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Recent findings revealed a correlation between vertebral bone quality based on T1-weighted (VBQThe aims of the study were to confirm the correlation between VBQThis was a retrospective cross-sectional study.The sample consisted of patients older than 18 years, who received treatment at a level-one university spine center of the German Spine Society for degenerative or traumatic reasons in 2017-2021.The outcome measures were the correlation of VBQs from different MRI sequences with vBMD and the association of VBQs with osteopenia/osteoporosis.Patients' VBQ was calculated based on the signal intensities of the vertebral bodies L1-4 in T1-, T2-, and STIR-weighted MRI. The VBQ was standardized according to the signal intensity of the cerebrospinal fluid. The vBMD was determined using data from a calibrated scanner (SOMATOM Definition AS+) and processed with CliniQCT (Mindways Software, Inc., USA). Groups were divided according to vBMD into the following groups: (I) osteoporosis/osteopenia (120 mg/mWe included 136 patients (women: 56.6%) in the study (69.7 ± 15.0 years). According to vBMD, 108 patients (79.4%) had osteoporosis/osteopenia. Women were affected significantly more often than men (p = .045) and had significantly higher VBQThis study confirms a significant correlation between VBQ

Higher levels of automated driving may offer the possibility to sleep in the driver’s seat in the car, and it is foreseeable that drivers will voluntarily or involuntarily fall asleep when they do not need to drive. Post-sleep performance impairments due to sleep inertia, a brief period of impaired cognitive performance after waking up, is a potential safety issue when drivers need to take over and drive manually. The present study assessed whether sleep inertia has an effect on driving and cognitive performance after different sleep durations. A driving simulator study with n = 13 participants was conducted. Driving and cognitive performance were analyzed after waking up from a 10–20 min sleep, a 30–60 min sleep, and after resting without sleep. The study’s results indicate that a short sleep duration does not reliably prevent sleep inertia. After the 10–20 min sleep, cognitive performance upon waking up was decreased, but the sleep inertia impairment faded within 15 min. Although the driving parameters showed no significant difference between the conditions, participants subjectively felt more tired after both sleep durations compared to resting. The small sample size of 13 participants, tested in a within-design, may have prevented medium and small effects from becoming significant. In our study, take-over was offered without time pressure, and take-over times ranged from 3.15 min to 4.09 min after the alarm bell, with a mean value of 3.56 min in both sleeping conditions. The results suggest that daytime naps without previous sleep deprivation result in mild and short-term impairments. Further research is recommended to understand the severity of impairments caused by different intensities of sleep inertia.

Background: Osteoporosis causes an increased fracture risk. Clinically, osteoporosis is diagnosed late, usually after the first fracture occurs. This emphasizes the need for an early diagnosis of osteoporosis. However, computed tomography (CT) as routinely used for polytrauma scans cannot be used in the form of quantitative computed tomography (QCT) diagnosis because QCT can only be applied natively, i.e., without any contrast agent application. Here, we tested whether and how contrast agent application could be used for bone densitometry measurements. Methods: Bone mineral density (BMD) was determined by QCT in the spine region of patients with and without the contrast agent Imeron 350. Corresponding scans were performed in the hip region to evaluate possible location-specific differences. Results: Measurements with and without contrast agent administration between spine and hip bones indicate that the corresponding BMD values were reproducibly different between spine and hips, indicating that Imeron 350 application has a location-specific effect. We determined location-specific conversion factors that allow us then to determine the BMD values relevant for osteoporosis diagnosis. Conclusions: Results show that contrast administration cannot be used directly for CT diagnostics because the agent significantly alters BMD values. However, location-specific conversion factors can be established, which are likely to depend on additional parameters such as the weight and corresponding BMI of the patient.

Background Cage implantations and autologous pelvic bone grafts are common surgical procedures to fuse the spine in cases of spinal disorders such as traumatic fractures or degenerative diseases. These surgical methods are designed to stably readjust the spine and to prevent late detrimental effects such as pain or increasing kyphosis. Benefits of these surgical interventions have been evaluated, but the long-term well-being of patients after the respective treatments has not yet been examined. This study was designed to evaluate the clinical outcome for patients who received iliac crest or cage implantations. Material and Methods Forty-six patients with traumatic fractures after they obtained an anterior fusion in the thoracic or lumbar spine (12 cages; mean age: 54.08 years; 34 pelvic bone grafts; mean age: 42.18 years) were asked to participate in the survey using a precast questionnaire according the Visual Analog Scale (VAS) Spine Score. Twenty-nine of them provided the data requested. Results Evaluation of the VAS scores of the patients, reporting at least 1 year after the surgery, revealed that cage implantations led to significantly better results with respect to all aspects of their daily life such as pain sensing, capability to undertake physical activities and exercise as compared with patients with autologous pelvic bone graft. Patients with autologous pelvic bone graft treatment reported a particularly poor overall satisfaction level concerning their long-term well-being. Conclusions Patients with cage implantation reported a higher degree of long-term well-being. The data provide evidence for a positive impact on the postsurgery quality of life after cage implantation.

