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Biomedical subjects

C Lüring

Publications and source records attributed to C Lüring.

32 records · Page 2Linked to original sources
PubMed2003

[Tissue toxicity of local anesthetics. An in vivo trial].

AIM: Local anesthetics are often administered intra-articularly after knee surgery. The aim of this study was to determine differences in irritancy of local anesthetics in an in vivo test performed on the chorioallantoic membrane of hen's eggs (HET-CAM test) to evaluate the specific irritation score. METHOD: After incubation for 9 days, the chorioallantoic membrane was prepared and then exposed to different local anesthetics (Naropin, Scandicain,Carbostesin,Xyloneural). RESULTS: We found no irritating values for the tested substances. No vascular injuries of the chorioallantoic membrane could be detected. Therefore, the irritation score was measured according to the standard protocol with an irritation score=0. CONCLUSION: Our results show that local anesthetics often used in clinics do not provoke severe vascular injuries as a sign of tissue toxicity. Therefore, the customary concentrations can be recommended for clinical use.

Allantois↗
PubMed2002

[Primary subcutaneous hematogenous osteomyelitis in childhood].

The most frequent form of bone infection is haematogenous osteomyelitis (HOM), typically affecting infants and children. Dependent on the virulence of the pathogen and the patients immune response, one can distinguish between the acute (AHOM) and primary subacute haematogenous osteomyelitis (PSHO). In contrast to AHOM, diagnosis of PSHO is severely impeded in that clinical and blood-chemistry findings usually do not enable differentiation from primary malignant bone tumors. With a comparable age predilection and clinical symptoms, as well as very similar conventional radiographic, MRI- and bone-scan-findings, the most important differential diagnosis is Ewing's-sarcoma. The here demonstrated case of a 12 year-old girl shows that PSHA may imitate a sarcoma very closely, even concerning such usually fairly reliable radiographic aspects like osteolysis and lamellar periostal bone reaction. Despite the use of MRI, the diagnosis initially remained uncertain and a malignant bony lesion could only be ruled out after open biopsy and histopathological evaluation.

Bacteremia↗
PubMed2002

A fluorometric method for the differentiation of algal populations in vivo and in situ.

Fingerprints of excitation spectra of chlorophyll (Chl) fluorescence can be used to differentiate 'spectral groups' of microalgae in vivo and in situ in, for example, vertical profiles within a few seconds. The investigated spectral groups of algae (green group, Chlorophyta; blue, Cyanobacteria; brown, Heterokontophyta, Haptophyta, Dinophyta; mixed, Cryptophyta) are each characterised by a specific composition of photosynthetic antenna pigments and, consequently, by a specific excitation spectrum of the Chl fluorescence. Particularly relevant are Chl a, Chl c, phycocyanobilin, phycoerythrobilin, fucoxanthin and peridinin. A laboratory-based instrument and a submersible instrument were constructed containing light-emitting diodes to excite Chl fluorescence in five distinct wavelength ranges. Norm spectra were determined for the four spectral algal groups (several species per group). Using these norm spectra and the actual five-point excitation spectrum of a water sample, a separate estimate of the respective Chl concentration is rapidly obtained for each algal group. The results of dilution experiments are presented. In vivo and in situ measurements are compared with results obtained by HPLC analysis. Depth profiles of the distribution of spectral algal groups taken over a time period of few seconds are shown. The method for algae differentiation described here opens up new research areas, monitoring and supervision tasks related to photosynthetic primary production in aquatic environments.

Journal Article↗
PubMedDate not supplied

[Tissue toxicity of antiseptics].

AIM: Local antiseptics are used for desinfection of skin and for lavage of wounds. The aim of this study was to determine the tissue toxicity of different antiseptics and to measure the irritation score (IS) and the irritation threshold (IT) for each substance. METHOD: The tissue compatibilities of Dibromol, Kodan, Jodobac, Octenisept, Lavasept 0.2 %, hydrogen peroxide, chlorhexidindigluconate 0.5 % and 2-propanol 60 % were evaluated in the in vivo hens eggs chorion-allantoic membrane test (HET-CAM). RESULTS: We found the most severe tissue toxicity for chlorhexidin digluconate 0.5 % (IS 20) and Kodan (IS 18). Irritating values were found for Dibromol (IS 14), Octenisept (IS 14) and 2-propanol 60 % (IS 13). Moderate vascular injuries were caused by Jodobac (IS 2). In the HET-CAM test Lavasept 0.2 % (IS 0) and hydrogen peroxide (IS 0) showed no tissue toxicity. CONCLUSION: Our results show that some of the tested antiseptics might cause severe vascular injuries as a sign of tissue toxicity. The tissue compatibility of Lavasept 0.2 % and hydrogen peroxide is much better than the compatibility of the other tested substances. With focus on the literature and our results, Lavasept 0.2 % can be recommended as the local antiseptic of choice.

