Osteoinduction and -conduction through absorbable bone substitute materials based on calcium sulfate: in vivo biological behavior in a rabbit model.

Calcium sulfate (CS) can be used as an antibiotically impregnated bone substitute in a variety of clinical constellations. Antibiotically loaded bone substitutes find specific application in orthopedic and trauma surgery to prevent or treat bone infections especially in relation to open bone defects. However, its use as a structural bone graft reveals some concerns due to its fast biodegradation. The addition of calcium carbonate and tripalmitin makes CS formulations more resistant to resorption leaving bone time to form during a prolonged degradation process. The aim of the present study was the evaluation of biocompatibility and degradation properties of newly formulated antibiotically impregnated CS preparations. Three different types of CS bone substitute beads were implanted into the tibial metaphysis of rabbits (CS dihydrate with tripalmitin, containing gentamicin (Group A) or vancomycin (Group B); Group C: tobramycin-loaded CS hemihydrate). Examinations were performed by means of x-ray, micro-computed tomography (micro-CT) and histology after 4, 6, 8 and 12 weeks. Regarding biocompatibility of the formulations, no adverse reactions were observed. Histology showed formation of vital bone cells attached directly to the implanted materials, while no cytotoxic effect in the surrounding of the beads was detected. All CS preparations showed osteogenesis associated to implanted material. Osteoblasts attached directly to the implant surface and revealed osteoid production, osteocytes were found in newly mineralized bone. Group C implants (Osteoset®) were subject to quick degradation within 4 weeks, after 6-8 weeks there were only minor remnants with little osteogenesis demonstrated by histological investigations. Group A implants (Herafill®-G) revealed similar degradation within atleast 12 weeks. In contrast, group B implants (CaSO4-V) were still detectable after 12 weeks with the presence of implant-associated osteogenesis atlatest follow-up. In all of these preparations, giant cells were found during implant degradation on surface and inside of resorption lacunae. None of the analyzed CS preparations triggered contact activation. All implants demonstrated excellent biocompatibility, with implants of Group A and B showing excellent features as osteoconductive and -inductive scaffolds able to improve mechanical stability.

New Method for Monitoring Partial Weight Bearing (PWB) of Outpatients with an Independent Insole Sensor System.

UNLABELLED: PURPOSE OF THE STUDY Partial weight bearing (PWB) is commonly prescribed post operatively following lower limb fractures and compliance with the weight bearing protocol is an essential element of the rehabilitation. So far it is unknown to what extent patients do comply with PWB during the healing process as instructed by the surgeon. Our aim is to assess a new device for real-time feedback and long-term measurement of PWB of outpatients. The device offers the possibility to monitor the outpatient's activity. The applicability, reliability and validity of the new device should be evaluated. MATERIAL AND METHODS 20 young, healthy subjects complete a course of 500 m that contained several stairs, with a PWB of 15 kg. During the entire test, the axial load, the acceleration and the temperature were measured with a novel insole sensor system. The results were compared with reference measurements performed with a force plate. RESULTS Altogether, the 20 subjects performed 11,106 steps during the completion of the walking circuit. In 23.6% of the steps, the subjects applied a PWB of 10 to 20 kg. In 5.5% of all steps, PWB was superior to 60 kg. The mean bias of the insole was 11,58 N. Limits of agreement were +/- 125 N and the interclass correlation coefficient was r = 0.945. CONCLUSIONS The presented sensor sole might be a useful tool to obtain more precise insight of outpatients' activity and load to the injured limb during the healing process. Furthermore, these results demonstrate that even young and healthy subjects are not able to keep the prescribed PWB. This raises the question, if patients who have been recently operated are able to follow the instructions concerning the PWB. KEY WORDS: partial weight bearing (PWB), insole sensor system, sensor sole, monitoring, outpatients.

Antimicrobial Formulations of Absorbable Bone Substitute Materials as Drug Carriers Based on Calcium Sulfate.

