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Wong C.,University Hospital of Hvidovre | Rasmussen J.,University of Aalborg | Simonsen E.,Copenhagen University | Hansen L.,Team Danmark | And 2 more authors.
Open Spine Journal | Year: 2011

Introduction: Previous studies of bone stresses in the human lumbar spine have relied on simplified models when modeling the spinal musculature, even though muscle forces are likely major contributors to the stresses in the vertebral bones. Detailed musculoskeletal spine models have recently become available and show good correlation with experimental findings. A combined inverse dynamics and finite element analysis study was conducted in the lumbar spine to investigate the effects of muscle forces on a detailed musculoskeletal finite element model of the 4th lumbar vertebral body. Materials and Methodology: The muscle forces were computed with a detailed and validated inverse dynamics musculoskeletal spine model in a lifting situation, and were then applied to an orthotropic finite element model of the 4th lumbar vertebra. The results were compared with those from a simplified load case without muscles. Results: In general the von Mises stress was larger by 30%, and even higher when looking at the von Mises stress distribution in the superio-anterior and central part of the vertebral body and in the pedicles. Conclusion: The application of spine muscles to a finite element model showed markedly larger von Mises stress responses in the central and anterior part of the vertebral body, which can be tolerated in the young and healthy spine, but it would increase the risk of compression fractures in the elderly, osteoporotic spine. © Wong et al.


Sonne C.,University of Aarhus | Dyck M.,Environment Canada | Riget F.F.,University of Aarhus | Beck Jensen J.-E.,University Hospital of Hvidovre | And 5 more authors.
Environmental Research | Year: 2015

Industrially produced chemicals have been a major environmental concern across our entire Globe since the onset of rapid industrial development around the early 1900. Many of the substances being used are known to be endocrine disrupting chemicals (EDCs) and are also known to be long-range dispersed and to biomagnify to very high concentrations in the tissues of Arctic apex predators such as polar bears (Ursus maritimus). A major concern relating to EDCs is their effects on vital organ-tissues such as bone and it is possible that EDCs represent a more serious challenge to the species' survival than the more conventionally proposed prey reductions linked to climate change. We therefore analyzed penile bone mineral density (BMD) as a key phenotype for reproductive success in 279 polar bear samples born 1990-2000 representing eight polar bear subpopulations. Since EDC concentrations were not available from the same specimens, we compared BMD with published literature information on EDC concentrations. Latitudinal and longitudinal BMD and EDC gradients were clearly observed, with Western Hudson bears having the highest BMD and lowest EDCs, and North East Greenland polar bears carrying the lowest BMD and highest EDCs. A BMD vs. polychlorinated biphenyls (PCB) regression analysis showed that BMD decreased as a function of the eight subpopulations' PCB concentrations and this relationship was close to being significant (p=0.10, R2=0.39). Risk quotient (RQ) estimation demonstrated that PCBs could be in a range that may lead to disruption of normal reproduction and development. It is therefore likely that EDCs directly affect development and bone density in polar bears. Canadian bears had in general the best health and the North East Greenland subpopulation being at the highest risk of having negative health effects. While reductions in BMD is in general unhealthy, reductions in penile BMD could lead to increased risk of species extinction because of mating and subsequent fertilization failure as a result of weak penile bones and risk of fractures. Based on this, future studies should assess how polar bear subpopulations respond upon EDC exposure since information and understanding about their circumpolar reproductive health is vital for future conservation. © 2014 Elsevier Inc.


Wong C.,University Hospital of Hvidovre | Pedersen S.A.,Hvidovre University Hospital Denmark | Kristensen B.B.,Hvidovre University Hospital Denmark | Gosvig K.,Hvidovre University Hospital Denmark | Sonne-Holm S.,University Hospital of Hvidovre
Spine | Year: 2015

