Intervertebral Disc Height Loss and Restoration: Outcomes and Implications

This thesis is unified around the theme of disc height loss. Current knowledge in the area of spine research identifies mechanical overload as the culprit for the initiation of injury to the spine. While genetic predispositions may play a factor in the severity of spine degeneration or in the resiliency to applied load, ultimately, injury occurs when a load exceeds a tissue’s tolerance. Disc height loss has the potential to be a primary factor in the progression of spinal degeneration. For example, disc height has been touted as a major component for the initiation of pathological and degenerative changes to the spine. Pathologic, non-recoverable disc height loss can occur through herniation or endplate fracture and could result in a degenerative cascade of injury that eventually involves the facet joints, narrows nerve root space, and increases stress at adjacent segments. What is not known is the degree to which disc height affects the degenerative cascade; that is, there is no quantitative data outlining the progression of mechanical consequences at adjacent segments or at the injured segment itself during disc height loss. Further, the degree to which restoring disc height, if even possible, will reverse the process of degeneration is not entirely clear. There is data which suggests that nucleus replacement can restore stress distributions within an injured disc, but the extent of repair material survivability is unknown. Finally, clinical categories of measuring spinal degeneration are based on visual cues and features from medical imaging. Understanding the links between joint visual cues and aberrant movement may help to guide clinical practice; researchers will gain greater insight into the mechanical consequences of anatomical features associated with degeneration. This thesis was comprised of three studies. Study 1 examined the effect of disc height loss and subsequent restoration using an injectable hydrogel on the relative kinematics of a segment with height loss and an adjacent segment. It was found that disc height loss produced an immediate effect, where relative angular displacement was reduced in the segment with height loss and increased in the adjacent segment. Restoring disc height with an injectable hydrogel brought the relative angular displacement of both segments back to their initial values. This study is the first of its kind to examine the immediate effects of disc height loss via loss of nucleus pulposus and restoration. Whether these effects are as clear in-vivo remains to be seen. Study 2 evaluated the efficacy of a novel repair strategy to restore the mechanical profile of a spine segment with disc height loss initiated via compressive fracture. The strategy employed the use of PMMA injected into the vertebral body to attempt to seal a fracture from above the disc, and an injectable hydrogel to restore disc height. The use of PMMA was found to restore the compressive stiffness of the injured segment to within approximately 20% of its initial value, while the use of the injectable hydrogel restored the sagittal plane rotational stiffness to within approximately 50-80% of its initial value. After further repetitive compression had been applied to the spine segment however, the restorative influence of both interventions was lost in terms of rotational and compressive stiffness. It was found that large cracks in the endplate prevented the hydrogel from being contained and quickly returned the segment back to its injured profile. Future efforts at restoring the disc while maintaining its anatomical structures need better methods of creating a sufficient seal inside the disc to allow it to re-pressurize and sustain the stresses encountered on a daily basis. Study 3 employed the use of a novel spine tracking algorithm developed as part of this thesis to evaluate sagittal plane cervical spine motion of a series of patient image sequences who had experienced trauma and had a chief complaint related to their neck, head, or shoulders. Some patients had evidence of disc height loss while others did not. Clinical subgroups were created that classified disc height loss as either moderate/severe (3 cases), mild (8 cases), or non-existent (9 cases). When normalized angular displacement of the C5/C6 segment in a group with moderate to severe height loss was compared to the same level in a group with no height loss, there was a statistically significant difference in angular displacement between the two groups (p = 0.004). Angular displacement at C5/C6 was 20.2% ± 2.3% of total measured neck angular displacement in the moderate/severe height loss group compared to 30.6% ± 4.0% of total measured neck angular displacement in the group without height loss. Based on the limited sample size of this study it would appear that disc height loss creates a loss in range of motion. This work has further revealed the heterogeneous nature of individual segmental movement patterns. However, in the group without height loss, there was a systematic trend seen of an increasing angular displacement with descending segmental level. This was not observed in those with moderate to severe disc height loss. The broad implications of this work are that disc height loss influences spine kinematics, which has implications with respect to further injury propagation through the spinal linkage. Angular displacement of a spine segment appears to be governed by its local stiffness. Restoration of disc height under real injury scenarios is a difficult proposition and any attempts at repair need to sufficiently seal the disc space and prevent extrusion of nucleus pulposus or hydrogel-based implants. We now appreciate the difficulty in this objective. Further, repeating the mechanism of injury will reduce the mechanical effects of the restorative intervention, preventing this is highly important

ELECTORAL LEGISLATION OF THE FIRST YUGOSLAV STATE (1918 – 1941)