Substitution of bones is a well-established, necessary procedure to treat bone defects in trauma and orthopedic surgeries. For prevention or treatment of perioperative infection, the implantation of resorbable bone substitute materials carrying antibiotics is a necessary treatment. In this study, we investigated the newly formulated calcium-based resorbable bone substitute materials containing either gentamicin (CaSO4-G [Herafill-G]), vancomycin (CaSO4-V), or tobramycin (Osteoset). We characterized the released antibiotic concentration per unit. Bone substitute materials were implanted in bones of rabbits via a standardized surgical procedure. Clinical parameters and levels of the antibiotic-releasing materials in serum were determined. Local concentrations of antibiotics were measured using antimicrobial tests of bone tissue. Aminoglycoside release kinetics in vitro per square millimeter of bead surface showed the most prolonged release for gentamicin, followed by vancomycin and, with the fastest release, tobramycin. In vivo level in serum detected over 28 days was highest for gentamicin at 0.42 µg/ml, followed by vancomycin at 0.11 µg/ml and tobramycin at 0.04 µg/ml. The clinical parameters indicated high biocompatibility for materials used. None of the rabbits subjected to the procedure showed any adverse reaction. The highest availability of antibiotics at 14.8 µg/g on day 1 in the cortical tibia ex vivo was demonstrated for gentamicin, decreasing within 14 days. In the medulla, vancomycin showed a high level at 444 µg/g on day 1, decreasing continuously over 14 days, whereas gentamicin decreased faster within the initial 3 days. The compared antibiotic formulations varied significantly in release kinetics in serum as well as locally in medulla and cortex.

In vivo quantification of gentamicin released from an implant coating.

Drug-releasing implants are gaining increasing interest. The present study reports a detailed physicochemical analysis of a polymeric coating based on poly(D,L-lactide) and the incorporated gentamicin combined with an in vitro and in vivo study of the gentamicin release. Differential scanning calorimeter, Fourier transform infrared spectroscopy, gel permeation chromatography and high-performance liquid chromatography showed no effect of the gamma sterilisation on the coating components or an interaction of the polymer and the gentamicin. Microbiological analysis revealed an inhibition of bacterial growth on the implant surface. For the in vivo study, gentamicin-coated wires were implanted into the tibiae of rats and harvested at different time points up to day 42. To monitor the release in vivo, gentamicin was quantified in serum, bone, endosteum, kidney, and on the explanted wires. Gentamicin was detectable over a time period of 42 days in the endosteum, up to seven days in the kidney, up to 4 h in the bone and at the end of the experiment on one of eight wires. The locally released gentamicin caused no histological changes of the kidney. Microbiologically active concentrations of released gentamicin were found in the endosteum up to 4 h after implantation. The combination of different methods supports the individual results, where quantification is complemented by visualisation or antimicrobial activity. This work demonstrates that the coating procedure results in no substantial alteration of the incorporated drug and that the in vitro burst release occurs also in vivo.

FDG µPET Fails to Detect a Disease-Specific Phenotype in Rats Transgenic for Huntington's Disease ­ A 15 Months Follow-up Study.

BACKGROUND: FDG-PET detects hypometabolism in premanifest and symptomatic Huntington's disease (HD). A cross-sectional study suggested that whole-brain FDG-PET is capable to detect a phenotype in transgenic (tg) HD rats. Recently, a longitudinal follow-up study showed no FDG-PET changes in tgHD rats. Both studies applied small sample sizes and analysis was limited to whole-brain or striatum. OBJECTIVE: We therefore performed a follow-up study in a larger cohort of tgHD and wild-type (wt) rats encompassing several pre-defined regions of interest (ROIs) and hypothesis free voxel-by-voxel SPM analysis to clarify whether FDG-PET can detect a phenotype in tgHD rats and to determine onset …and effect sizes of changes over time. METHODS: N = 19 tgHD- and n = 20 wt-rats, mixed gender, were included. Repeated small animal FDG-µPET and MRI were performed at 5,10,15, and 20 months of age. ROIs encompassing entire brain, cortex, striatum, thalamus, subventricular-zone, and cerebellum were placed manually on the MRI and transferred to the co-registered µPET. Mean and maximal FDG-PET activities within ROIs were calculated and normalized to cerebellar FDG uptake. Activity and spatially normalized FDG-µPET were compared between groups on a hypothesis-free voxel-by-voxel basis using SPM. RESULTS: FDG uptake showed changes over time in both tgHD- and wt-rats, however, there was no consistent difference between tgHD- and wt-rats in both the manual ROI and SPM analysis. CONCLUSIONS: In this transgenic rat model of HD FDG-µPET imaging does not detect significant alterations at the ages investigated. Further investigations are warranted employing other age groups and alternative imaging biomarkers for neuronal degeneration, respectively.

[Traumatic elbow dislocations in bouldering]. / Ellenbogenluxationsverletzungen beim Trendsport Bouldern.

Bouldering is a new trend sport which has become popular in recent years. From April 2011 to June 2012 a total of 5 patients with elbow dislocations from bouldering were admitted to our level 1 trauma center. The injuries varied from simple elbow dislocations to complex fracture dislocations. Elbow dislocations occurred during falling backwards when patients tried to protect themselves by retroversion of both arms. In all cases the falling height was less than 4 meters. The bouldering injury pattern, the diagnostic and therapeutic management as well as the rehabilitation program are described in detail in this article. To the best of our knowledge this is the first report on the special danger of bouldering for complex elbow injuries.

