Polarisation compensation in non-planar image-rotating OPO ring resonators

Non-planar image-rotating OPO ring resonators necessitate polarisation compensation in contrast to their planar counterparts. This is essential for maintaining phase matching conditions for non-linear optical conversion in the resonator during each cavity round trip. In this study, we examine the polarisation compensation and its impact on the performance of two types of non-planar resonators: RISTRA with a π2 image rotation and FIRE with a fractional image rotation (π2 fraction). The RISTRA is insensitive to mirror phase shifts, while the FIRE has a more complex dependence of polarisation rotation on mirror phase shifts. There has been debate over whether a single birefringent element can provide adequate polarisation compensation for non-planar resonators beyond RISTRA-type. Our results show that under certain experimentally feasible conditions, even FIRE resonators can achieve adequate polarisation compensation with a single half-wave plate. We validate our theoretical analysis through numerical simulations and experimental studies of OPO output beam polarisation using ZnGeP₂ non-linear crystals.

OF-Pelvis classification of osteoporotic sacral and pelvic ring fractures

Objectives

Osteoporotic fractures of the pelvis (OFP) are an increasing issue in orthopedics. Current classification systems (CS) are mostly CT-based and complex and offer only moderate to substantial inter-rater reliability (interRR) and intra-rater reliability (intraRR). MRI is thus gaining importance as a complement.

This study aimed to develop a simple and reliable CT- and MRI-based CS for OFP.

Methods

A structured iterative procedure was conducted to reach a consensus among German-speaking spinal and pelvic trauma experts over 5 years. As a result, the proposed OF-Pelvis CS was developed. To assess its reliability, 28 experienced trauma and orthopedic surgeons categorized 25 anonymized cases using X-ray, CT, and MRI scans twice via online surveys. A period of 4 weeks separated the completion of the first from the second survey, and the cases were presented in an altered order. While 13 of the raters were also involved in developing the CS (developing raters (DR)), 15 user raters (UR) were not deeply involved in the development process.

To assess the interRR of the OF-Pelvis categories, Fleiss’ kappa (κ_F) was calculated for each survey. The intraRR for both surveys was calculated for each rater using Kendall’s tau (τ_K). The presence of a modifier was calculated with κ_F for interRR and Cohen’s kappa (κ_C) for intraRR.

Results

The OF-Pelvis consists of five subgroups and three modifiers. Instability increases from subgroups 1 (OF1) to 5 (OF5) and by a given modifier. The three modifiers can be assigned alone or in combination.

In both surveys, the interRR for subgroups was substantial: κ_F = 0.764 (Survey 1) and κ_F = 0.790 (Survey 2). The interRR of the DR and UR was nearly on par (κ_F Survey 1/Survey 2: DR 0.776/0.813; UR 0.748/0.766). The agreement for each of the five subgroups was also strong (κ_F min.–max. Survey 1/Survey 2: 0.708–0.827/0.747–0.852). The existence of at least one modifier was rated with substantial agreement (κ_F Survey 1/Survey 2: 0.646/0.629).

The intraRR for subgroups showed almost perfect agreement (τ_K = 0.894, DR: τ_K = 0.901, UR: τ_K = 0.889). The modifier had an intraRR of κ_C = 0.684 (DR: κ_C = 0.723, UR: κ_C = 0.651), which is also considered substantial.

Conclusion

The OF-Pelvis is a reliable tool to categorize OFP with substantial interRR and almost perfect intraRR. The similar reliabilities between experienced DRs and URs demonstrate that the training status of the user is not important. However, it may be a reliable basis for an indication of the treatment score.

Cement augmentation as revision strategy for loosened thick-diameter non-fenestrated iliac screws - A biomechanical analysis

BACKGROUND

Loosened/pulled-out iliac screws can be a challenging complication, as revision opportunities are limited because more distal anchorage is impossible. Insertion of thick-diameter screws is an option in cases with loosened thin-diameter screws. However, this is occasionally infeasible in patients with loosened thick-diameter screws. Therefore, this study aimed to biomechanically analyze whether loosened/pulled-out thick iliac screws regain strong anchorage following cement augmentation.

METHODS

Six human pelvis specimens were dissected to isolate 12 hemipelves, and 9 × 80 mm iliac screws were implanted. The pullout maneuver was performed followed by cement augmentation of the same screw within the same screw hole. After cement hardening, pullout was performed again. Forces needed for pullout and the insertion torque were measured for the 12 iliac screws.

FINDINGS

Cement augmentation significantly increased stability, with the pullout forces required being as high as 953.23 N (standard deviation [SD] 1070.46 N; median 306.30 N) for the uncemented screws and 2897.53 N (SD 585.83 N; median 2907.81 N) after cement augmentation (p < 0.001). No correlation was found between insertion torques and pullout forces.

INTERPRETATION

While revision of loosened iliac screws can often be achieved using higher diameters, this method is limited by the thickness of the screws already in place. We demonstrated that cement augmentation significantly increases stability even in thick-diameter screws, achieving more pullout stability than before the initial pullout. This method may be a cost-effective and rapid option for revision, even with significant defects and with no thicker-diameter iliac screw being available.

