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Background and purposeThe pathomechanics of the Essex-Lopresti lesion are not fully understood. We used human cadavers and documented the genesis of the injury with high-speed cameras.Methods4 formalin-fixed cadaveric specimens of human upper extremities were tested in a prototype, custom-made, drop-weight test bench. An axial high-energy impulse was applied and the development of the lesion was documented with 3 high-speed cameras.ResultsThe high-speed images showed a transversal movement of the radius and ulna, which moved away from each other in the transversal plane during the impact. This resulted into a transversal rupture of the interosseous membrane, starting in its central portion, and only then did the radius migrate proximally and fracture. The lesion proceeded to the dislocation of the distal radio-ulnar joint and then to a full-blown Essex-Lopresti lesion.InterpretationOur findings indicate that fracture of the radial head may be preceded by at least partial lesions of the interosseous membrane in the course of high-energy axial trauma.

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Biomechanical analyses of the stress distribution and the force transfer in the human knee are essential to better understand the aetiology of joint diseases. Accuracy studies of commonly used capacitive or resistive-based stress distribution measurement systems have led to severe problems caused by an inaccurate experimental setup. For instance, in one study, overestimations of the measured forces in the sensor's centre were reported. Therefore, the primary aim of this study was to investigate the ability of capacitive and resistive-based sensors to measure forces in a homogenous pressure environment and the secondary goal was to analyse the influence of different calibration materials on the measurement accuracy. A Novel pressure vessel and metal indenters covered with different rubber materials were used in combination with a material testing machine to load the sensors. Four different linearly increasing nominal forces (925-3670 N) were applied and the deviations between the nominal and the measured forces were calculated. The capacitive measurement system showed errors between 1% and 7% in the homogenous pressure environment, whereas the errors of the resistive system were found to vary between 4% and 17%. The influence of the calibration material was observed to be greater for the resistive sensors (1-179%) than for the capacitive sensors (0.5-25%). In conclusion, it can be stated that - for the pressure measurement systems compared in this article - the capacitive one is less sensitive to the calibration method and the calibration material than the resistive system.