Elongational flow effects on the vortex growth out of Couette flow in ferrofluids.

The growth behavior of stationary axisymmetric vortices and of oscillatory, nonaxisymmetric spiral vortices in Taylor-Couette flow of a ferrofluid in between differentially rotating cylinders is analyzed using a numerical linear stability analysis. The investigation is done as a function of the inner and outer cylinder's rotation rates, the axial wave number of the vortex flows, and the magnitude of an applied homogeneous axial magnetic field. In particular, the consequences of incorporating elongational flow effects in the magnetization balance equation on the marginal control parameters that separate growth from decay behavior are determined. That is done for several values of the transport coefficient that measures the strength of these effects.

Viscoelastic convection: Few-modes model and numerical simulations of field equations for Maxwellian fluids.

The structure formation of convection rolls in Maxwellian fluids that are heated from below in a Rayleigh-Bénard setup is investigated close to onset with a simple few-modes ansatz and by solving the hydrodynamic field equations with a finite-difference method. Depending on the magnitude of the viscoelastic relaxation time one can have besides stationary convection also oscillatory patterns in the form of standing or traveling waves. The existence and stability regions of these convection structures are determined. The convection behavior of the model is compared with the results of full numerical simulations. Furthermore, the effect of modulating the heating periodically in time on the stability of the quiescent conductive state of the fluid and on its convection behavior is investigated as a function of the fluid's viscoelasticity.

[Memento mori: what can be learned from early paintings and woodcuts about death and dying in former times?]. / Memento mori: Was lehren die alten Abbildungen über das Sterben in früheren Zeiten?

What was the impression on death and dying from people living in the 15th century? To answer this question written information is rare on this topic, as few people were able to read at that time, but paintings and early woodcuts may be helpful. Danses macabres (Totentänze) could be seen in Tallinn (formerly Reval), Lübeck, Bern and other places: parts of the original dance macabre still exist in Tallinn, but those in Bern and Lübeck are destroyed; copies however may give a decent impression of their former appearance. At all these dances macabre the death invites persons for a dance: the pope, the Kaiser, the king, the queen, various noblemen and citizens, even young women and small children; to dance with the death meant to die. The death does not dance with any old person. At the time of these dances macabre epidemics and famines were frequent causes of untimely early death.--A booklet Ars moriendi was published about 1470 and taught people how to behave at their hour of death; various devils appear at the deathbed haggling for the soul of the dying person. Thereafter an angel convinces him to trust in god and to resist those false promises of the devil.Nowadays dying is quite different. Usually persons die at very old age and are frequently demented, they die in hospitals, even in intensive care units and possibly without attendance of family members. They may have suffered for a long time and have spent years in nursing homes. Today dying may be just a release from very long suffering.

Islands of instability for growth of spiral vortices in the Taylor-Couette system with and without axial through flow.

We present numerical calculations of the linearized Navier-Stokes equations for axially extended and axially localized spiral structures in the Taylor-Couette system. The eigenvalue surface for spiral vortices with azimuthal wave number M=2 shows significantly more structure than that for vortices with M=0 and 1. Islands are found in parameter space where axially periodic vortex perturbations can grow. Bicriticality of different axial wave numbers is observed. Furthermore, parameter islands of absolute instability are found where wave packets consisting of near-critical extended perturbations can grow and expand via oppositely moving fronts. Some results are compared with those of the Ginzburg-Landau approximation.

Three-dimensional convection of binary mixtures in porous media.

We investigate convection patterns of binary mixtures with a positive separation ratio in porous media. As setup, we choose the Rayleigh-Bénard system of a fluid layer heated from below. Results are obtained by a multimode Galerkin method. Using this method, we compute square and crossroll patterns, and we analyze their structural, bifurcation, and stability properties. Evidence is provided that, for a strong enough Soret effect, both structures exist as stable forms of convection. Some of their properties are found to be similar to square and crossroll convection in the system without porous medium. However, there are also qualitative differences. For example, squares can be destabilized by oscillatory perturbations with square symmetry in porous media, and their velocity isolines are deformed in the so-called Soret regime.

Combination of interfragmentary screws and locking plates in distal meta-diaphyseal fractures of the tibia: a retrospective, single-centre pilot study.

