Ulnar Slip Flexor Digitorum Superficialis Excision in Trigger Finger Surgery: Anatomic Study

The surgical treatment of trigger fingers may, in some instances, involve partial or complete resection of the flexor digitorum superficialis (FDS) tendon. Examples include continued triggering noted intraoperatively following A1 pulley release, associated proximal interphalangeal joint contractures, and postoperative residual or recurrent mechanical symptoms. Ulnar FDS slip excision in the palm only has been described, yet the anatomic consequences of a single-incision approach are not well quantified. The primary purpose of this cadaveric study is to quantify the residual distal FDS stump length and its relationship to the distal edge of A2 following ulnar slip excision in the palm.

Ulnar FDS slip excision in the palm was performed in 19 cadaveric digits. The length of the residual distal tendon stump was measured, both in absolute length and in relationship to the distal edge of the A2 pulley.

The palm only approach left a mean 26.2 mm (range 20-35 mm) of residual tendon within the sheath. The distance from the cut distal end of the slip to the distal edge of A2 averaged 4.9 mm (range 1-11 mm). On average, the total length of tendon resected from the sheath after A1 pulley release was 22.9 mm (range 18-29 mm). In all instances, Camper's chiasm remained intact, and the excised segment was shorter than the remaining distal tendon. A1 pulley release permitted an additional 7.6 mm (range 5-12 mm) of distal tendon excision.

Isolated FDS tendon slip excision in the palm leaves a substantial residual stump with variable proximity to the distal edge of the A2 pulley. In addition, this approach preserves Camper's chiasm, which has also been implicated as a site of persistent triggering.

Intraoperative assessment for distal triggering after FDS slip excision in the palm only may guide decision making regarding complete FDS slip excision.