High resolution sonography of the flexor tendons in trigger fingers.

A sonographic study was conducted to analyze changes of the flexor tendons in patients with trigger fingers. We evaluated thickness and echotexture of the flexor tendons of the fingers in 54 patients with 66 symptomatic digits using 10 and 13 MHz "small parts" transducers; the results were compared with those observed in 20 normal controls. Images were obtained on the volar surface of the hand, at the head of metacarpals, and at the base of first phalanx, where the first annular pulley of the digital canal is located and where the changes occurring during passive assisted extension of the fingers were evaluated. Normal tendons were 2.9 to 4.4 mm thick (mean, 3.71 +/- 0.46) and had fibrillar echotexture. Patients had tendons ranging from 3.8 to 6.7 mm (mean, 5.41 +/- 0.94); the difference from controls was highly significant (P < 0.001). A cyst was attached on the volar surface of the involved tendons in 15 cases. Diffuse thickening of the synovial sheath was present in 20 tendons, whereas 17 tendons had irregular internal echotexture. Extension movements caused changes in shape of both cysts and peritendinous envelopes. In conclusion, sonography seems able to identify a variety of pathologic changes affecting tendons in these patients and may help both to explain the pathophysiology of their clinical situation and guide therapeutic decisions.