The biomechanical characteristics of spinal dura mater in the context of its basic morphology.

PURPOSE: Spinal dura mater plays a crucial role in the biomechanics and protection of the spine. Therefore, the present study investigated the dura mater's mechanical and basic morphological properties to learn more about the biomechanical behaviour of this fibrous membrane. METHODS: Tissue strips, oriented in the longitudinal and circumferential directions, were cut from the cervical, thoracic, and lumbar vertebrae parts of the porcine spinal cord. Uniaxial tensile tests were performed using a device with a speed of 4 mm/min until rupture of the sample. RESULTS: It was demonstrated that the dura mater is a heterogeneous, anisotropic material. The longitudinal excised specimens showed the highest values of mechanical properties (ultimate force (FU), the stiffness coefficient (k), ultimate tensile strength (σUTS), and Young's modulus (E)) compared to those of the circumferentially. Confocal microscopy and sulforhodamine B (SRB) assay enabled us to visualise collagen and elastin elements more efficiently without a need for sample fixation. CONCLUSIONS: The spinal dura mater mechanical properties are not uniform along the entire length of the spinal cord, but, in the case of morphological features, no major differences were noticed. The utilisation of SRB occurred to be a non-destructive, fast, and efficient tool for visualising even the smallest elastic fibres on different depths of examined samples. The mechanical and morphological properties of the dura mater provided by this study can be further used in computational modelling to understand injury mechanisms better and help develop injury prevention strategies.

Investigations of Human Fascia Lata Elemental Composition-the Effect of Different Preservation and Mineralisation Methods.

Influence of fixation medium and storage conditions as well as impact of sample mineralisation procedure on determination of minerals in human fascia lata was examined and discussed. Freezing and storage in 10% neutral buffered formalin solution and in 2.5% glutaraldehyde were used as the preservation methods of the samples. The concentrations of, both essential and toxic, elements were measured by ICP-OES method in fascia lata samples mineralised with concentrated nitric acid in a closed microwave system and in open vessels heated on a hot plate. Freezing was found as the best preserving method of fascia lata samples because of the number of elements determined and determination precision. The trace element (Cd, Cr, Cu, Fe, Ni, Sr, Zn) concentrations obtained in samples decomposed using the conventional hot plate were different from analogous measurements in solutions obtained after application of closed vessels and microwave energy assistance. Differences between the mineral compositions of fascia samples variously preserved and mineralised were statistically evaluated and discussed. Interelement correlations were analysed taking into account an impact of various methods of sample conservation. Strong, positive association between element content was discovered for Cr-Ba, Mn-Ba, P-Ba, Sr-Ba, Sr-Ca, Zn-Ca, Mn-Cr, Pb-Cr, Sr-Cr, Mg-Fe, P-Fe, Pb-Ni, Ti-Ni and Sr-P pairs of elements.

The denticulate ligament - Tensile characterisation and finite element micro-scale model of the structure stabilising spinal cord.

BACKGROUND: Damage to the spinal cord is one of the most debilitating pathologies with considerable health, economic and social impact. Improved prevention, treatment and rehabilitation after spinal cord injury (SCI) requires the complex biomechanics of the spinal cord with all its structural elements and the injury mechanism to be understood. This comprehensive understanding will also allow development of models and tools enabling better diagnosis, surgical treatment with increased safety and efficacy and possible development of regenerative therapies. The denticulate ligaments play an important role in stabilising spinal cord within the spinal canal. They participate in spinal cord movements and play a role in determining the stress distribution during physiological but also traumatic loading. We present detailed tensile characterisation of the denticulate ligaments and a Finite Element micro-scale model of the ligament relating its structure with the distribution of stress under physiological loading. METHOD: Denticulate ligaments were dissected from cervical spinal levels from 6 porcine cervical specimens with fragments of the pia and dura mater and characterised in terms of their geometry and response to uniaxial tensile loading. The stress-strain characteristics were recorded until rupture of the ligament, ultimate parameters and Young's moduli were determined. The parametric micro-structural Finite Element model was constructed based on literature microscope and histological images of a denticulate ligament as a phenomenological representation of the complex microstructure of a soft tissue. The model was validated against the experimental data. RESULTS: Stress-strain characteristics obtained in tensile test were typical for a soft tissue behaviour. No statistically relevant differences in ultimate strength, strain and Young's moduli were observed between the ligaments harvested from different vertebral levels. Average ultimate tensile stress was 1.26 ±â€¯0.20 MPa at strain 0.51 ±â€¯0.00, rupturing force (1.01 ±â€¯0.21 N) was in agreement with results obtained previously. The Finite Element model accurately predicted the extension-load behaviour of the denticulate ligament in elastic regime. The micro-scale structural representation enabled capturing deformation modes representative of the experimentally observed behaviour. CONCLUSIONS: The presented stress-strain characteristics of the denticulate ligaments add valuable data to the understanding of the biomechanics of the spinal cord and enable development of more accurate models. The developed micro-scale model was capable of capturing biomechanical response of collagenous tissue under tensile loading, it can be applied for the prediction of other soft tissues behaviours. The denticulate ligament model should be included into future spinal cord models to fully represent the complex system's biomechanics and enable development of surgical aid tools to improve patient outcomes and future regenerative therapies.

