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Biomechanical data are often assumed to be doubly censored. In this paper, this assumption is evaluated critically for several previously published sets of data. Injury risk functions are compared using simple logistic regression and using survival analysis with 1) the assumption of doubly censored data and 2) the assumption of right-censored (uninjured specimens) and uncensored (injured) data. It is shown that the injury risk functions that result from these differing assumptions are not similar and that some experiments will require a preliminary assessment of data censoring prior to finalizing the experimental design. Some types of data are obviously doubly censored (e.g., chest deflection as a predictor of rib fracture risk), but many types are not left censored since injury is a force-limiting phenomenon (e.g., axial force as a predictor of tibia fracture). Guidelines for determining the censoring for various types of experiment are presented.

Crash test dummies rely on biomechanical data from cadaver studies to biofidelically reproduce loading and predict injury. Unfortunately, it is difficult to obtain equivalent measurements of leg loading in a dummy and a cadaver, particularly for bending moments. A methodology is presented here to implant load cells in the tibia and fibula while minimally altering the functional anatomy of the two bones. The location and orientation of the load cells can be measured in all six degrees of freedom from post-test radiographs. Equations are given to transform tibial and fibular load cell measurements from a cadaver or dummy to a common leg coordinate frame so that test data can be meaningfully compared.

Previous lateral knee bending and shear tests have reported knee joint failure moments close to failure bending moments for the tibia and femur. Eight tibias, eight femurs and three knee joints were tested in lateral bending and two knee joints were tested in lateral shear. Seven previous studies on femur bending, five previous studies on tibia bending, two previous studies on knee joint bending, and one on shear were reviewed and compared with the current tests. All knee joint failures in the current study were either epiphysis fractures of the femur or soft tissue failures. The current study reports an average lateral failure bending moment for the knee joint (134 Nm SD 7) that is dramatically lower than that reported in the literature (284-351 Nm), that reported in the current study for the tibia (291 Nm SD 69) and for femur (382 Nm SD 103).

Though rotation is thought to be the most common mechanism of foot and ankle injury in both automobile crashes and in everyday life, axial impact loading is considered responsible for most severe lower extremity injuries. In this study, dynamic axial impact tests were conducted on 92 isolated human lower limbs. The test apparatus delivered the impact via a pendulum-driven plate which intruded longitudinally to simulate the motion of the toepan in an automobile crash. Magneto-hydrodynamic (MHD) angular rate sensors fixed to the limbs measured ankle rotations during the impact event. Malleolar or fibula fractures, which are commonly considered to be caused by excessive ankle rotation, were present in 38% (12 out of 32) of the injured specimens. Ankle rotations in these tests were always within 10° of neutral at the time of peak axial load and seldom exceeded failure boundaries reported in the literature at any point during the impact event.

Calculating head accelerations and neck loading is essential for understanding and predicting head and neck injury. Most of the desired information cannot be directly measured in experiments with human volunteers. Achieving accurate results after applying the necessary transformations from remote measurements is difficult, particularly in the case of a head impact. The objective of this study was to develop a methodology for accurately calculating the accelerations at the center of gravity of the head and the loads and moments at the occipital condyles. To validate this methodology in a challenging test condition, twenty (20) human volunteers and a Hybrid III dummy were subjected to forehead impacts from a soccer ball traveling horizontally at speeds up to 11.5 m/s. The human subjects and the Hybrid III were instrumented with linear accelerometers and an angular rate sensor inside the mouth.