Study Design clinical study. Objectives Loosening of pedicle screws is a frequent complication in patients with osteoporosis. The indication for additional stabilization, such as cement augmentation, is more often based on the subjective intraoperative feeling of the surgeon than on a preoperative bone mineral density (BMD) measurement. Aim was to evaluate the correlation of the intraoperative perceived bone quality in comparison to the objectively measured BMD. Methods A total of 62 patients undergoing dorsal stabilization using pedicle screws at a level-1 trauma center were analyzed. The preoperative CT scan measured each instrumented vertebra's pedicle size and BMD. During the surgery, the perceived screw stability was graded by the respective surgeon for each screw. Results 204 vertebral bodies were evaluated. Looking at all implanted screws a significant correlation between the measured BMD and the perceived screw stability was found (Resident r = .450; R2 = .202; P < .001/Attending r = .364; R2 = .133; P < .001), but there was no significant correlation in the osteoporotic patients (Resident P = .148 / Attending P = .907). The evaluation of the screws implanted in osteoporotic vertebrae showed that the surgeons considered a total of 31% of these screws to be sufficiently stable. Conclusions There was no significant correlation between the measured BMD and the perceived pedicle screw stability in the group with osteopenic / osteoporotic bone (

Navigation systems are supposed to increase precision and support surgeons while they perform certain interventions. 2D, or nowadays 3D, systems are used in image-based approaches. Image-free navigation uses 3D printing.There are several studies on navigation procedures in trauma surgery. In contrast to limb surgery, the use of 3D navigation in pelvic and spine surgery is already well established. Navigation is especially regularly used to treat fractures of the posterior pelvic ring and for posterior stabilization of the cervical spine.To be able to utilize navigation systems optimally, the learning curve should be completed, and the technique should be used regularly. In addition, the surgeon should know the surgical technique without navigation in order to recognize potential errors of the navigation.Advantages include increased patient safety, reduction in radiation exposure and less invasive surgical procedures. However, among other disadvantages, initial costs are high.HINTERGRUND: Navigationssysteme sollen die Präzision erhöhen und den Operateur bei der Durchführung bestimmter Eingriffe unterstützen. Unterschieden werden eine bildbasierte und eine bildfreie Navigation. Bildbasierte Verfahren beruhen auf 2‑D- bzw. heutzutage meist auf 3‑D-Systemen. Bei der bildfreien Navigation wird u. a. der 3‑D-Druck eingesetzt.In der Literatur existieren zahlreiche Studien zu Navigationsverfahren in der Unfallchirurgie. Während sich die Navigation in der Extremitätenchirurgie nicht durchsetzen konnte, ist der Einsatz der 3‑D-Navigation in der Becken- und Wirbelsäulenchirurgie etabliert. Vor allem bei Frakturen des hinteren Beckenringes (SI-Verschraubung) und bei dorsalen Stabilisierungsoperationen der Halswirbelsäule wird die Navigation regelmäßig angewendet.Um die Navigation optimal einsetzen zu können, sollte die Lernkurve abgeschlossen sein und die Technik regelmäßig angewendet werden. Zudem sollte der Chirurg die Operationstechnik sicher in konventioneller Technik beherrschen, um potenzielle Fehler der Navigation zu erkennen.Vorteile sind neben der erhöhten Patientensicherheit, die reduzierte Strahlenbelastung sowie eine geringere Invasivität chirurgischer Eingriffe. Als Nachteile sind unter ökonomischen Gesichtspunkten u. a. die hohen Anschaffungskosten anzuführen.

Purpose In spinal surgery, surgical site infections (SSI) after dorsal spondylodesis lead to severe short- and long-term complications. Despite various clinical and serological evidence, the detection of a postoperative SSI remains crucial. In this retrospective cohort study, we determined the prognostic value of C-reactive protein (CRP) kinetics after open reduction and dorsal spondylodesis in the development of a SSI. Methods We retrospectively analyzed 192 patients from 2016 to 2018 undergoing open reduction and dorsal spondylodesis with and without SSI for 20 days at a level-I trauma center and assessed their serological and clinical characteristics. Results On day 7 and 8 after surgery, patients who developed a SSI displayed significantly higher CRP levels. A second peak after the initial maximum of CRP and a restricted failure to decline as well as a maximum CRP of more than 225 mg/l predict an infectious complication with a sensitivity of 92.9%, and a specificity of 78.2%. A binary logistic regression leads to 85.7% and 69.7%, respectively. A one-phase decay exponential regression can predict 75.6% of the variance after the initial peak of CRP. Conclusion Our study demonstrates a high value of postoperative CRP kinetics in SSI detection after dorsal spondylodesis. Moreover, we observed typical CRP levels with a specific course as indicative predictors that may facilitate an early SSI detection in clinical practice.

Purpose Inadequate anchoring of pedicle screws in vertebrae with poor bone quality is a major problem in spine surgery. The aim was to evaluate whether a modified thread in the area of the pedicle could significantly improve the pedicle screw fatigue strength. Methods Fourteen human cadaveric vertebral bodies (L2 and L3) were used for in vitro testing. Bone density (BMD) was determined by quantitative computed tomography. Vertebral bodies were instrumented by standard pedicle screws with a constant double thread on the right pedicle and a partial doubling of the threads–quad thread–(cortical thread) in the area of the pedicle on the left pedicle. Pulsating sinusoidal, cyclic load (0.5 Hz) with increasing peak force (100 N + 0.1 N/cycles) was applied orthogonal to the screw axis. The baseline force remained constant (50 N). Fatigue test was terminated after exceeding 5.4-mm head displacement (~ 20° screw tilting). Results The mean fatigue load at failure was 264.9 N (1682 cycles) for the standard screws and was increased significantly to 324.7 N (2285 cycles) by the use of cortical threaded screws (p = 0.014). This effect is particularly evident in reduced BMD (standard thread 241.2 N vs. cortical thread 328.4 N; p = 0.016), whereas in the group of vertebrae with normal BMD no significant difference could be detected (standard thread 296.5 N vs. cortical thread 319.8 N; p = 0.463). Conclusions Compared to a conventional pedicle screw, the use of a cortical threaded pedicle screw promises superior fatigue load in vertebrae with reduced bone quality.

