Development Of An Anthropomorphic Thigh For Impact Assessment

Modelling of body segments allows predictions to be made of their response characteristics during interactions with the environment. Once the segment or whole body has been replicated, their response to impact can be investigated. This along with an injury tolerence level provides an opportunity to assess the effectiveness of protective equipment. Head/neck models are used by the helmet industry to assess the effectiveness of crash and sport helmets. Wholebody models are used in the automotive and aircraft industries. No instrumented physical thigh model has been designed to assess soft tissue strain as a result of transverse impacts to the longitudinal axis. There is no appropriate means to assess the protection from injury of the numerous thigh pads used in sport. The aims of this study are: i) Determine the response of the human thigh (and its components) to transverse impacts to the longitudinal axis. ii) Select injury tolerence levels for thigh contusions. iii) Select synthetic materials with similar mechanical properties to those of the human thigh (muscle, skin and fat). iv) Design an instrumented physical model of the leg capable of predicting thigh contusions. The subjects will be seated with their thigh horizontal and a knee angle of 120 degrees. An ankle strap will be attached to a load cell. Testing will be performed at a given percent of maximal voluntary isometric cantraction for knee extension. A hemispherical striker under guided free-fall will impact the anterior mid thigh. An accelerometer will be mounted to the striker. Various drop heights may be employed dependinq on subject discomfort. Subjects have volunteered to an impact which will result in a thigh contusion. Testing will be carried out under medical supervision. Thigh skinfold and girth measurements will be taken. To estimate the internal force and the amount of dampening offerred by the biological components, cadaver material will be tested at drop heights which produced contusions in living subjects. Intact anterior thigh tissue (muscle, fascia, fat and skin) will be placed on a force platform and drop tests performed. The components (muscle, skin and fat) will also be assessed separately. Synthetic materials to represent muscle and skin and fat should display similar dampening properties as determined from cadaver impact tests. A force transducer positioned under the synthetic materials can then estimate the internal force and predict contusions

RISK OF HEAD INJURY FROM FALLS ON TAEKWONDO MATS

The aim of this project was to determine the risk of head injury from falls without protective headgear onto 5 different taekwondo mats. In addition, the combined shock absorption of the headgear and mats adopted by the Australian taekwondo team was assessed. An artificial headform with accelerometers was dropped from a height of 1.5 m onto the mats. The acceleration data were used to calculate the Head Injury Criterion (HIC). Results revealed that only one mat had sufficient shock absorption to generate a HIC value below the threshold for head injury for drops with the unprotected headfotm. The combination of the protective headgear and mats adopted by the Australian taekwondo team produced HIC values below the injury threshold. It is recommended that taekwondo athletes wear protective headgear at all times when training

BlOMECHANlCAL CHARACTERISTICS OF THE LOWER EXTREMITIES OF AMPUTEE VERSUS NORMAL SUBJECTS

The purpose o f this study was t o determine whether biomechanical characteristics of the non-amputated leg of unilateral lower extremity amputees significantly differed from the dominant leg of normal subjects. A comparison was made of the mean peak isokinetic knee extensor and ankle plantar flexor torques and mean performance in one- legged static and countermovement vertical jumps. Peak isokinetic torque was measured by a Cybex 11 a t 60 degrees.s. Vertical jump performance was captured on video tape and analysed using the Peak 2D Motion Measurement System. The heights o f the jumps were calculated from the difference in the position of the centre of gravity o f the body as determined by the segmentation method. Stump anthropometrics. Hanavan's (1964) model. and density data from Dempster (1955) were used t o c a l c u l a t e the volume. mass. and position of the centre of gravity of the residual limb of the amputee subjects. Four unilateral lower extremity .amputees, age 31.5 + 4.9 years and height 179.7 + 2.3 cm, were compared w i t h four normal subjects. age 31.1 + 4.1 years and height 179.2 + 1.8 cm. The result revealed that the mean peak isokinetic knee extensor (190+19nm) and ankle plantar flexor (84 +20nm) torques for the amputees were less than but not significantly (