacteria out while the incision heals.
After the surgery, your surgeon will perform wound dressing changes if necessary and continue antibiotics as needed. Continued incision monitoring is encouraged to watch for redness or persistent drainage. The patient is to focus on a healthy and high protein diet and physical therapy.
References:
- Aggarwal VK, Rasouli MR, Parvizi J. Periprosthetic joint infection: Current concept. Indian journal of orthopaedics. 2013 Feb;47(1):10-7.
- Ayoade F, Li DD, Mabrouk A, Todd JR. Prosthetic Joint Infection. StatPearls [Internet]. 2021 Jan 22.
If you have persistent Hip/Knee pain that is not improving, difficulty moving the joint, if you have red and inflamed joint which is tender to touch with persistent discharge from the wound Contact Straith Hospital and Schedule An Appointment! Our team of skilled physicians, nurses, therapists and more work hard to improve your strength so you can get back home safely. To learn more, give us a call at (248) 357-3360 or click here to view frequently asked questions.
THIS ARTICLE IS FOR EDUCATIONAL PURPOSES ONLY, IT DOES NOT CREATE A PHYSICIAN-PATIENT OR OTHER PROFESSIONAL RELATIONSHIP, AND IT SHOULD NOT BE INTERPRETED OR RELIED UPON AS MEDICAL ADVICE OR OPINION. EACH HEALTH CONDITION IS UNIQUE AND SHOULD BE EVALUATED, DIAGNOSED AND/OR TREATED WITH THE ASSISTANCE OF COMPETENT PROFESSIONALS.