Biomechanical study of external immobilization methods for tarsometatarsal fracture in chickens

• Grant number: 25/08860-6
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: July 01, 2025
• End date: April 30, 2027
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Clinics and Surgery
• Principal Investigator: Sheila Canevese Rahal
• Grantee: Guilherme Rech Cassanego
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil
• Associated research grant: 24/21341-5 - Immobilization methods for tarsometatarsal fractures in chickens: Biomechanical and Finite Element Method study, AP.R

Abstract

Biomechanical tests conducted through ex vivo trials provide valuable insights into implant behavior in fracture models, stress distribution in bones, and interfragmentary displacement, among other factors. This information is crucial for improving implant design and reducing complications associated with fracture healing before clinical application in vivo. Given the limited research on tarsometatarsal fracture immobilization in birds, this study aims to evaluate different external immobilization methods for mid-diaphyseal tarsometatarsal fractures using chickens as an experimental model. An external fixator based on the FESSA system will be utilized. Tarsometatarsal bones from 21 healthy, one-year-old laying hens will be used. Following euthanasia-due to causes unrelated to the present study-the bones will be collected and stored at -20°C until use. All bones will undergo measurement, radiographic analysis, and computed tomography to ensure structural integrity and adequate bone density. Three groups will be established: G1 (Control) - Intact bones used to determine mechanical testing forces; G2 - Modified unilateral external fixator (Type 1a); G3 - Modified unilateral external fixator (Type 1a) with an intramedullary "tie-in" pin. All implants will be manufactured from titanium. Each group will include seven specimens designated for compression testing and seven for four-point bending testing. In Groups 2 and 3, bone weight will be recorded before and after implant placement. Mechanical tests will be performed using a Universal Testing Machine to assess maximum force, deflection, stiffness, and energy absorption. Constructs will also be radiographically evaluated before and after mechanical testing. Data from the mechanical tests will be subjected to statistical analysis. Based on the results obtained, the tested methods may be applicable for treating fractures in birds in clinical settings. (AU)