Establishment and characterisation of an open mini-thoracotomy surgical approach to an ovine thoracic spine fusion model

Yong, Mostyn R, Saifzadeh, Siamak, Askin, Geoffrey N., Labrom, Robert D., Hutmacher, Dietmar W., & Adam, Clayton J. (2014) Establishment and characterisation of an open mini-thoracotomy surgical approach to an ovine thoracic spine fusion model. Tissue Engineering. Part C. Methods, 20(1), pp. 19-27.

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Background A large animal model is required for assessment of minimally invasive, tissue engineering based approaches to thoracic spine fusion, with relevance to deformity correction surgery for human adolescent idiopathic scoliosis. Here we develop a novel open mini–thoracotomy approach in an ovine model of thoracic interbody fusion which allows assessment of various fusion constructs, with a focus on novel, tissue engineering based interventions.

Methods The open mini-thoracotomy surgical approach was developed through a series of mock surgeries, and then applied in a live sheep study. Customized scaffolds were manufactured to conform with intervertebral disc space clearances required of the study. Twelve male Merino sheep aged 4 to 6 years and weighing 35 – 45 kg underwent the abovementioned procedure and were divided into two groups of six sheep at survival timelines of 6 and 12 months.

Each sheep underwent a 3-level discectomy (T6/7, T8/9 and T10/11) with randomly allocated implantation of a different graft substitute at each of the three levels; (i) polycaprolactone (PCL) based scaffold plus 0.54μg rhBMP-2, (ii) PCL-based scaffold alone or (iii) autograft. The sheep were closely monitored post- operatively for signs of pain (i.e. gait abnormalities/ teeth gnawing/ social isolation). Fusion assessments were conducted post-sacrifice using Computed Tomography and hard-tissue histology. All scientific work was undertaken in accordance with the study protocol has been approved by the Institute's committee on animal research.

Results. All twelve sheep were successfully operated on and reached the allotted survival timelines, thereby demonstrating the feasibility of the surgical procedure and post-operative care. There were no significant complications and during the post-operative period the animals did not exhibit marked signs of distress according to the described assessment criteria. Computed Tomographic scanning demonstrated higher fusion grades in the rhBMP-2 plus PCL-based scaffold group in comparison to either PCL-based scaffold alone or autograft. These results were supported by histological evaluation of the respective groups.

Conclusion. This novel open mini-thoracotomy surgical approach to the ovine thoracic spine represents a safe surgical method which can reproducibly form the platform for research into various spine tissue engineered constructs (TEC) and their fusion promoting properties.

Impact and interest:

4 citations in Scopus
4 citations in Web of Science®
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ID Code: 60840
Item Type: Journal Article
Refereed: Yes
Keywords: preclinical animal model, spinal surgery, polycaprolactone, growth factors, bone regeneration, open mini-thoracotomy, sheep thoracic spine
DOI: 10.1089/ten.TEC.2012.0746
ISSN: 1937-3392
Subjects: Australian and New Zealand Standard Research Classification > ENGINEERING (090000) > BIOMEDICAL ENGINEERING (090300) > Biomedical Instrumentation (090303)
Australian and New Zealand Standard Research Classification > ENGINEERING (090000) > BIOMEDICAL ENGINEERING (090300) > Medical Devices (090304)
Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > CLINICAL SCIENCES (110300) > Orthopaedics (110314)
Divisions: Current > Institutes > Institute of Health and Biomedical Innovation
Current > QUT Faculties and Divisions > Science & Engineering Faculty
Copyright Owner: Copyright 2014 Mary Ann Liebert, Inc. Publishers
Copyright Statement: This is a copy of an article published in the Tissue Engineering. Part C. Methods © 2013 Mary Ann Liebert, Inc. Publishers; Tissue Engineering. Part C. Methods is available online at:
Deposited On: 19 Jun 2013 00:42
Last Modified: 04 Jul 2017 16:18

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