Dynamic Failure Properties of the Porcine Medial Collateral Ligament-Bone Complex for Predicting Injury in Automotive Collisions

Abstract

The goal of this study was to model the dynamic failure properties of ligaments and their attachment sites to facilitate the development of more realistic dynamic finite element models of the human lower extremities for use in automotive collision simulations. Porcine medial collateral ligaments were chosen as a test model due to their similarities in size and geometry with human ligaments. Each porcine medial collateral ligament-bone complex (n = 12) was held in a custom test fixture placed in a drop tower to apply an axial impulsive impact load, applying strain rates ranging from 0.005 s-1 to 145 s-1. The data from the impact tests were analyzed using nonlinear regression to construct model equations for predicting the failure load of ligament-bone complexes subjected to specific strain rates as calculated from finite element knee, thigh, and hip impact simulations. The majority of the ligaments tested failed by tibial avulsion (75%) while the remaining ligaments failed via mid-substance tearing. The failure load ranged from 384 N to 1184 N and was found to increase with the applied strain rate and the product of ligament length and cross-sectional area. The findings of this study indicate the force required to rupture the porcine MCL increases with the applied bone-to-bone strain rate in the range expected from high speed frontal automotive collisions.

A biomechanical assessment to evaluate breed differences in normal porcine medial collateral ligaments

“…The high-load mechanical properties (failure deformation, failure strain, stiffness, and modulus) of porcine MCL were comparable to adult human MCL (Tables 3 and 4). Similar to our study of immature porcine MCL, Peck (2007) found that the majority of their mature porcine MCLs failed by tibial avulsion. Failure loads (703 7232 N) and stresses (65716 MPa) of mature porcine MCLs (Peck, 2007) were comparable to those obtained with our protocol (Tables 3 and 4).…”

“…Porcine MCL was assumed to have a rectangular cross-section and XSA was calculated from midsubstance width and thickness measurements. In the one other study that examined biomechanical properties of domestic pig MCLs, (Peck, 2007), the author indicated that they also used a rectangular assumption and found that mature porcine MCL XSA ranged from 6.1-20.1 mm 2 , which was similar to our findings of 8.8À 19.5 mm 2 for immature porcine MCLs. The high-load mechanical properties (failure deformation, failure strain, stiffness, and modulus) of porcine MCL were comparable to adult human MCL (Tables 3 and 4).…”

“…Previous knee ligament studies investigated porcine knees because of their similarity to adult human knees (Livesay et al, 1997;Peck, 2007;Xerogeanes et al, 1998;Yeow et al, 2008); however, pigs also have similar articular cartilage thickness and collagen fibre arrangement (Chu et al, 2010), cardiovascular and renal systems, gastrointestinal tracts, skin, and estrous cycles (Nunamaker, 1998;Sack, 1982) as humans. Pig is a promising model for human obesity because they are omnivorous and of similar metabolism (Guillerm-Regost et al, 2006;Spurlock and Gabler, 2008) and are well suited for genetic studies because of their distinct breeds, large successful litters, short gestation periods, and early sexual maturity as discussed in Germscheid (2008).…”