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Search Results: 1 - 10 of 297462 matches for " J. Bittersohl "
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Are there signs of acidification reversal in freshwaters of the low mountain ranges in Germany?
C. Alewell,M. Armbruster,J. Bittersohl,C. D. Evans
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2001,
Abstract: The reversal of freshwater acidification in the low mountain ranges of Germany is of public, political and scientific concern, because these regions are near natural ecosystems and function as an important drinking water supply. The aim of this study was to evaluate the status and trends of acidification reversal after two decades of reduced anthropogenic deposition in selected freshwaters of the low mountain ranges in the Harz, the Fichtelgebirge, the Bavarian Forest, the Spessart and the Black Forest. In response to decreased sulphate deposition, seven out of nine streams investigated had significantly decreasing sulphate concentrations (all trends were calculated with the Seasonal Kendall Test). The decrease in sulphate concentration was only minor, however, due to the release of previously stored soil sulphur. No increase was found in pH and acid neutralising capacity (defined by Reuss and Johnson, 1986). Aluminum concentrations in the streams did not decrease. Thus, no major acidification reversal can currently be noted in spite of two decades of decreased acid deposition. Nevertheless, the first signs of improvement in water quality were detected as there was a decrease in the level and frequency of extreme values of pH, acid neutralising capacity and aluminium concentrations in streams. With respect to nitrogen, no change was determined for either nitrate or ammonium concentrations in precipitation or stream water. Base cation fluxes indicate increasing net loss of base cations from all ecosystems investigated, which could be interpreted as an increase in soil acidification. The latter was due to a combination of continued high anion leaching and significant reduction of base cation deposition. No major improvement was noted in biological recovery, however, initial signs of recovery were detectable as there was re-occurrence of some single macroinvertebrate species which were formerly extinct. The results of this study have important implications for water authorities, forest managers and policy makers: the delay in acidification reversal suggests a need for ongoing intensive amelioration of waters, a careful selection of management tools to guarantee sustainable management of forests and the reduction of nitrogen deposition to prevent further acidification of soils and waters. Keywords: freshwater, acidification reversal, drinking water supply, forested catchments, Germany
Response of sulphur dynamics in European catchments to decreasing sulphate deposition
A. Prechtel,C. Alewell,M. Armbruster,J. Bittersohl
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2001,
Abstract: Following the decline in sulphur deposition in Europe, sulphate dynamics of catchments and the reversibility of anthropogenic acidification of soils and freshwaters became of major interest. Long-term trends in sulphate concentrations and fluxes in precipitation/throughfall and freshwaters of 20 European catchments were analysed to evaluate catchment response to decreasing sulphate deposition. Sulphate deposition in the catchments studied declined by 38-82% during the last decade. Sulphate concentrations in all freshwaters decreased significantly, but acidification reversal was clearly delayed in the German streams. In Scandinavian streams and Czech/Slovakian lakes sulphate concentrations responded quickly to decreased input. Sulphate fluxes in run-off showed no clear trend in Germany and Italy but decreased in Scandinavia, the Czech Republic and Slovakia. The decrease, however, was less than the decline in input fluxes. While long-term sulphate output fluxes from catchments were generally correlated to input fluxes, most catchments started a net release of sulphate during the early 1990s. Release of stored sulphate leads to a delay of acidification reversal and can be caused by four major processes. Desorption and excess mineralisation were regarded as the most important for the catchments investigated, while oxidation and weathering were of lesser importance for the long-term release of sulphate. Input from weathering has to be considered for the Italian catchments. Sulphate fluxes in German catchments, with deeply weathered soils and high soil storage capacity, responded more slowly to decreased deposition than catchments in Scandinavia and the Czech Republic/Slovakia, which have thin soils and relatively small sulphate storage. For predictions of acidification reversal, soil characteristics, sulphur pools and their dynamics have to be evaluated in future research. Keywords: acidification reversal, sulphur, sulphate release, Europe, catchments, deposition, lake, stream
Delayed gadolinium-enhanced magnetic resonance imaging of hip joint cartilage (dGEMRIC): pearls and pitfalls
Bernd Bittersohl
Orthopedic Reviews , 2011, DOI: 10.4081/or.2011.e11
Abstract: With the increasing advances in hip joint preservation surgery, accurate diagnosis and assessment of femoral head and acetabular cartilage status is becoming increasingly important. Magnetic resonance imaging (MRI) of the hip does present technical difficulties. The fairly thin cartilage lining necessitates high image resolution and high contrast-to-noise ratio (CNR). With MR arthrography (MRA) using intraarticular injected gadolinium, labral tears and cartilage clefts may be better identified through the contrast medium filling into the clefts. However, the ability of MRA to detect varying grades of cartilage damage is fairly limited and early histological and biochemical changes in the beginning of osteoarthritis (OA) cannot be accurately delineated. Traditional MRI thus lacks the ability to analyze the biological status of cartilage degeneration. The technique of delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) is sensitive to the charge density of cartilage contributed by glycosaminoglycans (GAGs), which are lost early in the process of OA. Therefore, the dGEMRIC technique has a potential to detect early cartilage damage that is obviously critical for decision-making regarding time and extent of intervention for joint-preservation. In the last decade, cartilage imaging with dGEMRIC has been established as an accurate and reliable tool for assessment of cartilage status in the knee and hip joint. This review outlines the current status of dGEMRIC for assessment of hip joint cartilage. Practical modifications of the standard technique including three-dimensional (3D) dGEMRIC and dGEMRIC after intra-articular gadolinium instead of iv-dGEMRIC will also be addressed.
