[2][3][5] In neonates, infants during the first year of life, and toddlers, the signs and symptoms of septic arthritis can be deceptive and mimic other infectious and non-infectious disorders.

[5] In children, septic arthritis is usually caused by non-specific bacterial infection and commonly hematogenous, i.e., spread through the bloodstream.

[6][7] Septic arthritis and/or acute hematogenous osteomyelitis usually occurs in children with no co-occurring health problems.

Other less common cause include specific bacteria as mycobacterium tuberculosis, viruses, fungi and parasites.

In adults, vulnerable groups include those with an artificial joint, prior arthritis, diabetes and poor immune function.

[5] Among the signs and symptoms of septic arthritis are: acutely swollen, red, painful joint with fever.

This position helps the infant accommodate maximum amount of septic joint fluid with the least tension possible.

The tendency to have multiple joint involvements in septic arthritis of neonates and young children should be closely considered.

[5] In adults, septic arthritis most commonly causes pain, swelling and warmth at the affected joint.

[13] In addition, some treatments for rheumatoid arthritis can also increase a person's risk by causing an immunocompromised state.

[5] The rate of septic arthritis varies from 4 to 29 cases per 100,000 person-years, depending on the underlying medical condition and the joint characteristics.

[13] Most cases of septic arthritis involve only one organism; however, polymicrobial infections can occur, especially after large open injuries to the joint.

[2] Septic arthritis should be considered whenever a person has rapid onset pain in a swollen joint, regardless of fever.

However, white cell count, ESR, and CRP are nonspecific and could be elevated due to infection elsewhere in the body.

[2] CRP more than 20 mg/L and ESR greater than 20 mm/hour together with typical signs and symptoms of septic arthritis should prompt arthrocentesis from the affected joint for synovial fluid examination.

[9] The synovial fluid should be collected before the administration of antibiotics and should be sent for gram stain, culture, leukocyte count with differential, and crystal studies.

More serious and life-threatening disorders as bone malignancies e.g. Ewing sarcoma and osteosarcoma may mimic septic arthritis associated with concurrent acute hematogenous osteomyelitis.

[5][24] In children, joint synovial fluid aspiration techniques aim at isolating the infectious organism by culture and sensitivity analysis.

[2] However, septic synovial fluid can have white blood cell counts as low as a few thousand in the early stages.

[2] While x-rays may not be helpful early in the diagnosis/treatment, they may show subtle increase in joint space and tissue swelling.

Every aspirate should be sent for culture, gram stain, white cell count to monitor the progress of the disease.

[14] The use of prophylactic antibiotics before dental, genitourinary, gastrointestinal procedures to prevent infection of the implant is controversial.

[2] Low-quality evidence suggests that the use of corticosteroids may reduce pain and the number of days of antibiotic treatment in children.

[13] This usually depends on how quickly treatment is started after symptoms occur as longer lasting infections cause more destruction to the joint.

[11][13][14] For those with Staphylococcus aureus septic arthritis, 46 to 50% of the joint function returns after completing antibiotic treatment.

[14] These rates increase depending on the offending organism, advanced age, and comorbidities such as rheumatoid arthritis.

[13][14][15] In children and adolescence septic arthritis and acute hematogenous osteomyelitis occurs in about 1.34 to 82 per 100,000 per annual hospitalization rates.