Periprosthetic Joint Infection

What are periprosthetic infections?

Periprosthetic infections (PJI) are a serious post-operative complication following a total joint reconstruction and a common cause for implant failure requiring revision surgery.

Infection may occur in the wound or deep around the joint prosthesis. It may occur during the hospital stay or after discharge from hospital. The symptoms may even develop years later after surgery. Minor infections in the wound area are generally treated with antibiotics. Major or deep infections may require extensive surgery and removal of the prosthesis.

What causes periprosthetic infections?

PJI are caused by bacteria (Staphylococcus Aureus and Staphylococcus Epidermidis) that cling on to the prosthesis and multiply causing infection.

Factors that increase the risk for periprosthetic infections include:

• Immunosuppressive agents (glucocorticoids, chemotherapy) and conditions (HIV)
• Perioperative surgical site infection
• Delay in wound healing
• Advanced age
• Rheumatoid arthritis - a pre-existing joint disease
• Revision joint reconstruction surgery individuals pose a greater risk.
• Diabetes mellitus
• Smoking
• Obesity

Classification

Acute infection: These are early post-operative infections occurring approximately 1-3 weeks of implantation.

Chronic infection: Infection that is present for more than 3 weeks.

Hematogenous infection: Infection acquired through the bloodstream at any time following surgery.

Symptoms of periprosthetic infections

Infections may present with an acute onset of fever, pain, swelling, effusion and erythema at the prosthesis site, and stiffness of the affected joint. Sometimes severe pain may be associated with wound drainage.

Physical examination may reveal the presence of a chronic sinus tract connecting with the prosthesis.

Diagnosis:

The doctor will review your medical history, perform a complete physical examination and may order a few tests such as

• Imaging studies: X-rays, Bone scans, Positron emission tomography (PET) to view the involved bone and soft tissues.
• Laboratory investigations: Blood tests such as C-reactive protein (CRP) and Erythrocyte Sedimentation Rate (ESR)] may be done.
• A joint (synovial fluid) aspiration refers to removal of fluid from the space around the joint.
• Culture and gram stain help identify the type of bacteria that is causing the infection.

Early diagnosis of periprosthetic infections is crucial for the best outcomes.

Treatment:

Non-surgical: Your doctor may prescribe oral or intravenous antibiotics.

Surgical treatment options include:

• Debridement: It is the removal of contaminated soft tissues and the implant surfaces are thoroughly cleansed.
• One-stage revision joint replacement technique is a surgery to remove the infected implant, followed by extensive debridement of the joint tissues and finally, reinsertion of the implant all done in one surgical procedure.
• Two-stage revision joint replacement technique: This technique involves 2 steps: First step involves removal of the infected implant. Antibiotic impregnated fillers are placed into the infected joint area and the wound is closed. This result in immobilization for a considerable period of time till the wound is healed. Second step – Once the infection subsides, a second surgery is planned to remove the fillers and implant a new prosthesis. Rehabilitation will be recommended after surgery.
• Intramedullary arthrodesis: It is the surgical fusion of the infected peri-prosthetic joint bones by inserting a metal rod into the bone marrow. This results in significant loss of motion and possible shortening of the bone.
• Amputation: It is the surgical excision of the affected part of the body to control pain. It is very rare and considered to be the last treatment option.

Prevention:

Infection control measures include:

• Pre and post-surgical antibiotic therapy.
• Short operation time.
• Strictly follow the pre and intraoperative sterilization methods.
• Antibiotic-loaded cement for prosthesis implantation.
• Preoperative screening for pathogenic bacteria.