Karel Jelen

Forensic Biomechanical Analysis of Falls from Height Using Numerical Human Body Models

Abstract:  This article describes the method of using human body models developed originally for the use in automotive safety in forensic reconstructions of falls from height. The MADYMO® software package and multibody human body models were used in forensic analyses of two real cases—a fatal fall from a window c. 13.8 m above the ground and a fall into a c. 2.5‐m deep cellar pit resulting in isolated ankle joint injury. The performed series of numerical simulations helped to reconstruct the events and to resolve legally relevant questions concerning various aspects of the falls. The benefits as well as limitations and potential biases associated with the use of numerical simulation in forensic biomechanical settings are discussed. The method has proven to be effective under specific circumstances, though the cost (both financial and temporal) still prevents it from wider use.

ANALYSIS OF PEAK PRESSURE, MAXIMAL FORCE, AND CONTACT AREA CHANGES DURING WALKING AND RUNNING WITH CONVENTIONAL AND SHOCK-ABSORBING INSOLES IN THE COMBAT BOOTS OF THE CZECH ARMY

The aim of this study was to determine changes of peak pressure, maximal force, and contact area in five foot regions with two different insoles during walking and running, thereby obtaining data contributing to optimization of footwear and reduction of lower leg injury. Twenty-six male soldiers participated in the study. Peak pressure, maximal force, and contact area were measured in five foot regions (lateral and medial heel, midfoot, lateral and medial forefoot, big toe, and toes 2, 3, 4, and 5) with two different insoles (conventional vs. custom molded shock-absorbing insoles) during a walking speed of 5 km/h and running speeds of 8 and 12 km/h using the Pedar-X tensometric system (Novel, St. Paul, MN). Measurements revealed that the shock-absorbing insoles significantly (p < 0.05) attenuated the peak pressures in heel and forefoot region and increased the contact area in the midfoot region which indicates a successful redistribution of forces that arise during the contact phase in walking and running. Shock-absorbing insoles hence may contribute to better plantar pressure distribution during walking and running, and effectively prevent lower leg injuries.

Calcaneal Tendon Collagen Fiber Morphometry and Aging

Fibrillar collagen in tendons and its natural development in rabbits are discussed in this paper. Achilles tendons from newborn (~7 days) to elderly (~38 months) rabbits were monitored in intact (n tendons=24) and microtome sectioned (n tendons=11) states with label-free second harmonic generation microscopy. After sectioning, the collagen fiber pattern was irregular for the younger animals and remained oriented parallel to the load axis of the tendon for the older animals. In contrast, the collagen fiber pattern in the intact samples followed the load axis for all the age groups. However, there was a significant difference in the tendon crimp pattern appearance between the age groups. The crimp amplitude (A) and wavelength (Λ) started at very low values (A=2.0±0.6 µm, Λ=19±4 µm) for the newborn animals. Both parameters increased for the sexually mature animals (>5 months old). When the animals were fully mature the amplitude decreased but the wavelength kept increasing. The results revealed that the microtome sectioning artifacts depend on the age of animals and that the collagen crimp pattern reflects the physical growth and development.

Valve interstitial cell culture: Production of mature type I collagen and precise detection

Collagen often acts as an extracellular and intracellular marker for in vitro experiments, and its quality defines tissue constructs. To validate collagen detection techniques, cardiac valve interstitial cells were isolated from pigs and cultured under two different conditions; with and without ascorbic acid. The culture with ascorbic acid reached higher cell growth and collagen deposition, although the expression levels of collagen gene stayed similar to the culture without ascorbic acid. The fluorescent microscopy was positive for collagen fibers in both the cultures. Visualization of only extracellular collagen returned a higher correlation coefficient when comparing the immunolabeling and second harmonic generation microscopy images in the culture with ascorbic acid. Lastly, it was proved that the hydroxyproline strongly contributes to the second‐order susceptibility tensor of collagen molecules, and therefore the second harmonic generation signal is impaired in the culture without ascorbic acid.

The Women's Pelvic Floor Biomechanics

The function of the pelvic floor is fundamentally influenced by the behaviour of several organs and the organ-linked processes. The aim of this work is to study the properties and changes of the women’s pelvic floor. The motive arises from the fact that pelvic floor dysfunctions badly influence the quality of life. The loss of the proper function in the pelvic floor results in a wide range of problems from asymptomatic and anatomic defects to vaginal eversion. All the aforementioned problems are frequently followed by urinating and defecating difficulties together with sexual dysfunctions.

DEVELOPMENT OF VERTICAL GROUND REACTION FORCE AFTER HIP SURGERY

Human walking as a method of locomotion, enabling individuals move from place to place, is completely unique throughout the animal kingdom and strictly specific to species Homo sapiens sapiens [Dungl, 2005]. This study deals with the development of the vertical walking dynamics after hip surgery. An essential role after the Total hip arthroplasty (THA) surgery is played by rehabilitation and work of the physiotherapist, which lead to improved physical condition of the patient. Most patients experience pain relief and improvement in joint function and mobility after THA. This study deals with the dynamic analysis of walking in a period of four months after THA surgery, when the patients completed their rehabilitation. Information about the development of vertical reaction force can thus be used to correct the timing of the rehabilitation process after total hip arthroplasty and can help the patient to quickly return to normal life.