Influence of body posture on foot load distribution in young school-age children.

Young school-age children are particularly prone to postural defects because they are in a period of development of the spine that is exposed to a number of factors impairing its normal growth. A change in the shape of the spinal column causes a shift in the centre of gravity. Therefore, this study attempted to assess the influence of body posture on distribution of the load transferred by the lower limbs. METHODS: For each of the examined children, this study determined the parameters describing the body posture with the use of the photogrammetric method and the parameters describing plantar force distribution. The statistical analyses were performed using the U Mann- Whitney test and the student's t-test. The correlations between the parameters of the body posture and the parameters describing the foot load distribution were analysed using the Pearson correlation coefficient. These analyses were performed at a statistically significant level of p < 0.05. RESULTS: The tests conducted showed an occurrence of postural defects in about 42% of the subjects and excessively uneven loading of the lower limbs in about 65% of the children. CONCLUSIONS: The authors obtained a medium intensity correlation between the analysed parameters for the groups of boys and girls.

Telocytes of Fascial Structures.

Currently, the exact role of telocytes within fascial structures is unknown. The morphology, distribution and behaviour of fascial telocytes as well as the mutual relationship between telocytes and other cellular fascia constituents should be definitely a subject of further studies. It will contribute to better understanding of the role of the fascial system in health and diseases, may shed light on the regeneration potential of these tissues and may help to find targets for future treatments for locomotor disorders, including fascial diseases. Last but not least, confirmation of the presence of telocytes within fascia may contribute to optimise the use of fascia as a graft material.

Morphological features of fascia lata in relation to fascia diseases.

Fascia lata is an important element of the fascial system, which forms the continuum of connective tissue throughout the body. This deep fascia envelops the entire thigh and hip area and its main function is to transmit mechanical forces generated by the musculoskeletal system of the lower extremities. Fascia lata is also known as a useful and easily harvested graft material. Despite its crucial role in lower extremity biomechanics and wide-ranging applications in plastic and reconstructive surgery, both the structure of fascia lata and particularly the cells populating this tissue are relatively unexplored and therefore poorly understood. The aim of this study was to characterize the main cell populations encountered within human fascia lata and to try to understand their role in health and diseases. Pathologically unchanged human fascia lata was obtained post mortem from adult males. The specimens were analyzed under light, electron, and confocal microscopy. On the basis of different visualization techniques, we were able to characterize in detail the cells populating human fascia lata. The main cells found were fibroblasts, fibrocytes, mast cells, cells showing myoid differentiation, nerve cells, and most interestingly, telocytes. Our results supplement the formerly inadequate information in the literature regarding the cellular components of deep fascial structure, may contribute to a better understanding of the pathogenesis of fascial disorders and improve fascia lata application as a graft material.

Qualitative and quantitative assessment of collagen and elastin in annulus fibrosus of the physiologic and scoliotic intervertebral discs.

The biophysical properties of the annulus fibrosus of the intervertebral disc are determined by collagen and elastin fibres. The progression of scoliosis is accompanied by a number of pathological changes concerning these structural proteins. This is a major cause of dysfunction of the intervertebral disc. The object of the study were annulus fibrosus samples excised from intervertebral discs of healthy subjects and patients treated surgically for scoliosis in the thoracolumbar or lumbar spine. The research material was subjected to structural analysis by light microscopy and quantitative analysis of the content of collagen types I, II, III and IV as well as elastin by immunoenzymatic test (ELISA). A statistical analysis was conducted to assess the impact of the sampling site (Mann-Whitney test, α=0.05) and scoliosis (Wilcoxon matched pairs test, α=0.05) on the obtained results. The microscopic studies conducted on scoliotic annulus fibrosus showed a significant architectural distortion of collagen and elastin fibres. Quantitative biochemical assays demonstrated region-dependent distribution of only collagen types I and II in the case of healthy intervertebral discs whereas in the case of scoliotic discs region-dependent distribution concerned all examined proteins of the extracellular matrix. Comparison of scoliotic and healthy annulus fibrosus revealed a significant decrease in the content of collagen type I and elastin as well as a slight increase in the proportion of collagen types III and IV. The content of collagen type II did not differ significantly between both groups. The observed anomalies are a manifestation of degenerative changes affecting annulus fibrosus of the intervertebral disc in patients suffering from scoliosis.

