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In certain situations, bones do not heal completely after fracturing. One of these situations is a critical-size bone defect where the bone cannot heal spontaneously. In such a case, complex fracture treatment over a long period of time is required, which carries a relevant risk of complications. The common methods used, such as autologous and allogeneic grafts, do not always lead to successful treatment results. Current approaches to increasing bone formation to bridge the gap include the application of stem cells on the fracture side. While most studies investigated the use of mesenchymal stromal cells, less evidence exists about induced pluripotent stem cells (iPSC). In this study, we investigated the potential of mouse iPSC-loaded scaffolds and decellularized scaffolds containing extracellular matrix from iPSCs for treating critical-size bone defects in a mouse model. In vitro differentiation followed by Alizarin Red staining and quantitative reverse transcription polymerase chain reaction confirmed the osteogenic differentiation potential of the iPSCs lines. Subsequently, an in vivo trial using a mouse model (n = 12) for critical-size bone defect was conducted, in which a PLGA/aCaP osteoconductive scaffold was transplanted into the bone defect for 9 weeks. Three groups (each n = 4) were defined as (1) osteoconductive scaffold only (control), (2) iPSC-derived extracellular matrix seeded on a scaffold and (3) iPSC seeded on a scaffold. Micro-CT and histological analysis show that iPSCs grafted onto an osteoconductive scaffold followed by induction of osteogenic differentiation resulted in significantly higher bone volume 9 weeks after implantation than an osteoconductive scaffold alone. Transplantation of iPSC-seeded PLGA/aCaP scaffolds may improve bone regeneration in critical-size bone defects in mice.

Healing large bone defects remains challenging in orthopedic surgery and is often associated with poor outcomes and complications. A major issue with bioengineered constructs is achieving a continuous interface between host bone and graft to enhance biological processes and mechanical stability. In this study, we have developed a new bioengineering strategy to produce oriented biocompatible 3D PLGA/aCaP nanocomposites with enhanced osseointegration. Decellularized scaffolds -containing only extracellular matrix- or scaffolds seeded with adipose-derived mesenchymal stromal cells were tested in a mouse model for critical size bone defects. In parallel to micro-CT analysis, SAXS tensor tomography and 2D scanning SAXS were employed to determine the 3D arrangement and nanostructure within the critical-sized bone. Both newly developed scaffold types, seeded with cells or decellularized, showed high osseointegration, higher bone quality, increased alignment of collagen fibers and optimal alignment and size of hydroxyapatite minerals.

Introduction Traditionally, thoracolumbar split and burst-split fractures are treated with combined antero-posterior bi-segmental fusion procedures. Especially in the lower lumbar spine, such interventions are invasive and are associated with increased risk of neurological and vascular complications. This retrospective study aims to determine whether percutaneous stent-kyphoplasty is a viable treatment option for these injuries in terms of kyphotic angle correction and patient safety. Methods From Nov. 2014 to Dec. 2017, 25 consecutive patients (9 female, mean age 58 years) with 8 thoracolumbar split and 17 burst-split fractures (T11 to L5) of different etiology (7 high vs. 18 low energy trauma) were treated with percutaneous stent-kyphoplasty (SpineJack®). CT and/or MR imaging was performed preoperatively in all patients while radiographs were obtained postoperatively and at each follow-up. The mean follow-up was 176 days (SD 130). All cases were evaluated retrospectively for complications regarding nervous damage, LOS, duration of opioid intake, pain-VAS, return to work time and change of radiographic kyphotic angle. Results The mean kyphotic angle did not change from 1.1° (SD 9.2°) preoperatively to 1.1° (SD 7.9°) postoperatively. Radiologically, the mean increase of the kyphotic angle between surgery and the last follow-up was 2.65° (SD 4.2°). The mean pain-VAS was reduced to 1.8 postoperatively (SD 2.5, p = 0.03). The mean opioid intake duration was 4 days. Conclusion SpineJack®-kyphoplasty appears to be a safe and expeditious, minimally invasive treatment option for thoracolumbar split or burst-split fractures. It may be considered as an alternative to combined anterior-posterior instrumented bi-segmental fusion with its associated surgical morbidity.

