Infection of an artificial hip or knee joint is one of the most feared complications in endoprosthetics (source 1). It can still occur decades after implantation - and then often entails lengthy and costly treatments with several operations. Therefore, joint prostheses carriers should take any infection and inflammation seriously and seek medical advice if in doubt, recommends the German Society for Endoprosthetics (in German: AE - Deutsche Gesellschaft für Endoprothetik)
The specialist society advises that even small wounds, such as those caused by cutting nails, gardening or playing with pets, should always be disinfected immediately and professionally, and that they should be kept in view throughout the healing process. If symptoms such as redness, swelling of the joint or persistent pain occur, these should be immediately checked by a doctor.
With approximately 440,000 implantations per year, hip and knee prostheses are regarded as safe and highly successful measures to restore freedom from pain and mobility from patients. Nevertheless, about 0.5 to 2 percent of all patients suffer from a periprosthetic infection of their hip or knee joint (source 1). "A colonization with harmful bacteria can occur both in the early phase after the operation and months to years afterward," says Professor Rudolf Ascherl, President of the German Society for Endoprosthetics. The pathogens initially cause inflammation in the implant environment. Later, the prosthesis-bearing bone dissolves. The result is pain and a loosening of the artificial joint.
In addition to periprosthetic infections, implant infections are also caused by the circulation of pathogens in the blood. "These infections, which are spread via the bloodstream, can be triggered by major inflammations such as those of the bladder or lungs," says Professor Karl-Dieter Heller, German Society for Endoprosthetics Vice President. "Other possible causes include bacterial sources such as chronic wounds (e.g. open legs or bed sores), a bloody dental treatment, a colonoscopy in which polyps are removed, or a rather inconspicuous injury during home chores," says Ascherl, who specializes in the treatment of periprosthetic infections.
"If the patient carries other foreign bodies, such as artificial heart valves, which have become infected, these germs can also be carried over to the joint prosthesis. They cannot protect themselves from bacterial colonization (source 2). "That's why bacteria prefer to stick there. Since they can multiply undisturbed on the artificial surface, even relatively few germs are able to trigger a serious infection," said Ascherl explaining the problem.
Within a few days, they begin a slime film forms on the surface of the prostheses. "Bacteria located within this biofilm are protected from attack by antibiotics and the immune system," explains the orthopedic surgeon. "A realistic chance to get the infection under control with antibiotics is therefore only in the first three weeks after the onset of symptoms." This makes it all the more important to initiate treatment quickly.
"Patients with an artificial joint should, therefore, take special care of their body from head to toe throughout their lives," says Ascherl. And he emphasizes: "Pain in the operated joint is always an alarm signal and must be clarified immediately by the doctor."
The demanding treatment of a prosthesis infection requires a great deal of experience. In addition, close cooperation between different disciplines, such as microbiology, infectious diseases, internal medicine or orthopedics, is essential. "That's why it's best to have patients in a specialized center," says Professor Carsten Perka, Secretary-General of the society. However, Ascherl continues, adequate care is underfinanced: "The few centers that still take care of these patients, at least in the specific case of Germany, have annual financing gaps amounting to millions. The president of the society demands that policy-makers urgently work to improve this situation.
1. Müller M et al.: The economic challenge of centralized treatment of patients with periprosthetic infections, Z Orthop Unfall 2018; 156: 407-413; DOI https://doi.org/10.1055/s-0044-100732
2. Flesch, Ingo et al.: Late infection in endoprosthetics, OP-JOURNAL 2017; 33: 142-148; DOI https://doi.org/10.1055/s-0043-102322