Partial tear vastus lateralis ultrasound

This long-axis ultrasound image shows a partial tear of the vastus lateralis tendon near the superior-lateral border of the patella. The hypoechoic (dark) area is swelling in the lateral suprapatellar pouch. The curved arrow points to the patella, which appears as a hyperechoic (bright white) curved line. The half-moon is superimposed on intact fibers of the vastus lateralis tendon, which appear as a series of wavy lines. The horizontal arrow points to the classic "stump sign" seen with retracted fibers of the torn vastus lateralis tendon. The tear lies deep to the intact tendon fibers.
Circle: Swelling in suprapatellar pouch.
Curved arrow: Patella.
Half-moon: Intact vastus lateralis tendon fibers.
Arrow: "Stump sign."