Mechanical characterization of fourth generation composite humerus

Abstract

Abstract:Mechanical data on upper extremity surrogate bones, supporting use as biomechanical tools, is limited. The objective of this study was to characterize the structural behavior of the fourth generation composite humerus under simulated physiologic bending, specifically, stiffness, rigidity, and middiaphysial surface strains. Three humeri were tested in four-point bending, in anatomically defined anteroposterior(AP) and mediolateral(ML) planes. Stiffness and rigidity were derived using load-displacement data. Principal strains were determined at the anterior, posterior, medial and lateral surfaces in the humeral mid-diaphysial transverse plane of one specimen using stacked rosettes. Linear structural behavior was observed within test range. Average stiffness and rigidity were greater in the ML (918+18 N/mm; 98.4+1.9 Nm 2 ) than the AP plane (833+16 N/mm; 89.3+1.6 Nm 2 ), with little interspecimen variability. The ML/AP rigidity ratio was 1.1. Surface principal strains were similar at the anterior (5.41 /N) and posterior (5.43 /N) gauges for AP bending, and comparatively less for ML bending, i.e., 5.1 and 4.5 /N, at the medial and lateral gauges, respectively. The study provides novel strain and stiffness data for the fourth generation composite humerus, and adds to published construct rigidity data. Results support use of this composite bone as a tool for modeling and experimentation.

Are Quadrilateral Surface Buttress Plates Comparable to Traditional Forms of Transverse Acetabular Fracture Fixation?

“…Second, we chose to use a synthetic tissue surrogate. Although cadaveric tissue testing may be considered the gold standard in producing results with the highest level of clinical translation and acceptance, prior studies have validated the surrogates against human tissue from a mechanical perspective [3,4,6,7,16,17]. The use of synthetic specimens also eliminates bone quality and heterogeneous geometry as confounding factors, which we considered to be an important a priori consideration to adequately interrogate biomechanical differences between the methods of fixation.…”

“…A synthetic tissue surrogate was chosen because of standardized geometry, homogeneous material properties, and prior laboratory work that has validated the surrogates against cadaveric human bone with comparative results for axial, torsional, and four-point bending stiffness as well as failure mechanism and failure load under different loading conditions [3,4,6,7,16,17]. Additionally, the use of a tissue surrogate eliminates potentially confounding variables associated with fresh-frozen cadaveric tissue, including bone quality and anatomic heterogeneity, which may affect biomechanical results and their interpretation.…”

Complex Distal Humerus Fractures—Comparison of Polyaxial Locking and Nonlocking Screw Configurations—A Preliminary Biomechanical Study

“…The fourth generation Sawbones represent the mechanical strength of bone from healthy young individuals and are described as a valid bone substitute with high reproducibility and uniform anatomy. 25,26 Nevertheless, the results from artificial bones may have limited transferability due to idealized material properties. The distal humerus fractures frequently occur in elderly patients; therefore, tests were repeated in cadaver bones.…”

Experimental validation of numerically predicted strain and micromotion in intact and implanted composite hemi-pelvises

“…Instead of real bone, a composite bone specimen has been used that possibly cannot reproduce all in-vivo conditions, precisely. However, composite bone has been successfully used in several biomechanical studies, since inter-specimen variability is small and therefore provides more consistency among specimens than cadaveric bone [29][30][31][32][33][34][35][36][37]47]. The support structure is still not entirely representative of the in-vivo situation, where there are no rigid constraints.…”

“…This pelvis is composed of foam enclosed with a cortical shell layer made of short glassfibre reinforced epoxy. This is considered to be a viable alternative to the cadaveric bone for biomechanical evaluation of bone and implant-bone structures [29][30][31][32][33][34][35][36][37], and represents a standardised geometry of a bone, with gross mechanical behaviour close to that of the human bone. Unlike human cadaveric bones it has very small inter-specimen variability.…”