Introduction: Pelvic binders (PB) have become an established first-line treatment for on scene use in suspected pelvic ring injuries. A sustained incidence of incorrect placements was reported, usually above the trochanteric region. We examined if malplacement is associated with worse clinical parameters related to resuscitation. Methods: Retrospective chart review, level 1 center over a 3-year period. Inclusion criteria: adult patients (18-69y/o), high-energy injury, presence of a pelvic binder on admission - patients without binders served as controls. Exclusions: geriatric patients (>70y/o), ground level falls. Malplacement of the binder was assessed and graded (grade 1:<5 cm above trochanter, grade 2:5-10 cm, grade 3 > 10 cm) from the initial computed tomography scan (3D reconstruction). Results: Seventy-six patients were included. Males (72%), mean age 47years (range 18-91, SD 19.4). Mean Injury Severity Score was 22.3 points (range 1 -48, SD 10.4) and mean Glasgow Coma Score on arrival was 10.8 points (range 3-15, SD 5.3). Fifty-three percent presented with a pelvic ring injury (74% of them with a type B or C fracture). Mean PB distance from the trochanteric region was 56 mm (range 41-247 mm, SD 54.5). Fifty percent of PBs were moderately displaced, 21% showed severe misplacement (>100 mm). Physiological parameters were unchanged regardless of the accuracy of PB placement. Conclusion: Incorrect placement of pelvic binders persists despite widespread implementation of the device. In our series, displacement was always cranially and had no effect on preclinical fluids received or parameters of resuscitation on arrival.

KPC-50 is a KPC-3 variant identified from a Klebsiella pneumoniae clinical isolate recovered in Switzerland in 2019. Compared to KPC-3, KPC-50 shows (i) a three- amino-acid insertion (Glu-Ala-Val) between amino acids 276 and 277, (ii) an increased affinity to ceftazidime, (iii) a decreased sensitivity to avibactam, explaining the ceftazidime-avibactam resistance, and (iv) an association with a sharp reduction of its carbapenemase activity.

BACKGROUND Information on long-term psychiatric sequelae after severe trauma is sparse. We therefore performed a survey addressing several symptoms related to post traumatic stress disorder (PTSD) in patients that sustained multiple injuries more than 20 years after trauma. METHODS Patients injured between January 1, 1973 and December 31, 1990 were contacted at least 20 years later. We included multiply injured patients aged between 3 and 60 years of age from a single level I Trauma center. A questionnaire based on the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) diagnostic criteria for PTSD, including individual symptoms related to intrusion, avoidance, and hyperarousal was sent to all patients. RESULTS 359 (56.35%) patients received a questionnaire. Out of these, 337 (93.87%) returned the questionnaire and were included in the study (223 males (66.17%) and 114 females (33.82%)). Mean follow-up was 29.5 ± 8.5 years. Nearly half the study population (47.18%) experienced lasting psychiatric sequelae, such as intrusive recollection (n= 65, 19.28%), avoidance (n= 92, 27.29%), or hyperarousal (n=95, 28.18%) at least monthly. Ten patients (2.96%) fulfilled all DSM-IV diagnostic criteria for PTSD. A total of 131 (38.87%) patients reported fair or poor general health status. There was no difference in injury severity in patients with or without PTSD (Injury Severity Score (ISS) 18.33 vs. 20.36, respectively, p = 0.52) or PTSD-related symptoms including intrusion (19.88 vs. 20.32, p=0.74), avoidance (19.99 vs. 20.3, p=0.79) and hyperarousal (19.36 vs. 20.68, p=0.26). CONCLUSION At least 20 years after injury, no correlation was found between the development of psychiatric complications and the severity of injury. While the rate of full-blown PTSD was low, nearly half the study population regularly suffered from at least one psychiatric symptom attributable to the initial trauma. Awareness for the development of psychiatric complications and early initiatio

Der 22-jährige Student stellte sich neun Wochen nach initialem Trauma, bei welchem er sich eine zweitgradig offene Unterschenkelschaftfraktur rechts zugezogen hatte, zur Zweitmeinung vor.

BACKGROUND Pelvic incidence (PI) has been linked to several degenerative processes within the spinopelvic system. Acetabular retroversion is a recognised risk factor for osteoarthritis of the hip. We therefore hypothesised that these two factors might be part of a specific anatomical variant associated with degenerative changes. This study was performed to clarify this issue. METHODS The pelvic incidence was measured on 589 computertomographical data sets acquired between 2008 and 2010. For 220 patients a 2D rendering in an antero-posterior view of the CT data set was performed to evaluate the parameters of acetabular retroversion. Those included the prominence of the ischial spine sign (PRISS), the cross-over sign (COS) and the posterior wall sign (PWS). Between 477 and 478 hips were evaluated depending on the parameter of retroversion. RESULTS The mean pelvic incidence was significantly lower in hips positive for the PRISS and the PWS. However, there were no significant differences between hips positive or negative for the COS. DISCUSSION As hypothesised, the lower PI values in PWS and PRISS positive hips suggest a link between PI and retroversion of the acetabulum. Whether this is of any clinical relevance remains, however, unknown. CONCLUSION Acetabular retroversion is linked to PI. In hips where the prominence of the ischial spine sign and/or the posterior wall sign was present, the mean pelvic incidence value was lower.

