State-of-the-art research in lower-limb prosthetic biomechanics-socket interface: a review.

Scientific studies have been conducted to quantify attributes that may be important in the creation of more functional and comfortable lower-limb prostheses. The prosthesis socket, a human-machine interface, has to be designed properly to achieve satisfactory load transmission, stability, and efficient control for mobility. The biomechanical understanding of the interaction between prosthetic socket and the residual limb is fundamental to such goals.

Numerical simulation of streaming potentials due to deformation-induced hierarchical flows in cortical bone.

Bone is a very dynamic tissue capable of modiA,fing its composition, microstructure, and overall geometry in response to the changing biomechanical needs. Streaming potential has been hypothesized as a mechanotransduction mechanism that may allow osteocytes to sense their biomechanical environment. A correct understanding of the mechanism for streaming potential will illuminate our understanding of bone remodeling, such as the remodeling associated with exercise hypertrophy, disuse atrophy, and the bone remodeling arounid implants.

Comparison of computational analysis with clinical measurement of stresses on below-knee residual limb in a prosthetic socket.

Interface pressures and shear stresses between a below-knee residual limb and prosthetic socket predicted using finite element analyses were compared with experimental measurements. A three-dimensional nonlinear finite element model, based on actual residual geometry and incorporating PTB socket rectification and interfacial friction/slip conditions, was developed to predict the stress distribution. A system for measuring pressures and bi-axial shear stresses was used to measure the stresses in the PTB socket of a trans-tibial amputee.

[Three-dimensional finite element analyses on the transtibial residual limb and its prosthetic socket].

This paper presents a method for developing a nonlinear finite element model to analyze the load transfer between the transtibial residual limb and its prosthetic socket. The model was developed on the basis of three-dimensional geometry of the residual limb, internal skeleton, soft liner and socket. Interface elements, were used to connect the skin and the liner to simulate the friction/slip boundary conditions.

Effectiveness and biomechanics of spinal orthoses in the treatment of adolescent idiopathic scoliosis (AIS).

In this prospective study, the effectiveness and biomechanical factors of spinal orthoses in the treatment of moderate adolescent idiopathic scoliosis (AIS) patients were investigated. In the first 20 months of orthotic treatment, the values of standing AP Cobb's angle, apical vertebral rotation, lumbar lordosis as well as thoracic kyphosis showed significant reduction (P<0.05), however, the angle of trunk inclination and trunk listing did not.

Digital filter design for peak detection of surface EMG.

A simple Low-Pass Differential (LPD) filter is often used for the Motor Unit Action Potential (MUAP) peak detection in needle EMG decomposition. Decomposition of surface EMG is much more difficult since surface EMG is more mixed than needle EMG. A successful peak detection of MUAPs is a first important step for EMG decomposition.

Supporting communication in rehabilitation engineering teams.

The objectives of this project were to examine how members of a colocated rehabilitation engineering team communicate during their work and hence deduce the implications of these communications for the design of video-based technologies to support communication among members of a virtual rehabilitation engineering team. Twenty-four assessment clinic sessions conducted by rehabilitation engineering team were recorded on videotape over a period of 3 years. These tapes were analyzed in considerable detail using a schema to identify and classify the talk and actions of the team members.

A histomorphometric observation of flows in cortical bone under dynamic loading.

Ferritin was used as a histological marker for interstitial fluid flows in four goats. Two transcortical pins were inserted into each tibia mediolaterally-one at the proximal side and one at the distal side of the diaphysis. For the experimental limb, dynamic loading was applied to the pins on the lateral side.

In vivo friction properties of human skin.

In vivo frictional properties of human skin and five materials, namely aluminium, nylon, silicone, cotton sock, Pelite, were investigated. Normal and untreated skin over six anatomic regions of ten normal subjects were measured under a controlled environment. The average coefficient of friction for all measurements is 0.

EMG analysis of voluntary elbow movements in subjects with spasticity.

Surface electromyography (EMG) signals were measured from the biceps brachii (BIC), the brachioradialis (BRD) and the triceps brachii (TRI) of seven young adults with pure spastic quadriplegia and eight normal individuals. The signals were analyzed in both the time domain and the frequency domain. The subjects sat in an adjustable chair and were asked to perform two voluntary tasks involving the elbow joint.

Finite element modelling of a residual lower-limb in a prosthetic socket: a survey of the development in the first decade.

A review is presented of the existing finite element models developed from 1987 to 1996 for the biomechanics of lower-limb prostheses. Finite element analysis can be a useful tool in investigating the mechanical interaction between the residual limb and its prosthetic socket, and in computer-aided design and computer-aided manufacturing of prosthetic sockets. Various assumptions and simplifications are made in these models to simplify the actual problem with complex geometry, material properties, boundary and interfacial conditions, as well as loading situations.

Biomechanical evaluation of the Milwaukee brace.

