Arch Hand Microsurg.  2018 Dec;23(4):239-247. 10.12790/ahm.2018.23.4.239.

Reduction Loss after Extension Block Kirschner Wire Fixation for Treatment of Bony Mallet Finger

• Kim B
• Nho JH
• Jung KJ
• Yun K
• Park E
• Park S

• KMID: 2427389
• DOI: http://doi.org/10.12790/ahm.2018.23.4.239

Abstract

PURPOSE
We investigated occurrence of reduction loss after extension block (EB) Kirschner wire fixation or additional interfragmentary fixation (AIF) and clinical results including extension lag of the distal interphalangeal joint for treating bony mallet finger.
METHODS
Forty-six patients were included with a mean follow-up of 28 months (range, 12-54 months). Twenty-seven patients were treated with EB K-wire fixation (Group A) while 19 patients were treated with AIF (Group B). We checked radiologic factors, such as amount of articular involvement, volar subluxation, mallet fragment angle, reduction loss, range of motion including extension lag, and functional outcomes using Crawford's criteria.
RESULTS
Reduction loss occurred in eight patients (17%). Differences in mean extension lag, age, preoperative volar subluxation and mallet fragment angle between patients with reduction loss and those with reduction maintaining were significant. However, there were no significant differences in gender, hand dominance, amount of articular involvement, AIF, or further flexion between reduction loss and reduction maintaining. As for patterns of displacement, there was a significant relationship between gap or step-off and extension lag. Using Crawford's evaluation criteria, functional outcomes were excellent in 31, good in 10, fair in 3, and poor in 2 patients.
CONCLUSION
Reduction loss should be careful in older age, smaller mallet fragment angle and preoperative volar subluxation.

Keyword

Mallet finger; Extension block; Additional interfragmentary fixation; Reduction loss

MeSH Terms

Fingers*
Follow-Up Studies
Hand
Humans
Joints
Range of Motion, Articular

Figure

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  Fig. 1 (A) Step-off was defined as more than 1 mm of displacement in the longitudinal direction. (B) Gap was defined as more than 1 mm of displacement in the anteroposterior direction. (C) Rotation was defined as more than 10 degrees in rotation of the dorsal fragment.

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  Fig. 2 Mallet fragment angle was defined as acute angle between an axis of distal phalanx and a line of fracture.

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  Fig. 3 Intraoperative fluoroscopic image showing that hematoma was removed using 23-G needle when the reduction was unsatisfactory. Satisfactory reduction was then achieved.

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  Fig. 4 (A) Patients of Group A were treated using modified extension block K-wire fixation alone. (B) Group B patients were treated by additional interfragmentary fixation.

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  Fig. 5 (A) Lateral radiograph showing a displaced mallet fracture with joint subluxation in a 22-year-old man (case number 4). (B) A postoperative radiograph showing subtle volar subluxation. (C) The 6-month follow-up radiograph showing a reduction loss with both gap and step off, resulting in volarly subluxation of distal phalanx. At the final follow-up, extension lag of the injured distal interphalangeal joint remained.

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  Fig. 6 (A) Lateral radiograph showing a displaced mallet fracture in a 49-year-old man (case number 5). (B) A postoperative radiograph showing an anatomic reduction. (C) The 6-month follow-up radiograph showing a reduction loss with step off. At the final follow-up, extension lag of the injured distal interphalangeal joint remained.

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