Study Design: Biomechanical study. Objectives: Failure of pedicle screws is a major problem in spinal surgery not only postoperatively, but also intraoperatively. The aim of this study was to evaluate whether cement augmentation may restore mounting of initially loosened pedicle screws. Methods: A total of 14 osteoporotic or osteopenic human cadaveric vertebral bodies (L2)—according to quantitative computed tomography (QCT)—were instrumented on both sides by conventional pedicle screws and cement augmented on 1 side. In vitro fatigue loading (cranial-caudal sinusoidal, 0.5 Hz) with increasing peak force (100 N + 0.1 N/cycles) was applied until a screw head displacement of 5.4 mm (∼20°) was reached. After loosening, the nonaugmented screw was rescue augmented, and fatigue testing was repeated. Results: The fatigue load reached 207.3 N for the nonaugmented screws and was significantly ( P = .009) exceeded because of initial cement augmentation (300.6 N). The rescue augmentation after screw loosening showed a fatigue load of 370.1 N which was significantly higher ( P < .001) compared with the nonaugmented screws. The impact of bone density on fatigue strength decreased from the nonaugmented to the augmented to the rescue-augmented screws and shows the greatest effect of cement augmentation on fatigue strength at low bone density. Conclusions: Rescue augmentation leads to similar or higher fatigue strengths compared with those of the initially augmented screws. Therefore, the cement augmentation of initially loosened pedicle screws is a promising option to restore adequate screw stability.

Information about kinematics in different functional spinal units before and after total disc arthroplasties is necessary to improve prostheses and determine indications. There is little information about the nonstationary instantaneous helical axis of rotation under lateral bending in the cervical spine before and after total disc arthroplasty.Kinematic analyses were performed with an established measuring apparatus on 8 human functional spinal units (C3/C4, C5/C6) under intact conditions and after total disc arthroplasty with two different types of prostheses: Bryan and Prestige. The instantaneous helical axis, migration, and stiffness of the segments were calculated.The instantaneous helical axis direction was always inclined ventrally. Ventral inclination was significantly higher in segment C3/C4 than in segment C5/C6 under all conditions (p 0.001). Both types of arthroplasties significantly increased ventral inclination compared to intact conditions. In both segments, the path length of the instantaneous helical axis' migration was significantly longer after total disc arthroplasty with Bryan (p = 0.001) and shorter after Prestige (p 0.001) prostheses than under intact conditions. After both types of arthroplasties, the migration path length was significantly longer and the stiffness was significantly lower in segment C3/C4 than in segment C5/C6.Both types of arthroplasties changed the kinematics of both segments during lateral bending. Altered instantaneous helical axis migration, greater ventral inclination and less stiffness after both arthroplasties indicate unphysiological motion. Both arthroplasties had greater impact on segment C3/C4 than on segment C5/C6 in terms of hypermobility. Increased translational motion after total disc arthroplasty with a Bryan prosthesis might be caused by the prosthetic design.

Die additive Fertigung schafft neue Gestaltungsfreiheiten. Im Rahmen des Prototypenbaus und der Kleinserienproduktion kann das Verfahren des selektiven Laserschmelzens genutzt werden. Die Verwendung in der Serienproduktion ist bisher aufgrund unzureichender Bauteilqualität, langen Anlaufzeiten sowie mangelnder Automatisierung nicht im wirtschaftlichen Rahmen möglich. Das Projekt „ReAddi“ möchte eine erste prototypische Serienfertigung entwickeln, mit der additiv gefertigte Bauteile für die Automobilindustrie wirtschaftlich produziert werden können. Additive manufacturing (AM) offers new freedom of design. The selective laser-powderbed fusion (L-PBF) process can be used for prototyping and small series production. So far, it has not been economical to use it on a production scale due to insufficient component quality, long start-up times and a lack of automation. The project ReAddi aims to develop a first prototype series production to cost-effectively manufacture 3D-printed components for the automotive industry.

Zusammenfassung Das selektive Laserstrahlschmelzen (LBM) steht aktuell an der Schwelle zum Einsatz für Kleinserien. Ein wesentlicher Nachteil des Verfahrens ist aktuell noch die geringe Reproduzierbarkeit der Prozessqualität. Einige aktuelle Forschungsarbeiten konzentrieren sich deshalb auf die Integration optischer Messtechnik zur Prozessüberwachung. Neben den optischen Verfahren zeigen erste Untersuchungen, dass auch akustische Sensoren zur Prozessüberwachung ein vielversprechender Ansatz sind. Eine große Herausforderung bei den akustischen Daten stellt die Datenverarbeitung dar, da das akustische Rohsignal nur schwer zu interpretieren ist. In dieser Arbeit wird ein neues Konzept für ein akustisches Prozessüberwachungssystem vorgestellt und in eine Versuchsumgebung integriert. Zum Aufzeichnen akustischer Signale werden in einem Design of Experiments Prozessparameter gezielt variiert und Testkörper verschiedener Bauteilqualität aufgebaut. Für einen ersten Nachweis der Eignung des Messsystems zur Überwachung des Prozesses wird ein künstliches neuronales Netz trainiert, um die verwendeten Prozessparameter (drei Laserleistungen) zu bewerten. Damit kann gezeigt werden, dass diese Messtechnik das Potential hat, den Prozess zu überwachen.

