Joint Replacement Surgery & Infection Treatment

Two of the most commonly performed elective surgeries or operations are the hip and knee replacement surgeries. Joint replacement surgery, for the majority of patients, will lead to a more active, pain-free life. However, like with any surgical procedure, there will be risks involved.

Although it is not common, there is a chance of infection stemming from the surgery that some patients might face.  Infections can be deep and internal, surrounding the artificial implant, or can be seen on the superficial level through wounds. An infection, whether it’s superficial or on a deeper level may develop as early as the duration of the hospital visit or arise shortly after being released while home. Infections can happen to the joint replacement infection even years after the surgery.

Why Consider Knee Joint Replacement and Hip Joint Replacement Surgery

Any type of infection in other areas of the body can also lead to the infection of the hip or knee replacements.  Infections are caused by viruses or bacteria. Although bacteria are abundant on our skin and the gastrointestinal tract, the immune system works hard and generally keeps the harmful bacteria in check.  For example, if bacteria ventures into the bloodstream, the natural immune system kicks in quickly to kill the invading, harmful bacteria.

However, hip and knee joint replacements are made from plastic or metal which the body sees as a foreign object making it difficult for the immune system to attack all of the bacteria that makes it to the area surrounding the implants. If bacteria gain access to the implants, they may multiply and cause an infection. Despite the advancements in preventative treatments and antibiotics, patients with an infection of the joint replacement more often than not, require surgery in order to cure the infection.

Causes of Joint Infection

A total joint can possibly become infected starting at the time of surgery, or can range from a few short weeks after or up to several years after recovery time is over and the surgery is completed. Common ways that bacteria can enter the body includes minor cuts or breaks in the skin, root canals, tooth extractions or other major dental procedures, and through wounds that are the result of other surgical procedures.

Certain people will face a higher risk for developing infections after any surgical procedure including a joint replacement procedure. Factors that will play a role in the increase the risk of infection includes:

  • Diabetes mellitus
  • Immune deficiencies (such as HIV, lymphoma)
  • Obesity
  • Peripheral vascular disease
  • Immunosuppressive treatments

Symptoms of Joint Infection

Signs and symptoms linked to the joint replacement becoming infected include:

  • Increased stiffness and  pain in a normally  well-functioning joint
  • Swelling
  • Redness  and extra warmth around the wound
  • Wound drainage
  • Fevers, night sweats, and chills
  • Fatigue

Doctor Examination

Proper treatment and early diagnosis are both important in retaining the implant if an infection is suspected.  Detailed physical exams will include:

Laboratory tests

Certain types of blood tests can be an important and helpful tool to identify an infection. For example, in addition to routine blood tests like a complete blood count (CBC), your surgeon will likely order two blood tests that measure inflammation in your body. These are the C-reactive protein (CRP) and the Erythrocyte Sedimentation Rate (ESR). Although neither of these tests confirms the presence of infection, if either or both of them are elevated, it raises the suspicion that an infection may be present. If results of these tests are normal, it is unlikely that your joint is infected.

Imaging tests

X-rays and bone scans can help your doctor determine whether there is an infection in the implants.

Treatment of Joint Infection

Treatment is easy when caught early to a superficial infection or infections just affecting the soft tissues of the joint or the skin but not yet has deep down into the artificial joint itself. Treatments include oral antibiotics or intravenous (IV) antibiotics; both routes have a high success rate. For an infection that gains a deeper access into the body and hits the joint itself, more times than not, require beyond the superficial tissues and gain deep access to the artificial joint almost always require surgical treatment.

Debridement

Surgical washout of the joint can cure deep infection or infection within several days. This procedure is known as debridement, and the surgeon performing the procedure will remove all of the soft tissues that are contaminated. The next step will be replacing plastic liners and a thorough cleansing of the implant and the spacers. After the procedure, a patient will take IV antibiotics for approximately 6 weeks.

Staged surgery

As a general rule of thumb, the longer lasting infections or the longer one is present, the more of a challenge it is harder it is to treat without a removal of the implant.

Late infections, or those that show up months to even years after a hip or knee joint replacement surgery and those infections that have been present for longer periods of time, will generally require a staged surgery.

The Initial  Stage Staged Surgery

  • Total removal of the implant
  • Washout of the soft tissues and the area surrounding joint
  • Placement of an antibiotic spacer
  • IV antibiotics

An antibiotic spacer is a type of medical device that is put in place to aid with the proper alignment of the joint and to maintain normal joint space. Treatment of infection also provides comfort and mobility to the patient.