A new minimally invasive U-shaped lumbopelvic stabilization technique

Lumbopelvic stabilization is a surgical technique used frequently to treat lumbosacral fractures; however, it can also be used in revision cases, infections, or during deformity correction. However, the related soft tissue complication rates associated with open lumbopelvic stabilization are high. Different authors have recently reported minimally invasive surgical techniques. We developed a rigid minimally invasive technique for lumbopelvic stabilization. We present our technique and also present preliminary results from 10 cases. We did not observe soft tissue-related complications in any patient. Implant removal was performed twice, to release healthy disks and because of implant prominence. One patient required revision surgery because of implant loosening due to osteoporosis, and one patient required revision surgery due to screw cap loosening. Postsurgical mobilization was good in all patients without further injuries; however, polytraumatized patients were limited by additional injuries. Thus, minimally invasive U-shaped lumbopelvic stabilization is a useful technique combining the soft tissue-related advantages of minimally invasive surgical techniques as well as a theoretically very rigid construct caused by strong implants.

Recommendations for the Diagnostic Testing and Therapy of Atlas Fractures

Im Jahr 2017 erstellten die Mitglieder der AG „obere HWS“ der Sektion „Wirbelsäule“ der DGOU in einem Konsensusprozess mit 4 Sitzungen Empfehlungen zur Diagnostik und Therapie oberer Halswirbelsäulenverletzungen unter Berücksichtigung der aktuellen Literatur. Der folgende Artikel beschreibt die Empfehlung für Frakturen des Atlasrings. Etwa 10% aller HWS-Verletzungen betreffen den Atlas. Die Diagnostik zielt im Wesentlichen auf die Detektion der Verletzung sowie die Beurteilung der Gelenkflächen hinsichtlich einer Lateralisationstendenz der Atlasmassive. Zur Klassifikation haben sich die Gehweiler-Klassifikation und ergänzend die Dickman-Klassifikation bewährt. Zum primären klinischen Screening hat sich die Canadian C-Spine Rule bewährt. Bildgebendes Verfahren der Wahl bei klinischem Verdacht auf eine Atlasverletzung ist die CT. Die MRT dient der Beurteilung der Integrität des Lig. transversum atlantis bei vorderer und hinterer Bogenfraktur. Die Indikation zur Gefäßdarstellung sollte großzügig gestellt werden. Viele Atlasfrakturen können konservativ in einer Zervikalorthese behandelt werden. Eine OP-Indikation ist gegeben bei bestehender oder drohender massiver Gelenkinkongruenz oder -instabilität, die am häufigsten bei Gehweiler-IIIB-Frakturen oder bei Gehweiler-IV-Frakturen vorliegt. Operative Standardtherapie ist die dorsale atlantoaxiale Fixation, entweder in transartikulärer Technik oder mittels Fixateur interne. Insbesondere bei jüngeren Patienten sollte die Möglichkeit einer isolierten Atlasosteosynthese geprüft werden. Dislozierte Gehweiler-IV-Frakturen mit sagittaler Spaltbildung können auch probatorisch im Halofixateur unter Ausnutzung der Ligamentotaxis behandelt werden; eine engmaschige Dislokationskontrolle ist obligat. Im Falle einer sekundären Dislokation ist auch hier eine operative Stabilisierung indiziert. Bei Mitbeteiligung des okzipitozervikalen Gelenks ist eine Einbeziehung des Okziputs in die Instrumentierung notwendig.

Classification of Osteoporotic Thoracolumbar Spine Fractures: Recommendations of the Spine Section of the German Society for Orthopaedics and Trauma (DGOU)

STUDY DESIGN

Expert opinion.

OBJECTIVES

Osteoporotic vertebral fractures are of increasing medical importance. For an adequate treatment strategy, an easy and reliable classification is needed.

METHODS

The working group "Osteoporotic Fractures" of the Spine Section of the German Society for Orthopaedics and Trauma (DGOU) has developed a classification system (OF classification) for osteoporotic thoracolumbar fractures. The consensus decision followed an established pathway including review of the current literature.

RESULTS

The OF classification consists of 5 groups: OF 1, no vertebral deformation (vertebral edema); OF 2, deformation with no or minor (<1/5) involvement of the posterior wall; OF 3, deformation with distinct involvement (>1/5) of the posterior wall; OF 4, loss of integrity of the vertebral frame or vertebral body collapse or pincer-type fracture; OF 5, injuries with distraction or rotation. The interobserver reliability was substantial (κ = .63).

CONCLUSIONS

The proposed OF classification is easy to use and provides superior clinical differentiation of the typical osteoporotic fracture morphologies.

Treatment of Fractures of the Thoracolumbar Spine: Recommendations of the Spine Section of the German Society for Orthopaedics and Trauma (DGOU)

STUDY DESIGN

consensus paper with systematic literature review.

OBJECTIVE

The aim of this study was to establish recommendations for treatment of thoracolumbar spine fractures based on systematic review of current literature and consensus of several spine surgery experts.