BACKGROUND Fractures of the pelvic ring including disruption of the posterior elements in high-energy trauma have both high morbidity and mortality rates. For some injury pattern part of the initial resuscitation includes either external fixation or plate fixation to close the pelvic ring and decrease blood loss. In certain situations--especially when associated with abdominal trauma and the need to perform laparotomies--both techniques may put the patient at risk of either pintract or deep plate infections. We describe an operative approach to percutaneously close and stabilize the pelvic ring using spinal implants as an internal fixator and report the results in a small series of patients treated with this technique during the resuscitation phase. FINDINGS Four patients were treated by subcutaneous placement of an internal fixator. Screw fixation was carried out by minimally invasive placement of two supra-acetabular iliac screws. Afterwards, a subcutaneous transfixation rod was inserted and attached to the screws after reduction of the pelvic ring. All patients were allowed to fully weight-bear. No losses of reduction or deep infections occurred. Fracture healing was uneventful in all cases. CONCLUSION Minimally invasive fixation is an alternative technique to stabilize the pelvic ring. The clinical results illustrate that this technique is able to achieve good results in terms of maintenance of reduction the pelvic ring. Also, abdominal surgeries no longer put the patient at risk of infected pins or plates.

BACKGROUND Although useful in the emergency treatment of pelvic ring injuries, external fixation is associated with pin tract infections, the patient's limited mobility and a restricted surgical accessibility to the lower abdomen. In this study, the mechanical stability of a subcutaneous internal anterior fixation (SIAF) system is investigated. METHODS A standard external fixation and a SIAF system were tested on pairs of Polyoxymethylene testing cylinders using a universal testing machine. Each specimen was subjected to a total of 2000 consecutive cyclic loadings at 1 Hz with sinusoidal lateral compression/distraction (+/-50 N) and torque (+/- 0.5 Nm) loading alternating every 200 cycles. Translational and rotational stiffness were determined at 100, 300, 500, 700 and 900 cycles. RESULTS There was no significant difference in translational stiffness between the SIAF and the standard external fixation when compared at 500 (p = .089), 700 (p = .081), and 900 (p = .266) cycles. Rotational stiffness observed for the SIAF was about 50 percent higher than the standard external fixation at 300 (p = .005), 500 (p = .020), and 900 (p = .005) cycles. No loosening or failure of the rod-pin/rod-screw interfaces was seen. CONCLUSIONS In comparison with the standard external fixation system, the tested device for subcutaneous internal anterior fixation (SIAF) in vitro has similar translational and superior rotational stiffness.

Background. External fixation is useful in the primary treatment of pelvic ring injuries. The present study compared the biomechanical stability of five different configurations of an external pelvic ring fixation system. Methods. Five configurations of an anterior external pelvic ring fixation system were tested using a universal testing machine. One single connecting rod was used in group “SINGLE,” two parallel connecting rods in group “DOUBLE,” two and four rods, respectively, in a tent-like configuration in groups “SINGLE TENT” and “DOUBLE TENT,” and a rhomboid-like configuration in group “RHOMBOID.” Each specimen was subjected to a total of 2000 consecutive cyclic loadings at 1 Hz lateral compression/distraction (±50 N) and torque (±0.5 Nm) loading alternating every 200 cycles. Translational and rotational stiffness were determined at 100, 300, 500, 700, and 900 cycles. Results. The “SINGLE TENT” and “RHOMBOID” configurations already failed with a preloading of 50 N compression force. The “DOUBLE” configuration had around twice the translational stability compared with the “SINGLE” and “DOUBLE TENT” configurations. Rotational stiffness observed for the “DOUBLE” and “DOUBLE TENT” configurations was about 50% higher compared to the SINGLE configuration. Conclusion. Using two parallel connecting rods provides the highest translational and rotational stability.

KPC-50 is a KPC-3 variant identified from a Klebsiella pneumoniae clinical isolate recovered in Switzerland in 2019. Compared to KPC-3, KPC-50 shows (i) a three- amino-acid insertion (Glu-Ala-Val) between amino acids 276 and 277, (ii) an increased affinity to ceftazidime, (iii) a decreased sensitivity to avibactam, explaining the ceftazidime-avibactam resistance, and (iv) an association with a sharp reduction of its carbapenemase activity.