U međuratnom jugoslavenskom izbornom zakonodavstvu razlikujemo dva razdoblja koja se podudaraju s općom podjelom političke povijesti Kraljevine. Dvadesetih godina vrijedilo je zakonodavstvo usvojeno 1920. i djelomično promijenjeno 1922. godine. Država je bila podijeljena na izborne jedinice. Glasali su samo muškarci, na tajnim izborima. Mandati su se dodjeljivali prema proporcionalnom sustavu. Tridesetih godina na snazi je bilo zakonodavstvo iz 1931., koje je ispravljeno 1933. godine. Još su uvijek glasali samo muškarci. Biralo se javno, i to za zemaljske liste kandidata. Izborni je zakon, unatoč proporcionalnoj podjeli mandata, favorizirao pobjedničku listu.Parliamentary life in the Kingdom of Serbs, Croats and Slovenes/Yugoslavia (1918–1941) can be divided in two periods. The first period spans from the 1920s to the second half of the 1930s. The milestone was in 1929 when King Alexander I forcibly dissolved the Parliament and introduced personal dictatorship. The first law was introduced in 1920 and amended merely two years later. The system was based on secret balloting and proportional representation. Eligible voters were adult male citizensand the same system remained in the 1930s. A voter would cast his vote by dropping the ball in the ballot box of his party. At the poll station there was one ballot box for each candidate party. This system had been used in the prewar Kingdom of Serbia due to the high rate of illiteracy. The law from 1920 adopted this method of voting for the same reason. In the 1920s the state was divided in more than 50 electoral units with a fixed number of seats. Parties hada candidate in each of them according to their interest. In each unit, the mandates were distributed separately. The 1931 Law retained the institution of proportional representation. But it was significantly modified by favoring the strongest party. The strongest party was given a larger share of seats comparing its share of votes. Following the idea of Unitarianism, the law introduced a state as a single electoral unit divided into subunits. A candidate list needed a candidate in the whole state and in every subunit. This had forced parties whose programs were mostly locally, nationally or religiously orientated to form a coalition before the election in order to run a candidate in the whole state. In the 1930s a voter expressed his decision by loudly and clearly declaring the name of their candidate to the electoral committee. Establishing a state as a single electoral unit in a multinational state, forcing parties to form coalition in advance and open voting were clearly a step backwards

O izborima u prvih dvadeset godina samostalne Slovenije

Prilog predstavlja izborno zakonodavstvo za parlamentarne izbore (Državni zbor) i predsjednika Republike. Slovenija je jedna od rijetkih država koja predsjednika, koji nema velike ovlasti, bira na izravnim izborima. Predstavljeni su i rezultati izbora u Državni zbor i izbori za predsjednika Republike. Stranke su se u Sloveniji počele osnivati nakon 1988. godine, iako Zakon o političkom ujedinjavanju (Zakon o političnem združevanju) još nije postojao. Registar stranki vodi Ministarstvo unutrašnjih poslova. U svibnju 2017. godine u Sloveniji je bilo registrirano 87 stranaka. Na izborima za zastupnike u Državnom zboru dovoljnu podršku za dobivanje zastupničkih mandata imalo je sedam ili osam stranaka. Broj birača 1992. godine iznosio je 1.500.000, a do 2011. godine taj je broj porastao na 1.700.000. Odaziv birača 1992. godine u postotcima bio je iznimno visok i iznosio je više od 85 %. Najvjerojatnije je razlog u tome što je bila riječ o prvim izborima u novi parlament, Državni zbor, te su istovremeno bili i prvi izbori za predsjednika Republike. Postotak odaziva birača na izbore u Državni zbor nakon toga je sve vrijeme do 2004. godine padao i tada je iznosio samo malo više od 60 %. Na parlamentarnim izborima 2008. i 2011. godine odaziv je porastao za otprilike 2,5 %. Slično je padao i odaziv birača na predsjedničkim izborima. U prvom krugu izbora za predsjednika 2012. godine sudjelovalo je više od trećine manje birača nego 1992. godine. I u drugim krugovima predsjedničkih izbora 2002., 2007. i 2012. godine odaziv birača bio je sve manji. U Sloveniji zastupnike biramo prema proporcionalnom sustavu u osam izbornih okruga. Svakom izbornom okrugu pripada 11 zastupničkih mjesta. Dva mjesta pripadaju zastupnicima manjina. Po jednog zastupnika biraju mađarska i talijanska manjina. Na izborima do zaključno 2008. godine pobjeđivale su velike stranke, koje su nastale tijekom stjecanja nezavisnosti Slovenije. Na izborima 2011., ali i 2014. godine, pobijedile su stranke koje su osnovane malo prije izbora kao odgovor na nezadovoljstvo birača prema postojećim strankama. Na prvim dvama predsjedničkim izborima (1992. i 1997.) pobjednik je izabran u prvom krugu; u oba slučaja pobijedio je Milan Kučan. Od izbora 2002. godine nadalje uvijek se odlučivalo u drugom krugu jer u prvom krugu nitko od kandidata nije dobio više od 50 % predanih glasova