METHODS

The project was initiated in September 2008 and published in Germany in 2011. It was redone in 2017 based on systematic literature review, including new AOSpine classification. Members of the expert group were recruited from all over Germany working in hospitals of all levels of care. In total, the consensus process included 9 meetings and 20 hours of video conferences.

RESULTS

As regards existing studies with highest level of evidence, a clear recommendation regarding treatment (operative vs conservative) or regarding type of surgery (posterior vs anterior vs combined anterior-posterior) cannot be given. Treatment has to be indicated individually based on clinical presentation, general condition of the patient, and radiological parameters. The following specific parameters have to be regarded and are proposed as morphological modifiers in addition to AOSpine classification: sagittal and coronal alignment of spine, degree of vertebral body destruction, stenosis of spinal canal, and intervertebral disc lesion. Meanwhile, the recommendations are used as standard algorithm in many German spine clinics and trauma centers.

CONCLUSION

Clinical presentation and general condition of the patient are basic requirements for decision making. Additionally, treatment recommendations offer the physician a standardized, reproducible, and in Germany commonly accepted algorithm based on AOSpine classification and 4 morphological modifiers.

Treatment of Injuries to the Subaxial Cervical Spine: Recommendations of the Spine Section of the German Society for Orthopaedics and Trauma (DGOU)

STUDY DESIGN

Expert consensus.

OBJECTIVES

To establish treatment recommendations for subaxial cervical spine injuries based on current literature and the knowledge of the Spine Section of the German Society for Orthopaedics and Trauma.

METHODS

This recommendation summarizes the knowledge of the Spine Section of the German Society for Orthopaedics and Trauma.

RESULTS

Therapeutic goals are a stable, painless cervical spine and protection against secondary neurologic damage while retaining maximum possible motion and spinal profile. The AOSpine classification for subaxial cervical injuries is recommended. The Canadian C-Spine Rule is recommended to decide on the need for imaging. Computed tomography is the favoured modality. Conventional x-ray is preserved for cases lacking a "dangerous mechanism of injury." Magnetic resonance imaging is recommended in case of unexplained neurologic deficit, prior to closed reduction and to exclude disco-ligamentous injuries. Computed tomography angiography is recommended in high-grade facet joint injuries or in the presence of vertebra-basilar symptoms. A0-, A1- and A2-injuries are treated conservatively, but have to be monitored for progressive kyphosis. A3 injuries are operated in the majority of cases. A4- and B- and C-type injuries are treated surgically. Most injuries can be treated with anterior plate stabilization and interbody support; A4 fractures need vertebral body replacement. In certain cases, additive or pure posterior instrumentation is needed. Usually, lateral mass screws suffice. A navigation system is advised for pedicle screws from C3 to C6.

CONCLUSIONS

These recommendations provide a framework for the treatment of subaxial cervical spine Injuries. They give advice about diagnostic measures and the therapeutic strategy.

Laser desorption single-conformation UV and IR spectroscopy of the sulfonamide drug sulfanilamide, the sulfanilamide-water complex, and the sulfanilamide dimer

We have studied the conformational preferences of the sulfonamide drug sulfanilamide, its dimer, and its monohydrated complex through laser desorption single-conformation UV and IR spectroscopy in a molecular beam. Based on potential energy curves for the inversion of the anilinic and the sulfonamide NH₂ groups calculated at DFT level, we suggest that the zero-point level wave function of the sulfanilamide monomer is appreciably delocalized over all four conformer wells. The sulfanilamide dimer, and the monohydrated complex each exhibit a single isomer in the molecular beam. The isomeric structures of the sulfanilamide dimer and the monohydrated sulfanilamide complex were assigned based on their conformer-specific IR spectra in the NH and OH stretch region. Quantum Theory of Atoms in Molecules (QTAIM) analysis of the calculated electron density in the water complex suggests that the water molecule is bound side-on in a hydrogen bonding pocket, donating one O-HO[double bond, length as m-dash]S hydrogen bond and accepting two hydrogen bonds, a NHO and a CHO hydrogen bond. QTAIM analysis of the dimer electron density suggests that the C_i symmetry dimer structure exhibits two dominating N-HO[double bond, length as m-dash]S hydrogen bonds, and three weaker types of interactions: two CHO bonds, two CHN bonds, and a chalcogen OO interaction. Most interestingly, the molecular beam dimer structure closely resembles the R dimer unit - the dimer unit with the greatest interaction energy - of the α, γ, and δ crystal polymorphs. Interacting Quantum Atoms analysis provides evidence that the total intermolecular interaction in the dimer is dominated by the short-range exchange-correlation contribution.

Site-specific binding of a water molecule to the sulfa drugs sulfamethoxazole and sulfisoxazole: a laser-desorption isomer-specific UV and IR study

Using isomer-specific IR spectroscopy, we show that sulfamethoxazole and sulfisoxazole exhibit distinct site specificities for binding a water molecule.