Allantois↗
PubMedDate not supplied

[Effect of posterior lumbar interbody fusion on the lumbar sagittal spinal profile].

AIM: To determine the effect of different cage geometries and posterior instrumentation on the sagittal spinal profile after monosegmental lumbar interbody fusion. METHOD: The study is based on a retrospective analysis of 119 patients with segmental instability, who were surgically managed by monosegmental PLIF with PEEK-Cages and dorsal instrumentation. RESULTS: At radiographic follow-up after surgery we found a significant improvement of the lumbar sagittal spinal profile, independent of the cage geometry utilised. A marked discrepancy between 0 degrees -standard and 4 degrees -trapezoid implants concerning the radiographic parameters lumbar lordosis, disc height, correction of spondylolisthesis and sacral inclination was not found. With the use of 4 degrees optimised cages in segment L4/5 slightly better results for segmental lordosis were obtained. Reliability of the radiographic evaluation, expressed as intra-observer error, was satisfactory. Cage geometry did not have an effect on the clinical result. By combining interbody fusion with pedicular instrumentation the reposition of slipped vertebra and distraction of the interbody space could more effectively be achieved. Patients without dorsal instrumentation had a higher rate of pseudarthrosis as well as a less satisfactory clinical outcome. CONCLUSION: These results show that normal sagittal alignment after single-level lumbar fusion can be achieved with rectangular and 4 degrees -wedged cages. Although results after utilization of 4 degrees -wedged cages do not significantly differ, these implants offer the surgeon one more sizing variation with which physiological lumbar lordosis may be attained. The combination of intersomatic implants with dorsal instrumentation achieves a more precise realignment and has a lower rate of cage-associated complications. It therefore seems prudent that an interbody fusion for the surgical management of lumbar segmental instability should be combined with pedicular instrumentation.

Equipment Failure Analysis↗
PubMedDate not supplied

[Total knee arthroplasty and high tibial osteotomy in osteoarthritis--results of a survey in traumatic surgery and orthopedic clinics].

AIM: Knee arthroplasties, both total (TKA) and unicondylar, as well as high tibial osteotomy (HTO) represent the main treatment options in severe osteoarthritis of the knee. The aim of this study was to collect detailed information regarding the current treatment strategies in Germany. METHODS: 220 departments of orthopaedic surgery and 250 departments of trauma surgery were asked about their treatment strategies in an anonymous nation-wide survey regarding the different operative procedures in HTO, TKA, revision TKA and related issues. Univariate analyses were performed and means, medians and rates were calculated. RESULTS: Questionnaire forms were answered by 54 % of the departments. The survey represents 31 138 TKA for the year 2002. In the mean 137 TKA were performed in each department. Posterior cruciate ligament retaining components were used in 67 %, resurfacing of the patella was performed in 19 % of cases. The incidence of revision TKA is about 10 % compared to the primary TKA cases. In comparison to a different survey from the year 1995, the absolute number of primary and revision TKA has increased by a factor of nearly three. Compared to the number of TKA, the proportion of HTO has declined to 12 % and the number of unicondylar knee arthroplasties represents 7 % of all cases. CONCLUSION: In the surgical treatment of severe osteoarthritis, TKA shows a highly increasing number, whereas HTO is decreasing. An increasing number of revision TKA can be observed. There is trend towards the cemented implantation technique. Patella resurfacing is not performed routinely in most German hospitals.

Arthroplasty, Replacement, Knee↗
PubMedDate not supplied

[Current treatment modalities for cartilage defects at the knee--results of a nation-wide survey of surgical trauma and orthopaedic clinics in Germany].

