An Overview of Knee-Thigh-Hip Injuries in Frontal Crashes in the United
States

INTRODUCTION
With the increasing use of safety belts and availability of air bags, more occupants survive serious car crashes (NHTSA, 2000). However, many people involved in frontal or offset crashes incur disabling lower extremity injuries. Though lower extremity injuries are usually not life threatening, the physical and psychosocial consequences of lower extremity injuries are often long lasting (Read, et al., 2002). Lower extremity injuries require comparatively longer periods of hospitalization and recovery than injuries to other body regions given the same AIS rating and often result in long term or permanent disability (Dischinger, et al., 1995, Read, et al., 2002). This is because the AIS mainly considers an injury’s “threat to life” and is not sensitive for classifying injuries according to the probable degree of residual impairment or functional limitation.

Lower extremities are the most frequently AIS 2+ injured body region in air bag equipped vehicles with a 5 percent risk of injury in frontal crashes (Kuppa, et al., 2001). Fifty percent of lower extremity injuries are to the knee-thigh-hip complex (Ore, et al., 1993, Kuppa, et al., 2001) that account for 45 percent of the life years lost to lower extremity injuries (Kuppa, et al., 2001).

In a detailed examination of the UK CCIS database, Pattimore (1991) noted that lower limb injury risk was very dependent on the type of impact sustained and the restraint status of the occupant. For restrained occupants, 68% of lower limb skeletal injuries occurred below the knee, while for unrestrained occupants, 51% of skeletal injuries involved the hip/pelvis.

Huelke, et al. (1991) examined the incidence of knee-thigh-hip injuries sustained by drivers and front seat passengers in frontal impacts in relation to other lower extremity injuries. Hip injuries accounted for 15%, thigh for 18%, and knee for 22% of all lower extremity injuries. The proportion of KTH injuries among all lower extremity injuries sustained by younger drivers and passengers (16-50 years of age) is greater (55%) than that sustained by older drivers and passengers (61+ years). Contacts with the instrument panel and steering wheel rim and column were the major source of knee-thigh-hip injuries in frontal crashes.

Ore, et al. (1993) examined knee, thigh, and hip injuries in relation to the age and gender of the front seat vehicle occupant. The effect of age on kneethigh- hip injury risk was more prominent for female occupants than male occupants. Ore et al. noted that among the ten most cost-intensive injuries of inpatients, injuries to the hip joint, pelvis and femur are the highest.

In spite of the high frequency of knee-thigh-hip injuries in frontal impacts and their associated high societal cost, there has been less attention paid to them. Air bags have been shown to reduce the frequency of severe head and chest injuries and therefore significantly change the injury profile of front seat occupants involved in frontal crashes. However, the influence of air bags on lower extremity injuries, and in particular injuries to the knee-thigh-hip complex, has not been examined effectively in previous field studies since they lacked sufficient number of air bag equipped vehicles in their real world crash dataset. Therefore, a detailed examination of knee-thigh-hip injuries and their relation to injuries to other body regions in frontal vehicular crashes was undertaken in this study.

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• An Overview of Knee-Thigh-Hip Injuries in Frontal Crashes in the United States
• Lower Extremity Injuries and Associated Injury Criteria
• Case Study: Neck Injuries in Automobile Collisions
• Case Study: Knee Injury Analysis in Heavy Truck v. Automobile Collision
• Case Study: Pedestrian Accident Analysis
• Effects of Head Restraint Position on Neck Injury in Rear Impact
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