Design considerations for a novel shape-memory-plate osteosynthesis allowing for non-invasive alteration of bending stiffness

Biomechanical stimuli play a major role in fracture healing. Changing the fixation stiffness through the course of healing might accelerate bone healing and prevent healing complications. Shape memory alloy (SMA) based implants were developed to allow for non-invasive stiffness alteration during the fracture healing process. To gain a deeper understanding of the implant functionality based on the alloy characteristics and geometric design, the mechanical properties of different shape memory alloys where mechanically characterized. SMA bone plates were manufactured and the structural bending stiffness of the implants was determined at different temperatures and configurations. The temperature required for complete recovery of shape after deformation increased continuously with increasing pseudo-plastic deformation in SMA probes. Full recovery was observed at temperatures ranging from 38°C to 52°C after pseudo-plastic deformations ranging from 0.2% to 1.0% outer fibre strain, respectively. The small fragment inverse-dynamisation implants revealed bending stiffnesses ranging from 0.09Nm² to 0.34Nm² in the initial state and from 0.16Nm² to 0.46Nm² after shape alteration. Dependent on the design, a relative gain of the implant stiffness ranging from 18.8% to 115.0% could be observed. The large inverse-dynamisation implants revealed bending stiffnesses from 3.7Nm² to 7.1Nm² before and 4.1Nm² to 12.6Nm² after triggering the shape memory effect. Dependent on the design a gain in stiffness from 11.8% to 117.2% was observed. Warming the SMA implant to 40°C for a short period of time, leads to a moderate increase in implant stiffness of up to 64.5%, while triggering the implant with 50°C leads to a maximum increase in stiffness of up to 127.3%. The Nitinol shape memory bone plates have a huge potential for improving the treatment of long shaft fractures by allowing for the increase, decrease or incremental change of implant stiffness in fracture stabilization. However, the interaction between design, material properties, and manufacturing processes need to be carefully considered for each specific application to achieve optimum function of SMA-based, stiffness altering, fracture-fixation implants.

[Limb salvage or amputation after severe trauma to the lower extremities : Evidence from the LEAP Study]

Deciding between reconstruction and primary amputation after severe high-energy trauma to the lower extremities is difficult and consequential. The Lower Extremity Assessment Project (LEAP) prospectively included and investigated patients with severe, limb-threatening injuries below the femur, with third-grade open fractures, defined soft-tissue damage and amputation wounds. This paper aims to review the key results of the LEAP study, which were published in several parts, in due consideration of the newer relevant literature, and to deduce the consequences for clinical practice. The main results are as follows: No score is sufficiently reliable to predict the success of reconstruction. Loss of muscle seems to be more momentous than loss of bone. Any accompanying injuries that should be taken into account in the individual treatment concepts are crucial to the results, in addition to comorbidities and other individual patient-related factors, such as alcoholism, smoking, insurance, and social background. Psychological impairment is frequent after these injuries and should therefore be addressed regularly with regard to rehabilitation.

[Limb salvage and amputation after trauma : Decision criteria and management algorithm]

The clinical decision-making process for patients with severe trauma of the extremities for primary amputation or to initiate extensive reconstructive measures for limb salvage in the best interests of the patient can be complex and difficult. The many factors influencing the decision-making process, such as local anatomical, pathomechanical, physiological, psychosocial and general factors are demonstrated and discussed. In the past, the role of scores supporting the decision-making process for amputation or limb salvage has been overestimated. In the LEAP study it could clearly be demonstrated that none of the sometimes highly complex scores could fulfill the expectations to predict successful limb salvage or the need for amputation. In this article it is shown that initiators and authors of scores achieved much higher sensitivity and specificity in the inaugural studies compared to the standardized and controlled conditions used in the LEAP study. For a long time, a lack of feeling in the feet was considered a safe and reliable criterion for amputation but the LEAP study has made a substantial contribution to demythologizing this as a lead symptom. Patients with severe trauma of the ankle or foot requiring a free flap or ankle arthrodesis have a significantly worse outcome compared to patients with a below knee amputation. Taking all these influencing factors into consideration, a comprehensive algorithm is presented that facilitates, strengthens and standardizes decision-making for amputation or limb salvage. This algorithm consists of four modules: 1) decision-making, 2) emergency treatment, 3) definitive treatment and 4) fine tuning. In the decision-making module not only local and general injury severity are addressed but the expected result, the general condition, comorbidities, compliance and the will of the patient are also included.

[Limb salvage versus amputation after severe lower extremity injury : Cases from clinical practice]

Following severe lower extremity injury, the potential outcome of a salvage procedure might often be questionable. Objective criteria should help in decision-making. From the clinical practice of a level I trauma center, we demonstrate three case reports and approaches following severe lower extremity injury.

[Sagittal Balance of the Spine--Clinical Importance and Radiographic Assessment]

Sagittal deformities of the spine frequently result in back pain, as patients have to expend much energy in compensation. The sagittal alignment of the spine is defined by its curvatures (lordosis and kyphosis) relative to the position of the pelvis. Diagnostic assessment is based on full spine a. p. and lateral X-rays. The sagittal balance is primarily described by different angles that can be measured, e.g. lumbar lordosis, pelvic incidence, pelvic tilt and thoracic kyphosis. The quality of life can best be estimated by subtracting lumbar lordosis from the pelvic incidence. However, initial evaluation of the sagittal balance can also be based on the sagittal vertical axis. The severity of imbalance can be described by the sagittal vertical axis and the pelvic tilt, but surgical therapy necessitates a more profound analysis, which can be based on the SRS-Schwab classification.