Biomechanical studies of the pelvis are usually performed using dissected pelvic specimens or synthetic bones. Thereby the stabilising effect of the surrounding soft tissues is analysed insufficiently. Biomechanical data for isolated anterior pelvic ring fractures are currently missing. Therefore, the purpose of this study was to develop a novel testing device for biomechanical analyses of the pelvis and to investigate two different anterior pelvic ring fractures in a cadaveric model with intact peripelvic soft tissues. A new biomechanical table construction which enables the fixation and testing of complete cadaveric specimens was developed. It was used to investigate the relative motion and stiffness changes due to unilateral osteotomy of the superior and inferior pubic ramus. Five cadavers with a mean age of 55.6 years (± 15.53 years) were included and loaded with a sinusoidal, cyclic (1 Hz), compressive force of up to 365 N over ten cycles for each condition. Biomechanical testing of the pelvis with complete appended soft tissues was feasible. Native stiffness without a pelvic fracture was 64.31 N/mm (± 8.33 N/mm). A standardised unilateral osteotomy of the superior pubic ramus reduced the stiffness under isolated axial load by 2% (63.05 N/mm ± 7.45 N/mm, p = 0.690). Additional osteotomy of the inferior pubic ramus caused a further, statistically not significant, decrease by 5% (59.57 N/mm ± 6.84 N/mm, p = 0.310). The developed test device was successfully used for biomechanical analyses of the pelvis with intact peripelvic soft tissues. In a first study, isolated unilateral fractures of the anterior pelvic ring showed no relevant biomechanical variation compared to the intact situation under isolated axial load. Only 7% of the measured stiffness was created by both unilateral pubic rami. Therefore, the clinical practice to treat unilateral anterior pelvic ring fractures conservatively is supported by the results of this study.

Stabilisation des atlantoaxialen Ubergangs durch eine alternative Schraubenposition im Halswirbelkorper 1 (HWK 1). Instabilitaten von HWK 1/HWK 2 durch Entzundung, Tumor oder Trauma. Vorhandensein sehr kleiner Pedikel von HWK 1. Varianten des Verlaufs der Arteria vertebralis. Uber den klassischen Mittellinienzugang zur oberen HWS erfolgt die modifizierte Instrumentation von HWK 1 mit Pedikelschrauben anstelle der klassischen Harms-Massa-lateralis-Schrauben bei unveranderter Instrumentation von HWK 2. Anschliesend erfolgt – je nach Indikation – die dorsale Spondylodese durch Eroffnung der Laminae und Anlagerung von keramischem Knochenersatzmaterial. Bei mobilen Patienten erfolgt die zusatzliche Ruhigstellung in der weichen Halskravatte fur 6 Wochen; die volle Belastbarkeit ist wieder nach 3–4 Monaten gegeben. Im Zeitraum von Januar 2017 bis September 2018 erfolgten in der Klinik der Autoren 21 Stabilisationen des atlantoaxialen Ubergangs. Das mittlere Alter betrug 72,52 ± 15,45 Jahre. Insgesamt wurden 42 Schrauben in HWK 1 gesetzt. Eine HWK‑1-Pedikelschraube konnte 21-mal (50 %) platziert werden. In den anderen 21 Fallen erfolgte die Instrumentation mit einer klassischen Harms-Massa-lateralis-Schraube. Komplikationen zeigten sich bei 3 Patienten. Insgesamt erscheint bei Beachtung der Kontraindikationen die Instrumentation von HWK 1 mit Pedikelschrauben als eine sichere Alternative zur Instrumentation mit Harms-Schrauben.

Revision von intraoperativ ausgerissenen Pedikelschrauben. Intraoperativ gelockerte/ausgerissene Pedikelschrauben. Keine. Entfernung der gelockerten/ausgerissenen Pedikelschraube. Austasten des Schraubenkanals und Reimplantation unter Verwendung einer anderen Trajektorie, eines groseren Schraubendurchmessers oder einer zementaugmentierten Pedikelschraube. Fruhfunktionelle Mobilisation und ggf. Einleitung einer Osteoporosetherapie. In einer biomechanischen Studie an humanen Kadaverwirbelkorpern erfolgte ein Dauerbelastungstest mit augmentierten sowie nichtaugmentierten Pedikelschrauben. Nach eingetretener Lockerung wurden eine nachtragliche Augmentation der gelockerten, nichtaugmentierten Schrauben und ein erneuter Dauerbelastungstest durchgefuhrt. Sowohl die initiale (p = 0,009) als auch die Augmentation nach Lockerung (p = 0,001) zeigten einen signifikanten Anstieg der Versagenslast verglichen mit den nichtaugmentierten Pedikelschrauben. In unserem eigenen Patientenkollektiv aus dem Zeitraum April 2016 bis August 2018 zeigte sich bei 11 von 542 mit Pedikelschrauben versorgten Patienten eine intraoperative Schraubenlockerung. Diese wurde in 6 Fallen mit einer nachtraglichen Augmentation und in 5 Fallen mit einem dickeren Schraubendurchmesser revidiert. In der postoperativen Kontrolle nach 6 Wochen zeigte sich keine dieser Schrauben erneut gelockert.

