Anatomic reduction of mallet fractures using extension block and additional intrafocal pinning techniques

Abstract

Background: The purpose of this article is to report the efficacy of the extension block pinning and additional intrafocal pinning technique applied to cases whose mallet fractures were not reduced with extension block pinning alone.

Methods: We retrospectively reviewed 14 digits with 14 patients who were treated with the extension block pinning and additional intrafocal pinning technique. There were eight men and six women with an average age of 34 years. The average articular surface involvement was 52%. The average follow-up was 16 months and the mean time from injury to operation was 23 days.

Results: All the cases achieved anatomic reduction of fractures. By Crawford's classification, 9 were excellent and 5 were good. The average active flexion of the distal interphalangeal joint was 78 degrees and the average extension loss was 1.8 degrees. Bone union was observed in all cases after a postoperative mean of 38.4 days. Complications such as skin necrosis, fracture of bony fragments, and nail-plate deformity were not found.

Conclusions: Additional intrafocal pinning technique is considered a simple and useful method to obtain anatomic reduction of mallet fractures in cases where extension block pinning alone is insufficient to restore the anatomic configuration of the articular surface.

Keywords: Extension block pinning; Intrafocal pinning technique; Mallet fractures.

Fig. 1

A 19-year-old woman presenting with a mallet fracture in the right third finger. (A) A preoperative lateral radiographic finding. (B) An extension block pinning shows incongruent reduction of the distal interphalangeal joint.

Fig. 2

Illustrations for surgical procedures. (A) Under C-arm image intensifier control, a 0.7 mm K-wire was inserted into the fracture site dorsally. (B) K-wire was tilted proximally and was then advanced through the palmar cortical bone. (C) With 30° flexion of the distal interphalangeal joint, a 0.9 mm extension block K-wire was inserted. (D) A 0.9 mm K-wire was inserted to fix the distal interphalangeal joint while the distal phalanx was extended to reduce the fracture fragment.

Fig. 3

A 27-year-old man with a 3-week injury of the left fifth finger. (A) A preoperative lateral radiographic finding demonstrates a displaced mallet fracture and a palmar subluxation of the distal interphalangeal joint in the left fifth finger. (B) A postoperative radiograph demonstrates anatomic reduction. (C) A lateral radiograph taken four months after pin removal demonstrates complete bony union. (D) Full active flexion and extension of the injured distal interphalangeal joint in the left fifth digit were regained at the last follow-up.