UNLABELLED: If distal tibia fractures cannot be treated with intramedullary nails, locking compression plates, such as the LCP Medial Distal Tibia Plate of Synthes, are used. Bridge plating with interfragmentary movement is the strategy for such osteosynthesis. Interfragmentary movement is difficult to predict. Too much movement leads to formation of more, but less stable callus; longer time until complete fracture healing has been reported. Interfragmentary movement can be controlled by the stability and flexibility of the osteosynthesis construct. We used interfragmentary screws to limit interfragmentary movement in certain cases. We noticed a tendency of faster fracture healing in patients with interfragment lag screw compared with those with sole bridge plating. We therefore retrospectively assessed our patients for time until clinical fracture healing (i.e., pain-free weight bearing and visible callus in both layers on conventional plain film radiographs) and callus formation. METHODS: Data (from patient chart and from regular visits) of 52 patients with fracture of the distal tibia were reviewed, of which 11 were lost to follow-up. After surgery, weight bearing was limited to 20 kg for 6 weeks and then increased in weekly intervals to the pain threshold. X-rays were taken after 3 days, 6, 12 and 24 weeks and when achieving full weight bearing. Time from surgery until ability to full weight bearing was measured and compared. Callus index was measured as quotient of callus thickness and diameter of corticalis both in a.p. and sagittal direction. Statistical evaluation was done with the Mann-Whitney U-test. RESULTS: A total of 41 patients could be analysed; of them, 30 patients had extra-articular fractures. Four patients had 43-B and seven patients had 43-C fractures. As many as 13/30 extra-articular fractures were treated with interfragmentary screws: In this group (n=11, without considering one patient with plate failure and one with pseudarthrosis) time to full weight bearing was 11.38 weeks versus 14.9 weeks without screw (n=14; without two pseudarthrosis and one deep infection) (p=0.044). Callus index at full weight bearing was significantly lesser in patients with screw compared with those without. CONCLUSION: Though interfragmentary screws seem to block necessary interfragmentary movement, we see callus formation as a sign of secondary fracture healing. The osteosynthesis construct with interfragmentary screw seems to be more stable and less flexible than sole bridge plating, leading to faster fracture healing. Interfragmentary screws might help to control and limit interfragmentary movement in certain cases.

[Proximal ulna fractures]. / Proximale Ulnafrakturen.

Proximal ulna fractures are common injuries in the upper extremity. The severity of injury ranges from isolated olecranon fractures to complex elbow fracture dislocations. Relevant anatomic features of the proximal ulna for fracture management are presented in the first part of this article. Furthermore, standard and recent techniques of surgical treatment are described in detail for olecranon and Monteggia fractures as well as for fractures of the coronoid process. Functional outcome and complications of fracture treatment are discussed.

Comminuted fractures of the proximal ulna--Preliminary results with an anatomically preshaped locking compression plate (LCP) system.

INTRODUCTION: The purpose of this investigation was to review the preliminary results and patients outcome following treatment with an anatomically preshaped LCP in patients with comminuted fractures of the proximal ulna. We hypothesized that this fixation system provides equal or superior results in fracture care when compared with other available plating devices, but results in better patient's comfort due to its low-profile design. PATIENTS AND METHODS: Between 2007 and 2009, 15 patients with comminuted fractures of the proximal ulna including three posterior Monteggia fractures were managed with the preshaped LCP olecranon plate. The patients were invited for clinical examination at a mean duration of 16 months, retrospectively. Validated patient-oriented assessment scores involving the Mayo Elbow Performance Index (MEPI) and the shortened Disability of the Arm, Shoulder and Hand (Quick-DASH) score, postoperative range of motion, objective muscle-strengths testing and patient's satisfaction were evaluated. All patients had follow-up radiographs. RESULTS: Fourteen patients were available for evaluation. The mean arc of elbow motion was 129°. The mean MEPI was 97 with good results in two patients and excellent results in 12 patients. The mean Quick-DASH was 13. Thirteen of fourteen patients documented satisfaction with their elbow outcome. There was one patient with symptomatic hardware and one patient complained about deficit of motion. In four patients the hardware was removed including two patients with elective removal. Fourteen fractures healed with ulnohumeral congruity after a mean time to union of 11 weeks. One fracture non-union occurred without mechanical failure or loss of reduction. CONCLUSION: Anatomically preshaped LCP olecranon plating is an effective fixation method for comminuted fractures of the proximal ulna allowing reliable stability for early elbow motion. The functional results are comparable with formerly described plating systems. A low rate of symptomatic hardware removal suggests better patient's compatibility.

End wall effects on the transitions between Taylor vortices and spiral vortices.