Percutaneous dilatational tracheostomy (PDT) in trauma patients: a safe procedure

PURPOSE

Percutaneous dilatational tracheostomy (PDT) is a standard procedure routinely performed on intensive care units. While complication rates and long-term outcomes have been studied in different patient populations, there are few studies known to these authors involving PDT in trauma patients and the complications which may result.

METHODS

Between March 2007 and August 2013, all instances and peri-procedural complications during PDT occurring on the trauma intensive care unit, a unit specialized in the care of injured patients and especially polytrauma patients, were documented. PDTs were performed by a surgeon with the assistance and supervision of another, using bronchoscopic guidance performed by the respiratory medicine department.

RESULTS

289 patients were included in the study, 225 men and 64 women with a mean age of 49 ± 21 years. Complications occurred in 37.4 % of cases. The most common complication, bleeding, occurred in 26.3 % of patients ranging from little to severe bleeding. Fracture of tracheal cartilage occurred in 6 % of PDT cases. Additional complications such as dislocation of the guidewire, hypotension, and oxygen desaturation were observed. Most complications did not require treatment. The second tracheal intercartilaginous space was successfully intubated in 82 % of cases.

CONCLUSIONS

PDT is a safe procedure in trauma patients. When considering the severity of complications such as major blood loss, pneumothorax, or death, this evidence suggests that PDT is safer in trauma patients compared to other patient cohorts.

BMP-2-transduced human bone marrow stem cells enhance neo-bone formation in a rat critical-sized femur defect

Synthetic graft materials are considered as possible substitutes for cancellous bone, but lack osteogenic and osteoinductive properties. In this study, we investigated how composite scaffolds of βTCP containing osteogenic human bone marrow mesenchymal stem cells (hBMSCs) and osteoinductive bone morphogenetic protein-2 (BMP-2) influenced the process of fracture healing. hBMSCs were loaded into βTCP scaffolds 24 h before implantation in a rat critical-sized bone defect. hBMSCs were either stimulated with rhBMP-2 or transduced with BMP-2 by gene transfer. The effect of both protein stimulation and gene transfer was compared for osteogenic outcome. X-rays were conducted at weeks 0, 1, 3, 6, 9 and 12 post-operatively. In addition, bone-labelling fluorochromes were applied at 0, 3, 6 and 9 weeks. Histological analysis was performed for the amount of callus tissue and cartilage formation. At 6 weeks, the critical-sized defect in 33% of the rats treated with the Ad-BMP-2-transduced hBMSCs/βTCP scaffolds was radiographically bridged. In contrast, in only 10% of the rats treated with rhBMP2/hBMSCs, 12 weeks post-treatment, the bone defect was closed in all treated rats of the Ad-BMP-2 group except for one. Histology showed significantly higher amounts of callus formation in both Ad-BMP-2- and rhBMP-2-treated rats. The amount of neocartilage was less pronounced in both BMP-2-related groups. In summary, scaffolds with BMP-2-transduced hBMSCs performed better than those with the rhBMP2/hBMSCs protein. These results suggest that combinations of osteoconductive biomaterials with genetically modified MSCs capable of secreting osteoinductive proteins may represent a promising alternative for bone regeneration. Copyright © 2015 John Wiley & Sons, Ltd.

Non-osteotomy and osteotomy large animal fracture models in orthopedic trauma research

Large animal fracture models are important in the field of orthopedic trauma research. New implants are tested in animals before being implanted into humans. Large animals like sheep or swine often are more properly to simulate conditions in humans, e.g. biomechanical demands, compared to rodents. Cited articles mainly analyze shock or fracture healing. Both osteotomy and non-osteotomy fracture models have been used in the past. However, comparative studies are rare and clear recommendation when to use which model are missing. This review will summarize large animal fracture models putting special emphasis on non-osteotomy fracture models.

Transcutaneous electromagnetic induction heating of an intramedullary nickel-titanium shape memory implant

PURPOSE

Inadequate mechanical stimuli are a major cause for nonunions following surgery for femoral and tibial shaft fractures. Adapting fixation rigidity during the course of fracture healing requires additional surgery. Nickel-titanium (NiTi) implants can change shape and rigidity by employing a temperature-dependent shape-memory effect. As a first step in the development of advanced intramedullary (IM) NiTi devices for fracture healing, this study aimed to test the feasibility and safety of transcutaneous electromagnetic induction heating of an IM NiTi implant in a rat model.

