Helga Vertommen

Gait assessment during the initial fitting of customized selective laser sintering ankle foot orthoses in subjects with drop foot

Background: Recently, additive fabrication has been proposed as a feasible engineering method for manufacturing of customized ankle foot orthoses (AFOs). Consequently, studies on safety, comfort and effectiveness are now carried out to assess the performance of such devices. Objective: Evaluate the clinical performance of customized (selective laser sintering) SLS-AFOs on eight subjects with unilateral drop foot gait and compare to clinically accepted (polypropylene) PP-AFOs. Study Design: Active control trial. Methods: For each subject two customized AFOs were fabricated: one SLS-AFO manufactured following an additive fabrication framework and one thermoplastic PP-AFO manufactured according to the traditional handcraft method. Clinical performance of both AFOs was evaluated during gait analysis. Results: A significant beneficial effect of both custom-moulded PP-AFO and customized SLS-AFO in terms of spatial temporal gait parameters and ankle kinematic parameters compared to barefoot gait of adults with drop foot gait are observed. No statistically significant difference between the effect of PP-AFO and of SLS-AFO was found in terms of spatial temporal gait parameters and ankle kinematic parameters. Conclusion: AFOs manufactured through the SLS technique show performances that are at least equivalent to the handcrafted PP-AFOs commonly prescribed in current clinical practice. Clinical relevance Manufacturing personalized AFOs with selective laser sintering (SLS) in an automated production process results in decreased production time and guarantees the consistency of shape and functional characteristics over different production time points compared to the traditional manufacturing process. Moreover, it reduces the dependency of the appliance on the experience and craftsmanship of the orthopaedic technician.

Towards analysis of foot motion using dynamic 3d surface scanning

Until now foot motion is mostly studied by markerbased 3D analysis. However, a recently developed dynamic 3D scanner is able to scan the entire foot surface at 49 Hz (Vialux). This creates a variety of possibilities for analysis of foot motion during gait. The aim of this study is the extraction of a segmented foot model from a dynamic 3D scan. Such a foot model would enable a motion analysis without the need to predefine segments, with data from quick and non-invasive measurements.

Development of an artificial foot enabling the simulation of the natural behaviour of the human unroll of the foot during walking and running

The percentage of sports and leisure shoes sold worldwide is gradually increasing. However, consumers have little or no objective information on the mechanical properties of the shoes. A justified selection protocol of sports and leisure shoes based on static and dynamic shoe properties considering the intended use is essential. Today, commonly accepted dynamic test protocols for (sports) shoes do not exist. The development of an artificial parametric foot as part of an innovative robot gait simulator is a tool to objectify shoe properties independently from possible compensations encountered during assessment of test persons. This contribution discusses the development of an artificial foot enabling objective testing of the mechanical and functional properties of sports and leisure shoes.

The effect of a subject-specific AFO on the muscle activation during gait of a test subject suffering from a hemiparetic anterior muscle insufficiency in the lower leg

Background An Ankle Foot Orthosis (AFO) is commonly used in clinical practice to assist gait of patients with different pathologies. The flexibility of the AFO depends on different design characteristics while specific mechanical requirements of the AFO are correlated with patient anatomy and pathology. To this day, the correlation between AFO-design and patient pathology is mainly based on the orthopaedic technician’s experience. The aim of this study is to investigate the influence of the stiffness of an AFO on the muscle-activation pattern of a subject suffering from an anterior muscle insufficiency of the lower leg using a personalized musculoskeletal model. Materials and methods Test subject was a 40-year old male suffering from a hemiparetic anterior muscle insufficiency of the lower leg. A musculoskeletal model of the lower limbs with 23 degrees of freedom and 92 muscles was scaled in OpenSim to match the test subject’s anthropometric data [1]. Muscle-definitions were adapted to simulate the patients’ pathology. A subject specific AFO was constructed using the selective laser sintering technique [2]. The actual stiffness of the AFO was determined using finite element analysis [3] and was 258 Nm/rad. Marker trajectories of an AFO-gait were used to calculate kinematic parameters and muscle-activation during gait using the musculoskeletal model. The AFO was simulated as an angle-dependent torque around the ankle with a neutral angle of 0°. The stiffness of the AFO was varied between 150 and 350 Nm/rad in steps of 25 Nm/rad. Results

Development of a model to analyse foot biomechanics using dynamic 3D surface scanning.

The foot is a complex structure, bearing the responsibility for the load and propulsion of the entire human body during walking. Important variations in foot form and structure exist individually, and complaints of biomechanically related foot problems are a well-known issue. Appropriate analysis of the foot motion during a core activity like walking is required for the prevention, diagnosis and treatment of these foot problems. The complex kinematics of the foot during rollover are mostly studied by 2D video analysis or marker-based 3D motion analysis (Vertommen 2012). However, these techniques are not able to gather full information about the 3D dynamic foot shape while walking. Detailed 3D data on the foot shape changes during rollover contain essential information on foot function and behaviour which are difficult or not detectable with the current measurement techniques. A recently developed dynamic 3D scanner (Vialux) is now able to scan the entire foot surface at 49Hz. In combination with force assessment, this innovative measurement technique has important potential in the field of biomechanics and motion analysis of the foot. To accomplish the extraction of relevant parameters from the 3D dynamic surface data, an appropriate foot model has to be developed. Such a model has the capacity to result in kinematic variables concerning motion of the bones and joints, as well as superimposed shape variables induced by soft tissue deformation in the foot. The aim of this study is the extraction of such a foot model from a dynamic 3D surface scan.

Development of a measurement protocol to define shoe parameters: deformation of shoe sole during running

values between unstable shoes and the reference shoe. However, comparing the unstable shoes and the barefoot condition, greater IEMG values (mVs) were identified in LG (0.24 0.12), VM (0.19 0.16), VL (0.17 0.22) and RF (0.21 0.16) during barefoot standing. For COP excursion, no significant differences could be evaluated between the unstable shoes, as well as compared to the stable reference condition. During barefoot standing compared to unstable and reference condition the COP excursion was significantly larger (Figure 2).

The development of methods and procedures to determine the dynamic and functional properties of sports shoes

footwear condition ( p5 0.001). While peak AJC eversion angle was greater for both footwear conditions, TIR was less when running in footwear ( p5 0.001). The peak eversion findings may be related to rearfoot motion being over estimated due to tracking the heel counter and not the foot for footwear conditions (Stacoff et al. 1992). The thigh segment angle at TD and peak TIR supported adjustments being made due to mode of cushioning.