Analyzing ligament prestrain in a multibody model of an ankle joint with random sampling.

: Modeling an ankle joint is a challenge, especially when considering complex phenomena such as prestrain. In the literature two main approaches to ligament prestrain can be found in ankle modeling. The first one assumes a strain-free configuration, effectively omitting the prestrain, while in the second one the slack lengths are obtained by shortening the ligament lengths in the rest configuration by 2%.

Assessing the behavior of a hybrid model of the knee with contact surrogate under parameter uncertainties.

Modeling the knee is an important factor in increasing the quality of life of both healthy individuals and patients. Nevertheless, the intricate nature of the knee makes this problem complicated. In this study, an extension to an established planar knee joint model with Hertzian contact pairs is proposed with contact mechanics based on polynomial chaos expansion surrogate.

Selected aspects of the application of the hybrid circulatory system in the analysis of heart insufficiency.

Purpose: There are many causes of heart failure, one of them being valvular heart disease. In this case, the stage and type of the disease can significantly affect the hemodynamic parameters of the left ventricle of the heart. In turn, these parameters can significantly influence the mode, type and strategy of clinical treatment.

Differential evolution and cost-maps for needle path planning in Baker's cyst aspiration.

Purpose: The Baker's cysts appear within the popliteal fossa along with the progression of degenerative changes. Removal of its contents through aspiration is often a necessary complement to treatment at various stages of the development of gonarthritis.

Methods: The paper presented a procedure for needle automatic needle path planning in cyst aspiration in transverse plane.

Analyzing Uncertainty of an Ankle Joint Model with Genetic Algorithm.

Recent studies in biomechanical modeling suggest a paradigm shift, in which the parameters of biomechanical models would no longer treated as fixed values but as random variables with, often unknown, distributions. In turn, novel and efficient numerical methods will be required to handle such complicated modeling problems. The main aim of this study was to introduce and verify genetic algorithm for analyzing uncertainty in biomechanical modeling.

A Planar Model of an Ankle Joint with Optimized Material Parameters and Hertzian Contact Pairs.

The ankle is one of the most complicated joints in the human body. Its features a plethora of elements with complex behavior. Their functions could be better understood using a planar model of the joint with low parameter count and low numerical complexity.

Structural and Material Optimization for Automatic Synthesis of Spine-Segment Mechanisms for Humanoid Robots with Custom Stiffness Profiles.

Typical artificial joints for humanoid robots use actual human body joints only as an inspiration. The load responses of these structures rarely match those of the corresponding joints, which is important when applying the robots in environments tailored to humans. In this study, we proposed a novel, automated method for designing substitutes for a human intervertebral joint.

Path planning for minimally-invasive knee surgery using a hybrid optimization procedure.

The aim of this study was to develop a procedure for medical tool path planning in minimally-invasive knee surgery. The collision-free paths for the tool were obtained using the control locations method with a hybrid optimization strategy. The tool and knee elements were described with surface meshes.

A novel planning solution for semi-autonomous aspiration of Baker's cysts.

Background: A Baker's cyst is a pathological structure located near a kneepit, which causes discomfort and reduces mobility of the knee. It is commonly treated with aspiration, which often requires MRI scanning and US guidance. The aim of this study was to propose a novel planning solution for semi-autonomous aspiration of the Baker's cyst using only MRI imaging.

Load analysis of a patellofemoral joint by a quadriceps muscle.

Purpose: The aim of this paper is to develop a model of the patellofemoral joint by considering the linear displacement along axis of cylindrical joint and to use this model in the analysis of the femur spatial displacements caused by the quadriceps muscle force.

Method: The linear displacement along the axis of cylindrical joint of the patellofemoral joint is computed using optimization methods - minimization of the difference between the modeled and measured spatial displacements of the femur with respect to the tibia over the full range of the knee flexion. Then, the instantaneous screw displacements of the femur with regard to the tibia and corresponding muscle forces are computed for the model developed.

A novel kinematic model for a functional spinal unit and a lumbar spine.

Purpose: The aim of this paper is to present the novel model for the functional spinal unit and spine designed as a rigid mechanism and solve it with methods commonly used in robotics.

Method: The structure of the intervertebral joint is analyzed with special attention paid to elements defining the displacements in the joint. The obtained mechanism is then numerically solved using a constraint equations method.