Surgical hip dislocation in symptomatic cam femoroacetabular impingement: what matters in early good results?
M J?ger, B Bittersohl, C Zilkens, HS Hosalkar, K Stefanovska, S Kurth, R Krauspe
European Journal of Medical Research , 2011, DOI: 10.1186/2047-783x-16-5-217
Abstract: Femoroacetabular impingement (FAI) that constitutes a repetitive impact of the proximal femur against the acetabular rim is a well known observation in young adults with persisting groin pain and limited range of hip motion [1]. Depending on the underlying mechanism, FAI is further classified as cam-, pincer- or mixed-type. In cam-FAI, the impingement results from an insufficient femoral head-neck offset that may cause cartilage and labrum damage especially during hip flexion. In pincer-FAI, the impingement arises from focal or general acetabular over-coverage probably provoking continuous frontal contact between femoral neck and acetabular labrum during hip flexion. In mixed-FAI, a combination of both mechanisms revealing a damage pattern with combined cam and pincer pathology may be observed.FAI by itself is not a disease per definition and a variety of factors such as biological tissue integrity remain important. However, emerging evidence has been anticipated that the repetitive abnormal abutment between proximal femur and acetabular rim may eventually lead to early osteoarthritis (OA) of the hip joint [1-3]. In order to possibly stop or delay the onset of the same as well as for managing symptoms, surgical treatment may become necessary [4].The safe surgical hip dislocation for correction of the morphological abnormality represents a well established technique that proved a low rate of complication and allows for examination and treatment of the entire joint during surgery [2,5-8]. However, recently only a small number of reports in the English literature can be referred that depict the clinical outcome of this approach in various types of FAI [2,5,9-12] and treatment of various grades of FAI is still a point for discussion - in research meetings as well as in daily clinical practice.Therefore, our aim in this study was to evaluate the clinical outcome of patients who had undergone surgical hip dislocation and debridement due to symptomatic cam-FAI within a fol
Migration pattern of cementless press fit cups in the presence of stabilizing screws in total hip arthroplasty
C Zilkens, S Djalali, B Bittersohl, T K?licke, CN Kraft, R Krauspe, M J?ger
European Journal of Medical Research , 2011, DOI: 10.1186/2047-783x-16-3-127
Abstract: The acetabular implant design and materials in cementless total hip arthroplasty (THA) have improved markedly over the past decades. Reduced roughness or improved polishing of the internal surface of the cup. Optimized conformity of the liner with the metal shell of the acetabular component, improved congruity of the screw heads in the acetabular shell, better liner locking mechanisms and other factors such as modification of the outer surface to promote bone ingrowth lead to an increase of the survivorship of cementless acetabular components with and without screw fixation [1-6].Some data suggest that additional screw fixation in press-fit implants may support the initial stability and osseointegration and also prevent late migration of the acetabular component [1,3,7-10].Opponents of the use of additional screws have suggested that a press-fit technique with underreaming of the acetabular socket will provide adequate initial fixation so that adjunctive screw fixation is not indicated and insufficient to prevent late migration [11-13]. Furthermore, the screw holes may facilitate the egress of polyethylene particles through the shell and eventually cause periimplant pelvic osteolysis [3]. Avoiding screw fixation may also reduce operative time and time of revision surgery [2], implant costs [14] and prevent complications associated with screw placement such as vascular and nerve injury [7]Evaluation of clinical (reoperations, outcome data) and radiographic parameters (osteolysis, bone loss, radiolucency, radiodensity) associated with cementless porous-coated acetabular component design and poly-ethylene that is sterilized in an inert environment and stored in a vacuum provided by barrier packaging should allow a more equitable study of acetabular fixation than was possible in the past.The aim of this study was to evaluate initial acetabular implant stability and late acetabular implant migration of press fit cups with additional screw fixation of the acetabular compo
Spinning around or stagnation - what do osteoblasts and chondroblasts really like?
