Ultrasound visualization of central slip injuries of the finger extensor mechanism

To evaluate the ability of ultrasound to detect a central tear of the finger extensor tendon mechanism.

Twelve fresh-frozen and thawed cadaver fingers were used. All fingers had a midradial incision with exposure of the extensor mechanism over the proximal interphalangeal joint. Six fingers had a sharp transection of the central slip. The other 6 fingers were used as sham dissection controls. All fingers had the exposure closed by suture and then were examined by a musculoskeletal ultrasonographer.

All 12 fingers were identified correctly as either sham controls with intact central slips or as injury models that had a transected central slip. Thus there was a sensitivity of 100% a specificity of 100%, and a positive predictive value of 1.000, which were statistically significant.

Diagnostic ultrasound is a very accurate noninvasive study that can identify central slip injuries in the extensor mechanism of the finger. We recommend that clinically suspected cases of boutonniere injury be scanned by high-frequency ultrasound to confirm the diagnosis and allow either early initiation of splinting or eliminate the need for prolonged splinting required for this injury.