Vet Comp Orthop Traumatol 2022; 35(04): 230-238
DOI: 10.1055/s-0042-1745785
Original Research

Extended Computed Tomography Scale Images Provide a Detailed Assessment of Metal Screws and Are Superior to Standard Computed Tomography Scale Images and Digital Radiography at Detecting Experimentally Induced Screw Fractures In Vitro

1   Diagnostic Imaging Department, Davies Veterinary Specialists, Hitchin, United Kingdom
Ines Carrera
2   Willows Referral Centre, Solihull, United Kingdom
Andy Holdsworth
1   Diagnostic Imaging Department, Davies Veterinary Specialists, Hitchin, United Kingdom
› Author Affiliations
Funding None.


Objectives (1) To compare the ability of standard computed tomography (CT) scale (SCTS) and extended CT scale (ECTS) images, produced using conventional CT technology, to provide detailed assessment of metal screws in vitro. (2) To assess how screw size, type, and orientation relative to the Z-axis of the gantry affect implant assessment. (3) To test the ability of SCTS, ECTS, and radiography to diagnose screw failure when there is negligible screw fragment displacement.

Study Design Part 1: 12 screws of different size, type, and composition were scanned in three orientations (parallel or 0°; oblique or 45°; and perpendicular or 90°) relative to the Z-axis of the gantry. SCTS and ECTS reconstructions were made for each screw, in each plane, to assess implant shape, structure, and diameter. Part 2: fatigue-failure was induced in four screws commonly used to stabilize canine humeral intracondylar fissures. Screws were then reassembled achieving grossly perfect apposition and alignment of the fragments. Ability to detect implant failure was tested using SCTS, ECTS, and radiography.

Results ECTS provided better screw assessment compared with SCTS resulting in clear visualization of the structure in 8/12 versus 0/12 screws and shape in 12/12 versus 11/12 screws; however, results were affected by screw size, type, and orientation. ECTS identified all in vitro screw fractures with negligible screw fragment displacement; however, success was affected by screw orientation: 4/4 fractures identified with a 90° angle, 1/4 for 45°, and 0/4 for 0°. SCTS and radiography did not identify any of them.

Conclusion The results indicate that ECTS reconstructions are useful for assessment of metal screws and for detection of nondisplaced screw fractures.

Authors' Contributions

All authors provided substantial contribution to this manuscript: J.L. was involved in conception of the study, study design, acquisition of data and data analysis and interpretation, A.H. was involved in conception of the study, study design and data analysis and interpretation, C.I. was involved in conception of the study, study design and data analysis and interpretation. All the authors contrinbuted to drafting and revising the manuscript, approval of submitted manuscript and are publicy accountable for the relevant content of the manuscript.

Animal Care Statement

The authors confirm that this research has been conducted without the use of live animals in a manner likely to be approved by an ethics committee in most countries.

Previous affiliation of authors one and three (J.L. and A.H.) during collection of the data and confection of the manuscript: Southern Counties Veterinary Specialists, Hampshire, BH24 3JW, United Kingdom.

Publication History

Received: 22 October 2021

Accepted: 23 February 2022

Article published online:
15 June 2022

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