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Bone Joint J. 2019 Oct;101-B(10):1263-1271. doi: 10.1302/0301-620X.101B10.BJJ-2019-0410.R1.

Single versus dual Kirschner wires for closed reduction and intramedullary nailing of displaced fractures of the fifth metacarpal neck (1-2 KiWi): a randomized controlled trial.

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Department of Hand, Replantation and Microsurgery, BG Klinikum Unfallkrankenhaus Berlin gGmbH, Berlin, Germany.
Department of Trauma, Reconstructive Surgery and Rehabilitative Medicine, University Medicine Greifswald, Greifswald, Germany.
Centre for Clinical Research, BG Klinikum Unfallkrankenhaus Berlin gGmbH, Berlin, Germany.
Burn Centre and Department of Plastic Surgery, BG Klinikum Unfallkrankenhaus Berlin gGmbH, Berlin, Germany.
Department of Research, Business Division Medicine, BG Kliniken - Klinikverbund der gesetzlichen Unfallversicherung gGmbH, Berlin, Germany.



The aim of this study was to investigate whether clinical and radiological outcomes after intramedullary nailing of displaced fractures of the fifth metacarpal neck using a single thick Kirschner wire (K-wire) are noninferior to those of technically more demanding fixation with two thinner dual wires.


This was a multicentre, parallel group, randomized controlled noninferiority trial conducted at 12 tertiary trauma centres in Germany. A total of 290 patients with acute displaced fractures of the fifth metacarpal neck were randomized to either intramedullary single-wire (n = 146) or dual-wire fixation (n = 144). The primary outcome was the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire six months after surgery, with a third of the minimal clinically important difference (MCID) used as the noninferiority threshold. Secondary outcomes were pain, health-related quality of life (EuroQol five-dimensional questionnaire (EQ-5D)), radiological measures, functional deficits, and complications.


Overall, 151/290 of patients (52%) completed the six months of follow-up, leaving 83 patients in the single-wire group and 68 patients in the dual-wire group. In the modified intention-to-treat analysis set, mean DASH scores six months after surgery were 3.8 (sd 7.0) and 4.4 (sd 9.4), respectively. With multiple imputation (n = 288), mean DASH scores were estimated at 6.3 (sd 8.7) and 7.0 (sd 10.0). Upper (1 - 2α)) confidence limits consistently remained below the noninferiority margin of 3.0 points in the DASH instrument. While there was a statistically nonsignificant trend towards a higher rate of shortening and rotational malalignment in the single wire group, no statistically significant differences were observed across groups in any secondary outcome measure.


A single thick K-wire is sufficient for intramedullary fixation of acute displaced subcapital fractures of the fifth metacarpal neck. The less technically demanding single-wire technique produces noninferior clinical and radiological outcomes compared with the dual-wire approach. Cite this article: Bone Joint J 2019;101-B:1263-1271.


Boxers fracture; Hand surgery; Metacarpal neck fracture; Randomized trial

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