Psoas abscess is a purulent collection within the psoas muscle, usually spreading from spinal, urinary, or gastrointestinal infections. Clinical presentation is often insidious and easily missed: “Flank” or lower-back painDull, persistent ache that radiates to the anterior hip or groin; movement, walking, or hip extension markedly worsens the pain. Flexion contracture of the hipInvoluntary flexion and external rotation relieve tension on the psoas sheath, so patients walk with a limp or cannot fully straighten the leg. Palpable or visible massA tender, sausage-shaped swelling may be felt below the inguinal ligament or in the lateral flank, especially if the abscess is... Learn more