title: Fracture mechanics of the femoral neck in a composite bone model: effects of platen geometry.
abstract: Load applicator (platen) geometry used for axial load to failure testing of the femoral neck varies between studies and the biomechanical consequences are unknown. The purpose of this study was to determine if load application with a flat versus a conical platen results in differing fracture mechanics. Femurs were aligned in 25° of adduction and an axial compressive force was applied to the femoral heads at a rate of 6 mm/min until failure. Load application with the conical platen resulted in an average ultimate failure load, stiffness, and energy to failure of 9067 N, 4033 N/mm, and 12.12 J, respectively. Load application with the flat platen resulted in a significant (p<0.05) reduction in ultimate failure load (7620 N) and stiffness (2924 N/mm). Energy to failure (12.30 J) was not significantly different (p=0.893). Different fracture patterns were observed for the two platens and the conical platen produced fractures more similar to clinical observations. Use of a flat platen underestimates the strength and stiffness of the femoral neck and inaccurately predicts the associated fracture pattern. These findings must be considered when interpreting the results of prior biomechanical studies on femoral neck fracture and for the development of future femoral neck fracture models.
authors: Department of BioMedical Engineering, Steadman Philippon Research Institute, Vail, CO, USA.
authors: Sean D
authors: SD
authors: Smith
authors: Department of BioMedical Engineering, Steadman Philippon Research Institute, Vail, CO, USA.
authors: Kyle S
authors: KS
authors: Jansson
authors: Department of BioMedical Engineering, Steadman Philippon Research Institute, Vail, CO, USA; The Steadman Clinic, Vail, CO, USA.
authors: Marc J
authors: MJ
authors: Philippon
authors: Department of BioMedical Engineering, Steadman Philippon Research Institute, Vail, CO, USA; The Steadman Clinic, Vail, CO, USA.
authors: Robert F
authors: RF
authors: LaPrade
authors: Department of BioMedical Engineering, Steadman Philippon Research Institute, Vail, CO, USA. Electronic address: cwijdicks@sprivail.org.
authors: Coen A
authors: CA
authors: Wijdicks
mesh_terms: D000368:Aged; D001696:Biomechanical Phenomena; D005260:Female; D005265:Femoral Neck Fractures / Q000209:etiology*; D005270:Femur Head / Q000502:physiology; D005272:Femur Neck / Q000502:physiology*; D006801:Humans; D008297:Male; D008953:Models, Anatomic; D016474:Weight-Bearing
keywords: Axial load to failure; Biomechanical model; Femoral neck fracture; In vitro