A novel omnidirectional tin-alloyed ring retractor for craniotomy in neurosurgery: technical note

  • Bikei RyuEmail author
  • Shinsuke Sato
  • Tatsuya Inoue
  • Takakazu Kawamata
  • Yoshikazu Okada
Technical Note


In neurosurgical operations, proper craniotomy using retractors is necessary. Various surgical instruments are used for this purpose, including standard retractors and multipurpose head frame retractor systems. However, the conventional multipurpose head frame system is often not optimal for use in some craniotomies and postures because of its size and complexity of setting. We have invented a new omnidirectional tin-alloyed (ODT) ring retractor for craniotomy with malleability and shape memory characteristics to resolve these issues. It is principally elliptical in shape, approximately 30 × 20 cm in diameter, and sufficiently firm. Accordingly, this ODT ring can retract the surgical field in all directions. Here, we report our experiences of 281 neurosurgical craniotomies using this ODT ring retractor system in various craniotomy sites and postures. Our novel ODT ring retractor is useful because of its low profile, multidirectional retractability, and less obstructiveness with its malleability. It could be used with pediatric patients where strong traction is not desirable.


Device Omnidirectional Retractor Technique Craniotomy Neurosurgery 



All the authors have approved the manuscript and agree with submission to your esteemed journal. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. We thank our operating room staff at St. Luke’s Medical University for their best work and cooperation. We also thank Editage ( for English language editing.

Author contributions

Y.O. initiated the project and invented the device presented in this manuscript. B.R., S. S., T.I., K.K., and Y.O. were involved in the design of experiments. B.R., S. S., T.I., and Y.O conducted experiments and analyzed data. B.R. and Y.O. wrote the manuscript. All authors discussed the results and commented on the paper.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical approval

All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee (the institutional review board of St. Luke’s International Hospital, 19-R078) and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Informed consent

For this type of study, formal consent is not required.


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2020

Authors and Affiliations

  1. 1.Department of NeurosurgerySt Luke’s International HospitalTokyoJapan
  2. 2.Department of Neuroendovascular TherapySt Luke’s International HospitalTokyoJapan
  3. 3.Department of NeurosurgeryTokyo Women’s Medical UniversityTokyoJapan

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