infizierte Hüftprothesen
Prosthetic hip infections are one of the most severe complications of total hip arthroplasties.
Epidemiology
Prosthetic hip infections complicate around 0.57% of total hip arthroplasties .
Risk factors
Risk factors for prosthetic hip infections can be separated into pre-operative and post-operative risk factors.
Pre-operative risk factors may include:
- existing underlying infection
- previous local surgery
Post-operative risk factors may include:
- immunosuppression
- immunosuppressive drugs
- immunosuppressive conditions, e.g. poorly controlled diabetes mellitus, HIV, malnutrition
- inflammatory arthropathies
- lifestyle factors
- obesity
- intravenous drug use
- alcoholism
- smoking
Clinical presentation
- pain at the site of the arthroplasty
- stiffness of the prosthetic joint
- swelling around the site
- overlying skin redness
- tenderness
Pathology
The main methods by which a prosthetic joint can become infected are:
- directly during implantation
- haematogenous spread
- reactivation of a latent infection
The most common causative micro-organisms are Gram-positive bacteria, including Staphylococcus aureus, Staphylococcus epidermidis and coagulase-negative Staphylococcus. Infections may also be caused by fungi such as Candida .
Radiographic features
Plain radiograph
Plain radiographs are the main imaging method utilized in diagnosis of prosthetic joint infections. Signs that may be seen include:
- periosteal reaction
- wide band of radiolucency at the cement-bone or metal-bone interface
- patchy osteolysis
- implant loosening
- bone resorption around the implant
- transcortical sinus tracts
CT
CT is useful in helping to distinguish between septic and aseptic loosening of the joint .
Nuclear medicine
Bone scintigraphy (Tc-99m)
Bone scintigraphy is a highly sensitive method for diagnosing prosthetic joint infections, but it is not very specific, as increased periprosthetic bone activity can be due to a variety of causes .
PET
The use of PET in prosthetic joint infections is a relatively novel application. FDG-PET is thought to be highly sensitive and specific for diagnosis infection in hip prostheses, and may aid pre-operative planning .
Treatment and prognosis
Orthopedic surgery is indicated in most cases, unless the patient is not fit for surgery. Surgical options include:
- polyethylene exchange with component retention and intravenous antibiotic therapy
- one-stage replacement arthroplasty
- two-stage replacement arthroplasty
- resection arthroplasty
In very severe cases, amputation may be necessary.