M. Rauschmann

Functional morphology of the nasal complex in the Harbor Porpoise (Phocoena phocoena L.)

Toothed whales (Odontoceti, Cetacea) are the only aquatic mammals known to echolocate, and probably all of them are able to produce click sounds and to synthesize their echoes into a three‐dimensional “acoustic image” of their environment. In contrast to other mammals, toothed whales generate their vocalizations (i.e., echolocation clicks) by a pneumatically‐driven process in their nasal complex. This study is dedicated to a better understanding of sound generation and emission in toothed whales based on morphological documentation and bioacoustic interpretation. We present an extensive description of the nasal morphology including the nasal muscles in the harbor porpoise (Phocoena phocoena) using macroscopical dissections, computer‐assisted tomography, magnetic resonance imaging, and histological sections. In general, the morphological data presented here substantiate and extend the unified “phonic lips” hypothesis of sound generation in toothed whales suggested by Cranford et al. (J Morphol 1996;228:223–285). There are, however, some morphological peculiarities in the porpoise nasal complex which might help explain the typical polycyclic structure of the clicks emitted. We hypothesize that the tough connective tissue capsule (porpoise capsule) surrounding the sound generating apparatus is a structural prerequisite for the production of these high‐frequency clicks. The topography of the deep rostral nasal air sacs (anterior nasofrontal and premaxillary sacs), narrowing the potential acoustic pathway from the phonic lips to the melon (a large fat body in front of the nasal passage), and the surrounding musculature should be crucial factors in the formation of focused narrow‐banded sound beams in the harbor porpoise. Anat Rec, 292:902–920, 2009.

Begutachtung von Wirbelsäulenverletzungen

ZusammenfassungBeurteilung und Begutachtung anatomisch definierter Verletzungen der Wirbelsäule, von Wirbelkörperfrakturen und -luxationen, Bandscheibenzerreißungen oder Einblutungen in die Weichteile bereiten in der Regel keine Schwierigkeiten. Die verbleibende Beeinträchtigung geht dem Schadensausmaß parallel. Diskrepanzen zwischen Beschwerden des Probanden und den objektiven Untersuchungsbefunden können auf unfallfremde Faktoren zurückzuführen sein, seien es das Entschädigungsverfahren selbst oder andere psychische oder psychosoziale Faktoren. Im Aufsatz werden die Grundlagen der Begutachtung von Wirbelsäulenverletzungen erläutert und praktische Hinweise zum Aufbau eines Gutachtens gegeben. Besonderes Gewicht wird dabei der Zusammenhangsbegutachtung eingeräumt. Der Beitrag enthält Hinweise zur Einschätzung struktureller Wirbelsäulenverletzungen, die auf Bewertungskriterien beruhen, die sich in den letzten Jahrzehnten als verbindlich herausgebildet haben.AbstractAppraisals and expert opinions of clearly identified injuries of the spine, ranging from fractures and dislocations to intervertebral disc ruptures and haemorrhage into soft tissue are generally unproblematic. The residual functional deficit is commensurate with the extent of damage. However, differences between the patient’s symptoms and objective findings can be unrelated to the injury, and are often explained by the actual compensation process or other psychological/psychosocial factors. The current article discusses a basis for providing expert medical opinions, as well as a number of practical tips on the German medical insurance system. Particular attention is paid to expert opinions on causality. The article also includes information on the evaluation of structural injuries to the spine on the basis of assessment criteria that have proven to be reliable and authoritative in recent decades.Appraisals and expert opinions of clearly identified injuries of the spine, ranging from fractures and dislocations to intervertebral disc ruptures and haemorrhage into soft tissue are generally unproblematic. The residual functional deficit is commensurate with the extent of damage. However, differences between the patients symptoms and objective findings can be unrelated to the injury, and are often explained by the actual compensation process or other psychological/psychosocial factors. The current article discusses a basis for providing expert medical opinions, as well as a number of practical tips on the German medical insurance system. Particular attention is paid to expert opinions on causality. The article also includes information on the evaluation of structural injuries to the spine on the basis of assessment criteria that have proven to be reliable and authoritative in recent decades.

