How Can I Prevent an Infection after a Knee Replacement?

Purulent infection after artificial joint replacement is a very serious complication. Although the infection rate has fallen from about 10% in the early years to the current 1% to 3%, due to the increasing use of artificial joint replacement, the number of patients with concurrent infections has gradually increased.

Basic Information

Visiting department: orthopedics
Common causes: Nosocomial infection, the most common pathogen is Staphylococcus

Common symptoms: Acute joint swelling, pain, fever
Contagious: no

Causes of joint infections after artificial joint replacement

Infections after artificial joint replacement should be regarded as nosocomial infections, and the pathogenic bacteria are highly resistant. The most common is Staphylococcus, accounting for 70% to 80%. Gram-negative bacilli, anaerobic bacteria, and non-A group streptococci are also common.

Clinical manifestations of joint infections after artificial joint replacement

Most infections occur within a few months after the operation, and can occur as early as two weeks after the operation, and can occur as late as a few years later.

Early manifestations are acute joint swelling, pain, and fever, such as postoperative pneumonia and urinary tract infections. The pain of the infection is even worse at night. It is deep and persistent pain or jumping pain. The symptoms can be relieved after the application of antibiotics. The pain of mechanical loosening of the prosthesis is related to exercise or weight bearing, and it is aggravated by strenuous exercise. It must be clear that the infection is confined to superficial tissues or deep into the joints. If the wound drainage is purulent and does not respond to antibiotic treatment, deep infections surrounding the prosthesis must be considered.

Late infections are often painless. Some patients have fever, and the number of white blood cells in peripheral blood increases in 10% of patients.

Examination of joint infection after artificial joint replacement

Diagnostic puncture is necessary. If the conventional culture of tissue or synovial fluid is negative, and a high degree of suspicion of infection is required, special culture techniques are required. The growth of anaerobic bacteria requires complex nutrition.

1. X-ray inspection

Ordinary X-rays can only be reflected after a few weeks or months of infection. X-ray translucent bands are formed between bone and bone cement, cortical edges are thin, and the periosteum response is lamellar, with increased bone density and translucent areas. It must be compared with previous radiographs to detect early changes.

2. Intra-articular angiography

Can show the outline of the joint cavity, as well as the location and extent of the infection, if the sinus has reached the skin surface. Can be used for sinusography to assist diagnosis.

3. Radionuclide scintigraphy

^{The uptake of 99m} Tc and ⁶⁷ Ga citrate can help diagnosis, but ^99m Tc is not specific, and ⁶⁷ Ga citrate is only moderately specific.

Differential diagnosis of joint infections after artificial joint replacement

1. Fever symptoms must be distinguished from other complications.

2. Persistent joint pain must be distinguished from pain caused by mechanical loosening of the prosthesis.

3. Painless artificial joint infection caused by Staphylococcus epidermidis is more difficult to distinguish from loosening of the prosthesis. This must be confirmed by X-rays and other inspections.

Complications of joint infection after artificial joint replacement

May be accompanied by loosening of the prosthesis.

Treatment of joint infections after artificial joint replacement

1. Use effective antibiotics based on bacterial culture and sensitivity experiments. If joint replacement surgery is needed, antibiotics should be used for 6 to 12 weeks before surgery.

2. Surgical treatment of patients with early infection should remove infected hematoma, remove infected tissue, place irrigation suction tube, and continue irrigation and suction. However, infection often affects the tissue surrounding the prosthesis, and the retention rate of the prosthesis is less than 20%. After the above treatments cannot control infection and delayed infection, the prosthesis and bone cement are generally removed. After the infection is completely eliminated, arthroplasty is performed after about 1 year, and osteotomy can also be used to improve the patient's gait.