We present numerical simulations as well as experimental results concerning transitions between Taylor vortices and spiral vortices in the Taylor-Couette system with rigid, nonrotating lids at the cylinder ends. These transitions are performed by wavy structures appearing via a secondary bifurcation out of Taylor vortices and spirals, respectively. In the presence of these axial end walls, pure spiral solutions do not occur as for axially periodic boundary conditions but are substituted by primary bifurcating, stable wavy spiral structures. Similarly to the periodic system, we found a transition from Taylor vortices to wavy spirals mediated by so-called wavy Taylor vortices and, on the other hand, a transition from wavy spirals to Taylor vortices triggered by a propagating defect. We furthermore observed and investigated the primary bifurcation of wavy spirals out of the basic circular Couette flow with Ekman vortices at the cylinder ends.

Binary-fluid-mixture convection with low-frequency modulated heating.

The response behavior of binary fluid convection to low-frequency temporal modulation of the heating is studied for the case of a negative Soret coupling between temperature and concentration gradients. Numerical simulations using a finite difference method are carried out for ethanol-water mixtures subject to realistic boundary conditions. We study in particular the response when the Rayleigh number periodically drops below the saddle node in the bifurcation diagram of convective solutions under stationary heating, i.e., into a regime where convection would die out in the absence of modulation. Quasiperiodic traveling waves, several different periodic traveling waves, and synchronously modulated patterns with fixed spatial phase are found as stable solutions depending on parameters. The symmetry properties of the different periodic traveling waves are discussed. Anomalous variations of the mixing behavior relative to advection are observed and explained. Lateral and temporal Fourier decompositions are used together with other diagnostic tools to analyze the complex bifurcation and spatiotemporal properties that are caused by the interplay of modulated heating, nonlinear advection, Soret induced gradients, and mixing of the fluid.

Influence of homogeneous magnetic fields on the flow of a ferrofluid in the Taylor-Couette system.

We investigate numerically the influence of a homogeneous magnetic field on a ferrofluid in the gap between two concentric, independently rotating cylinders. The full Navier-Stokes equations are solved with a combination of a finite difference method and a Galerkin method. Structure, dynamics, symmetry properties, bifurcation, and stability behavior of different vortex structures are investigated for axial and transversal magnetic fields, as well as combinations of them. We show that a transversal magnetic field modulates the Taylor vortex flow and the spiral vortex flow. Thus, a transversal magnetic field induces wavy structures: wavy Taylor vortex flow (wTVF) and wavy spiral vortex flow. In contrast to the classic wTVF, which is a secondarily bifurcating structure, these magnetically generated wavy Taylor vortices are pinned by the magnetic field, i.e., they are stationary and they appear via a primary forward bifurcation out of the basic state of circular Couette flow.

Roll and square convection in binary liquids: a few-mode Galerkin model.

We present a few-mode Galerkin model for convection in binary fluid layers subject to an approximation to realistic horizontal boundary conditions at positive separation ratios. The model exhibits convection patterns in form of rolls and squares. The stable squares at onset develop into stable rolls at higher thermal driving. In between, a regime of a so-called cross roll structure is found. The results of our few-mode model are in good agreement with both experiments and numerical multimode simulations.

Stationary and oscillatory convection of binary fluids in a porous medium.

We investigate numerically stationary convection and traveling wave structures of binary fluid mixtures with negative separation ratio in the Rayleigh-Bénard system filled with a porous medium. The bifurcation behavior of these roll structures is elucidated as well as the properties of the velocity, temperature, and concentration fields. Moreover, we discuss lateral averaged currents of temperature and concentration. Finally, we investigate the influence of the Lewis number, of the separation ratio, and of the normalized porosity on the bifurcation branches.

[Cases from the area between geriatrics and trauma surgery. Examples from the medical arbitration board]. / Fälle aus dem Grenzgebiet zwischen Geriatrie und Unfallchirurgie. Aus der Arbeit der Schlichtungsstelle.

Medical arbitration boards ("Schlichtungsstellen", expert panels for extrajudicial malpractice claim resolution) try to settle claims of suspected malpractice between patients and their physicians and to avoid court trials. Numerous studies found an increasing incidence of adverse events with rising age. Injuries that occur in the hospital are frequently beyond the specialty of the treating physician. Therefore, the physician has to broaden his diagnostic view beyond the borders of his own specialty to recognize injuries in his patients and to prevent malpractice claims.In this paper, we report on adverse events in elderly patients where the geriatrician/internist was accused of negligence for not having promptly recognized a fracture after a fall or having chosen an inadequate operative procedure. For example, the importance of weight bearing osteosynthesis, mandatory in hip fractures in the elderly population to prevent long-term immobilization, is discussed.Adverse events due to negligence are more frequent among the elderly; the reasons are discussed. They will never be entirely preventable. The data presented in this report may be helpful to recognize fractures in time and to ensure adequate treatment, in order to reduce the number of court claims.