Septic arthritis and its aetiopathogenesis

Hello students and friends, today we are going to learn what is septic arthritis, its aetiopathogenesis, symptoms, diagnosis, treatment, and complications.

Firstly we have to know the meaning of septic and arthritis.

Septic: sepsis is a term that generally refers to a severe infection that transmits via the bloodstream.

Arthritis: swelling and pain in the joints.

Now let's discuss what is septic arthritis?

Septic arthritis is caused by pyogenic organisms that is why it is also termed as pyogenic arthritis, infective arthritis(as there is an infection in a joint through the bloodstream), or supportive arthritis.

There is a painful infection in the joint which is typically acute at present, but it may present as sub-acute or chronic arthritis.

Commonest joint affected- Knee joint is more prone.

Other joints- Hip joint, shoulder joint, Elbow joint.

Aetipathogenesis

• Males>Females.
• Commonly children are affected.
• Staphylococcus aureus is the commonest causative organism.

Other organisms are:

1. Streptococcus pneumococcus
2. Gonococcus.

Other predisposing factors are:

1. Poor hygiene
2. Diabetes
3. Poor resistance

• Infants and elderly ones are at higher risk of developing septic arthritis.
• Septic arthritis can also occur due to any injury through which germs enter into the joint.
• The organisms will follow any of the following routes to reach the joint and cause septic arthritis-

Hematogenous route

• It is the commonest route.
• Infection is caused in the form of pyoderma, septicemia, throat infection, etc.

Penetrating wound

• By penetrating any cut wound organism may enter and cause septic arthritis.
• Commonly knee joint is affected.

Iatrogenic

• Infection may cause during femoral artery puncture or by intra-articular steroid injection used in different arthritis.

Umbilical cord sepsis

• Sepsis in infants.
• When sepsis occurs in the umbilical cord it can travel to the joints.

~When organisms reach the joint by following any of the above routes, there is an inflammatory response generated in the synovium which results in the exudation of fluid within the joint.
~In joint exudate, inflammatory granulation tissue, and lysosomal enzymes are present which destroys the joint cartilage.
~As joint cartilage is destroyed and exudation of joint fluid is caused, at the latter stage there is a complete loss of movement in the joints(ankylosis).

Symptoms

1. Swelling in the joint
2. The joint area becomes red and warm
3. Fever
4. Discomfort
5. Difficulty in using affected limb.

Diagnosis

Diagnosis in an early stage is important for improvement in joints.

1. Physical examination

A child with acute septic arthritis shows the following symptoms-

1.  Swelling
2. Redness
3. Acute septic arthritis is associated with high-grade fever and malaise.
4. Difficulty in using affected limb.
5. Throbbing pain.

A child with subacute septic arthritis shows the following symptoms-

1. A child does not allow anybody to touch the joint.
2. The movement of the joint is improper.
3. Painful limps in the lower limb can be noticed.
4. Some amount of joint movement is possible.

By palpating the joint we can diagnose high temperature around the joint, tenderness, and effusion.

When any active or passive movement is initiated, there is severe pain and muscle spasm is seen.

2. Radiological examination

1. X-ray- It helps in the diagnosis of joint spaces and soft tissue shadow corresponding to the distended capsule due to swelling of the joint.
2. Ultrasound- It helps in detecting deep joints like the shoulder and hip joint.

3. Blood test

1. The blood test shows neutrophilic leucocytes.
2. Erythrocyte sedimentation rate is markedly elevated in the case of septic arthritis.

4. Joint aspiration

1. It is the fastest and best method for the diagnosis of septic arthritis.
2. The fluid which is aspirated through the joint shows features of acute septic inflammation.
3. Till one gets the culture reports, gram staining is done to provide clues to the type of organism.

Treatment

In early-stage

• By parenteral route, a broad spectrum of antibiotics is administered.
• A combination of Cefratriaxone and cloxacillin is given in an appropriate dose.
• As per sensitivity reports and aspirate culture, medications are subsequently changed.
• The joint must be at rest by using a splint or traction.
• Whenever pus is aspirated through the joint(arthrotomy) or fluid is aspirated arthroscopically for culture or investigation, the joint must be washed and closed with a suction drain.
• As the inflammation is controlled in an early stage, the patients improve and the joint is then gradually mobilized.

In late-stage

• The joint doesn't move.
• In such cases, after an arthrotomy and extensive debridement of the joint, the joint is immobilized in the position of optimum function.
• By immobilizing, the disease heals and ankylosis occurs in that position.

Complications

1. Pathological dislocation of the joint.
2. Osteoarthritis
3. Deformity and stiffness in the joint.

Hope you all find this helpful for you, if you have any query related to this topic or any other topic then you all are free to contact me via contact us or you can also ask your doubts on the comment box. Thank you! 

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