Immobilization methods for tarsometatarsal fractures in chickens: Biomechanical and Finite Element Method study

• Grant number: 24/21341-5
• Support Opportunities: Regular Research Grants
• Start date: May 01, 2025
• End date: April 30, 2028
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Clinics and Surgery
• Principal Investigator: Sheila Canevese Rahal
• Grantee: Sheila Canevese Rahal
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil
• Associated researchers: Marcelo José Carbonari ; Maria Jaqueline Mamprim de Arruda Monteiro ; Rafael Cerântola Siqueira
• Associated scholarship(s): 25/08860-6 - Biomechanical study of external immobilization methods for tarsometatarsal fracture in chickens, BP.DR

Abstract

There is a lack of studies to determine more adequate immobilization methods for tarsometatarsus fractures in birds. Implants are often applied without due care with safe corridors. Therefore, the present study aims to evaluate, through biomechanical tests and the finite element method (FEM), different immobilization methods for middle diaphyseal fracture of the tarsometatarsus, using chicken as an experimental model. The use of the tarsometatarsus will be an opportunity to test the modified external fixator based on the FESSA, which is under development by our team and at the beginning of patent evaluation by the Unesp Innovation Agency, in addition to the test with elastic pins, not yet applied in birds. For this, the tarsometatarsus bones of 28 healthy chickens, one-year-old, will be used. After euthanasia for reasons not associated with the present study, the tarsometatarsal bones will be collected and stored in a freezer at -20ºC until use. All bones will be measured, radiographed, and submitted to tomographic examination to ensure the absence of lesions and adequate density. Four groups will be formed: G1 (control) - the whole bones will be used to determine the forces for the mechanical testing; G2 - modified unilateral external fixator (Type 1a); G3 - modified unilateral external fixator (Type 1a) with a tie-in intramedullary pin; G4 - two elastic pins. All external fixators will be made of titanium. For each group, seven specimens will be determined for the compression test and seven for the four-point bending test. In Groups 2, 3, and 4, the bones will be weighed before and after implant application. The mechanical tests will be performed in a Universal Testing Machine to determine the maximum force, deflection, stiffness, and energy. The constructions will be evaluated radiographically before and at the end of the mechanical tests. To perform the FEM, computed tomography of a tarsometatarsal will be used. The three-dimensional geometries of the implants will be built using the information provided by the manufacturer. The same tests (axial compression and four-point bending) performed in the in vitro test will be simulated. Data from mechanical tests and FEM will be submitted to statistical analysis. Based on the results, the methods will be used in birds admitted with fractures. (AU)