Operative Stabilisation osteoporotischer Wirbelkorperfrakturen. Osteoporotische Frakturen der Brust- und Lendenwirbelsaule. Keine. Praoperative Detektion der zu erwartenden Knochendichte. Einbringen von Pedikelschrauben in speziellen Trajektorien, Augmentation des Schraubenlagers und Verwendung alternativer Implantate. Fruhfunktionelle, orthograde Mobilisation und ggf. Einleitung einer Osteoporosetherapie. In einer biomechanischen Studie an humanen Kadaverwirbelkorpern konnte eine hochsignifikante Korrelation von Knochendichte und Pedikelschraubenstabilitat nachgewiesen werden (r2 = 0,839; p 120 mg/cm3) aufweisen. Somit sind diese als nicht mehr ausreichend stabil anzusehen und es sollte uber ein Verfahren zur zusatzlichen Stabilisation nachgedacht werden. In einem Dauerbelastungsversuch konnte gezeigt werden, dass eine Zementaugmentation im osteoporotischen Wirbelkorper zu einer Steigerung der Versagenslast um ca. 52 % fuhrt (Versagenslast nicht augmentiert: 173 N, augmentiert: 263 N; p = 0,001). Weitere, von anderen Arbeitsgruppen durchgefuhrte Studien belegen den Effekt verschiedener Schraubentrajektorien und alternativer Implantate zur Verbesserung der Stabilitat bei der Versorgung osteoporotischer Wirbelkorperfrakturen.

Ziel der Operation ist die Wiederherstellung des sagittalen Profils bei einem Mismatch der spinopelvinen Parameter und hohem Leidensdruck des Patienten. Klinisch symptomatische, sagittale Imbalance bei Degeneration, Zustand nach Trauma oder nach stattgehabten Wirbelsaulenoperationen, welche durch eine konservative Therapie nicht adaquat zu behandeln sind. Schwere Allgemeinerkrankung des Patienten, lokale oder systemische Entzundungen. Uber einen dorsalen Zugang erfolgt zunachst die Instrumentation mit Pedikelschrauben. Anschliesend die Resektion der dorsalen Wirbelkorperstrukturen und eine Osteotomie im Wirbelkorper bis an das vordere Langsband, woruber eine Relordosierung durchgefuhrt werden kann. Schonung mit Belastungslimitation von 5 kg fur 3 Monate. Verbot des tiefen Sitzens fur diese Zeit. Die Pedikelsubtraktionsosteotomie ist in der Literatur als zuverlassige Methode zur Behandlung einer sagittalen Imbalance beschrieben. Die hohe Rate an beschriebenen Komplikationen muss praoperativ mit dem Patienten besprochen werden.

Loosening of pedicle screws is a frequently observed complication in spinal surgery. Because additional stabilization procedures such as cement augmentation or lengthening of the instrumentation involve relevant risks, optimal stability of the primarily implanted pedicle screw is of essential importance. The aim of the present study was to investigate the effect of increasing the screw diameter on pedicle screw stability.A total of 10 human cadaveric vertebral bodies (L4) were included in the present study. The bone mineral density was evaluated using quantitative computed tomography and the pedicle diameter using computed tomography. The vertebrae underwent instrumentation using 6.0-mm × 45-mm pedicle screws on 1 side and screws with the largest possible diameter (8-10-mm × 45-mm) on the other side. Fatigue testing was performed by applying a cyclic loading (craniocaudal sinusoidal 0.5 Hz) with increasing peak force (100 N + 0.1 N/cycle) until screw head displacement of 5.4 mm was reached.The mean fatigue load was 334 N for the 6-mm diameter screws and was increased significantly to 454 N (+36%) for the largest possible diameter screws (P 0.001). With an increase in the fatigue load by 52%, this effect was even more pronounced in vertebrae with reduced bone density (bone mineral density120 mg/cmIncreasing the pedicle screw diameter from a standard 6-mm screw to the largest possible diameter (8-10 mm) led to a significantly greater fatigue load.

Background This study was designed to evaluate the treatment outcome of very young children with congenital scoliosis aged 3 years or under after surgery with a vertical expandable prosthetic titanium rib (VEPTR)-based distraction device. Methods A retrospective study of 13 children undergoing implantation of a vertical expandable rib-based distraction device. From September 2007 to June 2018, 13 children (7 male and 6 female patients) with congenital scoliosis were followed after treatment with a VEPTR. The outcome parameters were complications, thoracic height, kyphosis, lordosis, and coronal major scoliosis curve. In addition, the American Society of Anaesthesiologists (ASA) score, assisted ventilation rating, and hemoglobin and body mass index were analyzed. Data were examined separately by 2 investigators. Results The mean age at initial surgical treatment was 24.4±10.6 months, follow-up was 91.5±23.1 months. The mean number of surgical procedures per patient was 14±3.9 (total 182 operations). Apart from planned operations every 6 months, 5 unplanned operations (2.7%) were performed. The major scoliosis curve improved significantly from 55.2±21.9 degrees to 40.5±18.7 degrees, thoracic spine height T1-T12 significantly from 111±12 mm to 137±23 mm, T1-S1 height significantly from 211±13 mm to 252±36 mm and space available for the lung from 80.9%±11.3% to 84.4%±8.8% (preoperatively and at 5-y follow-up, respectively). Kyphosis increased significantly from 30±21.4 degrees to 42.6±23.5 degrees and lordosis from 32.4±20.9 degrees to 37.6±10.4 degrees. Hemoglobin levels were virtually unchanged. Weight increased from 10.6±2.8 kg to 20.2±5.0 kg at final follow-up, but body mass index decreased from 16.6±3.7 kg/m² to 15.7±2.9 kg/m². Conclusions The expandable rib-based distraction device is an effective method to treat severe congenital scoliosis in very young children. It can control the deformity and promotes spinal and thoracic growth. Level of evidence Level IV.