METHODS

In 51 rats, NiTi implants were introduced into the left distal femur. Forty-four animals were transferred to an induction coil, and the implant was electromagnetically heated to temperatures between 40° and 60 °C Blood samples were drawn before and four hours after the procedure. Interleukin (IL)-1, IL-4, IL-10, tumour necrosis factor alpha (TNF-α) and interferon gamma (IFN-γ) were measured. Animals were sacrificed at three weeks. Histological specimens from the hind leg and liver were retrieved and examined for inflammatory changes, necrosis or corrosion pits.

RESULTS

All animals successfully underwent the surgical procedure. Following transcutaneous induction heating, target temperature was confirmed in 37/44 rats. Postoperative controls showed no signs of undue limitations. Neither cytokine measurements nor histological specimens showed any significant differences between groups. There were no corrosion pits or necrosis.

CONCLUSION

We conclude that electromagnetic induction heating of IM NiTi implants is feasible and safe in a rat femur model. These findings reflect a further step in the development of novel concepts for IM fracture fixation that might lead to better fracture healing, less patient discomfort and less need for surgical interventions.

Vertebral fractures in motor vehicle accidents - a medical and technical analysis of 33,015 injured front-seat occupants

Spinal injuries pose a considerable risk to life and quality of life. In spite of improvements in active and passive safety of motor vehicles, car accidents are regarded as a major cause for vertebral fractures. The purpose of this study was to evaluate the current incidence of vertebral fractures among front-seat occupants in motor vehicle accidents, and to identify specific risk factors for sustaining vertebral fractures in motor vehicle accidents. Data from an accident research unit were accessed to collect collision details, preclinical data, and clinical data. We included all data on front-seat occupants. Hospital records were retrieved, and radiological images were evaluated. We analysed 33,015 front-seat occupants involved in motor vehicle accidents over a 24-year period. We identified 126 subjects (0.38%) with cervical spine fractures, 78 (0.24%) with thoracic fractures, and 99 (0.30%) with lumbar fractures. The mean relative collision speeds were 48, 39, and 40 kph in subjects with cervical, thoracic, and lumbar spine fractures, respectively, while it was 17.3 kph in the whole cohort. Contrary to the overall cohort, these patients typically sustained multiple hits rather than simple front collisions. Occupants with vertebral fractures frequently showed numerous concomitant injuries; for example, additional vertebral fractures. The incidence of vertebral fractures corresponded with collision speed. Safety belts were highly effective in the prevention of vertebral fractures. Apart from high speed, complex injury mechanisms as multiple collisions or rollovers were associated with vertebral fractures. Additional preventive measures should focus on these collision mechanisms.

Noninvasive induction implant heating: an approach for contactless altering of mechanical properties of shape memory implants

This article shows an approach to change the properties of an orthopaedic shape memory implant within biological tissue, using contactless induction heating. Due to inducing the one way-memory effect, triggered by the rise of temperature within the implant, the geometry and hence the mechanical properties of the implant itself, are altered. The power uptake of the implant, depending on the induction parameters as well as on its position within the induction coil, is shown. Thermographic measurements are carried out in order to determine the surface temperature distribution of the implant. In order to simulate biological tissue, the implant was embedded in agarose gel. Suitable heating parameters, in terms of a short heating process in combination with a reduced heat impact on the surrounding environment, were determined.

Evolution of amide stacking in larger γ-peptides: triamide H-bonded cycles

The single-conformation spectroscopy of two model γ-peptides has been studied under jet-cooled conditions in the gas phase. The methyl-capped triamides, Ac-γ(2)-hPhe-γ(2)-hAla-NHMe and Ac-γ(2)-hAla-γ(2)-hPhe-NHMe, were probed by resonant two-photon ionization (R2PI) and resonant ion-dip infrared (RIDIR) spectroscopies. Four conformers of Ac-γ(2)-hPhe-γ(2)-hAla-NHMe and three of Ac-γ(2)-hAla-γ(2)-hPhe-NHMe were observed and spectroscopically interrogated. On the basis of comparison with the predictions of density functional theory calculations employing a dispersion-corrected functional (ωB97X-D/6-311++G(d,p)), all seven conformers have been assigned to particular conformational families. The preference for formation of nine-membered rings (C9) observed in a previous study [James, W. H., III et al., J. Am. Chem. Soc. 2009, 131, 14243] of the smaller analog, Ac-γ(2)-hPhe-NHMe, carries over to these triamides, with four of the seven conformers forming C9/C9 sequential double-ring structures, and one conformer a C9/C14 bifurcated double ring. The remaining two conformers form C7/C7/C14 H-bonded cycles involving all three amide NH groups, unprecedented in other peptides and peptidomimetics. The amide groups in these structures form a H-bonded triangle with the two trimethylene bridges forming loops above and below the molecule's midsection. The structure is a natural extension of amide stacking, with the two terminal amides blocked from forming the amide tristack by formation of the C14 H-bond. Pair interaction energy decomposition analysis based on the fragment molecular orbital method (FMO-PIEDA) is used to determine the nonbonded contributions to the stabilization of these conformers. Natural bond orbital (NBO) analysis identifies amide stacking with a pair of n → π* interactions between the nitrogen lone pairs and π* orbitals on the carbonyl of the opposing amide groups.