Study Design. A prospective, randomized triple-blinded crossover design treating with either botulinum toxin A (BXT) or saline (NaCl). Objective. To examine the efficacy of BTX treatment in cerebral palsy scoliosis (CPS). Summary of Background Data. Intramuscular injections with BTX have been used off label in treating CPS. 1 prospective study has been conducted, demonstrating in both radiological and clinical improvement, whereas showing no side effects or complications. Methods. Subjects (brace-treated CPS between 2 and 18 yr) were injected using ultrasonic-guidance with either NaCl or BTX in selected spine muscles with 6 mo intervals (block randomization, sealed envelope). Radiographs of the spine and clinical follow-up were captured before and 6 weeks after each injection. Primary outcome parameter was radiological change in Cobb angle, where a 7° change was regarded as an effect (1 SD). Radiological parameters were measured before and 6 weeks after treatment by 3 experienced doctors separately. Moreover, clinical results were evaluated by the pediatric quality of life score and systematic open questioning of the parents about the child's wellbeing. Subjects, researchers, and monitors were blinded during the trial. Appropriate permissions (2008- 004584-19) and no funding were obtained. Results. 16 cerebral palsy patients (GFMCS III-V) with CPS were consecutively included, whereas 6 patients were excluded. There were no drop-outs to follow-up, but 1 possible serious adverse event of pneumonia resulting in death was recorded and the study was terminated. No significant radiological or clinical changes were detected when compared with NaCl injections using Wilcoxon matched pair signed-rank test. Conclusion. No positive radiological or clinical effects were demonstrated by this treatment, except for the parent's initial subjective but positive appraisal of the effect. However, the study was terminated due to 1 possible severe adverse event and scheduled numbers needed to treat (hence power) were not reached. © 2015 Wolters Kluwer Health, Inc. All rights reserved.


Wong C.,University Hospital of Hvidovre | Mikkelsen P.,Hospital of Glostrup | Hansen L.B.,Copenhagen University | Darvann T.,Copenhagen University | Gebuhr P.,University Hospital of Hvidovre
Danish Medical Bulletin | Year: 2010

INTRODUCTION: Fractures of the tibial shaft are relatively common injuries. There are indications that tibial shaft fractures share characteristics in terms of site, type and local fracture mechanisms. In this study, we aimed to set up a mathematical, computer-based model using finite element analysis of the bones of the lower leg to examine if such a model is adequate for prediction of fracture locations and patterns. In future studies, we aim to use these biomechanical results to examine fracture prevention, among others, and to simulate different types of osteosynthesis and the process of bony healing. The biomechanical results are the basis for fracture healing, biomechanical fall analysis and stability analysis of osteosynthesis. MATERIAL AND METHODS: A finite element model of the bony part of the lower leg was generated on the basis of computed tomography data from the Visible Human Project. The data consisted of 21,219 3D elements with a cortical shell and a trabecular core. Three types of load of torsion, a direct lateral load and axial compression were applied. RESULTS: The finite element linear static analysis resulted in relevant fracture localizations and indicated relevant fracture patterns. CONCLUSION: In the present study, we have successfully simulated fracture mechanisms, obtained adequate fracture locations and achieved an indication of the fracture morphology. The method of fracture simulation employed showed good agreement with known clinical data and data from prior mechanical testing. This substantiates the validity of fracture simulation for future studies examining tibial fractures, fracture healing and prevention.


Bang U.C.,University Hospital of Hvidovre | Benfield T.,University Hospital of Hvidovre | Benfield T.,Copenhagen University | Bendtsen F.,University Hospital of Hvidovre | And 5 more authors.
Clinical Gastroenterology and Hepatology | Year: 2014

Background & Aims: Cirrhosis and chronic pancreatitis (CP) are accompanied by inflammation and malnutrition. Both conditions can have negative effects on bone metabolism and promote fractures. We evaluated the risk of fractures among patients with CP or cirrhosis and determined the effect of fat malabsorption on fracture risk among patients with CP. Methods: We performed a retrospective cohort study using the Danish National Patient Register to identify patients diagnosed with CP or cirrhosis. We analyzed data collected from January 1, 1995, to December 31, 2010, on 20,769 patients (35.5% women with cirrhosis and 11,972 patients (33.5% women) with CP. Each patient was compared with 10 age- and sex-matched controls. We also assessed the risk of fractures among patients with CP who received pancreatic enzyme substitution (PES) for fat malabsorption. Results: During the study period, bone fractures occurred in 3954 patients with cirrhosis and 2594 patients with CP. The adjusted hazard ratio (HR) for any fracture was 2.4 in patients with cirrhosis (95% confidence interval [CI], 2.2-2.5) and 1.7 in patients with CP (95% CI, 1.6-1.8). The relative risk of low-trauma fractures was highest among individuals younger than 50 years old. Alcohol as an etiology was associated with an increased risk of fracture compared with patients with nonalcoholic cirrhosis (HR, 2.4 vs 1.5; P < .0001) and CP (HR, 2.0 vs 1.5; P < .0001). Patients with CP receiving PES for fat malabsorption had a lower risk of fractures than other CP patients (HR, 0.8; 95% CI, 0.7-0.9). However, increasing the duration of treatment with PES was associated with an increased risk of fracture. Conclusions: Patients, especially younger patients, with cirrhosis or CP have an increased risk of fractures of all types. © 2014 AGA Institute.