Although, the history of orthotic treatment for idiopathic scoliosis goes back more than fifty years, the mechanism of curve control by spinal orthosis is still controversial. Hypothetical explanations have been provided but few, if any, have been tested clinically. This study aims at the biomechanical evaluation of a spinal orthosis (Milwaukee brace) in order to improve understanding about the mechanism of curves control in orthotic movement.

Biomedical gait evaluation of the immediate effect of orthotic treatment for flexible flat foot.

Flexible flat foot subjects attending the prosthetics and orthotics units come with prescriptions from orthopaedic surgeons for arch supports. Usually a pair of thermoformed plastic inserts are fabricated and fitted to treat the patients. However the effect of the orthotic treatment is not yet clear.

Development of a simple approach to modify the supporting properties of seating foam for pressure relief.

Pressure sores are a major problem frequently encountered by persons who use wheelchairs. Custom seat design, including contoured seating and various modular seating devices, has become an important option for pressure relief, especially when the market size is small and the variations of individual needs and requirements are large. An alternative approach in custom seating design for pressure relief is proposed in this paper.

Estimating the effective Young's modulus of soft tissues from indentation tests--nonlinear finite element analysis of effects of friction and large deformation.

A nonlinear finite element model was developed to investigate the biomechanics of indentation, particularly the influence of friction and large deformation on the calculation of the effective Young's modulus from the cylindrical, flat-ended indentation test of soft tissues. A new kappa table was given for calculation of the effective Young's modulus to account for the effects of layered geometry with consideration of the larger deformation. The results indicate that the effect of friction on the calculation of Young's modulus becomes significant with a large aspect ratio and with a large Poisson's ratio.

Three-dimensional motion analysis of the voluntary elbow movement in subjects with spasticity.

The purpose of this study was to quantitatively compare the difference in voluntary upper extremity movements between subjects with and without spasticity. Eight normal subjects (mean 26.7 +/- 2.

An audit of the combined non-operative and orthotic management of ruptured tendo Achillis.

At this institution we have introduced combined non-operative and orthotic treatment for ruptured tendo Achillis. An outcome audit was performed to assess this treatment. Patients were treated in a short-leg cast in the equinus position.

Potential for use of a House of Quality Matrix technique in rehabilitation engineering.

This article describes a concept of using the House of Quality matrix tool to aid the process of designing customized seating. The work of a cross-function team in two seating clinics was videotaped. At a later date the information derived from the videotapes was analyzed using a House of Quality matrix.

Effects of limb perturbation on surface recorded nerve action potentials.

The field action potentials are a convolution of source strength and the propagating-point source responses (PPSRs). Surface-recorded peripheral nerve potentials are strongly influenced by the volume-conductor properties of the limb. In this paper the PPSRs are solved based on finite-element formulation, which allows solutions to forward volume-conductor problems involving curved nerves in arbitrarily shaped, inhomogeneous, anisotropic limbs.

An elbow joint movement control model with visual feedback.

A motor program generator control model is proposed to simulate neuromuscular control. Three muscles (Biceps, Triceps, Brachialis) driving elbow joint flexion in a plane are simulated by integrating their nonlinear dynamic property and spinal neural circuitry. The motor descending commands are described by a visual feedback signal from the joint and an excitation signal for the motor neuron pool.

Muscle fatigue monitoring using wavelet decomposition of surface EMG.

Monitoring the local muscle fatigue in maximum voluntary isometric contraction is successful using median frequency and mean power frequency of the surface EMG. However, it has very limited success in maximum voluntary dynamic contraction. We showed that the relaxation electromechanical delay was a reliable fatigue indicator during the maximum voluntary isokinetic concentric contraction.

Deformation-induced hierarchical flows and drag forces in bone canaliculi and matrix microporosity.

Existing theories for interstitial flows in bone have only examined the contributions from different flow systems separately, such as the flows through the microporosity, the canaliculi, and the Haversian canals. An overall model encompassing the hierarchical microstructure is important to our understanding of the actual physics of flows in bone. The flow-induced drag forces and streaming electrical potentials could interact with the osteocytes to effect biological responses.

Scanning Acoustic Microscopy of human and canine cortical bone microstructure at high frequencies.

An Olympus UH3 Scanning Acoustic Microscope (Tokyo, Japan) has been used in the burst mode at 400 and 600 MHz to study the elastic properties of osteons and osteonic lamellae in both canine and human compact cortical bone. The nominal resolution at each frequency is within the width of an individual lamella. Three important new observations have been made regarding the acoustic properties of individual lamellae.

Evaluation of a simple approach to modify the supporting property of seating foam cushion for pressure relief.

To provide pressure relief at the high pressure areas of the buttocks, small holes were drilled on the polyurethane (PU) foam cushion under the ischial tuberosities areas. This modification was done to locally lower the supporting property of the cushion. This approach could be easily implemented in the clinical setting.