In-vitro External Fixation Pin-Site Model Proof of Concept: A Novel Approach to Studying Wound healing in Transcutaneous Implants


External fixation is an essential surgical technique for treating trauma, limb lengthening and deformity correction, however infection is common, with infection rates ranging from 4.5 to 100% of cases. Throughout the literature researchers and clinicians have highlighted a relationship between excessive movement of the pin and skin and an increase in the patient’s risk of infection, however, currently no studies have addressed this role of pin-movement on pin-site wounds. This preliminary study describes a novel in vitro pin-site model, developed using a full-thickness human skin equivalent (HSE) model in conjunction with a bespoke mechanical system which simulates pin-movement. The effect of pin-movement on the wound healing response of the skin equivalents was assessed by measuring the expression of pro-inflammatory cytokines. Six human skin equivalent models were divided into three test groups: no pin as the control, static pin-site wound and dynamic pin-site wound (n = 3). On day 3 concentrations of IL-1α and IL-8 showed a significant increase compared to the control when a static fixation pin was implanted into the skin equivalent (p < 0.05) and (p < 0.005) respectively. Levels of IL-1α and IL-8 increased further in the dynamic sample compared to the static sample (p < 0.05) and (p < 0.0005). This study demonstrates for the first time the application of HSE model to study external-fixation pin-movement in vitro. The results of this study demonstrated pin-movement has a negative effect on soft-tissue wound-healing, supporting the anecdotal evidence reported in the literature, however further analysis of wound heading would be required to verify this hypothesis.

Publication DOI:
Divisions: College of Engineering & Physical Sciences > School of Engineering and Technology > Mechanical, Biomedical & Design
College of Health & Life Sciences > School of Biosciences
College of Engineering & Physical Sciences > Aston Institute of Materials Research (AIMR)
College of Engineering & Physical Sciences
Funding Information: The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the Aston University College of Engineering and Physical Science.
Additional Information: Copyright © IMechE 2024. This article is distributed under the terms of the Creative Commons Attribution 4.0 License ( which permits any use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access pages (
Uncontrolled Keywords: External fracture fixation,human skin equivalent,pin-site infection,Surgical Wound Infection/therapy,Bone Nails,External Fixators,Humans,Wound Healing/physiology,Fracture Fixation/methods,Interleukin-8,Mechanical Engineering
Publication ISSN: 2041-3033
Last Modified: 14 Jun 2024 07:35
Date Deposited: 04 Mar 2024 17:50
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Related URLs: https://journal ... 544119241234154 (Publisher URL)
http://www.scop ... tnerID=8YFLogxK (Scopus URL)
PURE Output Type: Article
Published Date: 2024-03-03
Published Online Date: 2024-03-03
Accepted Date: 2024-02-13
Authors: McCall, Blake
Rana, Karan
Sugden, Kate (ORCID Profile 0000-0001-6323-1082)
Junaid, Sarah (ORCID Profile 0000-0001-9460-710X)



Version: Published Version

License: Creative Commons Attribution

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