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Biomechanics

Biomechanics - Poster Session E

Poster D2 - Parametric Finite Element Analysis of Padding Material for Pediatric Commotio Cordis Prevention

Saturday, October 26, 2024
10:00 AM - 11:00 AM EST
Location: Exhibit Hall E, F & G

Introduction:  Commotio Cordis occurs when a projectile strikes the sternum over the heart during the T-wave upstroke of ventricular repolarization, subsequently leading to sternum deformation, cardiac arrest, and eventual death. Instances of commotio cordis are fatal with a survival rate of 60% only when immediate resuscitation is possible [1]. When not possible, survival rate can drop to as low as 3% [2]. High risk individuals include athletes aged between 8 to 18 who play sports with fast-moving projectiles, such as baseball, hockey, and lacrosse. 47% of Commotio Cordis cases happen during participation in such activities [2]. Chest protectors currently on the market provide inadequate protection against chest injury and Commotio Cordis. One study reported that one third of Commotio Cordis cases have occurred despite chest protection being present [3]. Commercial chest protectors are made from materials which fail to protect the sternum from fatal deformations. This establishes a need for a novel chest protector which incorporates both material choice and design to effectively absorb and distribute impacts from a fast-moving projectile. Using finite element analysis (FEA), this study aims to develop a new chest protector for the adolescent athletes using a layered composite padding for optimized mechanical protection of the body, which will minimize strain and stress in the sternum region, thus reducing Commotio Cordis risk.

Materials and

Methods:  FEA software was used to simulate a baseball impact onto the left side of the thorax, with a protective padding present. A nonlinear FEA of thorax was developed using the geometry from CT scans of an adolescent. ABAQUS (Dassault Systèmes, RI, USA) was used to create the baseball, padding, and simplified baseball bat FEMs and incorporated with the thorax. 7,440 hexahedral elements of type C3D8R were used. The following equation was used to determine the elastic modulus of the cortical bones of a 10 year old’s ribs [4]: E(age) = -0.0029316(age)2+ 0.28851(age) +8.3468 = 8.64 GPa
The control case for the impact forces was simulated by moving the baseball at 45 mph and hitting the thorax over the heart . A padding was then added in front of the thorax and the baseball impact was analyzed. 4 different materials were analyzed for the chest padding: (i) EVA foam, (ii) soft foam, (iii) hyperfoam, and (iv) expanded polypropylene crushable foam. Additionally, these materials were combined to form 2 types of composites: (a) hyperfoam and EVA foam, and (b) hyperfoam and polypropylene foam. Stress and deformation values were predicted for each material 73 mili-seconds after the ball was launched at the padding.

Results, Conclusions, and Discussions: 

Results: The FEA simulation predicted that a composite of polypropylene crushable foam and hyperfoam allowed for the least amount of deformation of the ribs(maximum deformation = 5.55 µm). This composite also showed the lowest stress value on the ribs, with a maximum of 0.753 MPa and lowest strain value of 74 µε. Along with the composite material, polypropylene crushable foam alone also provided good protective chest padding with the maximum deformation of the ribs predicted as 2.77 mm, the maximum stress as 2.55 MPa, and the maximum strain as 530µε, respectively. Soft foam was predicted to provide the worst protection with a maximum deformation predicted as 7.2mm , along with a maximum stress and strain of 64.8 MPa and 7.3 mε, respectively.

Discussion: This study used a numerical FEA approach to identify the types of foam that were most effective in preventing rib deformation under a high velocity small projectile impact which can lead to Commotio Cordis. The results help to understand how to create more effective chest protection devices for adolescents. One study identified that pressure distribution on impact is an essential factor to preventing severe injury and or death [5]. Although Polypropylene has been cited to have material properties consistent with good pressure distribution [6], [7], our discovery of a composite material showing improved protective capabilities can better inform the creation of future chest protectors. In future studies, FEA will simulate Commotio Cordis with additional material and geometric complexities, including the soft tissues (cartilage), non-linear shape, and the microstructure of the padding material to quantify the dispersion of absorbed energy from high velocity impacts.

Conclusion: It is found that polypropylene crushable foam, in layered combination with hyperfoam, can increase impact resistance, decrease stress, strain, and impact energy to create an effective and lightweight chest padding. In future studies, this information can be used on more complex FEA models to determine the best chest protection for adolescent athletes.

Acknowledgements (Optional):  [1] O. Okorare et al., “Sudden Cardiac Death: An Update on Commotio Cordis,” Cureus, vol. 15, no. 4, p. e38087, doi: 10.7759/cureus.38087.
[2] L. E. Palacio and M. S. Link, “Commotio Cordis,” Sports Health, vol. 1, no. 2, pp. 174–179, Mar. 2009, doi: 10.1177/1941738108330972.
[3] M. A. Escobar and M. G. Caty, “Chapter 114 - Thoracic Injuries in Children,” in Pediatric Critical Care (Fourth Edition), B. P. Fuhrman and J. J. Zimmerman, Eds., Saint Louis: Mosby, 2011, pp. 1520–1527. doi: 10.1016/B978-0-323-07307-3.10114-4.
[4] B. Jiang, L. Cao, H. Mao, C. Wagner, S. Marek, and K. H. Yang, “Development of a 10-year-old paediatric thorax finite element model validated against cardiopulmonary resuscitation data,” Comput. Methods Biomech. Biomed. Engin., vol. 17, no. 11, pp. 1185–1197, Aug. 2014, doi: 10.1080/10255842.2012.739164.
[5] G. J. Dickey, K. Bian, X. Liu, H. R. Khan, and H. Mao, “Identifying Vulnerable Impact Locations to Reduce the Occurrence of Deadly Commotio Cordis Events in Children’s Baseball: A Computational Approach,” J. Biomech. Eng., vol. 144, no. 5, p. 051005, May 2022, doi: 10.1115/1.4052886.
[6] E. I. Drewniak, D. B. Spenciner, and J. J. Crisco, “Mechanical Properties of Chest Protectors and the Likelihood of Ventricular Fibrillation Due to Commotio Cordis,” Nov. 2007, doi: 10.1123/jab.23.4.282.
[7] P. Rumianek, T. Dobosz, R. Nowak, P. Dziewit, and A. Aromiński, “Static Mechanical Properties of Expanded Polypropylene Crushable Foam,” Materials, vol. 14, no. 2, p. 249, Jan. 2021, doi: 10.3390/ma14020249.