Also, spacers are loaded with antibiotics and made with bone cement. The antibiotics will be able to flow into the surrounding tissues and joint helping the body to eliminate the entire infection.  Patients who choose to undergo a staged surgery will generally need a minimum of six full weeks, possibly longer, of oral or IV intravenous antibiotics and the duration of therapy. Infectious disease professionals will team up with the orthopedic surgeons and will work closely to determine which treatment route is best as well as which antibiotics each individual patient will be on.  Antibiotics will be either oral or IV (intravenous).

The infectious disease team and surgeon determine if the infection has cleared up and been totally cured. The patient will once again be an eligible candidate for a revision surgery or a totally new total hip or knee implant. This is stage two, or the second procedure in the treatment plan for all types of joint replacement infections. The surgeon, during all revision surgeries, will remove the antibiotic spacer, move onto the next step which is to repeat the washout of the joint, and then move on to the last step, which is to re-implant all the components of a totally new hip or knee.

Prevention of Joint Infection

Take note of these measures below to minimize the risk of infection from the beginning and early phases of the original joint replacement surgery. These steps help a lot to lower the risk leading to an infection even without a scientifically proven method. The most important known measures to lower the risk of infection after total joint replacement include:

  • Antibiotics before and after surgery
  • Preoperative chlorhexidine wash
  • Short operating time and minimal operating room traffic
  • Antibiotic prophylaxis
  • Preoperative nasal screening for bacterial colonization
  • Use of strict sterile technique and sterilization instruments

What is a prosthetic joint infection?
Bacterial joint infection is a serious and a painful condition of the joint. It is also called septic arthritis. Bacteria can enter the joint and cause significant damage, especially when the joint is artificial joint. Most of the bacteria that travels to the artificial joint comes through the blood. It is important for any infection anywhere to be aggressively treated, especially skin or superficial infections. It is recommended to take antibiotics before dental cleaning because bacteria from the mouth can travel to the artificial joint through the blood and cause an infection.
How common is periprosthetic joint infection?
The possibility of getting a periprosthetic joint infection is from 0.5% to 7%. It is the number one reason for failure after a total knee replacement and number three reason for failure after a hip replacement.
How is infection of artificial joint diagnosed?
An infection is diagnosed based on history, physical examination, and on running the results of the blood and also by doing aspiration of the joint. There is a history of the patient to ensure significant pain, redness, swelling, and ability to bear weight. The physical findings will show a swollen joint, tenderness all over the joint, and significantly decreased range of motion and inability to bear weight on the joint. Usually it occurs in an acute manner within hours. Blood tests include running a CBC and ESR and CRP. There are also specialized tests available to diagnose joint infection. What is the most confirmatory test for diagnosing infection of artificial joint. Aspiration of the joint is a confirmatory test for diagnosing infection. We look for the total number of cells and inflammatory cells in the joint and also do a culture sensitivity of the fluid. A culture sensitivity allows us to look at the antibiotics that the infected joint will be susceptible to.
How is infection of artificial joint treated?
Artificial joint infection is treated in a variety of ways depending on the time the infection is diagnosed, whether the implants are still fixed or they’re loose, depending upon the life expectancy and the medical conditions of the patient. If the infection is diagnosed early and if the infection is inside the joint, irrigation of the debridement of the joint usually is sufficient. This is done to prevent it from becoming a chronic infection. The surgery involves cleaning the joint and usually changing the exchangeable pieces in the joint. The changeable pieces in the hip joint include the head of the stem that goes into the thigh bone and the plastic that goes inside the cup. The parts that are affixed to the bone are not removed or exchanged. If the implant is loose, the implant needs to be removed and needs to be replaced with an antibiotic spacer. Antibiotic spacer is cement loaded with extremely high dose of antibiotics. The first involves removing the implant, placing the antibiotic spacer, and treating the patient with additional IV antibiotics. After about four to six weeks the antibiotics are stopped, aspiration of the joint is done to confirm that the infection is eradicated, and then revision surgery is performed in which the antibiotic spacer is removed and the final prosthesis is placed into the joint. This procedure is called a staged reconstruction for treating artificial infected joints. The final scenario is a patient in which the medical conditions are significant, the life expectancy is very low, and chronic antibiotic suppression is used to treat these infections. Chronic antibiotic suppression means that the patient gets antibiotics for the rest of their lives.
What are the reasons for infection of total hip replacements?

Infection of total hip replacement can be immediately after the surgery, which what I call “acute” postoperative infections. There could be “delayed” deep infections which happen from three months to the next two years.

“Late” infections which typically happen after 2 years are called hematogenous (blood bourne) infections because these infections are most commonly because of bacteria seeding the joint and these bacteria have originated elsewhere from the hip joint.