ELECTORAL LEGISLATION OF THE FIRST YUGOSLAV STATE (1918 – 1941)

U međuratnom jugoslavenskom izbornom zakonodavstvu razlikujemo dva razdoblja koja se podudaraju s općom podjelom političke povijesti Kraljevine. Dvadesetih godina vrijedilo je zakonodavstvo usvojeno 1920. i djelomično promijenjeno 1922. godine. Država je bila podijeljena na izborne jedinice. Glasali su samo muškarci, na tajnim izborima. Mandati su se dodjeljivali prema proporcionalnom sustavu. Tridesetih godina na snazi je bilo zakonodavstvo iz 1931., koje je ispravljeno 1933. godine. Još su uvijek glasali samo muškarci. Biralo se javno, i to za zemaljske liste kandidata. Izborni je zakon, unatoč proporcionalnoj podjeli mandata, favorizirao pobjedničku listu.Parliamentary life in the Kingdom of Serbs, Croats and Slovenes/Yugoslavia (1918–1941) can be divided in two periods. The first period spans from the 1920s to the second half of the 1930s. The milestone was in 1929 when King Alexander I forcibly dissolved the Parliament and introduced personal dictatorship. The first law was introduced in 1920 and amended merely two years later. The system was based on secret balloting and proportional representation. Eligible voters were adult male citizensand the same system remained in the 1930s. A voter would cast his vote by dropping the ball in the ballot box of his party. At the poll station there was one ballot box for each candidate party. This system had been used in the prewar Kingdom of Serbia due to the high rate of illiteracy. The law from 1920 adopted this method of voting for the same reason. In the 1920s the state was divided in more than 50 electoral units with a fixed number of seats. Parties hada candidate in each of them according to their interest. In each unit, the mandates were distributed separately. The 1931 Law retained the institution of proportional representation. But it was significantly modified by favoring the strongest party. The strongest party was given a larger share of seats comparing its share of votes. Following the idea of Unitarianism, the law introduced a state as a single electoral unit divided into subunits. A candidate list needed a candidate in the whole state and in every subunit. This had forced parties whose programs were mostly locally, nationally or religiously orientated to form a coalition before the election in order to run a candidate in the whole state. In the 1930s a voter expressed his decision by loudly and clearly declaring the name of their candidate to the electoral committee. Establishing a state as a single electoral unit in a multinational state, forcing parties to form coalition in advance and open voting were clearly a step backwards

O mentorstvu v slovenskem šolskem muzeju

The article examines mentorship at the Slovenian School Museum. It argues that museums are places of value, which play an active part in the functioning of society and are incorporated in the processes of lifelong learning. Additionally, it examines how museums were included in the system of practical student training during the reform of university programmes. The general characteristics of mentorship at the Slovenian School Museum are presented under a number of headings, with special focus on the mentorship in practical student training. The characteristics of the latter are examined employing qualitative analysis of mentors’ observations, and students’ reports on practical student training completed between 2009 and 2016. By examining past mentorship experience, the article argues for the practice of collecting reports on student training in museums, for the purpose of further analysis and study. The article draws attention to the importance of work experience in museums, which represents a way for the students to supplement their theoretical knowledge, as well as learn about the functioning of museums and the mission of the curator. Finally, the article highlights the importance of the continuing education of mentors and argues that a shift in the organisation and evaluation of mentoring work in museums is required, with an aim of offering a higher quality work experience to students, and improving the implementation of practical student training programmes.Prispevek obravnava izkušnje mentorstva v Slovenskem šolskem muzeju. Predstavi muzeje kot prostor vrednot, ki se s svojo vlogo in nalogami aktivno vključujejo v delovanje družbe in so vpeti v procese vseživljenjskega izobraževanja. Prikaže, kako so se ob prenovi študijskih programov tudi muzeji vključili v sistem praktičnega usposabljanja študentov. Kakšne so nasploh značilnosti mentorstva v Slovenskem šolskem muzeju, smo predstavili v več sklopih mentorskega dela in postavili v ospredje mentorstvo v praktičnem usposabljanju študentov. Kakšne so značilnosti tega mentorstva, smo raziskovali na podlagi kvalitativne analize refleksij o mentorstvu študentom in poročil študentov o opravljenem praktičnem usposabljanju od 2009 do 2016. Prispevek s pogledom v preteklost mentorstva spodbudi idejo o uporabnosti zbiranja spominov o študentskih praksah v muzejih za nadaljnje analize in študije. Opozori na pomen izkušnje dela študentov v muzeju kot nadgradnjo teoretskega znanja, spoznavanja zakonitosti muzejskega dela in poslanstva poklica kustosa. Poudari pomen nadaljnjega izobraževanja mentorjev, spodbudi premik pri organiziranju in vrednotenju mentorskega dela v muzejih v korist bolj kvalitetnih in bolje izpeljanih študentskih praks

