Abstract
Purpose: We carried out a biomechanical study by finite element analysis to compare treatment with a plate and treatment with a nail in pseudoarthrosis of the humeral shaft.
Materials and methods: We used a cadaver humerus and the two fixation devices to generate the geometry with design software (CATIA® v4.2). We then modelled the shapes with finite element analysis software (MSC.Patran®) and created three experimental models: healthy humerus, humerus with shaft pseudoarthrosis stabilised with AO plate and humerus with shaft pseudoarthrosis stabilised with locking nail. Both implants were titanium. The three models were subjected to nine different load conditions and the results compared.
Results: The nail model is stiffer than the plate in compression (3002.80 vs 789.68 N/mm), traction (6576.73 vs 1559.90 N/mm) and torsion (4.67 vs 2.73 N/mm). However, the plate model is biomechanically superior to the nail under other load conditions (mediolateral flexion, anteroposterior flexion, anteroposterior shear and mediolateral shear).
Conclusions: Although we can understand and compare the stability of the plate model with the nail, joint clinical and biomechanical studies are needed to determine the minimum stiffness required so that it will not interfere with the process of union under different load conditions.
The abstracts were prepared by Dr. E. Carlos Rodríguez-Merchán, Editor-in-Chief, Spanish Journal of Orthopaedics and Traumatology (Revista de Ortopedia y Traumatología). Correspondence should be addressed to him at: Sociedad Española de Cirugía Ortopédica y Traumatología (SECOT), Calle Fernández de los Ríos 108, 28015-Madrid, Spain
