The presented analysis concerns the inter-domain and inter-protein interface in protein complexes. We propose extending the traditional understanding of the protein domain as a function of local compactness with an additional criterion which refers to the presence of a well-defined hydrophobic core. Interface areas in selected homodimers vary with respect to their contribution to share as well as individual (domain-specific) hydrophobic cores. The basic definition of a protein domain, i.e., a structural unit characterized by tighter packing than its immediate environment, is extended in order to acknowledge the role of a structured hydrophobic core, which includes the interface area. The hydrophobic properties of interfaces vary depending on the status of interacting domains—In this context we can distinguish: (1) Shared hydrophobic cores (spanning the whole dimer); (2) Individual hydrophobic cores present in each monomer irrespective of whether the dimer contains a shared core. Analysis of interfaces in dystrophin and utrophin indicates the presence of an additional quasi-domain with a prominent hydrophobic core, consisting of fragments contributed by both monomers. In addition, we have also attempted to determine the relationship between the type of interface (as categorized above) and the biological function of each complex. This analysis is entirely based on the fuzzy oil drop model.

(1) Background: Static foot deformities, including hallux valgus, are common deformities. The subject under consideration is the role of extrinsic and intrinsic muscles working within muscular systems that shape the arches of the foot and the alignment of the toes. (2) Methods: Based on a literature review, the muscle systems were analyzed. The systems under consideration were as follows: “tendon stirrup” (system I); muscles complementary to the tendon stirrup (system II); “foot lever” (system III); muscles complementary to system III (system IV); “reins of hallux” (system V), a muscular system having distal inserts on the hallux. The shape of the foot arches was analyzed in this context. (3) Results: The correct arch architecture of the foot stabilized mainly by the extrinsic muscle systems determining the function of the intrinsic muscle systems of the foot is described. The proper function of muscular systems shaping the arches of the foot is a prerequisite for the proper function of muscles directly responsible for the alignment of the big toe (hallux) and other foot toes. (4) Conclusion: The action of muscles should be considered in groups (systems) because the action of the group of muscles results in the creation of a new quality of movement. The analysis of individual muscle-pulling forces, especially the moments of force in the weight-bearing foot, may lead to extremely incorrect conclusions. In pathological cases, the restoration of the correct arches of the foot guarantees the recovery of the correct function of the pulling forces of the foot muscles responsible for the physiological alignment of the hallux. This is especially important concerning conservative and surgical treatment of hallux valgus.

Background: This article presents an example application of an e-learning tool for presenting cases with the aim of acquainting medical students with the procedures performed by a court expert in assessing causes and effects of an accident at work. Methods: The present publication is based on medico-legal expertise dealing with the case of a 51-year-old manual worker of a carpentry company who, due to lack of proper training in handling the machine, severely injured his hand. The main advantage of this publication is the presentation of a series of cause-effect events at every stage of the patient’s treatment that led to minor and major complications and adverse effects. Their starting point was the employer’s evident error, i.e., failure to provide the worker with proper training in handling the machine. Results and conclusions: The discussed orthopedic case has been implemented in the CASUS base (mainly using the program “Virtual Patients” as tool for case presentation) in the form of a description of a properly carried out diagnostic procedure and equipped with the expert’s opinion and explanation of possible inappropriate decisions.

(1) Background: This publication focuses on processes that disrupt the proper development of the hip. Four pathomechanisms underlying human developmental defects are described in the literature, i.e., dysplasia, malformation, disruption, and deformity. In the case of hip development, arguably the greatest challenge involves confusion between dysplasia and deformity, which often leads to misdiagnosis, incorrect nomenclature, and incorrectly chosen treatment. (2) Methods: A review of the scientific literature was performed. (3) Results: The paper presents a description of hip joint development disorders in the context of their pathomechanisms. An attempt was made to answer the question of whether these disorders are rooted in a primary disorder of tissue growth, resulting in incorrect anatomy, or are the result of anatomical deformations with secondary modifications in tissue structures—of a degenerative or adaptive nature—based on Delpech–Hueter–Volkmann growth and remodeling laws. In addition, the emphasis is placed on the presence of so-called clinically and diagnostically mute cases. We suggest augmenting diagnostic procedures with genetic tests to increase the sensitivity of screening. (4) Conclusions: Based on the arguments, a new division of developmental hip disorders is proposed.

Background: This paper concerns the study of forces acting on the upper ankle joint of a human in static and quasi-dynamic positions. This paper aimed to determine the pressure forces on the axis of the upper ankle joint in the position of the body tilting forward and backward, as well as in a neutral position. Methods: A model with designated centres of gravity (including and excluding the weight of the platform imitating the foot) and the point of gravity imitating the proximal insertion of the triceps surae and tibialis anterior muscles was developed for this study. The forces and the weight of the tilted object were measured using dynamometers. A method for determining the arms of gravitational forces and the angle of inclination of an object is presented. The function describing the distribution of gravitational loading along its tilting part was described. Next, all measurements and calculations were referred to the human body. Results: Measurements of muscle force, body gravity, the arms of these forces, and the angles of the object’s inclination on the axis of rotation are presented. A methodology for determining the pressure force on the human upper ankle joint axis is presented. The distribution of the value of the pressure force and its components from the maximal forward, through the vertical body position, up to the maximal backward position of the body tilt, is provided. Conclusions: The ankle joint pressure force is the vector sum of the force of gravity and the force of the muscle counteracting the body tilt. This force is the smallest in the vertical body position and increases with the body tilt. It reaches 5.23 times the weight of the tilting part of the body when the body is tilted to its maximum forward position, and 3.57 times the weight when the body tilts backward. Regardless of the direction of the body tilt, the joint pressure vector always runs through the axis of the upper ankle joint.

Modern clinical and sports medicine increasingly uses training and diagnostic equipment. They allow monitoring of the training process, cycle control, and evaluation of the basic parameters. These devices are used to carry out the training process for healthy people as well as for the rehabilitation of persons with impaired organ movement functions. The developed measurement properties allow defining many parameters and biomechanical functions. They can estimate the state of a particular biomechanical group and monitor its efficiency for a long period of time. The main aim of the research was to determine the impact of the type of load on the dynamic parameters during straightening of the knee joint. It compared parameters of the sick and healthy limbs under the influence of a particular load. The article presents the results of measurements of dynamic parameters of the knee joint. Measurements were obtained during the use of different types of loads for healthy people. The second part of the article concerns the comparison of functions in the sick and healthy limbs of the test person.