C Zilkens, T L?gters, B Bittersohl, R Krauspe, S Lensing-H?hn, M J?ger
European Journal of Medical Research , 2010, DOI: 10.1186/2047-783x-15-1-35
Abstract: Human MSCs were isolated and cultivated onto the surface of a 3 × 3 mm porcine collagen I/III carrier. After incubation, cell cultures were transfered to the different cutures systems: regular static tissue flasks (group I), spinner flasks (group II) and rotating wall vessels (group III). Following standard protocols cells were stimulated lineage specific towards the osteogenic and chondrogenic lines. To evaluate the effects of applied cytomechanical forces towards cellular differentiation distinct parameters were measured (morphology, antigen and antigen expression) after a total cultivation period of 21 days in vitro.Depending on the cultivation technique we found significant differences in both gen and protein expression.Cytomechanical forces with rotational components strongly influence the osteogenic and chondrogenic differentiation.Bone grafting is a common procedure in orthopaedic surgery and the implantation of autologous bone grafts supplying osteoinductive growth factors, osteogenic cells, and a structural scaffold, has become the gold standard for the surgical treatment of bone defects caused by trauma, tumor, infection or congenital abnormalities. In addition, bone grafts are frequently used for spinal fusion, joint revision surgery, corrective osteotomy and bone reconstruction. The amount of bone available for autografting is limited and bone graft harvesting procedures are associated with a multitude of risks, such as pain, neurovasculare injury, persisting haematoma or infection at the donor site [1-3]. The application of allograft bone as an alternative treatment option carries the potential risk of infection and graft failure as a consequence of the reduced osteoinducitvity of allograft bone [4]. Several biomaterials such as metal alloys, ceramics or bone cements have been used for decades as permanent implants to overbridge or stabilize bone defects. Although those bone substitutes have proven utility, they have often resulted in complications such
Hip arthrodesis in the pediatric population: where do we stand?
Bernd Bittersohl,Daniela Zaps,James D. Bomar,Harish S. Hosalkar
Orthopedic Reviews , 2011, DOI: 10.4081/or.2011.e13
Abstract: Reconstructive and salvage procedures have continued to evolve in orthopedic surgery with changing functional demands of the population as well as advances in implants and surgical techniques. What used to be popular or traditional care at some point may eventually become a thing of the past, and this is true as far as many orthopedic surgical procedures are concerned. Understanding the etiology, pathogenesis, and managing and postponing the destructive pathway of osteoarthritis (OA) has been the goal of orthopedists since the specialty began in the early part of 18th century. Options of treating the severe sequelae of an arthritic joint have varied in different treatment eras. Management options have changed from a spectrum of non-treatment and slow suffering to muscle and soft-tissue releases, interposition arthroplasty and eventual extreme options like joint fusion or arthrodesis. The concept and advent of joint replacement surgery started a new era in the management of OA and was a dream come true in many ways. Mobility and stability are achieved together during the arthroplasty (joint replacement) that allowes the patient to maintain a good level of function. Arthroplasty certainly has its pros and cons as we have discovered in the past six decades. Pushing the envelope to younger population has its limitation in terms of longevity of the prosthesis, early loosening, need for repeated revisions that at some point may not be technically possible and risk of infection and disastrous consequences like PE and death associated with the gravity of the procedure. As infrequent as it is in today’s clinical practice, arthrodesis of the hip joint has a role and remains a solid option for a well selected case. The purpose of this review is to discuss the current indications in the pediatric population and outline surgical techniques for hip arthrodesis while pointing out limitations and shortcomings.
