SCIENTIFIC ARTICLE Plate Osteosynthesis of Proximal Ulna Fractures—A Biomechanical Micromotion Analysis Michael Hackl, MD, *†‡ Katharina Mayer,§ Mareike Weber,§ Manfred Staat, PhD,§ Roger van Riet, MD, PhD,k Klaus Josef Burkhart, MD, PhD,{ Lars Peter Müller, MD, PhD, *† Kilian Wegmann, MD, PhD*† Purpose Double plating has been promoted, in recent years, as an alternative treatment method for proximal ulna fractures. This study aimed to compare the biomechanical properties of double-plate osteosynthesis with posterior plate fixation using a novel investigational design utilizing a 3-dimensional camera system to analyze fracture micromotion. Methods Fourteen fresh-frozen specimens were available for this study. Mayo type IIA fractures of the olecranon were created and internal fixation was performed with either an angular stable posterior plate or angular stable double plates. Fracture micromotion was evaluated by means of digital image correlation with a 3-dimensional camera system before and after dynamic cyclic loading from 15  to 90  of elbow flexion with a pulling force of 25 N to 80 N. Results Micromotion of fragments was less pronounced in double-plate osteosynthesis when compared with single plates before and after cyclic loading. However, overall results were similar. Two of the single plates failed during cyclic loading but there were no failures in the double plates. Conclusions This biomechanical analysis shows that single and double plating results in comparable stability of fixation. Although the double-plating technique tends to provide more stable fixation, relevant differences were not observed. Clinical relevance Double plating potentially represents an efficient option for fixation of proximal ulna fractures. It could decrease the risk of soft tissue complications owing to their low profile and the superior soft tissue coverage. (J Hand Surg Am. 2017;-(-):1.e1-e7. Copyright Ó 2017 by the American Society for Surgery of the Hand. All rights reserved.) Key words Proximal ulna, olecranon, fracture, double plating, posterior plating. O PEN REDUCTION AND INTERNAL fixation is indi- cated in most proximal ulna fractures. 1e3 Tension band wiring is most commonly used for noncomminuted olecranon fractures. 3 In cases of fracture comminution or involvement of the proximal ulnar shaft, most surgeons recommend plate fixation. 3e5 Precontoured plates have become popular in recent years, but most of the currently available plates fail to reproduce the complex anatomy of the proximal ulna and thus might lead to poor reduction. 6e9 The biggest From the *Center for Orthopedic and Trauma Surgery, University Medical Center of Cologne; the †Cologne Center for Musculoskeletal Biomechanics, Medical Faculty; the ‡Institute of Anatomy I, University of Cologne, Cologne; the §Institute of Bioengineering, Aachen University of Applied Sciences, Jülich; the {Department of Shoulder and Elbow Surgery, ARCUS Sportklinik, Pforzheim, Germany; and the kDepartment of Orthopedic Surgery, Monica Hospital, Antwerp, Belgium. Received for publication August 5, 2016; accepted in revised form May 15, 2017. Medartis and Stryker provided the implants used in this study. K.J.B., L.P.M. and K.W. are consultants for Medartis. R.V.R. is a consultant for Acumed. The rest of the authors declare that they have no relevant conflicts of interest. Corresponding author: Michael Hackl, MD, Center for Orthopedic and Trauma Surgery, University Medical Center of Cologne, Kerpener Straße 62, D-50937 Cologne, Germany; e-mail: michaelhackl@live.de. 0363-5023/17/---0001$36.00/0 http://dx.doi.org/10.1016/j.jhsa.2017.05.014 Ó 2017 ASSH r Published by Elsevier, Inc. All rights reserved. r 1.e1