Optimum amount of an insurance sum in life insurance

Personal insurance represents one of the sources of personal social security as a category of personal property. How to get a proper life insurance is a frequently asked question. When insuring material objects (car, house...), the problem is usually not in the amount of the taken insurance. With life insurance (abstract goods), problems as such occur. In this paper, we wish to present a model that, according to the financial situation and the anticipated future, makes it possible to calculate the optimum insurance sum in life insurance

Influence of Polyvalence Professionals on Product Development Process Efficiency

Product development is one of a company’s key processes for meeting customer demands, providing long-term market share growth, revenues and company value. The main question we are addressing in this paper is how the professionals with more and better developed competencies (polyvalence professionals) increase efficiency of the product development process. We presume that the efficiency of the product development process is significantly influenced by the matching rate between the competencies of professionals and the task requirements of the process. The hypothesis was tested in an international study in which five footwear companies from three European countries participated. By analysing variances and using correlation and regression analyses, we prove the influence of polyvalence professionals on the product development process efficiency. We also prove that polyvalence professionals are the strategic resources who provide a company’s long-term competitive advantage, allowing efficient development of new products thus having high response rate to customer demands

DIE EINZELHEITEN UND UNTERSCHIEDE ZWISCHEN DEN WAHLEN IN SLOWENIEN UND KROATIEN IN DEN JAHREN 1920–1927

Der Artikel stellt die grundlegenden Eigenschaften des Wahlgesetzes im Königreich der Serben, Kroaten und Slowenen aus den Jahren 1920 und 1922 dar. Die Autoren legen den Schwerpunkt auf einige durch das Wahlgesetz entstandene Ähnlichkeiten und Unterschiede. Die unterschiedliche Größe der Wahlkreise verursachte, dass in manchen Wahlkreisen der Wahlkampf im gesetzlichen Sinne ausgeglichen war, obwohl die Parteien unterschiedliche Möglichkeiten für den Wahlerfolg hatten. Weiterhin werden die Wahlergebnisse aus den Jahren 1920, 1923, 1925 und 1927 in Slowenien und in Banalkroatien präsentiert. In beiden Provinzen sind die Ergebnisse vergleichbar im Sinne der Überlegenheit einer Partei. Die Besonderheit in Kroatien war eine große Anzahl nichtkroatischer Wähler, die die kroatischen Parteien nicht unterstützt haben

Structure-function relationships at the human spinal disc-vertebra interface.

Damage at the intervertebral disc-vertebra interface associates with back pain and disc herniation. However, the structural and biomechanical properties of the disc-vertebra interface remain underexplored. We sought to measure mechanical properties and failure mechanisms, quantify architectural features, and assess structure-function relationships at this vulnerable location. Vertebra-disc-vertebra specimens from human cadaver thoracic spines were scanned with micro-computed tomography (μCT), surface speckle-coated, and loaded to failure in uniaxial tension. Digital image correlation (DIC) was used to calculate local surface strains. Failure surfaces were scanned using scanning electron microscopy (SEM), and adjacent sagittal slices were analyzed with histology and SEM. Seventy-one percent of specimens failed initially at the cartilage endplate-bone interface of the inner annulus region. Histology and SEM both indicated a lack of structural integration between the cartilage endplate (CEP) and bone. The interface failure strength was increased in samples with higher trabecular bone volume fraction in the vertebral endplates. Furthermore, failure strength decreased with degeneration, and in discs with thicker CEPs. Our findings indicate that poor structural connectivity between the CEP and vertebra may explain the structural weakness at this region, and provide insight into structural features that may contribute to risk for disc-vertebra interface injury. The disc-vertebra interface is the site of failure in the majority of herniation injuries. Here we show new structure-function relationships at this interface that may motivate the development of diagnostics, prevention strategies, and treatments to improve the prognosis for many low back pain patients with disc-vertebra interface injuries. © 2017 The Authors. Journal of Orthopaedic Research® Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 36:192-201, 2018