Future Work

The surrogate is biofidelic at the low speeds (Biofidelity Rank < 1). However, the biofidelity could be improved at the high-speed impact conditions (50 and 60mph). Even if the biofidelity is acceptable, there are other qualities a surrogate needs to have for it to be an effective surrogate for certification testing. The surrogate needs to be repeatable. A small group of this equipment should be tested on different dates to determine if the surrogate provides a repeatable result. The next issue is reproducibility. This test would evaluate the ability to compare results from SSTS’s at different facilities.

This provides the ability to see how consistent results the surrogate provides when multiple versions of the surrogate are created and implemented. Finally, the surrogate needs to be tested for durability.

The surrogate should be able to endure repetitive testing without damaging or degrading.

Another study that could provide beneficial information would be using the SSTS to test equipment previously tested by Link et al. (2004). The SSTS has proven to be biofidelic, but it is unclear why the equipment in this study has proven effective compared with the 2004 study. Testing the 2004 equipment could show that manufacturers have improved the effectiveness of their products between 2004 and 2010.

APPENDIX A

Height (cm) Width(cm) Thickness (cm)

Height (cm) Width(cm) Thickness (cm)

Height (cm) Width(cm) Thickness (cm)

Entry

#

Surface Area (cm^2)

Reinforced Surface Area (Hard

Plastic) (cm^2)

Reinforced Surface

Area (Rubber)

(cm^2)

Min Max Min Max Min Max

85 796.374 na 20.00 24.70 38.95 0.735 2.207

86 902.737 235.583 na 33.65 20.35 31.05 0.796 2.701 87 851.053 232.014 ^na 32.05 20.65 30.80 0.796 2.860 88 822.435 232.014 96.172 ^na 29.90 21.90 31.75 0.888 2.544 89 492.043 159.678 na 22.90 23.75 35.35 0.729 3.056

APPENDIX B

Lacrosse Equipment Results for 30mph Best Condition

Pad

APPENDIX C

Lacrosse Equipment Results for 50mph Best Condition

Pad

APPENDIX D

Lacrosse Equipment Results for 30mph Worst Condition

Pad

Pad

Cardiac Mean

(N)

Distributed Mean (N)

Total

Mean

(N)

88 234.57 130.82 287.69

89 251.64 397.14 587.72

90 194.75 182.52 367.80

91 339.51 156.43 459.84

92 148.05 165.18 311.46

93 228.80 211.42 420.56

Total 218.25 220.89 401.09

APPENDIX E

Lacrosse Equipment Results for 50mph Worst Condition

Pad

Pad

Cardiac Mean

(N)

Distributed Mean (N)

Total

Mean

(N)

87 79.79 807.18 830.35

88 814.34 353.67 985.24

89 299.33 799.47 1061.78

90 944.78 175.02 979.95

91 1033.88 175.29 1080.96

92 436.55 551.64 979.47

93 413.61 701.42 1052.59

Total 901.81 352.79 1135.47

APPENDIX F

Impact Load Correlation between Projectile and Surrogate

y = 0.8102x R² = 0.8392

0 200 400 600 800 1000 1200 1400 1600 1800 2000

0 500 1000 1500 2000 2500

S u rr o g a te L o a d ( N )

Projectile Load (N)

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ABSTRACT

DEVELOPMENT OF A BIOMECHANICAL SURROGATE FOR THE EVALUATION OF COMMOTIO CORDIS PROTECTION

by NATHAN DAU

May 2012 Advisor: Dr. Cynthia Bir

Major: Biomedical Engineering Degree: Doctor of Philosophy

Commotio Cordis (CC) has proven to be life threatening for young athletes as it is the second leading cause of mortality in youth sports. In the past 15 years, researchers have been working to understand the pathophysiology of this event. It has been proven that impacts directly over the cardiac silhouette during a vulnerable period of the cardiac cycle can cause CC. In order to reduce the occurrence of CC in sports, chest protectors need to be tested for efficacy. Currently there is no biofidelic surrogate to serve this purpose. In order to test equipment to a given standard of protection, a biomechanical surrogate is needed that models the human response to impacts observed in sports.

