Causes of Procedural Failures of Closed Reductions using an Extension-Block Pin for Bony Mallet Finger

Abstract

This retrospective study evaluated procedural failures of closed reductions using an extension-block Kirschner wire (K-wire) for bony mallet finger. A total of 132 patients who underwent a closed reduction for bony mallet finger in a procedure using an extension-block K-wire were radiographically assessed. Radiographs were used to evaluate (1) postoperative displacement of the reduction before or after K-wire removal and (2) inaccurate reduction of the fragment immediately after surgery. The causes of procedural failure and bone union were evaluated using radiographs and medical records of the intraoperative findings. Out of 132 patients, 17 with procedural failure were enrolled. Displacement of the reduction before and after K-wire removal occurred in seven and six cases, respectively. Inaccurate reduction immediately after surgery occurred in four cases. The most common cause of procedural failure was inaccurate insertion of the K-wire to fix the distal interphalangeal joint (eight cases) followed by inaccurate insertion of the extension-block pin (five cases). All patients had bone union regardless of the displacement of the reduction or inaccurate reduction of the fragment. Caution should be exercised during the reduction and fixation when an extension-block K-wire is used in a closed reduction procedure.

Keywords: bony mallet finger; displacement of the reduction; mallet finger; postoperative displacement; procedural failure.

Fig. 1

( A ) The Kirschner wire was inserted in close proximity to the fracture site. ( B ) Displacement of the volar fragment.

Fig. 2

( A ) Extension-block pin shown deviating from the center of the head of the proximal phalanx. ( B ) Sufficient compression was not applied to the fragment.

Fig. 3

( A ) Displacement of the reduction after Kirschner wire (K-wire) removal. ( B ) Two months after K-wire removal. ( C ) Bone union at 6 months after K-wire removal. ( D ) Twelve months after K-wire removal.

Fig. 4

A longitudinal line drawn along the axis of the middle phalanx helps the surgeon to insert accurately the Kirschner wire into the center of the middle phalanx.