Bang U.C.,University Hospital of Hvidovre | Hyldstrup L.,University Hospital of Hvidovre | Hyldstrup L.,Copenhagen University | Jensen J.E.B.,University Hospital of Hvidovre | Jensen J.E.B.,Copenhagen University
Osteoporosis International | Year: 2014

Summary: We used Danish registers to identify patients with osteoporosis, who had been treated with parathyroid hormone and evaluated the probability of developing cancer.We did not find an increased risk of cancer among the patients treated with parathyroid hormone. Introduction: We evaluated the incidences of malignancies and mortality in osteoporotic patients treated with rPTH. Methods: Using Danish nationwide registers, we identified patients diagnosed with osteoporosis in the period 1995 through 2010. Each patient treated with rPTH ("case") was compared with 10 gender- and age-matched patients who did also have osteoporosis but did not receive rPTH ("control"). Results: A total of 4,104 cases (80.3% females) were identified. The mean age at the beginning of rPTH treatment was 70.9 (SD 9.7) years. During a follow-up time of 10,118 person-years for the cases and 88,005 person-years for the controls, a total of 255 cases (6.2%) compared with 2,103 controls (5.1%) experienced a cancer (Chi square, p =0.003). We found an adjusted cancer related HR of 1.1 (95%CI 0.9-1.4) among the cases. Lung cancer was the only cancer type with a significantly increased rate among patients receiving rPTH (HR 1.7; 95% CI 1.3-2.3). No cases developed osteosarcomas and nine controls developed osteosarcoma. During follow-up, 627 (15.3%) cases died and 4,175 (10.2%) controls died, which yielded an excess mortality risk of 26% (95% CI 16-37%). This could be due to differences in the prevalence of vertebral fractures between the rPTH-treated and non-treated patients. Conclusion: This study did not support the hypothesis describing a possible link between rPTH treatment and the development of cancer. We also conclude that osteosarcoma has not been diagnosed in any Danish patient receiving rPTH since the year 2003 when it was introduced on the market. © International Osteoporosis Foundation and National Osteoporosis Foundation 2013.


Thomsen M.G.,University Hospital of Hvidovre | Husted H.,University Hospital of Hvidovre | Otte K.S.,University Hospital of Hvidovre | Holm G.,University Hospital of Hvidovre | Troelsen A.,University Hospital of Hvidovre
BMC Musculoskeletal Disorders | Year: 2013

Background: Little information exists to support that patients care about flexion beyond what is needed to perform activities of daily living (ADL) after Total knee arthroplasty (TKA). The purpose of this study was to investigate if the achievement of a higher degree of knee flexion after TKA would result in a better patient perceived outcome. Methods. The study is a randomized, double-blinded, controlled trial in which 36 patients (mean age: 67.2 yrs) undergoing one-stage bilateral TKA randomly received a standard cruciate-retaining (CR) TKA in one knee and a high-flex posterior-stabilized (PS) TKA in the contra lateral knee. At follow-up ROM, satisfaction, pain, "feel" of the knee and the abilities in daily activities were assessed. Results: At 1-year follow-up we found an expected significantly higher degree of knee flexion of 7°in the high-flex knees (p = 0.001). The high-flex TKA's showed a mean active flexion of 121°. In both TKA's the median VAS pain score was 0, the median VAS satisfaction score was 9, and the median VAS score of the patient "feel" of the knee was 9 at 1-year follow-up. Further, there were no significant differences between the knees in the performance of daily activities. Conclusions: As expected the high-flex TKA showed increased knee flexion, but no significant differences in the patient perceived outcomes were found. This suggests little relevance to the patients of the difference in knee flexion - when flexion is of this magnitude - as pain free ROM and high patient satisfaction were achieved with both TKA's. Trial registration. ClinicalTrials.gov: NCT00294528. © 2013 Thomsen et al.; licensee BioMed Central Ltd.