AIM: A local cartilage defect at the knee is mostly followed by arthritis after a period of time. Up to now there are no options to adequately regenerate hyaline cartilage in vivo. Hence, the present strategies try to create a repair tissue with hyaline-like characteristics or to repair defects by transplanting autologous osteochondral cylinders. The objective of this study was to collect data about the current treatment of local cartilage defects of the knee in Germany. METHOD: In a countrywide anonymous survey, 250 German trauma surgery and 220 orthopaedic surgery departments were asked about their diagnostic procedures and their treatment strategies when addressing a local cartilage defect of the knee. RESULTS: 230 (48.9 %) of the questionnaires were returned and evaluated. We found differences between the two specialities: the orthopaedic departments are more progressive in applying autologous chondrocyte transplantation (ACT) (28.3 % versus 13.6 %) and osteochondral transplantation (OCT) (69.1 % versus 56.3 %). Only 5.2 % of the German surgeons perform periostal grafting for local cartilage defects. CONCLUSION: There are still discrepancies about the therapy for local cartilage defects of the knee. Our survey illustrates the present status of cartilage repair strategies in Germany.

Cartilage↗
PubMedDate not supplied

[Therapy of femoral head osteonecrosis: results of a national survey].

AIM: The therapy for osteonecrosis (ON) of the femoral head is controversially discussed in the literature. The aim of this study was to ascertain the current treatment concepts of ON in Germany and to compare them with the results reported in the literature. METHODS: 219 Departments of Orthopedic Surgery were asked for their treatment strategies in an anonymous country-wide survey regarding the etiology, diagnosis and therapy (conservative, operative) of ON. Univariate analyses were performed and means, medians and rates were calculated. RESULTS: 43 % of ON were idiopathic, 28 % were due to alcoholism and another 17 % were seen after steroid intake. All departments performed biplanar X-rays for diagnosis of ON and 78 % of departments obtained additional magnet resonance imaging. In the early stages of ON (stage I, II) 33 % of orthopedic clinics recommend a conservative treatment (protected weight bearing, high energy shock wave, pulsed electromagnetic fields) while 67 % prefer surgery (79 % core decompression, 15 % flexion osteotomy, 6 % total hip arthroplasty). In the later stages (stage III, IV) most clinics perform an operative treatment (11 % core decompression, 10 % flexion osteotomy, 79 % total hip arthroplasty). CONCLUSION: Results of ON of the femoral head are unsatisfactory after protected weight bearing. No randomized clinical trials and no mid-term results are available for high energy shock wave or pulsed electromagnetic fields therapy. In the early stages of ON core decompression shows good results. However, in he later stages with secondary arthritis of the hip, total hip arthroplasty remains the gold standard.

Femur Head Necrosis↗
PubMedDate not supplied

[Acute tissue toxicity of PMMA bone cements].

AIM: Local toxic reactions are one possible reason for fibrous tissue formation at the interface between bone and PMMA bone cement. Most of the numerous in vitro studies have shown severe cytotoxicity of bone cements and their components. However, in vivo investigations of the local tissue toxicity of bone cements have so far seldom been performed. METHODS: The in-vivo hens-egg chorion-allantoic-membrane test (HET-CAM), a well established replacement procedure for experiments with higher vertebrates, is used for the testing of potentially toxic solid and fluid substances. It was performed with PMMA bone cements, their components and their monomer extracts to measure in vivo biocompatibility. RESULTS: We showed that local toxic tissue reactions occurred, especially at the beginning of the processing phase of PMMA bone cements. We also proved that certain components of PMMA bone cements have poor tissue compatibility and sometimes cause severe local tissue changes. CONCLUSIONS: In the development of PMMA bone cements and when drafting the recommendations for their use, attention should be paid to their biocompatibility as well as their mechanical properties.

Animal Testing Alternatives↗
PubMedDate not supplied

[Extracorporeal single dose and radiographic dosage in image-controlled and fluoroscopic navigated pedicle screw implantation].

AIM: Goal of the current study was to compare radiation dose and fluoroscopy time of fluoroscopic computer assisted pedicle screw implantation versus the conventional technique. METHOD: For each of 10 specimens two pedicle screws were placed using conventional technique (group 1) and two screws were inserted with fluoroscopic navigation system (group 2) contralateraly. RESULTS: For implantation of two pedicle screws the mean radiation dose was 0.041 mSv in group 1 and 0.029 mSv in group 2. Fluoroscopy time was 34 seconds in group 1 and 25 seconds in group 2. The differences of radiation dose and fluoroscopy time for group 1 and 2 were statistically significant (radiation dose p = 0.00044, fluoroscopy time p = 0.00039). CONCLUSION: We achieved significantly lower radiation dose and fluoroscopy time with fluoroscopic computer assisted pedicle screw implantation compared with the conventional technique. Concerning exposure to radiation for patients and personnel fluoroscopic navigated screw insertion is to favour.

