Background Lower extremity injuries are the most frequent AIS 2+ injured body region for occupants in air bag equipped vehicles. About half of these injuries occur below the knee and, of those, ankle and foot injuries are the most frequent and responsible for long-term impairment. Laboratory tests simulating frontal impacts with toe pan intrusion have shown that the Thor-Lx/HIIIr responses are repeatable and the Hybrid III dummy upper body responses (HIC, chest G, chest deflections, and femur force) are not affected by the type of leg (below knee) used. An NPRM is being drafted to bring the Thor-Lx/HIIIr into Part 572 of the Code of Federal Regulations. The Thor-Lx/HIIIr is also the likely lower extremity device that will be used in future frontal and frontal-offset high-speed testing.

Objectives Compare the risk of AIS 2+ below-knee injuries in NCAP tests using the Thor-Lx/HIIIr to that in real world full frontal crashes. This will provide an estimate of the performance of the proposed injury criteria when applied to the Thor-Lx/HIIIr measurements in assessing lower extremity injury risk. This vehicle crash test data would also assist in determining countermeasures to mitigate lower extremity injuries.

Proposed Approach Compile a database of the risk of various below knee injuries for different vehicles tested in the NCAP program with the Thor-Lx/HIIIr. It may be necessary to perform tests on additional older vehicles to supplement available NCAP data. Estimate the average risk of injury based on sales volume. Estimate the risk of various AIS 2+ below knee injuries from NASS CDS data files, CODES, and/or other sources of injury data, and compare to that obtained from the NCAP test data. The evaluation could take 2-5 years, depending on the need for additional test data, and until sufficient crash data accumulate.