PMMA‐hydroxyapatite composite material retards fatigue failure of augmented bone compared to augmentation with plain PMMA: In vivo study using a sheep model

Polymethylmethacrylate (PMMA) is the most commonly used void filler for augmentation of osteoporotic vertebral fracture, but the differing mechanical features of PMMA and osteoporotic bone result in overload and failure of adjacent bone. The aim of this study was to compare fatigue failure of bone after augmentation with PMMA-nanocrystalline hydroxyapatite (HA) composite material or with plain PMMA in a sheep model. After characterization of the mechanical properties of a composite material consisting of PMMA and defined amounts (10, 20, and 30% volume fraction) of HA, the composite material with 30% volume fraction HA was implanted in one distal femur of sheep; plain PMMA was implanted in the other femur. Native non-augmented bone served as control. Three and 6 months after implantation, the augmented bone samples were exposed to cyclic loading and the evolution of damage was investigated. The fatigue life was highest for the ovine native bone and lowest for bone-PMMA specimens. Bone-composite specimens showed significantly higher fatigue life than the respective bone-PMMA specimens in both 3- and 6-month follow-up groups. These results suggest that modification of mechanical properties of PMMA by addition of HA to approximate those of cancellous bone retards fatigue failure of the surrounding bone compared to augmented bone with plain PMMA.

Insertion of the artificial disc replacement: a cadaver study comparing the conventional surgical technique and the use of a navigation system.

Study Design. Comparison of total disc replacement (TDR) with and without computer-assisted surgical navigation. Objective. To test and evaluate the accuracy of computer-assisted navigation for the lumbar spine by comparing the traditional C-arm-aided insertion of an arthroplasty device to the navigation-aided insertion of the implant. Summary of Background Data. Previous studies have shown that poor placement of the CHARITÉ disc can be correlated to worse clinical results. Because of parallax effect, exclusive use of fluoroscopy could make placement of the artificial disc less accurate. False positioning may also lead to spondylolisthesis, disc degeneration of the adjacent segment, subsidence of the disc, and failure of the implant. Methods. Ten human cadaver spine specimens were used at 3 lumbar segments (L3–L4, L4–L5, and L5–S1). Before implantation, all artificial discs were planned for “ideal” placement on a digital computed tomography image. Fifteen lumbar intervertebral disc prostheses (Depuy, Raynham, MA) were placed using Vector Vision image guidance (BrainLAB AG, Munich, Germany), by an inexperienced TDR-surgeon. Fifteen lumbar intervertebral disc prostheses were placed with exclusive use of fluoroscopy by an experienced TDR-surgeon. After insertion, DICOM computed tomography scans were analyzed using computer software to assess placement accuracy of each disc prosthesis. Results. The navigated placement of the disc was significantly more accurate. Only 3 navigated disc prostheses were suboptimal and none was poorly placed. Conclusion. Surgical computer-assisted navigation may be a useful tool in the hands of a spine surgeon to achieve more accurate placement of the disc prosthesis. Because of the parallax effect, computer-assisted navigation offers more placement accuracy than stan- dard fluoroscopy. Because the accurate placement of total disc prosthesis has been correlated with better clinical outcome, further study regarding the navigation of the TDR is essential.

Minimizing the surgical approach in patients with spondylitis.

Minimizing the surgical approach in treating patients with spinal infections by using local antibiotic treatment and avoiding a ventral approach reduces the anesthesia and surgical risks in patients with comorbidities. In this study we used calcium sulphate pellets (OsteoSet® T and the OsteoSet® Bone-void Filler kit®) as a delivery system for different antibiotics. Of a group of 32 patients with histologically and microbiologically diagnosed spondylitis, a cohort of 16 patients was treated by just a dorsal surgical approach in combination with a local antibiotic delivery system. Of these 16 patients, 14 patients showed a normalization of the infection parameters, no more bone loss in the spondylitic region, and a bony fusion after 6 to 9 months postoperatively. Two patients died from septic circumstances 4 and 6 weeks postoperatively. Two patients had to have one revision surgery because of a seroma; no other complications caused by the calcium sulphate pellets were observed. The use of calcium sulphate pellets as antibiotic delivery system allows a controlled local antibiotic therapy with an osteoconductive material in combination with a minimized surgical approach. Furthermore, calcium sulphate pellets have proven their reliable capability as bone void filler. Level of Evidence: Therapeutic study, Level IV-1 (case series). See the Guidelines for Authors for a complete description of levels of evidence.