Body Burden↗
PubMedDate not supplied

[Residual stability of different interbody fusion techniques after pedicle screw loosening].

INTRODUCTION: In spinal surgery, postoperative failure of pedicle screw instrumentation due to loosening of the implant at the bone-screw interface is a clinically relevant problem. While there are numerous biomechanical studies dealing with stability after internal fixation, little is known about the remaining segmental stability after pedicle screw loosening. We hypothesize that, in cases of implant loosening, the remaining stability is dependent on whether the segment received an isolated pedicle screw instrumentation or a 360 degrees instrumentation. METHODS: Motion analysis was performed under static, damage-free, sagittal strain (preload 100 N) on intact (controls) and posterior monosegmental L5/6 destabilized lumbar spines of sheep. Spine preparations underwent a flectional torque. Changes of spinal profile were radiographically documented, digitalized and then evaluated. Primary insertion of the conical pedicle screws was performed with a torque of 1.4 Nm. Pedicle screw loosening was simulated by turning the inserted screw back either 180 degrees or 540 degrees . Specimens instrumented with screws of differing diameters (5.5 mm and 6.7 mm) as well as non-instrumented pedicles were also compared. RESULTS: Independent of the type of instrumentation, we found that a loosening of pedicle screws increased remaining segmental motion. In maximal flexion (20 degrees ) and loosening of pedicle screws by 540 degrees, we found a statistically significant increase of remaining segmental motion with sole pedicle instrumentation (- 3.1 degrees ) in contrast to 360 degrees instrumentation (- 1.6 degrees ). For extension, a significant discrepancy between the two stabilization methods could not be shown. In cases where screws were firmly inserted, there was no advantage of using pedicle screws with an increased diameter of 6.7 mm. Independent of the type of fixation method, 5.5 mm screws that were inserted in widened pedicles showed a marked decrease of primary segmental stability. CONCLUSION: This study suggests that, concerning the remaining stability, 360 degrees instrumentation is superior in cases where pedicle screw loosening has occurred. The screw diameter plays an only subordinate role in primary segmental stability when the pedicle screws are inserted firmly.

Animals↗
PubMedDate not supplied

[Stability of pedicle screws in comparison to anterior vertebral body screws after kyphoplasty augmentation].

AIM: Aim of the study was to compare stability of pedicle screws and ventral implanted screws after insertion in soft or cured kyphoplasty cement. METHODS: Pedicle screws were inserted in a total of 40 thoracolumbar vertebrae of 10 different formalin-fixed human specimens: each 10 pedicle screws were implanted in soft (group 1) and cured cement (group 2), each 10 ventral screws were placed in soft (group 3) and cured (group 4) cement. Pedicle screws were then evaluated for biomechanical axial pullout resistance. RESULTS: Mean pull-out force was 452 N (range 60-1 125 N) in group 1, 367 N (range 112-840 N) in group 2, 364 N (range 65-875 N) in group 3 and 271 N (range 35-625 N) in group 4. CONCLUSION: Implantation of pedicle screws and ventral implanted screws in soft and cured kyphoplasty cement is a sufficient method. We achieved more stability with pedicle screws compared with ventral implanted screws in soft and cured cement. No significant difference was seen.

Bone Cements↗
PubMedDate not supplied

[Is there evidence in evidence-based medicine? A comparison of common gradation systems and critical evaluation].

AIM: Evidence-based medicine is still discussed controversially. The current literature offers a huge amount of tables, recommendations and modifications for the levels of evidence and degrees of recommendations. The scientist who is critical of new techniques and who wants to continue his education might be confused by the different recommendations. Unfortunately, the gradation of the recommendations is not always cited which has led to the controversially held discussion about evidence-based medicine. It was, therefore, the aim of the current article to present the most often used gradations and to discuss them critically. METHOD: In the current study we performed an analysis of the currently used recommendations and gradations in evidence-based medicine and discussed them critically. RESULTS: The great number of the available divisions to evidence-based medicine are often technical and partially differ considerably. An unambiguous assignment of the evidence classes and of recommendation degrees can only succeed if the source is indicated clearly. CONCLUSION: As far as the authors are concerned, the confusing status of evidence-based medicine makes one gradation necessary, which should be accepted and used worldwide.

Evidence-Based Medicine↗