Joint Infection

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.

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 blood stream, 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 for infection include:

  • 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 confirm 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

Superficial infections, or infections just affecting the soft tissues of the joint or the skin but not yet  has deep down into to the artificial joint itself can be easily treated and caught early. 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 –  When caught within several days of the infection starting ,  deep infections at times be cured with a surgical washout of the joint. This procedure is known as a  debridement, and the surgeon performing the  procedure will  remove all of the soft tissues that are contaminated. The next step will the thorough cleansing of the  implant  and the spacers or plastic liners are replaced. After the procedure, IV antibiotics will be prescribed 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 of this staged surgery includes:

  • 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 into  place to aid with the proper alignment of the joint and to maintain normal joint space. It also provides patient comfort and mobility while the infection is being treated.

Spacers also have been 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 orthopaedic 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).  Blood work will be done throughout the treamtment to evaluate how well the antibiotics are working.

The infectious disease team and surgeons determine that 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

From the beginning and early phases of the original joint replacement surgery, several important measures are put into place and taken to play a role in the minimization of  the risk of infection. Many of the steps have been scientifically proven proven to lower the risks leading to an infection, and some, even with out a science proven record, are just thought to help. 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