The goal of this dissertation was to develop and validate a biomechanical surrogate that can predict the risk of CC.

The first step in developing a biomechanical surrogate is the identification of an effective injury criterion that can predict the injury outcome. Porcine specimens were impacted directly over the heart during the vulnerable portion of their cardiac cycle. Impacts were conducted with a lacrosse ball at four speeds that have been proven effective to induce CC in a porcine model (30, 40, 50, and 60mph). Ten

injury criteria were evaluated, and impact force proved to be the most effective injury criterion (Somer’s D = 0.52).

Human response corridors were developed for the same impact conditions using Post Mortem Human Specimens (PMHS). These data were used to evaluate existing thoracic biomechanical surrogates. Three surrogates were tested in the same impact conditions and none were found to be biofidelic (Biofidelity Rank > 2). A new Sports Specific Thoracic Surrogate (SSTS) was developed and validated using the human response corridors (Biofidelity Rank = 1.2). The SSTS was used to evaluate 70 lacrosse chest protectors from ten (10) manufacturers. These data provided a broad survey of the current level of CC protection commercially available. A statistical analysis was conducted on ten (10) pieces of equipment from seven of the manufacturers. All of the equipment proved to be effective in limiting impact force and reducing the risk of CC. Equipment efficacy could be improved by utilizing this surrogate as a development tool to evaluate new chest protector designs. It could also be used in certification testing by an organization such as National Operating Committee on Standards for Athletic Equipment (NOCSAE). The development of a NOCSAE certification standard would encourage manufacturers to improve the CC protection offered.

AUTOBIOGRAPHICAL STATEMENT

NATHAN ZACHARY DAU

EDUCATION:

2012 PhD Biomedical Engineering Wayne State University 2008 MS Biomedical Engineering Wayne State University

2001 BS Applied Physics Kettering University

PROFESSIONAL EXPERIENCE:

2005 to Date Wayne State University Research Assistant

2001 to 2005 Autoliv Electronics of America Algorithm Calibration Engineer NOTABLE PUBLICATIONS:

 Dau, N, Cavanaugh, J, S, Bir, C, Link, M. (2011) Evaluation of Injury Criteria for the Prediction of Commotio Cordis from Lacrosse Ball Impacts. Stapp Car Crash Journal, 5.

 Pollard, JD, Deyhim, A, Rigby, RB, Dau, N, King, C, Fallat, LM, Bir,C. (2010) Comparison of pullout strength between 3.5 mm fully th readed, bicortical screws and 4.0 mm partially threaded, cancellous screws in the fixation of medial malleolar fractures. J Foot Ankle Surg. 49(3): 248-52.

 Link, M, Bir, C, Dau, N, Madias, C, Estes, M, Maron, B. (2008) Protecting Our Children from the Consequences of Chest Blows on the Playing Field: A time for science of marketing. Pediatrics, 122(2): 437-9.

 McKay, B, Dau, N, Staley, S, Dougherty, P, Bir, CA. (2010) Lower Leg Trauma Related to Anti-vehicular Landmines. Orthopaedic Research Society Annual Meeting, New Orleans, LA.

 Dau, N, Link, M, Madias, C, Bir, C. (2008) Correlation of Impact Force and Left Ventricular Pressure for Chest Impacts in an Animal Model for Evaluation of Commotio Cordis Protection, American Society of Mechanical Engineers Summer Bioengineering Conference, Marco Island, FL.

 Dau, N., Link, M. S., Madias, C., Bir, C. (2007) Evaluation of Injury Criteria for Predicting Commotio Cordis. American Society of Biomechanics Conference, Palo Alto, FL.

NOTABLE ACHEIVEMENTS:

2010 – Awarded 2^nd place in manuscript submission competition by the American College of Foot and Ankle Surgeons.

2009 – Awarded the Engineering Society of Detroit (ESD) Alpha Award for innovatation in Engineering and Technology for the development of the MiL-Lx Biomechanical Surrogate.

2007 – Awarded the American Society of Biomechanics (ASB) Presidents Award for the best poster abstract submission to the annual conference.

In document Development of a biomechanical surrogate for the evaluation of commotio cordis protection (Page 159-180)