Pediatric Septic Hip Definition: Bacterial infection of the hip joint space and synovial fluid

Background:

Often limb held in abduction, flexion and external rotation which increases joint space

Look for pain with passive range of motion

Fever (absent in up to 20% of patients)

Salmonella in sickle cell disease ( S. aureus still the most common in this group)

Other agents to consider in specific populations

S. aureus is the most common causative organism across age groups

Though Kocher criteria is the most studied decision tool, it is far from perfect. A Kocher Caird 2006 ) but a positive screen should heighten suspicion

Consider application to pediatric patients with an acute irritable hip where both of these diagnoses are considered

Ideally performed with either fluoroscopy or ultrasound for guidance ( Plumb 2015

Consider aspiration in the OR

Obtain X-rays of hip to assess for alternate pathology (fracture, oseomyelitis, LCP, SCFE) and for presence of effusion

Often, when the decision is difficult, orthopedics will want to know the patient’s response to analgesia

Well appearing child who is ambulating after an NSAID is less concerning for septic arthritis

This is both therapeutic and diagnostic

If US negative but continued suspicion, can obtain MRI

Ultrasound to confirm presence of effusion as absence greatly decreases (but does not eliminate) risk of septic arthritis

In toxic patient with hip pain and fever, treat as sepsis of any other cause

Editor’s Note: While some resources suggest nafcillin as first line, many clinicians opt for vancomycin in all patients since the prevalence of MRSA has increased dramatically in recent years.

Take Home Points

Septic arthritis of the hip can be a difficult diagnosis to make. Consider it in all patients with hip pain or limp and fever.

In toxic appearing patients with hip pain/new inability to bear weight and fever, do not delay orthopedic consultation for imaging or labs. Source control in the OR is paramount.

No single test can rule in or out septic arthritis of the hip. Apply the Kocher criteria to help risk stratify patients but be aware of the limitations of this decision tool.