Objective Posterior-anterior spondylodesis is often used to stabilize the spine in various pathologies. The anterior procedure is often performed via thoracoscopy. It is unclear whether the anterior procedure should be performed immediately after posterior instrumentation or after the patient has convalesced. This retrospective study compared perioperative safety and morbidity in 1-stage versus 2-stage posterior-anterior fusion surgery with a thoracoscopic anterior approach. Methods All consecutive patients who underwent surgery for posterior-anterior spinal stabilization from 2006 to 2013 were included. American Society of Anesthesiologists score, preoperative and postoperative laboratory values, operation duration, blood loss, intensive care unit stay, pain, postoperative hospital stay, perioperative complications, and preoperative and postoperative Eastern Cooperative Oncology Group and Frankel scores were assessed. A subset of the cohort was selected by propensity score matching to eliminate possible selection bias. Results There were 247 patients who underwent 1-stage (n = 104) or 2-stage (n = 143) stabilization with thoracoscopic fusion. Spinal pathologies were fracture, malignancy, pyogenic spondylodiscitis, degenerative spinal disorders, and failed previous surgery. One-stage and 2-stage procedures were similar in terms of preoperative, surgical, and postoperative variables, including complication rates, except that the 1-stage procedure was associated with greater pain 2 days after surgery and shorter hospital stay. The propensity score–matched cohort of 64 pairs yielded similar results with only 1-stage patients showing elevated visual analog scale score on postoperative day 2 (3.8 vs. 2.4, P = 0.043). Conclusions One-stage stabilization was as safe as 2-stage stabilization and associated with shorter hospitalization. Greater pain after the 1-stage procedure, which resolved 30 days after surgery, reflects the fact that 2-stage patients already had pain relief when they underwent thoracoscopy.

Frakturen im Bereich der Wirbelsaule zahlen zu den haufigsten klinischen Manifestationen der Osteoporose. Beim Vorliegen instabiler oder sekundar kyphosierter Frakturen ist die dorsale Instrumentation oft die Therapie der Wahl. Eine Lockerung der eingebrachten Pedikelschrauben ist die haufigste Versagensursache dieser Instrumentationen. Sowohl die Zementaugmentation als auch die Verlangerung der Instrumentationsstrecke stehen als Optionen zur Verfugung, um die Stabilitat der dorsalen Instrumentation zu verbessern. In einer biomechanischen Untersuchung haben wir anhand von 12 humanen Wirbelsaulen (Th11–L3) eine kurzstreckige sowie langstreckige Versorgung jeweils mit konventionellen und zementaugmentierten Pedikelschrauben miteinander verglichen. Es erfolgte ein biomechanischer Ermudungstest mit einer sinusformigen, kraniokaudalen Dauerbelastung und zyklischer Laststeigerung. Die Zementaugmentation von Pedikelschrauben hat keinen so deutlichen Effekt auf die Stabilitat von Pedikelschrauben, wie aus biomechanischen Pull-out-Tests vermutet. Eine Verlangerung der Instrumentationsstrecke fuhrt, verglichen mit der Zementaugmentation, zu einem deutlich hoheren Stabilitatszuwachs im biomechanischen Belastungstest an der osteoporotischen Wirbelsaule.

Loosening of pedicle screws is one major complication of posterior spinal stabilisation, especially in the patients with osteoporosis. Augmentation of pedicle screws with cement or lengthening of the instrumentation is widely used to improve implant stability in these patients. However, it is still unclear from which value of bone mineral density (BMD) the stability of pedicle screws is insufficient and an additional stabilisation should be performed. The aim of this study was to investigate the correlation of bone mineral density and pedicle screw fatigue strength as well as to define a threshold value for BMD below which an additional stabilisation is recommended. Twenty-one human T12 vertebral bodies were collected from donors between 19 and 96 years of age and the BMD was measured using quantitative computed tomography. Each vertebral body was instrumented with one pedicle screw and mounted in a servo-hydraulic testing machine. Fatigue testing was performed by implementing a cranio-caudal sinusoidal, cyclic (0.5 Hz) load with stepwise increasing peak force. A significant correlation between BMD and cycles to failure (r = 0.862, r 2 = 0.743, p 120 mg/cm3). There is a close correlation between BMD and pedicle screw stability. If the BMD of the thoracolumbar spine is less than 80 mg/cm3, stability of pedicle screws might be insufficient and an additional stabilisation should be considered.