Verbesserung des Operationsoutcomes in der Wirbelsäulenchirurgie

OBJECTIVES Because international data have a low level of evidence, a variety of treatment approaches for lumbar spine fusion operations are justified based on long-established or safety aspects. The aim of this work is to present an overview of evidence-based peri- and intraoperative treatment measures to shorten the recovery and increase patient satisfaction. MATERIALS AND METHODS This review article is based on a selective literature search that also included PubMed on peri- and intraoperative treatment measures for lumbar spinal surgery. RESULTS AND DISCUSSION Peri- and intraoperative treatment algorithms have a significant influence on postoperative recovery and patient outcome after lumbar spinal surgery. Recent studies show that intraoperative blood loss and blood transfusion can be significantly reduced by optimizing patient positioning and dorsoventral combined warming measures to maintain body temperature. These measures are supplemented by the use of local infiltration of anesthesia and vasoconstrictive drugs at the start and high-dose administration of tranexamic acid in the early stages of the operation. Use of an epidural catheter significantly reduces postoperative, systemic analgesia use and allows rapid mobilization to be initiated. Immobilizing drain and corset treatments can be limited to complex cases. These treatment measures promote patient satisfaction, lead to high-quality, evidence-based care, and contribute to a shorter hospital stay and convalescence of the patient.

Effect of lumbar disc replacement on the height of the disc space and the geometry of the facet joints

In a study on ten fresh human cadavers we examined the change in the height of the intervertebral disc space, the angle of lordosis and the geometry of the facet joints after insertion of intervertebral total disc replacements. SB III Charité prostheses were inserted at L3-4, L4-5, and L5-S1. The changes studied were measured using computer navigation software applied to CT scans before and after instrumentation. After disc replacement the mean lumbar disc height was doubled (p < 0.001). The mean angle of lordosis and the facet joint space increased by a statistically significant extent (p < 0.005 and p = 0.006, respectively). By contrast, the mean facet joint overlap was significantly reduced (p < 0.001). Our study indicates that the increase in the intervertebral disc height after disc replacement changes the geometry at the facet joints. This may have clinical relevance.

Von der „railway spine“ zum Schleudertrauma — Geschichte und aktuelle Bedeutung seelischer Störungen nach entschädigungspflichtigen Ereignissen

ZusammenfassungSeelische Störungen nach Unfallereignissen spielen für die Versicherungswirtschaft eine wesentliche Rolle. Die Ausgaben hierfür sind in den letzten Jahrzehnten kontinuierlich gestiegen. Als Schlüsselbegriff ist die posttraumatische Belastungsstörung anzusehen. Diese Bezeichnung wurde erst innerhalb der letzten zwei Jahrzehnte in die internationalen diagnostischen Manuale aufgenommen, obwohl psychische Reaktionen nach Unfallereignissen seit mehr als 100 Jahren beschrieben werden. Im vorliegenden Aufsatz werden die seelischen Störungen nach Unfällen im jeweiligen historischen Kontext untersucht. Berücksichtigt werden unter anderem die Folgen von Eisenbahnunfällen im 19 Jahrhundert („railway spine“), Haftpflichtunfälle, die gesetzliche und private Unfallversicherung sowie die psychologischen Folgen derjenigen Katastrophen, die das 20. Jahrhundert kennzeichneten, den 1. Weltkrieg, die nationalsozialistische Herrschaft, die Verfolgung politischer Gegner und den 2. Weltkrieg mit seinen Folgen. Abschließend wird näher auf das Schleudertrauma eingegangen. Die Untersuchung zeigt, dass es sich bei den verschiedenen Störungen nicht um eine einheitliche Krankheitsentität handelt. Seelische Reaktionen nach Unfällen werden nur zu einem geringeren Teil durch das Ereignis an sich verständlich, wesentlicher sind der geschichtliche und soziale Hintergrund und die Tatsache des Versichertseins.AbstractAlthough post traumatic stress disorder was only recently admitted into the international classification systems, psychological reactions to traumatic incidents have been frequently described for far more than 100 years. The article describes the mental reactions to a trauma in different historical situations. Included are the „railway spine“ injuries of the 19. century, victims of accidents where third party liability could be claimed and the psychological consequences of the catastrophes which characterized the 20. century; World War One, the rule of National Socialism, World War Two, the expulsion and persecution of political opponents. In the last part the article deals with the whiplash injury. The analysis suggests that different reactions don’t describe an identical disorder. It seems that reactions to injuries are mainly influenced by the historical and social background and the fact of being insured.

