A biomechanical in-vitro study on an alternative fixation technique of the pubic symphysis for open book injuries of the pelvis

Christoph Böhler; Emir Benca; Lena Hirtler; Florian Kolarik; Martin Zalaudek; Winfried Mayr; Reinhard Windhager

doi:10.1016/j.injury.2021.11.050

A biomechanical in-vitro study on an alternative fixation technique of the pubic symphysis for open book injuries of the pelvis

Injury. 2022 Feb;53(2):339-345. doi: 10.1016/j.injury.2021.11.050. Epub 2021 Dec 3.

Authors

Christoph Böhler¹, Emir Benca², Lena Hirtler³, Florian Kolarik², Martin Zalaudek⁴, Winfried Mayr⁵, Reinhard Windhager²

Affiliations

¹ Department of Orthopedics and Trauma Surgery, Medical University of Vienna, Vienna, Austria. Electronic address: christoph.boehler@meduniwien.ac.at.
² Department of Orthopedics and Trauma Surgery, Medical University of Vienna, Vienna, Austria.
³ Division of Anatomy and Cell Biology, Medical University of Vienna, Vienna, Austria.
⁴ Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria.
⁵ Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.

PMID: 34895919
DOI: 10.1016/j.injury.2021.11.050

Abstract

Purpose: Implant failure rates remain high after plate fixation in pelvic ring injuries. The aim of this study was to compare an alternative fixation technique with suture-button devices and anterior plate fixation in partially stable open-book injuries.

Material and methods: We acquired 16 human fresh frozen anatomic pelvic specimens. The sacrospinous, sacrotuberous, and anterior sacroiliac ligaments were bilaterally released, and the pubic symphysis transected to simulate a partially stable open-book (AO/OTA 61-B3.1) injury. The specimens were randomly assigned to the two fixation groups. In the first group two suture-button devices were placed in a criss-crossed position through the symphysis. In second group a six-hole plate with standard 3.5 unlocked bicortical screws was used for fixation. Biomechanical testing was performed on a servo-hydraulic apparatus simulating bilateral stance, as described by Hearn and Varga. Cyclic compression loading with a progressively increasing peak load (0.5 N/cycle) was applied until failure. The failure mode, the load and the number of cycles at failure and the proximal and distal distance of the symphysis during testing were compared.

Results: There was no implant failure in either of the two groups. Failures occurred in nine pelvises (56.2%) at the fixation between the sacrum and the mounting jig and in seven pelvises (43.8%) in the sacroiliac joint. Neither the ultimate load nor the number of cycles at failure differed between the surgical techniques (p = 0.772; p = 0.788, respectively). In the suture button group the mean ultimate load was 874.5 N and the number of cycles at failure was 1907.9. In the plate group values were 826.1 N and 1805.6 cycles, respectively. No significant differences at proximal and distal diastasis of the symphysis were monitored during the whole loading process.

Conclusion: The fixation with suture button implants showed comparable results to anterior plate fixation in open-book injuries of the pelvis.

Keywords: Biomechanics; Fixation technique; Open book injuries; Plate fixation; Suture-button implants.

MeSH terms

Biomechanical Phenomena
Bone Plates
Cadaver
Fracture Fixation, Internal
Humans
Pelvis
Pubic Symphysis* / surgery