Acute postoperative infections happen within the first three months of surgery and it’s important to distinguish whether these infections are superficial or deep. Superficial infections are outside the fascia and do not affect the inside of the joint. Deep infections are infections where the actual artificial joint is seeded with the bacteria.

The best way to differentiate a superficial from a deep infection is by doing aspiration of the hip joint and looking for cell count, culture sensitivity, Gram stain, etc. A cell count has to be differential- which means we look at individual white cells – lymphocytes etc. Aspirated cell count is an extremely useful test. The cell count for artificial joints that are infected are significantly lower than the counts associated with primary joint infection ie native joints getting infected.

Deep delayed infections occur after three months and could be from the surgery or could be from a hematogenous infection from elsewhere in the body including urinary tract infection or the nasal tract. Depending upon how the infection manifests, one option is to do irrigation and debridement (surgical cleaning) and exchanging of the head and the plastic and then treating the patient with IV antibiotics to achieve resolution of the infection.

Late hematogenous infection occur typically after two years and is from a source away from the hip joint. In these circumstances, the patient typically has to have a two stage reconstruction in which the joint has to be removed, antibiotic spacer has to be placed inside the hip joint, and after treatment with IV antibiotics, the antibiotic spacer is removed and the final hip revision is placed into position.

The advantage of the antibiotic spacers is that the antibiotic spacers eludes huge amount of antibiotics and kills the infection. Such high level of antibiotics is impossible to achieve through an IV dose because of possible toxicity to the body. The best way to treat late hematogenous infection is “staged reconstruction”. However, if the patient has significant medical problems with the extreme limitation of life expectancy, another option is to do removal of the implant which is called the “hanging hip” or “Girdlestone operation of the hip”.

There’s also been studies which show that a single-stage revision is an option for infected joint in which the infected joint is removed. Thorough debridement is done on the joint and a new hip joint is placed in position at the same time the infected joint is removed.

Studies looking at a single stage revision for infected joint arthroplasty are fairly limited.

What is an antibiotic spacer?
Antibiotic spacer is cement loaded with high-dose antibiotics. The antibiotics flow into the joint and the surrounding tissues and kill the infection. It is placed inside the joint and therefore high dose of antibiotics can be used. Usually this high of a dose cannot be used intravenously because it is a lethal dose. Antibiotic spacers are of two types. Static and articulating. I use articulating antibiotic spacers because the range of the hip joint is maintained after the articulating spacer. The amount of bone eroded from the infection is decreased because of the articulating joint spacer. Additionally, the revision surgery can be done in a less invasive manner.
What is a spacer in the hip joint?

A spacer in the hip joint is made from a cement mold. The measurement of the infected artificial hip joint that is to be removed is determined preoperatively and intraoperatively and there are molds of different sizes that can be used to create the antibiotic cement spacer.

My preferred method is to make the spacer even before making the incision so that the operative time is decreased. I do thorough planning preoperatively and I select the spacer preoperatively. I mix about 10 grams of tobramycin and 10 grams of vancomycin and make the cement spacer. I also peel off the plastic from the cement spacer before the incision is made.

After that, the incision is made, the infected prostheses is removed, and the cement antibiotic spacer is placed into position. Before placing the cement, the spacer, it’s very important to do a thorough debridement. I thoroughly clean out the femoral canal and remove the acetabulum so that the infected tissue is extracted as much as possible and then the cement spacer is placed into position.

After closure of the wound, IV antibiotics are given postoperatively for about four to six weeks and aspiration is performed after six weeks to ensure there’s no infection and then the patient is again scheduled for removal of the antibiotic spacer and placement of a revision hip surgery.

In these type of surgeries, the tourniquet has to be let down, and although hemostasis is achieved, there may be blood loss intraoperatively which may need a blood transfusion.

For patients who undergo a spacer, the spacer is not strongly adherent to the bone because it’s an antibiotic spacer, and the idea is not to cement it to the bone because removing the spacer in the second stage will lead to more bone loss.

Therefore, in patients who get a spacer, there is blood loss, not during the surgery but during the postoperative period. Patients who get a spacer after the removal of the knee joint do a transfusion on the second or the third day.

Joint Infection Case Studies

Why choose Dr. Kakare?

As a top joint replacement specialist in New York City, Dr. Karkare has a stellar reputation, extensive experience, ensuring patients have the broadest array of safe and effective treatment options to relieve pain and other symptoms.

Dr. Nakul Karkare - NY Orthopedic SurgeonDr. Karkare does a thorough examination of each patient to gauge if an anterior method would be a good choice before any procedure is performed.

This enables every patient to make an informed, educated decision so they can feel confident in their care every step of the way.

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