Cement distribution in vertebroplasty pedicle screws with different designs

ZusammenfassungDie Auswirkungen der verminderten Knochendichte machen sich im Falle einer Spondylodese besonders bemerkbar. Zur besseren Fixierung der Schrauben im Knochen wurde die Zementaugmentation zum Gegenstand vieler Studien, die die biomechanische Überlegenheit und den erhöhten Auszugswiderstand der zementaugmentierten Schrauben nachgewiesen haben. Aufgrund inadäquater, aber auch gefährlicher Zementverteilungen im Wirbelkörper, bestand die Notwendigkeit zur Entwicklung alternativer Applikationsformen im Vergleich zu der konventionellen Technik. Pedikelschrauben mit seitlichen Öffnungen und einem zentralen Bohrloch wurden eigens für diese Anwendung entwickelt. Diese neuen Schrauben erlauben eine gute Zementaugmentation und vergrößern den Schraubendurchmesser, aber auch die Oberflächenkohäsion zwischen den drei Komponenten (Schraube-Zement-Knochen). Die Zementverteilung kann durch die Auswahl der seitlichen Öffnungen (Größe und Lage) entsprechend beeinflusst werden. Schrauben mit konisch zulaufendem Kerndurchmesser und distal gelegenen weiten Öffnungen führen zur Entstehung einer uniformen Zementwolke.AbstractThe effects of deteriorated bone density become particularly apparent in cases where spinal instrumentation is needed. Cement augmentation of pedicle screws for better bone purchase became the subject of many studies, which proved the biomechanical superiority and the increased pullout strength of cement augmented screws. Inadequate, and sometimes dangerous, cement distribution made the need for development of special implants inevitable. Pedicle screws with side openings and a central drill hole allow cement augmentation through the implant and increase not only the screw diameter but also the interfacial strength between the three components (screw-cement-bone). Accordingly cement distribution can be affected by the selection of the side openings (size and position). Screws with conical core and distally situated side openings facilitate the development of uniform cement dough.The effects of deteriorated bone density become particularly apparent in cases where spinal instrumentation is needed. Cement augmentation of pedicle screws for better bone purchase became the subject of many studies, which proved the biomechanical superiority and the increased pullout strength of cement augmented screws. Inadequate, and sometimes dangerous, cement distribution made the need for development of special implants inevitable. Pedicle screws with side openings and a central drill hole allow cement augmentation through the implant and increase not only the screw diameter but also the interfacial strength between the three components (screw-cement-bone). Accordingly cement distribution can be affected by the selection of the side openings (size and position). Screws with conical core and distally situated side openings facilitate the development of uniform cement dough.

Zementverteilung bei Vertebroplastieschrauben unterschiedlichen Designs

ZusammenfassungDie Auswirkungen der verminderten Knochendichte machen sich im Falle einer Spondylodese besonders bemerkbar. Zur besseren Fixierung der Schrauben im Knochen wurde die Zementaugmentation zum Gegenstand vieler Studien, die die biomechanische Überlegenheit und den erhöhten Auszugswiderstand der zementaugmentierten Schrauben nachgewiesen haben. Aufgrund inadäquater, aber auch gefährlicher Zementverteilungen im Wirbelkörper, bestand die Notwendigkeit zur Entwicklung alternativer Applikationsformen im Vergleich zu der konventionellen Technik. Pedikelschrauben mit seitlichen Öffnungen und einem zentralen Bohrloch wurden eigens für diese Anwendung entwickelt. Diese neuen Schrauben erlauben eine gute Zementaugmentation und vergrößern den Schraubendurchmesser, aber auch die Oberflächenkohäsion zwischen den drei Komponenten (Schraube-Zement-Knochen). Die Zementverteilung kann durch die Auswahl der seitlichen Öffnungen (Größe und Lage) entsprechend beeinflusst werden. Schrauben mit konisch zulaufendem Kerndurchmesser und distal gelegenen weiten Öffnungen führen zur Entstehung einer uniformen Zementwolke.AbstractThe effects of deteriorated bone density become particularly apparent in cases where spinal instrumentation is needed. Cement augmentation of pedicle screws for better bone purchase became the subject of many studies, which proved the biomechanical superiority and the increased pullout strength of cement augmented screws. Inadequate, and sometimes dangerous, cement distribution made the need for development of special implants inevitable. Pedicle screws with side openings and a central drill hole allow cement augmentation through the implant and increase not only the screw diameter but also the interfacial strength between the three components (screw-cement-bone). Accordingly cement distribution can be affected by the selection of the side openings (size and position). Screws with conical core and distally situated side openings facilitate the development of uniform cement dough.The effects of deteriorated bone density become particularly apparent in cases where spinal instrumentation is needed. Cement augmentation of pedicle screws for better bone purchase became the subject of many studies, which proved the biomechanical superiority and the increased pullout strength of cement augmented screws. Inadequate, and sometimes dangerous, cement distribution made the need for development of special implants inevitable. Pedicle screws with side openings and a central drill hole allow cement augmentation through the implant and increase not only the screw diameter but also the interfacial strength between the three components (screw-cement-bone). Accordingly cement distribution can be affected by the selection of the side openings (size and position). Screws with conical core and distally situated side openings facilitate the development of uniform cement dough.