Abstract des Autors

New release devices to prevent severe knee injuries during backward falls are slowly taken into consideration to improve the effectiveness of ski safety bindings. Therefore ski binding producers developed new binding systems with multidirectional release at the toe piece adapted to the dominating injury mechanism backward - and backward-rotation fall. The aim of the study was to verify the effect of a new binding generation which pretend to fulfil an adequate multidirectional release. In a special binding test device of the German "Arbeitsgemeinschaft Skiforschung", twelve bindings of different producers were tested close to the existing testing device for ski bindings (DIN ISO 9462, IAS 100). Only in four bindings the vertical release force of the toe binding could be adjusted. Two bindings out of these allow for an infinitely variable adjustment related to the rotational release pattern. We used a standard setting for all bindings (indicator value Z = 8.5). Data was collected for a simulated unidirectional backward fall and backward fall with rotational components. The release torque -My was measured to verify the vertical release mechanism of the toe binding, which should protect the knee during the unidirectional backward fall. Simulating the backward-rotation-fall, the release torque -Myss was measured while the toe of the skiboot was rotated 10 mm out of the longitudinal axis of the ski. Our results varied from complete failure to sufficient release pattern. We experienced binding breakage in one case before release. The torque for -My was found to vary from 258 Nm to 520 Nm. A reduction of -Myss in comparison to -My could be demonstrated in eleven out of the twelve measured bindings. The correlation of the value -My to -Myss differed between +2% and -61%. The multidirectional backward release system at the toe binding could be a great advantage for the prevention of knee injuries. The knowledge of the in vivo limiting stiffness value for soft tissue as the ACL is still not known in skiing. Therefore we recommend three principles. An individual adjustable toe binding setting for backward release. A fixed correlation between the proved standard lateral release and the multidirectional backward release as well as important reduction of the value -Myss in correlation to -My to protect the knee against its higher vulnerability when additional rotation load acts. Verf.-Referat