QuestionSBA
QuestionChoice
This patient will require admission and intravenous flucloxacillin, although ideally a knee aspiration should be done prior to starting antibiotics if possible, to provide the best chance of growth of any pathogens
33134
b
Intravenous flucloxacillin
QuestionChoice
This patient would warrant a knee x-ray given the examination findings, although it is not the first priority. A joint aspiration followed by intravenous antibiotics must be given first for possible septic arthritis
33137
e
Knee X-ray
QuestionChoice
This patient may benefit from intravenous fluids as he is pyrexial and tachycardic with likely septic arthritis, although it is not the immediate priority. A joint aspiration followed by intravenous antibiotics must be given first
33136
d
Intravenous fluids
QuestionChoice
This patient has presented with an acute, hot, tender, swollen joint with suspicion of septic arthritis. This can destroy joints quickly with irreversible loss of joint function, and so knee aspiration and intravenous antibiotics should be started
33135
c
Discharge with oral flucloxacillin
QuestionChoice
This patient has presented with an acute, hot, tender, swollen joint after a previous soft tissue injury around the knee. This raises concerns for septic arthritis. An urgent knee aspiration must be conducted, ideally prior to starting antibiotics. If there is an unavoidable delay in performing a knee aspiration or the patient is septic, then antibiotics can be given first
33133
a
Knee aspiration
QuestionComment
how do we know he isn't septic?
16876
QuestionComment
It's never too late to quit med and start something else
22557
User
subscriber
Monoclonal Metabolism
User
subscriber
Monoclonal Wilsons
QuestionComment
surely since this guy has a history of trauma, although fracture etc is unlikely, you would want an X-ray before sticking a needle in the joint?
62313
User
subscriber
Positive Whiff Test
Concept
Chapter
# 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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2658
Septic Arthritis
Topic
37
Orthopaedics
6627
Acute, hot, and swollen joints after an injury may suggest septic arthritis, requiring urgent knee aspiration for accurate diagnosis and treatment.
A 65-year-old man has presented with 24 hours of worsening painful swelling of his right knee. He recently fell onto his right side while cycling 3 days earlier, sustaining some grazes on his right leg but no other acute injuries. He has type 2 diabetes but no other medical problems.

On examination, he is pyrexial and tachycardic. His right knee is hot to touch, erythematous, and markedly swollen. There is a reduced range of motion and he is not able to weight bear.

Which of the following is the best next step in the management of this patient?
a