Fig. 25.

Bone avulsion. Palmar plate. a, b Sagittal conventional sonograms obtained on the palmar aspect of the proximal inter-phalangeal joint of the third finger in a patient with previous joint sprain. In a, the palmar plate (white arrow) is detached (void arrowhead) from the base of the middle phalanx (MP). Note a fluid effusion (asterisk) inside the palmar proximal joint recess. In a slightly more medial image (b), a cortical fragment (white arrowhead) avulsed from the base (black arrowhead) of the proximal phalanx is evident. US can appreciate both the size of the avulsed fragment and then the entity of the proximal retraction. PP proximal phalanx, FTs flexor digitorum tendons