Electron microscopy of human fascia lata: focus on telocytes.

From the histological point of view, fascia lata is a dense connective tissue. Although extracellular matrix is certainly the most predominant fascia's feature, there are also several cell populations encountered within this structure. The aim of this study was to describe the existence and characteristics of fascia lata cell populations viewed through a transmission electron microscope. Special emphasis was placed on telocytes as a particular interstitial cell type, recently discovered in a wide variety of tissues and organs such as the heart, skeletal muscles, skin, gastrointestinal tract, uterus and urinary system. The conducted study confirmed the existence of a telocyte population in fascia lata samples. Those cells fulfil main morphological criteria of telocytes, namely, the presence of very long, thin cell processes (telopodes) extending from a relatively small cell body. Aside from telocytes, we have found fibroblasts, mast cells and cells with features of myofibroblastic differentiation. This is the first time it has been shown that telocytes exist in human fascia. Currently, the exact role of those cells within the fascia is unknown and definitely deserves further attention. One can speculate that fascia lata telocytes likewise telocytes in other organs may be involved in regeneration, homeostasis and intracellular signalling.

Mineral composition of human fascia lata.

The mineral composition of pathologically unchanged human fascia lata was examined here using inductively coupled plasma optical emission spectrometry (ICP-OES) method for the first time. The total concentrations of Ag, Al, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, P, Pb, Sr, Ti, V and Zn were simultaneously measured in the tissue secured during autopsy. The age-related changes and between-gender differences in mineral composition of the examined tissue were investigated and discussed.

Chemical composition of human and canine fascia lata.

The fascial system is an integral part of the musculoskeletal system. It is a three-dimensional network of connective tissue spreading ubiquitously throughout the body, surrounding muscles, bones, internal organs, nerves, vessels, and other structures. The basic biophysical properties of the fascial system are determined by its structure and chemical composition. This study aimed to determine the elemental composition of pathologically unchanged fascia lata of the thigh, collected during autopsies on humans and dogs. The wide spectrum of elements analysed included both macro and micro elements. The analyses were conducted using scanning electron microscopy with X-ray microanalysis (SEM-EDS). Concentrations of the following macro and micro elements were determined: C, N, O, Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, Fe Co, Ni, Cu, and Zn. The obtained results showed significant differences between human and canine fascia lata regarding the content of most of the examined elements (p < 0.05), except for N. These data may in future provide a starting point for the establishment of reference values for the content of various elements in normal fascial tissue and may also serve to verify the usefulness of experimental animal material as a substitute for human tissue.

Spectroscopic techniques in the study of human tissues and their components. Part I: IR spectroscopy.

Among the currently used methods of monitoring human tissues and their components many types of research are distinguished. These include spectroscopic techniques. The advantage of these techniques is the small amount of sample required, the rapid process of recording the spectra, and most importantly in the case of biological samples - preparation of tissues is not required. In this work, vibrational spectroscopy: ATR-FTIR and Raman spectroscopy will be used. Studies are carried out on tissues: tendons, blood vessels, skin, red blood cells and biological components: amino acids, proteins, DNA, plasma, and deposits.

Spectroscopic techniques in the study of human tissues and their components. Part II: Raman spectroscopy.

Among the currently used methods of monitoring human tissues and their components many types of research are distinguished. These include spectroscopic techniques. The advantage of these techniques is the small amount of sample required the rapid process of recording the spectra, and most importantly in the case of biological samples - preparation of tissues is not required. In this work vibrational spectroscopy: ATR-FTIR and Raman spectroscopy will be used. Studies are carried out on tissues: tendons, blood vessels, skin, red blood cells and biological components: amino acids, proteins, DNA, plasma, and deposits.

Determination of the mechanical properties of the skin of pig foetuses with respect to its structure.

