Journal List > J Korean Soc Surg Hand > v.21(4) > 1106538

J Korean Soc Surg Hand. 2016 Dec;21(4):212-217. Korean.
Published online December 26, 2016.
Copyright © 2016. The Korean Society for Surgery of the Hand
Evaluation of Fragment Reduction Feasibility When Treating Bony Mallet Finger Using Extension Block K-Wire Technique
Ki Ho Lee,1 Seung Hoo Lee,2 Young Ho Lee,2 Min Bom Kim,2 Jihyeong Kim,2 and Goo Hyun Baek2
1Armed Forces Yangju Hospital, Yangju, Korea.
2Department of Orthopaedic Surgery, Seoul National University Hospital, Seoul, Korea.

Correspondence to: Seung Hoo Lee. Department of Orthopaedic Surgery, Seoul National University Hospital, 101 Daehak-ro, Jongno-gu, Seoul 03080, Korea. TEL: +82-2-2072-2368, FAX: +82-2-740-2718, Email:
Received October 18, 2016; Revised November 30, 2016; Accepted December 01, 2016.

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.



The purpose was to evaluate fragment reduction feasilibty when applying extension block Kirschner-wire technique for bony mallet finger.


We treated 48 displaced mallet finger fractures by a two extension block Kirschner-wire technique. Among these operation group, we found dorsal rotation of fragment in 18 cases, making it difficult to get anatomical reduction. The patients were divided into two groups. One group of 30 patients did not show dorsal rotation of fragment and anatomical reduction was achieved easily. Another group of 18 patients showed dorsal rotation of fragment and additional methods was applied to achieve anatomical reduction.


Joint surface involvement was significant greater in groups showing dorsal rotation of fragment than group which did not show (57.1% and 49.7%, respectively) (p=0.01). The groups whose joint surface involvement more than 50% had higher risk of dorsal rotation of fragment than the group less than 50%, with the odds ratio of 6.11.


We could encounter the cases which showed dorsal rotation of the fracture fragment when treating the bony mallet finger with extension block K-wire technique especially the joint surface involvement was more than 50%. So if we can evaluate the extents of joint surface involvement and prepare additional method preoperatively when dorsal rotation of fragment is expected, it is possible to get more favorable results.

Keywords: Mallet fracture; Mallet finger; Extension block; Reduction feasibility; Fragment reduction


Fig. 1
A 24-year-old woman has a bony mallet finger injury of little finger. Intraoperative C-arm image with two extension block K-wire technique10.
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Fig. 2
(A) Bony mallet finger injury showing 42% of joint surface involvement. (B) Anatomical reduction was achieved without dorsal rotation of fragment by two-extension block technique.
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Fig. 3
(A) Bony mallet finger injury showing 51.7% of joint surface involvement. (B) Dorsal rotation of fragment was noted even though two-extension block technique.
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Table 1
Comparison of characteristics and parameters between the group without dorsal rotation and with dorsal rotation
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Table 2
Incidence of dorsal rotation of the fragment according to articular surface involvement
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