title: Development of a twenty-one-component finite element distal hind limb model: stress and strain in bovine digit structures as a result of loading on different floorings.
abstract: Finite element modeling is a unique way of introducing technical and material research into medical science. A bovine distal hind limb was scanned using computed tomography for geometric image capture and the data were subsequently divided (segmented) into 4 tissue types: bone, bone marrow, soft tissue, and the horn capsule. Material data from previous studies were integrated into the model. Flexor tendons were assembled as longitudinal structures starting at their cross-sectional areas at the height of the metatarsophalangeal joint, proceeding in the plantaro-distal direction and meeting the distal phalanx at the tuberculum flexorium. Three different flooring situations (full support floor, bearing weight in the abaxial half of the lateral claw and in the dorsal halves of both claws, respectively) were created to evaluate the effects of loading. Full support resulted in von Mises stress levels between 3.5 and 1.5 MPa for the osseous structures and some regions of the segmented soft tissue; stress patterns in the bulb and sole of the claw capsule (1.5 MPa) and in the floor (0.5 MPa) were similar to pressure plate data in vivo and in vitro, with corresponding strain values of 2.4%. Reduced support resulted in higher stresses (up to approximately 8 MPa) in bones, claw capsules, and tendons; high strains ( approximately 11%) were found in the soft tissue, depending on how the floor was constructed. Although the models may still be anatomically improved, stress and strain calculations are possible with results comparable to related research, and the model shows interaction between the 2 digits. This possibly will help with further understanding of the biomechanical function of this 2-digit structure. With respect to clinical interpretation, reduced support to the bovine hind limb increases focal stress peaks in the different tissues, which may indicate a location of potential injury.
authors.affiliation: Clinic for Orthopedics in Ungulates, University of Veterinary Medicine, 1210 Vienna, Austria. christine.hinterhofer@vu-wien.ac.at
authors.forename: C
authors.initials: C
authors.lastname: Hinterhofer
authors.forename: H
authors.initials: H
authors.lastname: Haider
authors.forename: V
authors.initials: V
authors.lastname: Apprich
authors.forename: J C
authors.initials: JC
authors.lastname: Ferguson
authors.forename: S N
authors.initials: SN
authors.lastname: Collins
authors.forename: C
authors.initials: C
authors.lastname: Stanek
mesh_terms: D000822:Animal Husbandry; D000818:Animals; D002417:Cattle / Q000033:anatomy & histology / Q000502:physiology*; D005260:Female; D005430:Floors and Floorcoverings; D006724:Hoof and Claw / Q000000981:diagnostic imaging / Q000502:physiology*; D035002:Lower Extremity / Q000000981:diagnostic imaging / Q000502:physiology*; D008954:Models, Biological; D011312:Pressure; D011859:Radiography