Differential epidural block for definitive diagnosis of snapping hip joint

Snapping hip joint syndrome is defined as snapping phenomenon accompanied by motion of the hip joint. It occurs from various causes, and its diagnosis and treatment are often difficult. We gave anesthesia for surgery against snapping hip joint under patient's active motion for definitive regional diagnosis. Differential epidural block, which precludes pain while maintaining motor function, was performed by 0.25% bupivacaine, 0.5% lidocaine, and additional administration of fentanyl by 25 micrograms. Although the mechanism of differential nerve block remains to be unknown, the case suggests that effective pain block preserving motor function may be achieved by differential epidural block in combination with low concentration of local anesthetics and small dose of opioid.