Z-osteotomy in hallux valgus: clinical and radiological outcome after Scarf osteotomy
Marcus Jaeger,Michael Schmidt,Alexander Wild,Bernd Bittersohl
Orthopedic Reviews , 2009, DOI: 10.4081/or.2009.e4
Abstract: Correction osteotomies of the first metatarsal are common surgical approaches in treating hallux valgus deformities whereas the Scarf osteotomy has gained popularity. The purpose of this study was to analyze short- and mid-term results in hallux valgus patients who underwent a Scarf osteotomy. The subjective and radiological outcome of 131 Scarf osteotomies (106 hallux valgus patients, mean age: 57.5 years, range: 22-90 years) were retrospectively analyzed. Mean follow-up was 22.4 months (range: 6 months-5 years). Surgical indications were: intermetatarsal angle (IMA) of 12-23°; increased proximal articular angle (PAA>8°), and range of motion of the metatarsophalangeal joint in flexion and extension >40°. Exclusion criteria were severe osteoporosis and/or osteoarthritis. The mean subjective range of motion (ROM) of the great toe post-surgery was 0.8±1.73 points (0: full ROM, 10: total stiffness). The mean subjective cosmetic result was 2.7±2.7 points (0: excellent, 10: poor). The overall post-operative patient satisfaction with the result was high (2.1±2.5 points (0: excellent, 10: poor). The mean hallux valgus angle improvement was 16.6° (pre-operative mean value: 37.5°) which was statistically significant (p<0.01). The IMA improved by an average of 5.96° from a pre-operative mean value of 15.4° (p<0.01). Neither osteonecrosis of the distal fragment nor peri-operative fractures were noted during the follow-up. In keeping with our follow-up results, the Scarf osteotomy approach shows potential in the therapy of hallux valgus. 筻
Open reduction and internal fixation of displaced clavicle fractures in adolescents
Harish S. Hosalkar,Gaurav Parikh,James D. Bomar,Bernd Bittersohl
Orthopedic Reviews , 2012, DOI: 10.4081/or.2012.e1
Abstract: The literature available on patient oriented outcomes of operative management for clavicle fractures in adolescents is fairly limited. The purpose of this study was to analyze the potential of open reduction and internal fixation for displaced mid-shaft clavicle fractures in adolescent patients. We reviewed our series of surgical cases performed in 19 adolescents (mean age: 14.6 years) with displaced unilateral clavicle fractures. Baseline data acquisition included demographic and radiographic variables. A Synthes LCP clavicular plate was utilized for fixation in all cases. Follow-up data included functional outcome assessment using the Quick Disability of Arm, Shoulder, and Hand Questionnaire (DASH), the simple shoulder test (SST) and additional binary questions. At a mean follow-up of 16 months, quick DASH scores were 4.0 (range: 0-35.5) and mean number of positive yes responses on the SST for all operative patients was 11 (range: 9-12). All cases proved complete radiological union at the 3-month follow-up. All patients returned to full athletics at a mean time of 14 weeks (range: 12-17 weeks). Two patients had minimal hypertrophic scars while no patient was noted with keloid formation or neurovascular deficit. One patient complained of implant prominence and occasional symptoms of discomfort at the 15 month follow-up and opted for implant removal. This was successfully performed with uneventful full recovery. All patients were fully satisfied with their choice for surgical intervention. Anatomical reduction with internal fixation and early mobilization of adolescent displaced clavicle fractures remains a viable treatment option with predictable results and no major complications in reliable hands.
Magnetic resonance imaging of hip joint cartilage and labrum
Christoph Zilkens,Falk Miese,Marcus Jager,Bernd Bittersohl
Orthopedic Reviews , 2011, DOI: 10.4081/or.2011.e9
Abstract: Hip joint instability and impingement are the most common biomechanical risk factors that put the hip joint at risk to develop premature osteoarthritis. Several surgical procedures like periacetabular osteotomy for hip dysplasia or hip arthroscopy or safe surgical hip dislocation for femoroacetabular impingement aim at restoring the hip anatomy. However, the success of joint preserving surgical procedures is limited by the amount of pre-existing cartilage damage. Biochemically sensitive MRI techniques like delayed Gadolinium Enhanced MRI of Cartilage (dGEMRIC) might help to monitor the effect of surgical or non-surgical procedures in the effort to halt or even reverse joint damage.
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