Thomsen M.G.,University Hospital of Hvidovre | Husted H.,University Hospital of Hvidovre | Bencke J.,University Hospital of Hvidovre | Curtis D.,University Hospital of Hvidovre | And 2 more authors.
Journal of Bone and Joint Surgery - Series B | Year: 2012

The purpose of this study was to investigate whether a gender-specific high-flexion posterior-stabilised (PS) total knee replacement (TKR) would offer advantages over a high-flex PS TKR regarding range of movement (ROM), 'feel' of the knee, pain and satisfaction, as well as during activity. A total of 24 female patients with bilateral osteoarthritis entered this prospective, blind randomised trial in which they received a high-flex PS TKR in one knee and a gender-specific high-flexion PS TKR in the other knee. At follow-up, patients were assessed clinically measuring ROM, and questioned about pain, satisfaction and daily 'feel' of each knee. Patients underwent gait analysis pre-operatively and at one year, which yielded kinematic, kinetic and temporospatial parameters indicative of knee function during gait. At final follow-up we found no statistically significant differences in ROM (p = 0.82). The median pain score was 0 (0 to 8) in both groups (p = 0.95). The median satisfaction score was 9 (4 to 10) in the high-flex group and 8 (0 to 10) in the gender-specific group (p = 0.98). The median 'feel' score was 9 (3 to 10) in the high-flex group and 8 (0 to 10) in the gender-specific group (p = 0.66). Gait analysis showed no statistically significant differences between the two prosthetic designs in any kinematic, kinetic or temporospatial parameters. Both designs produced good clinical results with significant improvements in several gait parameters without evidence of any advantage in the gender-specific design. ©2012 British Editorial Society of Bone and Joint Surgery.


Wong C.,University Hospital of Hvidovre
Danish medical bulletin | Year: 2010

INTRODUCTION: Fractures of the tibial shaft are relatively common injuries. There are indications that tibial shaft fractures share characteristics in terms of site, type and local fracture mechanisms. In this study, we aimed to set up a mathematical, computer-based model using finite element analysis of the bones of the lower leg to examine if such a model is adequate for prediction of fracture locations and patterns. In future studies, we aim to use these biomechanical results to examine fracture prevention, among others, and to simulate different types of osteosynthesis and the process of bony healing. The biomechanical results are the basis for fracture healing, biomechanical fall analysis and stability analysis of osteosynthesis. MATERIAL AND METHODS: A finite element model of the bony part of the lower leg was generated on the basis of computed tomography data from the Visible Human Project. The data consisted of 21,219 3D elements with a cortical shell and a trabecular core. Three types of load of torsion, a direct lateral load and axial compression were applied. RESULTS: The finite element linear static analysis resulted in relevant fracture localizations and indicated relevant fracture patterns. CONCLUSION: In the present study, we have successfully simulated fracture mechanisms, obtained adequate fracture locations and achieved an indication of the fracture morphology. The method of fracture simulation employed showed good agreement with known clinical data and data from prior mechanical testing. This substantiates the validity of fracture simulation for future studies examining tibial fractures, fracture healing and prevention.


PubMed | University Hospital of Hvidovre
Type: Journal Article | Journal: Liver international : official journal of the International Association for the Study of the Liver | Year: 2016

We assessed the impact of propranolol on death, risk of hepatorenal syndrome and peritonitis in patients with cirrhosis.This study was a retrospective observational study and data were retrieved from Danish databases. We used our own criteria to stratify the patients into groups of patients with mildly decompensated cirrhosis or severely decompensated cirrhosis. A subgroup of patients with a history of peritonitis was also analyzed. Follow-up time was limited to 2 years from cohort entry. The reported hazard ratios (HR) with 95% confidence interval (CI) were based on a propensity score matched cohort.Among 3719 patients, we found 3075 patients with mildly and 644 with severely decompensated cirrhosis. Propranolol was used by 20% of the patients. Among the patients with mildly decompensated cirrhosis, propranolol use vs. non-propranolol was related with a HR of 0.7 (95% CI 0.6-0.9) and among the patients with severely decompensated cirrhosis, the HR was 0.6 (95% CI 0.4-0.9). Reduced mortality was found for doses of propranolol lower than 160 mg/day only. Among 361 patients with peritonitis, we found reduced mortality in the propranolol group with a HR of 0.5 (95% CI 0.3-0.8). The use of propranolol was associated with a HR of 0.4 (95% CI 0.2-0.9) for developing peritonitis during follow-up among patients with severely decompensated cirrhosis.In patients with decompensated cirrhosis, we found an association between propranolol use and reduced mortality risk for doses lower than 160 mg/day.

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