[Recommendations for the treatment of thoracolumbar and lumbar spine injuries]

This paper gives recommendations for treatment of thoracolumbar and lumbar spine injuries. The recommendations are based on the experience of the involved spine surgeons, who are part of a study group of the "Deutsche Gesellschaft für Unfallchirurgie" and a review of the current literature. Basics of diagnostic, conservative, and operative therapy are demonstrated. Fractures are evaluated by using morphologic criteria like destruction of the vertebral body, fragment dislocation, narrowing of the spinal canal, and deviation from the individual physiologic profile. Deviations from the individual sagittal profile are described by using the monosegmental or bisegmental end plate angle. The recommendations are developed for acute traumatic fractures in patients without severe osteoporotic disease.

Electromagnetic induction heating of an orthopaedic nickel--titanium shape memory device

Shape memory orthopaedic implants made from nickel-titanium (NiTi) might allow the modulation of fracture healing, changing their cross-sectional shape by employing the shape memory effect. We aimed to show the feasibility and safety of contact-free electromagnetic induction heating of NiTi implants in a rat model. A water-cooled generator-oscillator combination was used. Induction characteristics were determined by measuring the temperature increase of a test sample in correlation to generator power and time. In 53 rats, NiTi implants were introduced into the right hind leg. The animals were transferred to the inductor, and the implant was electromagnetically heated to temperatures between 40 and 60°C. Blood samples were drawn before and 4 h after the procedure. IL-1, IL-4, IL-10, TNF-α, and IFN-γ were measured. Animals were euthanized at 3 weeks. Histological specimens from the hind leg and liver were retrieved and examined for inflammatory changes, necrosis, and corrosion pits. Cytokine measurements and histological specimens showed no significant differences among the groups. We concluded that electromagnetic induction heating of orthopedic NiTi implants is feasible and safe in a rat model. This is the first step in the development of new orthopedic implants in which stiffness or rigidity can be modified after implantation to optimize bone-healing.

[Quad driving--life-endangering fun? A medical and technical analysis]

AIM

Quads or all-terrain vehicles do not seem to play a major role either in traffic accidents or in hospital admissions in Germany. However, reports about spectacular quad crashes in the press are not that infrequent. In contrast, no scientific survey or study regarding the issue of quad crashes in Germany has been published so far. Thus, this study aims to evaluate the present incidence of quad crashes, accident circumstances and resulting injury patterns, and to discuss possible consequences.

METHOD

At a level I trauma centre, data from accident and hospital records of quad drivers were analysed focusing on the following parameters: injury type, localisation and mechanism, treatment details, abbreviated injury scale (AIS) score, maximum AIS (MAIS) score, delta-v, collision speed, and other technical parameters. Comparisons to motorcycle accidents were performed. RESULT During a five-year period from 2005 to 2009, there were ten admissions of quad drivers out of around 11 000 emergency trauma patients (0.1 %). Five accidents had happened off-road, four were traffic accidents. Eight patients were male; the mean age was 30 years. The mean total hospital stay was 15 days; there was a mean of 1.5 stays per patients with 2.0 surgical procedures needed. One patient died, only two recovered fully. The accident research data bank revealed 14 cases of quad accidents out of 18 990 (0.1 %). The mean impact velocity was 35 km/h (motorcyclists 40.0 km/h). The most frequent injury mechanism was a collision with a car. The upper extremity was the predominant injured region (AIS 0.7), while it was the lower extremity for motorcyclists (AIS0.91). The maximum AIS were 1.4 in quad drivers and 1.49 in motorcyclists.

CONCLUSIONS

Although the absolute incidence of quad accidents in Germany is low, they pose a relatively high risk for severe injuries. Possible reasons are the comparatively low active and passive safety of quads as well as limited experience with quad driving and the "fun" aspect which might provoke risky driving behaviour. Larger series from the US report a high incidence of drug abuse among quad casualties as well as very limited use of helmets. In Germany, helmet usage has been mandatory since 2006. Possible additional measures to prevent a rise in quad accidents could be the total prohibition of alcohol consumption for quad drivers as well as special courses or driving licenses or an increase of the legal age for driving quads.

Jet-cooled vibronic spectroscopy and asymmetric torsional potentials of phenylcyclopentene

