Hip Ultrasound and Arthrocentesis

General Info/Intro

Bedside ultrasound can be used to evaluate and diagnose hip effusions when concerned for septic joint. It is both effective in visualizing an effusion and assisting in arthrocentesis.¹ Emergency physicians with ultrasound training have been shown to be capable of visualizing effusions of the hip with a sensitivity between 80-85% and specificity between 98-100%.²

Diagnosis

• Orient curvilinear probe with the indicator toward the patient’s umbilicus (approximately 30 degrees off axis of the femoral shaft)
• Locate femoral head and neck and measure the largest fluid collection
• >5mm effusion or >2mm effusion compared to healthy side = positive finding

Procedure

• Use sterile probe cover and sterile technique
• Orient needle in long axis (parallel to the probe) to visualize the entire shaft during aspiration
• Common labs include cell count with diff, gram stain, and culture (most important)

Recap

• Orient probe marker to umbilicus
• Effusion >5 mm or a difference >2 mm from asymptomatic contralateral side = positive finding

Bottom Line/Pearls & Pitfalls

• No fluid does not necessarily mean a negative septic joint

Figures

Further Reading / References