QuestionSBA
QuestionChoice
Whilst it is important to obtain samples for microbiology to determine whether the knee is the source of infection and help guide antimicrobial therapy in a joint containing a prosthesis, this is best undertaken in the theatre environment. In suspected septic joints where there is no prosthesis involved, it would be reasonable to undertake aspiration in an aseptic manner in the ward or the Emergency Department prior to starting antibiotics
32634
b
Aspiration of the joint on the ward
QuestionChoice
This patient remains unwell despite broad-spectrum antibiotics. As a prosthesis is involved, he will likely need a surgical washout of the joint in theatres and may even need removal of the prosthesis to control his sepsis. Samples should be taken intraoperatively for microbiology. Aspiration of a septic joint where there is a prosthesis should never be undertaken outside of the sterile theatre environment, as by performing the aspiration, you run the risk of introducing infection
32633
a
Surgical washout
QuestionChoice
A PCA may be of benefit in helping this patient with his pain; however, it would not help treat the underlying cause of his illness and therefore is not the next step in the management of his sepsis
32636
d
Start a patient controlled analgesia (PCA)
QuestionChoice
It may be worth speaking to the microbiologists and changing the antibiotics to a different combination; however, it would be difficult for them to provide advice without a causative organism or confirmed diagnosis. As this patient has been on broad-spectrum antibiotics for 48 hours and is not improving, it is important to get source control of his sepsis, and this is best done by a washout in theatres
32635
c
Change antibiotics
QuestionChoice
A CT of the knee would be beneficial if you were trying to determine whether there was osteomyelitis or bone involvement which would be a more chronic infection. Also, as this patient has had a recent prosthesis made of metal, there would likely be a significant artefact from this. So imaging would unlikely move you forward in management
32637
e
CT of the knee
QuestionComment
Would you not give analgesia first then do the washout straight after?
22269
QuestionComment
If you're taking them to be anaesthetised you probably wouldn't bother with analgesia before 
23598
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lil' aneurysm
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Monoclonal Gas
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# Summary

Septic arthritis is an infection of the joint characterized by acute inflammation and swelling. It is caused by a bacterial or viral pathogen that infects the synovial fluid. The most commonly implicated organism is Staphylococcus aureus. Noteworthy clinical signs include a tender, swollen joint with reduced mobility, often accompanied by systemic illness. Key investigations include joint aspiration for Microscopy Culture and Sensitivity, along with blood tests showing increased white blood cell count and elevated ESR/CRP. Management typically involves IV antibiotics, joint washout under general anaesthesia, and physiotherapy once the acute infection has resolved.

# Definition

Septic arthritis is an infection of the joint, specifically the synovial fluid. It is typically caused by a bacterial or viral pathogen and necessitates prompt medical intervention due to the high risk of joint damage and other severe complications.

# Epidemiology

Septic arthritis has an annual incidence of 4-10 cases per 100,000 patients in Western Europe. It can affect individuals of any age, though certain populations are at a higher risk due to underlying conditions.

# Aetiology

The most prevalent organism implicated in septic arthritis is Staphylococcus aureus. Other responsible organisms include:

-   Gonococcus: primarily in sexually active individuals
-   Streptococcus spp.
-   Gram-negative bacilli

Risk factors contributing to septic arthritis include:

-   Pre-existing joint diseases such as rheumatoid arthritis
-   Chronic kidney disease
-   Immunosuppressive states
-   Presence of prosthetic joints

# Signs and Symptoms

The clinical presentation of septic arthritis usually involves:

-   Acute onset of tender, swollen joint
-   Reduced range of joint movement
-   Systemic symptoms such as fever, malaise, or chills

# Differential Diagnosis

Differential diagnoses for septic arthritis include:

-   Gout and pseudogout: characterized by intense joint pain, redness, and swelling, often in the big toe or knee.
-   Osteoarthritis: presents with joint pain, stiffness, and sometimes swelling, generally improving with movement.
-   Rheumatoid arthritis: marked by joint pain, swelling, and stiffness, often symmetrical and worse after rest.
-   Lyme disease: may show erythema migrans rash, flu-like symptoms, and possibly migratory joint pains.

# Investigations

Diagnostic investigations for septic arthritis include:

-   Joint aspiration for Microscopy, Culture, and Sensitivity: The aspirate usually appears turbid and yellow, resembling pus.
-   Blood tests: elevated white cell count, high ESR/CRP
-   Blood cultures: to identify causative organisms
-   Imaging: X-ray of the joint may be performed to evaluate for osteomyelitis or other complications.

# Management

The treatment of septic arthritis involves:

-   IV antibiotics guided by local antibiograms and susceptibilities
-   Consideration of joint washout under general anaesthesia to remove infected material
-   Physiotherapy following the resolution of acute infection to restore joint function

Complications of septic arthritis can include:

-   Osteomyelitis: infection of the bone
-   Chronic arthritis: persistent joint inflammation
-   Ankylosis: joint fusion resulting in immobility

# References

[Click here for the BNF Treatment Summary for Musculoskeletal infections](https://bnf.nice.org.uk/treatment-summary/musculoskeletal-system-infections-antibacterial-therapy.html)

[Click here for the BMJ Best Practice Summary of Septic Arthritis](https://bestpractice.bmj.com/topics/en-us/486)
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Septic Arthritis
Topic
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Orthopaedics
6527
In cases of septic arthritis involving a prosthesis, surgical washout is essential if symptoms persist despite broad-spectrum antibiotics.
A 63-year-old male has been admitted to hospital with sepsis following a recent total knee replacement. His knee is red, hot and swollen, and so he is started on broad-spectrum antibiotics. After 48 hours, he is still pyrexial, in significant pain, and his inflammatory markers continue to rise.

What is the next step in management?
a