Die „posterior vertebral column resection“ (PVCR) ist eine Reservetechnik zur Behandlung schwerer thorakaler Kyphosen mit bereits eingetretenen oder zeitnah drohenden neurologischen Komplikationen. Diese Technik sollte aufgrund des hohen Komplikationsspektrums nur ausgewahlten Patienten empfohlen werden. Das Ziel der Operation ist die einzeitige Resektion des Wirbelkorpers uber eine Kostotransversektomie mit einer 360°-Spondylodese. Nach Resektion des Wirbelkorpers gelingt eine Aufrichtung einer zuvor bestehenden kyphotischen Fehlstellung. Ausgepragte Kyphosen der Brustwirbelsaule (BWS) nach osteoporotischen Sinterungsfrakturen mit bereits eingetretenen oder zeitnah drohenden neurologischen Komplikationen auf einer oder mehreren Hohen. Allgemeine Kontraindikationen gegen chirurgische Eingriffe, ASA >3 (American Society of Anesthesiologists). Zuerst erfolgt eine Stabilisierung der Wirbelsaule mit mindestens 2 Wirbelkorpern kranial und kaudal der „vertebral column resection“ (VCR). Einzeitig werden anschliesend eine Laminektomie mit Kostotransversektomie sowie die Resektion des Wirbelkorpers durchgefuhrt. Die ventrale Abstutzung erfolgt durch das Einbringen eines Mesh-Cages in den ventralen Defekt. Durch die Kompression uber die Langstrager wird die Fehlstellung reponiert und die Mesh-Cages verklemmt. Abschliesend wird die 360°-Spondylodese von dorsal durch Aufmeiseln der Wirbelgelenke und die Anlagerung von Knochen bzw. Knochenersatzmaterial komplettiert. Funktionelle Nachbehandlung mit Vermeidung von Spitzenbelastungen und Behandlung der Osteoporose. In einer von den Autoren durchgefuhrten retrospektiven Studie wurden 10 Patienten mit dieser Operationstechnik analysiert. Die Ergebnisse zeigen eine sehr gute Korrektur der kyphotischen Fehlstellung bei einem moderaten Komplikationsspektrum.

To evaluate different stabilisation techniques for acromioclavicular (AC) joint separations, including direct AC repair, and to compare the properties of the stabilised and native joints.An established in vitro testing model for the AC joint was used to analyse joint stability after surgical reconstruction [double TightRope (DTR), DTR with AC repair (DTR + AC), single TR with AC repair (TR + AC), and PDS sling with AC repair (PDS + AC)]. Twenty-four human cadaveric shoulders were randomised by age into four testing groups. Joint stiffness was measured by applying an axial load during defined physiological ranges of motion. Similar tests were performed for the native joints, after dissecting the coracoclavicular and AC ligaments, and after surgical reconstruction. Cyclic loading was performed for 1000 cycles with 20-70 N and vertical load to failure determined after cyclic testing.Axial stiffness for all TR groups was significantly higher than for the native joint (DTR 38.94 N/mm, p = 0.005; DTR + AC 37.79 N/mm, p = 0.015; TR + AC 45.61 N/mm, p 0.001 vs. native 26.05 N/mm). The axial stiffness of the PDS + AC group was similar to that of the native joint group (21.4 N/mm, n.s.). AC repair did not significantly influence rotational stiffness. Load to failure was similar and600 N in all groups (n.s.).Reconstruction of AC dislocations with one or two TRs leads to stable results with a higher stiffness than the native joints. For the PDS + AC group, axial stiffness was similar to the native situation, although there might be a risk of elongation. Direct AC repair showed no significantly increased stability in comparison with reconstructions without direct AC repair. Thus, a direct AC repair seems to be dispensable in clinical practice, while TRs or PDS cerclages appear to provide sufficiently stable results.

Currently, the laser powder bed fusion (L-PBF) process cannot offer a reproducible and predefined quality of the processed parts. Recent research on process monitoring focuses strongly on integrated optical measurement technology. Besides optical sensors, acoustic sensors also seem promising. Previous studies have shown the potential of analyzing structure-borne and air-borne acoustic emissions in laser welding. Only a few works evaluate the potential that lies in the usage during the L-PBF process. This work shows how the approach to structure-borne acoustic process monitoring can be elaborated by correlating acoustic signals to statistical values indicating part quality. Density measurements according to Archimedes’ principle are used to label the layer-based acoustic data and to measure the quality. The data set is then treated as a classification problem while investigating the applicability of existing artificial neural network algorithms to match acoustic data with density measurements. Furthermore, this work investigates the transferability of the approach to more complex specimens.

Intraoperative revision of initially loosened pedicle screws.Intraoperatively loosened/stripped pedicle screws.None.Removal of the loosened/stripped pedicle screw. Checking the screw channel and re-implantation using a different trajectory, a larger screw diameter or a cement-augmented pedicle screw.Early functional mobilization and initiation of osteoporosis therapy if indicated.A biomechanical study with human vertebral bodies was performed. Augmented and not augmented pedicle screws were tested until loosening using a fatigue testing setup. After loosening occurred a subsequent augmentation of the loosened, not augmented screw was performed, and it was tested using a fatigue test again. Both the initial (p = 0.009) and the augmentation after loosening (p = 0.001) showed a significant increase in failure load compared to the non-augmented pedicle screws. In our own patient collective from April 2016 to August 2018, 11 of 524 patients treated with pedicle screws showed intraoperative screw loosening. This was revised in 6 cases with a subsequent augmentation and in 5 cases with a larger screw diameter. In the postoperative control at 6 weeks, none of these screws showed loosening again.

Operative stabilisation of osteoporotic vertebral fractures.Fractures of the thoracic and lumbar spine.None.Preoperative determination of expected bone mineral density. Implantation of pedicle screws in special trajectories, cement augmentation of the screws and use of alternative implants.Early functional mobilisation and initiation of osteoporosis therapy if indicated.A biomechanical cadaver study with human vertebral bodies was performed. There was a highly significant correlation between bone mineral density and the fatigue load (r

Stabilization of the atlantoaxial transition by an alternative screw position in C1.Instabilities C1/C2 due to inflammation, tumor or trauma.Presence of a very small pedicle of C1. Variations in the course of the vertebral arteries.The midline approach to the upper cervical spine is used for the modified instrumentation of C1 with pedicle screws instead of Harms screws and for the unaltered instrumentation of C2. Depending on the indication, dorsal spondylodesis is performed by opening the laminae and attaching ceramic bone substitute material.In mobile patients, additional immobilisation with a soft collar is recommended for 6 weeks. Full recovery is given 3-4 months after surgery.From January 2017 to September 2018, 21 stabilizations of the atlantoaxial transition were performed. The mean age was 72.52 ± 15.45 years. A total of 42 screws were placed in C1. In all, 21 (50%) C1 pedicle screwscould be placed, and in other 21 cases Harms screws were used. Complications were seen in 3 patients. Overall, considering the contraindications, the instrumentation of C1 with pedicle screws appears as a safe alternative to instrumentation with Harms screws.

