An unusual cause of A2 pulley rupture in a 49-year-old man.

A 49-year-old man presented to his family physician with pain in the third finger that occurred after he tried to grasp a falling heavy object. His finger was forcefully extended from a semi-flexed position. On clinical examination extension was normal. However, flexion was slightly limited and extremely painful at the end point of flexion. Ultrasound of the finger was performed and showed that the flexor tendons at the level of the proximal phalanx were at an abnormally increased distance from the bone (Fig. A, B). Both the superficial and deep flexor were also markedly thickened. The normal slips at the side of the tendon representing the A2 pulley were replaced by a heterogeneous mainly hypoechoic area. Fluid was seen deep to the tendons in between the latter and the bone. MR imaging was performed using a dedicated wrist coil on 3 T (Fig. C-D). On transverse and sagittal proton density weighted images the flexor tendons were seen to be located at some distance from the bone at the midlevel of the proximal phalanx. The ulnar attachment of the A2 pulley could not be visualized, and the radial attachment was thickened, elongated and exhibited high signal intensity on the transverse images. Fluid sensitive sequences showed fluid in the synovial sheath and also in between the tendons and the bone.