Systematic review of studies examining transtibial prosthetic socket pressures with changes in device alignment

Suitable lower-limb prosthetic sockets must provide an adequate distribution of the pressures created from standing and ambulation. A systematic search for articles reporting socket pressure changes in response to device alignment perturbation was carried out, identifying 11 studies. These were then evaluated using the American Academy of Orthotists and Prosthetists guidelines for a state-of-the-science review. Each study used a design where participants acted as their own controls. Results were available for 52 individuals and 5 forms of alignment perturbation. Four studies were rated as having moderate internal and external validity, the remainder were considered to have low validity. Significant limitations in study design, reporting quality and in representation of results and the suitability of calculations of statistical significance were evident across articles. Despite the high inhomogeneity of study designs, moderate evidence supports repeatable changes in pressure distribution for specific induced changes in component alignment. However, there also appears to be a significant individual component to alignment responses. Future studies should aim to include greater detail in the presentation of results to better support later meta-analyses

AN EXPERIMENTAL AND ANALYTICAL STUDY OF IMPACT FORCES DURING HUMAN JUMPING

Impact forces during landing in dismounts from the horizontal bar onto regulation gymnastic mats and in jumping from a height of 0.45 m onto a hard surface were measured. A two degree-of-freedom dynamic model was developed to predict the forces in landing on the hard surface. The periods of the two peaks that can be identified from experimental data were used in the determination of the system parameters. The peak forces recorded in gymnasts' landing ranged from 8.2 to 11.6 times the body weight. Maximum forces in jumping from 0.45 m, which ranged from 5.0 to 7.0 times the body weight, were accurately predicted by the mode

A viscoelastic sphere model for the representation of plantar soft tissue during simulations

Simulations of human body during locomotion require a realistic representation of the foot which is the major interacting part of the body with the environment. Most simulation models consider the foot to be a rigid link, and impose unrealistic kinematic conditions. This study utilizes a viscoelastic sphere model with realistic properties, which can be used to represent the plantar surface of the foot during locomotion. The mechanical properties of the sphere are identified using experimental data on heel pads (Valiant, 1984). To check the validity of the model the results of the experimental study are reproduced by simulating the impact tests. Sensitivity analyses of the model parameters are carried out. The model is found to be insensitive to variations in stiffness and damping properties. The change in the thickness of the soft tissue, however, affected the maximum force of deformation proportionally. ii symmetrical pressure distribution for the sphere during impact is calculated. It is concluded that the viscoelastic sphere model, presented here, can be incorporated into a foot model to represent the plantar surface of the foot

Stress analysis and fixation problems in joint replacement

The aims and scopes of stress analyses, and the three most commonly applied methods (i.e. experimental strain-gauge techniques, analytical `closed-form' solutions, and finite element methods) are discussed with particular reference to total hip replacemen