An overview of knee-thigh-hip injuries in frontal crashes in the United States

Injuries to the knee-thigh-hip complex (KTH) are a frequent, debilitating, and expensive consequence of automobile crashes. This paper examines the influence of frontal crash modes, restraint status, occupant age and gender, and vehicle body type and model year on the frequency and risk of KTH injuries and their associated loss in quality of life and societal cost. The NASS-CDS data files for the years 19932001 were examined to estimate the frequency and risk of KTH injuries in real world frontal crashes. The crash mode was defined by the direction of impact and the vehicle crush profile. The injury codes of the Abbreviated Injury Scale (AIS, 1990) were used to link injury information with the Functional Capacity Index (FCI) and the economic cost of each type of injury. The loss in quality of life was estimated as Life-years Lost to Injury (LLI) that considers the life expectancy of the injured occupant and the FCI of the injury. Injuries to the knee-thigh-hip (KTH) complex account for 18% of all AIS 2+ injuries sustained by front seat occupants involved in frontal automobile crashes and 23% of the associated LLI. The comprehensive cost of lower extremity injuries is $7.64 billion annually with KTH complex injuries accounting for 52% of the costs. Hip injuries account for 58% of the LLI associated with AIS 2+ KTH injuries. The risk and proportion of AIS 2+ hip injuries is higher in newer vehicle models than older models of air bag equipped vehicles. Risk of AIS 2+ KTH injuries for restrained occupants is higher in air bag equipped vehicles than in no air bag vehicles.