The ultraviolet spectroscopy of the S(1) <-- S(0) transition of 1-phenylcyclopentene (PCP) was studied by resonant-two-photon ionization (R2PI), laser-induced fluorescence (LIF) and single vibronic level fluorescence (SVLF). UV-UV hole-burning (UVHB) spectroscopy was used to determine that there is only one spectroscopically distinct conformer in the supersonic expansion. The excitation spectrum shows extensive vibronic structure extending to over 1000 cm(-1) above the electronic origin (34,646 cm(-1)). Much of the vibronic structure is similar to that of styrene and other singly substituted benzene derivatives, with Franck-Condon (FC) activity predominantly in substituent-sensitive benzene modes. Sizeable FC progressions were also found in the inter-ring torsion, reflecting a large displacement in the inter-ring angle upon electronic excitation. No evidence for FC activity in the ring-puckering coordinate is observed. The torsional potentials of the ground and excited states were determined from the experimental transition frequencies by fitting the calculated to the experimental torsional frequency spacings in an automated least-squares fitting procedure. The S(1) torsional potential is a symmetric single-well potential centered around a locally planar equilibrium geometry at a torsional angle of varphi = 0 degrees . The energy levels are reproduced by a cosine term potential function with torsional parameters V(2) = 3765 cm(-1) and V(4) = -183 cm(-1). The S(0) torsional potential possesses a twisted equilibrium geometry that is strongly asymmetric about varphi = 0 degrees due to the non-planarity of the cyclopentene ring. The best-fit potential parameters uses a sin/cos potential function (odd/even), with V = 948 cm(-1), V = -195 cm(-1), V = -162 cm(-1) and V = -268 cm(-1). The shape of the potentials are similar to those predicted by relaxed potential energy scans calculated at the DFT, CIS and TDDFT//CIS levels of theory. The change in the torsional angle varphi upon electronic excitation was determined to be approximately 15 degrees from fits of the displacement delta of the S(0) torsional potential with respect to the S(1) potential. The simulated shift of the S(0) potential with respect to the S(1) potential of approximately 15 degrees is in very good agreement with that obtained from B3LYP calculations.

[Injury situation of novice drivers in road traffic--a medical and technical analysis]

AIM

Novice drivers are at high risk for crash involvement. We performed an analysis of causations, injury patterns and distributions of novice drivers in cars and on motorcycles in road traffic as a basis for proper measurements.

METHOD

Data of accident and hospital records of novice drivers (licence < 2 years) were analysed focusing on the following parameters: injury type, localisation and mechanism, abbreviated injury scale (AIS), maximum AIS (MAIS), delta-v, collision speed and other technical parameters and compared with those of experienced drivers.

RESULTS

In 18 352 accidents in the area of Hannover (years 1985-2004), 2602 novice drivers and 18 214 experienced drivers were recorded as having an accident. Novice car drivers were more often and more severely injured whereas on motorcycles the experienced drivers were at higher risk. Novice drivers of both groups sustained more often extremity injuries. 4.5 % of the novice car drivers were not restrained by seatbelts as compared to 3.7 % of the experienced drivers and 6.1 % of the novice motorcycle drivers did not wear a proper helmet (versus 6.5 %). Severe injuries were sustained in 20 % at collision speeds below 30 km/h and in 80 % at collision speeds above 50 km/h. Novice car drivers drove significantly older cars. The risk profile of novice drivers is similar to that of drivers older than 65.

CONCLUSION

Structural protection and special lectures like skidding courses could be proper measurements next to harder punishment of violations.

How to prevent overlooking cervical spine injuries: pitfalls in spinal diagnostics

Many patients with a cervical spine injury do not show clinical signs of the injury. Therefore, cervical spine trauma may not be recognized, especially in unconscious and multiply injured patients. Due to proximity to the spinal cord, neurological deficits inclusive of complete tetraplegia are possible. Since cervical spine injuries are typically associated with injuries at other spinal levels, accurate knowledge of the trauma mechanism is essential. Even mild clinical symptoms need to be carefully evaluated in a standardized fashion with clinical and radiological examinations including plane X-rays and possibly CT scans.

[Tetanus vaccination in the accident and emergency department]

While tetanus is a rare disease in industrialized countries, this infectious disease is still responsible for up to 1,000,000 deaths per year in the developing world. In Germany, the introduction of a country-wide vaccination program (STIKO) has led to a decrease in the frequency of tetanus infection from 115 cases per year in the 1960s to fewer than 15 cases per year in the years from 1990 to 2000. In spite of all the treatment now available, tetanus infection still has a lethal outcome in up to 40% of cases. The Robert-Koch Institute recommends active or passive vaccination depending on the wound classification and the patient's current vaccination status. Since when patients have multiple trauma the emphasis while they are being treated for shock is on stabilisation and diagnosis, there is a real risk of underestimating the size and the level of contamination of existing wounds. Since it is not possible to ascertain the patient's vaccination status in most cases, we recommend simultaneous immunization of polytraumatized patients with skin lesions using Tetanol-Tetagam early in the course of the diagnostic procedures while the patients are still in the emergency room.

[Percutaneous cementing techniques of the spine -- chances and limits]

Vertebroplasty and Kyphoplasty represent minimal-invasive techniques for cement augmentation of vertebral bodies. Both procedures are successfully used for pain-relieving stabilizations of osteoporotic fractures or malignant processes. Advantages of kyphoplasty over vertebroplasty are to be seen in the possibility of deformity correction as well as in a decreased risk of cement extrusions which represent the most important potential for clinical complications. Long-term experiences with the effect of cementing are sparse. Thus it seems even more important, to judge indications and possibilities realistically. The decision whether and when to perform an augmentation is influenced by multiple factors. These include age of the patient, age of the fracture, degree of deformation and further degenerative changes of the spine. This article summarizes the present research and literature und is thought to provide guidelines for the aforementioned decision making processes.