Skin is an important barrier protecting the organism against external environmental factors. Determination of its mechanical characteristics as regards its structure has significant scientific and application value. In this work, uniaxial tensile tests were conducted to determine the basic mechanical parameters of skin with respect to its structure. The subject of the study were skin samples taken from domestic pig foetuses. They were excised from different parts of body, in the direction parallel to the long axis of the body. Regardless of the sampling site, the tests revealed no significant differences in the values of the maximum tensile strength (2.08 ± 0.25 MPa) and the conventional Young's modulus (5.87 ± 1.52 MPa). The mechanical and structural tests confirmed that regardless of the sampling region the skin of domestic pig foetuses may constitute a human skin substitute model.

Biomechanical effect of rapid mucoperiosteal palatal tissue expansion with the use of osmotic expanders.

The comparative study was performed to investigate the biomechanical properties (maximum tangential stiffness, maximum tangential modulus and tensile strength) of expanded mucoperiosteal palatal tissue after rapid expansion regimen correlated with histological findings. Rabbit palatal model was used to correlate the non-operated control group, sham-operated control (subperiosteal tissue dissection) groups and 24- and 48-hour tissue expansion groups. There was no observed damage of tissue collagen network in both tissue expansion groups analyzed immediately after expansion, and biomechanical profile was not significantly different from the profile of control groups. However, rapid tissue expansion activates remodeling of mucoperiosteal tissue structure that revealed significant changes in mechanical properties during the 4-week follow-up. The 24-hour expansion induced transient increase of resilience observed 2 weeks after surgery in comparison to the control groups. As a result of maturation of newly created collagen fibers and mucoperiosteum rebuilding, there were no significant differences between any of the analyzed tensile parameters 4 weeks after the 24-hour expansion. Increased and elongated inflammatory response and connective matrix synthesis observed during healing of 48-hour expanded tissue led to a significant decrease of tensile strength value in comparison to the control groups. Even though 4 weeks after surgery, the resilience of 48-hour expanded tissue was similar to the control groups, tissue healing was not completed and limited scar formation might considerably change the final biomechanical tissue profile. These findings provide new information about tensile properties to rapid mucoperiosteal palatal tissue expansion with the use of osmotic expanders for cleft palate repair by tissue augmentation.

[The evaluation of the properties of the silicone-rod and tissue reation after 5,5 years period of implantation]. / Ocena wlasciwosci preta silikonowego oraz odczynu tkanek po 5,5 letnim okresie implantacji.

In this study we presented a case of prolonged detention of the temporary flexor tendon prosthesis after implantation in the hand. The silicone-rod removed after more than 5 years was subject to an examination: scanning microscopy, measurement of hardness, scanning differential calorimetry, spectroscopy in infra-red and resistance examinations. The obtained results were compared with a findings after examinations of the new, not used silicone-rod. The greatest changes were observed in maximum value of tensile strength (sigmaB) of the material after test of uniaxial tensile tests, which was about 30% smaller for a silicone-rod after implantation. The other result of investigations didn't reveal an important differences between a new and a used rod. The comparison of the tissue reaction was performed by collection a part of sheath in described case and a part of sheath produced around a rod after 10 weeks period of implantation. The generation of a capsules consisted of fibrous connective tissue with concomitant inflammation process was observed in both cases in histopathological view. Silicone rubber is a material which preserve its most important properties even after prolonged period of implantation.

Mechanical response of brain to mechanical stimuli--animal model investigation.

BACKGROUND AND PURPOSE: Conventional neurosurgical procedures give surgeons both tactile and visual feedback. Unlike conventional procedures, minimally invasive surgery is devoid of haptic feedback. Incorporation of tactile feedback into neurosurgical robotic systems can greatly enhance the results of minimally invasive procedures. Hence, the ultimate goal of the research presented here is to define the force response of the brain to different types of mechanical stimuli (short- and long-term). The experimental results describe the force responses of brain during indentation tests. MATERIAL AND METHODS: Seven ovine head specimens with exposed brain were fixed to an MTS Synergie 100 testing machine using a rigid clamp--metallic frame with sharp-end screws. Four regions were loaded by a hemispherically-ended cylindrical indentor. Each of the indentations applied to the brain was divided into two general stages: insertion and hold which was constant for 180 s. Measurements for the following 3 loading velocities were conducted. The force response of brain to mechanical stimulus was acquired for each case. RESULTS: The force response of brain to short-term mechanical stimulus depends on both loading velocities and regions of indentation, whereas the long-term force response depends on the history of loadings. CONCLUSIONS: The development of minimally invasive neurosurgical systems requires estimation of the mechanical response of brain to contact with surgical devices. For this reason, investigation of the force response of brain employing different boundary conditions is necessary.