Cement augmentation of pedicle screws is known to increase their mechanical strength. Aim was to evaluate the impact of cement augmentation on pedicle screw fatigue strength in dependence of the bone mineral density (BMD). Twenty-one human L2 vertebral bodies from donors between 19 and 96 years of age were used for in vitro experiments. BMD was measured using quantitative computed tomography (QCT). Two pedicle screws were inserted in each specimen and unilaterally augmented with bone cement. Fatigue testing was performed using a cranio-caudal sinusoidal, cyclic load (0.5 Hz) with increasing compression force (100 N + 0.1 N/cycles). Results were evaluated for the BMD groups: normal: BMD > 120 mg/cm3, osteopenic: BMD 80–120 mg/cm3, and osteoporotic: BMD

It is becoming increasingly common for a patient to have ipsilateral hip and knee replacements. The inter-prosthetic (IP) distance, the distance between the tips of hip and knee prostheses, has been thought to be associated with an increased risk of IP fracture. Small gap distances are generally assumed to act as stress risers, although there is no real biomechanical evidence to support this. The purpose of this study was to evaluate the influence of IP distance, cortical thickness and bone mineral density on the likelihood of an IP femoral fracture. A total of 18 human femur specimens were randomised into three groups by bone density and cortical thickness. For each group, a defined IP distance of 35 mm, 80 mm or 160 mm was created by choosing the appropriate lengths of component. The maximum fracture strength was determined using a four-point bending test. The fracture force of all three groups was similar (p = 0.498). There was a highly significant correlation between the cortical area and the fracture strength (r = 0.804, p < 0.001), whereas bone density showed no influence. This study suggests that the IP distance has little influence on fracture strength in IP femoral fractures: the thickness of the cortex seems to be the decisive factor. Cite this article: Bone Joint J 2014;96-B:1378–84.

Osteoporotic fractures with severe kyphosis and neurologic deficits often require decompression and stabilisation. To reduce the risk of procedure-related complications, single-stage posterolateral vertebrectomy and a 360-degree fusion can be performed. An adequate reduction of kyphotic deformity through this approach has not been reported. The aim of this study is to investigate the efficacy of kyphotic deformity reduction by this approach in osteoporotic situation. A retrospective analysis and chart review was performed for 10 consecutive patients who underwent posterolateral decompression and posterior vertebrectomy with dorsal mesh stabilisation and reduction of kyphotic deformity. Preoperative back pain was 8.6 on a visual analogue scale; it was reduced to 5.5 at discharge and 3.7 at the latest follow-up (18 months). The Frankel score improved from D to E (three patients) or was equal (E). Radiological segmental kyphosis was corrected from a mean of 25° to 5° (p

Metastatic epidural spinal cord compression (MESCC) often requires anterior–posterior decompression and stabilization. To reduce approach-related complications, single-stage posterolateral vertebrectomy and 360° fusion is often performed. However, a sufficient reduction of kyphotic deformity through this approach has not been reported. The purpose of this study is to investigate the efficacy of kyphotic deformity reduction by this approach in MESCC. A retrospective analysis and chart review was performed for 14 consecutive patients who underwent a vertebrectomy and decompression from a posterolateral approach. Anterior mesh stabilization of the ventral column is used as hypomochlion for the posterior compression manoeuvre, which leads to reduction of the kyphotic deformity. Pre-operative back pain was 7.2 on a visual analogue scale. Back pain was reduced to 4.4 at discharge and 2.0 at the latest follow-up with a mean follow-up of 12 months (p

Aims Loosening of pedicle screws is a major complication of posterior spinal stabilisation, especially in the osteoporotic spine. Our aim was to evaluate the effect of cement augmentation compared with extended dorsal instrumentation on the stability of posterior spinal fixation. Materials and Methods A total of 12 osteoporotic human cadaveric spines (T11-L3) were randomised by bone mineral density into two groups and instrumented with pedicle screws: group I (SHORT) separated T12 or L2 and group II (EXTENDED) specimen consisting of T11/12 to L2/3. Screws were augmented with cement unilaterally in each vertebra. Fatigue testing was performed using a cranial-caudal sinusoidal, cyclic (1.0 Hz) load with stepwise increasing peak force. Results Augmentation showed no significant increase in the mean cycles to failure and fatigue force (SHORT p = 0.067; EXTENDED p = 0.239). Extending the instrumentation resulted in a significantly increased number of cycles to failure and a significantly higher fatigue force compared with the SHORT instrumentation (EXTENDED non-augmented + 76%, p < 0.001; EXTENDED augmented + 87%, p < 0.001). Conclusion The stabilising effect of cement augmentation of pedicle screws might not be as beneficial as expected from biomechanical pull-out tests. Lengthening the dorsal instrumentation results in a much higher increase of stability during fatigue testing in the osteoporotic spine compared with cement augmentation. Cite this article: Bone Joint J 2016;98-B:1099–1105.