Infection of joint prostheses: why does it occur?

Infection of joint prostheses is a comparatively frequent complication following joint replacements. Prosthesis placement is a really widespread surgery nowadays, which helps to treat quite a few pathologies related to the bone apparatus.

Many of the cases involve hip or knee prostheses. Although they’re procedures with excellent results, they’ll have complications, as with some other surgical technique. Why does this infection occur? What are its symptoms? Below, we’ll answer these questions.

What’s joint prosthesis infection?

Joint prosthesis infection can also be often called ‘periprosthetic infection’. It’s a complication that compromises each the joint alternative area and the adjoining tissues.

Arthroplasty is the medical name for this procedure. In accordance with information from the Clínica Universidad de Navarra, around 30,000 interventions of this sort are performed in Spain yearly. This can be a secure procedure that, generally, produces a notable improvement within the patient’s quality of life.

The joints more than likely to get replaced by a prosthesis are the hip and the knee.

Even so, as stated in a publication in Clinical Microbiology Reviews, a minority of patients will experience device failure and require additional surgery sooner or later of their lives. It’s estimated that 2-4% of arthroplasty cases end in infection.

The large problem is that it might cause other serious complications, in addition to high costs to the healthcare system. In itself, it’s normally attributable to the patient’s own bacteria, which form a gelatinous matrix on the prosthesis.

What happens is that these microorganisms adhere to the surface of the prosthesis. Once there, they multiply and provides rise to this matrix, which known as a biofilm. This can be a mechanism that defends them from the motion of antibiotics, making them more immune to treatment.

Why can joint prosthesis infection occur?

Infection of joint prostheses might be attributable to several types of bacteria. As we’ve got identified, they adhere to the prosthesis and form a biofilm. To do that, they organize themselves in layers, one on top of the opposite. This explains why those present in the deeper layers are more immune to antibiotics.

Nonetheless, the prosthesis itself also alters the function of certain cells of the immune system, akin to phagocytes. All these aspects favor the progression of the infection and make it difficult to treat.

The bacteria normally involved are staphylococci. Inside this group, probably the most frequent microorganisms are Staphylococcus aureus and Staphylococcus epidermidis. Other agents involved are the next:

• Escherichia coli
• Pseudomonas aeruginosa
• Enterococcus spp

It may be a polymicrobial infection. That’s, it could be attributable to a couple of bacterium. Fungal infections are less frequent.

Kinds of infection

Infection of joint prostheses is generally classified in line with the time of evolution. Some authors distinguish between acute and chronic infection. Nonetheless, as explained within the Prioam Guide, it might even be classified as follows

• Early postoperative infection (PPI)
• Late chronic infection (LCI)
• Acute hematogenous infection (AHI)

Those that only distinguish between acute and chronic infection include acute hematogenous infection in the primary group.

Early postsurgical infection or acute infection

Early postsurgical infection is that which occurs in the primary month after prosthesis placement. Some consider that it’s still considered acute infection up to 3 months after surgery.

There are a series of criteria that help to discover such a joint prosthesis infection. There is generally dehiscence and suppuration of the surgical wound. As well as, when fluid is faraway from the joint and examined within the laboratory, the presence of bacteria is commonly detected.

In these cases, early diagnosis and treatment are vital. In this fashion, the necessity to switch the prosthesis attributable to infection might be avoided.

Acute hematogenous infection

Acute hematogenous infection occurs when the main focus of infection is elsewhere within the body. In other words, the bacteria can come from one other process akin to pneumonia, urinary tract infection, endocarditis, etcetera. What happens is that they’re mobilized with the blood and find yourself colonizing the prosthesis.

Infection of an articular prosthesis of chronic type

A chronic infection is generally considered when three months have passed from the position of the prosthesis. It’s more complicated to treat than acute ones, since the bacterial biofilm has matured and can’t be removed.

This condition evolves progressively and insidiously. Pain persists for months, although there aren’t any clear signs of infection or fever. In some cases, abscesses and fistulas could also be present. In these cases, alternative of the prosthesis is generally vital.

Associated symptoms

The symptoms of joint prosthesis infection vary depending on whether or not they are acute or chronic. It’s vital to notice that about half of the cases are chronic. Subsequently, one in every of the predominant symptoms is inflammatory pain.

The issue is that arthroplasties could cause pain without necessarily causing infection. Hence, it’s sometimes difficult to achieve an accurate diagnosis. Along with pain, there could also be an absence of functionality in the joint.

In cases of acute infection, patients normally present fever. The surgical wound doesn’t heal properly and there could also be oozing of purulent material through the wound. The world is generally swollen, warm, and red.

How is joint alternative infection diagnosed?

The diagnosis of such a infection ought to be made early. This prevents the infection from becoming chronic and the operation from having to be repeated. In an effort to achieve this, it’s vital to observe the patient properly and to be attentive to any warning signs.

Nonetheless, there are quite a lot of complementary tests that may help within the diagnosis. Considered one of these is positron emission tomography. This can be a technique that uses a glucose tracer. This molecule is captured by the bacteria causing the infection.

Thus, via the scan, the areas where the bacteria are situated might be appreciated. Other useful tests are synovial fluid evaluation and blood tests. Ultrasounds and X-rays can be useful.

Available treatments

Infection of joint replacements requires multidisciplinary treatment. In all sorts, medical and surgical procedure is generally combined. The medical treatment is predicated on reducing pain and administering specific antibiotics to cure the infection.

Surgery might be used to wash and debride the tissues. In cases where the infection is chronic, prosthesis alternative is prone to be required. This might be done as a one-stage or two-stage procedure.

That’s, the brand new prosthesis might be placed in the identical surgery. The 2-stage option involves removing the prosthesis, cleansing the world, and placing a spacer containing antibiotics. Then, in one other operation, the brand new prosthesis is placed.

In an effort to establish antibiotic treatment, it’s really helpful to first discover the causative germ and its sensitivity to those drugs. The duration of treatment might be long. In some cases, akin to knee prostheses, six months of treatment could also be really helpful.

Remember: An infection of joint prostheses might be serious

Although this isn’t a quite common complication, an infection of prostheses may be very feared by surgeons. It is because in some cases it requires further surgery and alternative of the prosthesis.

It’s vital for patients to concentrate on the signs and symptoms with the intention to have the ability to discover an infection early. As well as, physicians should make the diagnosis as quickly as possible, as this reduces the likelihood of needing to operate again.

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