Biomechanical Analysis of Thoracolumbar Spine Fractures in Indianapolis-Type Racing Car Drivers During Frontal Impacts

Links

Abstract

Measurements taken from real-world Indianapolis-type racing car crashes indicate a high injury risk for the thoracolumbar spine. Hybrid III, 50th percentile male dummy model predictions obtained from CART HANS® MADYMO simulations confirm that high load levels are found in the thoracolumbar region. However, simulations using the MADYMO Human Facet Model (HFM) have raised concern about the predictability of the multi-segmented ellipsoid spine model. This study analyzes the ability of a newly developed MADYMO Race Car Driver occupant model, with an adapted ellipsoid spine from the HFM, to predict occupant kinematics, intervertebral loads and moments in the thoracolumbar spinal region. Potential factors influencing spinal loads and moments in Indianapolis-type racing car drivers during frontal impacts were also analyzed. These include spinal curvature, seat back angle, shoulder belt mounting locations and under thigh seat pans referred to as a leg hump. Analysis of the results from this study suggest that alterations in restraint and seat geometry, particularly reducing the seatback angle from 45- to 25-degrees from vertical and raising shoulder belt anchors 75 mm above horizontal, would reduce the risk of thoracolumbar spine injury in Indianapolis-type racing car drivers during frontal impacts. The simulations conducted in this study demonstrate the strong influence of spinal geometry and seating position on injury prediction outcomes. Additionally, a six-point restraint system, helmeted head and C-shaped spinal geometry significantly influence neck flexibility kinematics predicted by the driver model. When the driver model maintains the natural spinal curvatures in an upright seating configuration, the neck does not flex or whip excessively and spinal compression and flexion decreases. In contrast, the C-shaped spine in a 45- degree reclined seating position produces more compression and flexion on the anterior portion of the vertebral body thus predicting increased injury risk for anterior wedge compression fractures. To reduce and prevent such injuries to ITRC drivers, the data suggests sitting the driver more upright and positioning the shoulder belts in a way that maintains the natural spinal curvatures.

Cited Works (9)

Year	Entry
1990	White AA III, Panjabi MM. Clinical Biomechanics of the Spine. 2nd ed. Philadelphia, PA: J.B. Lippincott Company; 1990.
1999	Demetropoulos CK, Yang KH, Grimm MJ, Artham KK, King AI. High rate mechanical properties of the Hybrid III and cadaveric lumbar spines in flexion and extension. In: Proceedings of the 43rd Stapp Car Crash Conference. October 25-27, 1999; San Diego, CA. Warrendale, PA: Society of Automotive Engineers:279-294. SAE 99SC18.
1983	Denis F. The three column spine and its significance in the classification of acute thoracolumbar spinal injuries. Spine. November–December 1983;8(8):817-831.
1984	Yang KH, King AI. Mechanism of facet load transmission as a hypothesis for low-back pain. Spine. September 1984;9(6):557-565.
2006	Moore KL, Dalley AF. Clinically Oriented Anatomy. 5th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2006.
1998	Melvin JW, Baron KJ, Little WC, Gideon TW, Pierce J. Biomechanical analysis of Indy race car crashes. In: Proceedings of the 42nd Stapp Car Crash Conference. November 2-4, 1998; Tempa, AZ. Warrendale, PA: Society of Automotive Engineers:247-266. SAE 983161.
1973	Prasad P. The Dynamic Response of the Spine During +G_Z Acceleration [PhD thesis]. Detroit, MI: Wayne State University; 1973.
2001	Melvin JW, Bock H, Anderson K, Gideon T. Development and field performance of indy race car head impact padding. Stapp Car Crash J. 2001;45:415-436. SAE 2001-22-0019.
2005	de Lange R, van Rooij L, Mooi H, Wismans J. Objective biofidelity rating of a numerical human occupant model in frontal to lateral impact. Stapp Car Crash J. 2005;49:457-479. SAE 2005-22-0020.