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1.  A Novel Shape Memory Plate Osteosynthesis for Noninvasive Modulation of Fixation Stiffness in a Rabbit Tibia Osteotomy Model 
BioMed Research International  2015;2015:652940.
Nickel-titanium shape memory alloy (NiTi-SMA) implants might allow modulating fracture healing, changing their stiffness through alteration of both elastic modulus and cross-sectional shape by employing the shape memory effect (SME). Hypotheses: a novel NiTi-SMA plate stabilizes tibia osteotomies in rabbits. After noninvasive electromagnetic induction heating the alloy exhibits the SME and the plate changes towards higher stiffness (inverse dynamization) resulting in increased fixation stiffness and equal or better bony healing. In 14 rabbits, 1.0 mm tibia osteotomies were fixed with our experimental plate. Animals were randomised for control or induction heating at three weeks postoperatively. Repetitive X-ray imaging and in vivo measurements of bending stiffness were performed. After sacrifice at 8 weeks, macroscopic evaluation, µCT, and post mortem bending tests of the tibiae were carried out. One death and one early implant dislocation occurred. Following electromagnetic induction heating, radiographic and macroscopic changes of the implant proved successful SME activation. All osteotomies healed. In the treatment group, bending stiffness increased over time. Differences between groups were not significant. In conclusion, we demonstrated successful healing of rabbit tibia osteotomies using our novel NiTi-SMA plate. We demonstrated shape-changing SME in-vivo through transcutaneous electromagnetic induction heating. Thus, future orthopaedic implants could be modified without additional surgery.
PMCID: PMC4475735  PMID: 26167493
2.  Smoking and Risk of Prosthesis-Related Complications after Total Hip Arthroplasty: A Meta-Analysis of Cohort Studies 
PLoS ONE  2015;10(4):e0125294.
Increasing evidence suggests that smoking may increase the incidence of prosthesis-related complications after total hip arthroplasty (THA). We performed a meta-analysis of cohort studies to quantitatively evaluate the association between smoking and the risk of prosthesis-related complications after THA.
Relevant articles published before August 15, 2014, were identified by searching the PubMed, EMBASE and Cochrane library databases. Pooled risk ratios (RRs) or weighted mean differences (WMDs) with 95% confidence intervals (CIs) were calculated with either a fixed- or random-effects model.
Six cohort studies, involving a total of 8181 participants, were included in the meta-analysis. Compared with the patients who never smoked, smokers had a significantly increased risk of aseptic loosening of prosthesis (summary RR=3.05, 95% CI: 1.42-6.58), deep infection (summary RR=3.71, 95% CI: 1.86-7.41) and all-cause revisions (summary RR=2.58, 95% CI: 1.27-5.22). However, no significant difference in the risk of implant dislocation (summary RR= 1.27, 95% CI: 0.77-2.10) or length of hospital stay (WMD=0.03, 95% CI: -0.65-0.72) was found between smokers and nonsmokers.
Smoking is associated with a significantly increased risk of aseptic loosening of prosthesis, deep infection and all-cause revisions after THA, but smoking is not correlated with a risk of implant dislocation or the length of hospital stay after surgery.
PMCID: PMC4409354  PMID: 25909602
3.  Overweight and obesity in hip and knee arthroplasty: Evaluation of 6078 cases 
World Journal of Orthopedics  2015;6(1):137-144.
AIM: To evaluate a possible association between the various levels of obesity and peri-operative charac-teristics of the procedure in patients who underwent endoprosthetic joint replacement in hip and knee joints.
METHODS: We hypothesized that obese patients were treated for later stage of osteoarthritis, that more conservative implants were used, and the intra-and perioperative complications increased for such patients. We evaluated all patients with body mass index (BMI) ≥ 25 who were treated in our institution from January 2011 to September 2013 for a primary total hip arthroplasty (THA) or total knee arthroplasty (TKA). Patients were split up by the levels of obesity according to the classification of the World Health Organization. Average age at the time of primary arthroplasty, preoperative Harris Hip Score (HHS), Hospital for Special Surgery score (HSS), gender, type of implanted prosthesis, and intra-and postoperative complications were evaluated.
RESULTS: Six thousand and seventy-eight patients with a BMI ≥ 25 were treated with a primary THA or TKA. Age decreased significantly (P < 0.001) by increasing obesity in both the THA and TKA. HHS and HSS were at significantly lower levels at the time of treatment in the super-obese population (P < 0.001). Distribution patterns of the type of endoprostheses used changed with an increasing BMI. Peri- and postoperative complications were similar in form and quantity to those of the normal population.
CONCLUSION: Higher BMI leads to endoprosthetic treat-ment in younger age, which is carried out at significantly lower levels of preoperative joint function.
PMCID: PMC4303782  PMID: 25621218
Adiposity; Total knee arthroplasty; Total hip arthroplasty; Obesity; Overweight; Prosthesis
4.  Non-Osteotomy and Osteotomy Large Animal Fracture Models in Orthopedic Trauma Research 
Orthopedic Reviews  2014;6(4):5575.
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.
PMCID: PMC4274451  PMID: 25568730
fracture; large animal; sheep; fracture healing; non-osteotomy fracture model
5.  Repair of segmental long-bone defects by stem cell concentrate augmented scaffolds: a clinical and positron emission tomography - computed tomography analysis 
International Orthopaedics  2013;37(11):2231-2237.
Treating segmental long-bone defects remains a major challenge. For defects >3 cm, segmental transport represents the gold standard, even though the method is time consuming and afflicted with several complications. The aim of this study was to evaluate healing of such defects after grafting an osteogenic scaffold previously seeded with stem cell concentrate.
We evaluated five patients with segmental long-bone defects (3–14 cm) treated with bone marrow aspirate concentrates (BMAC) seeded onto a bovine xenogenous scaffold. The healing process was monitored by X-rays and positron emission tomography–computed tomography (PET-CT) three months after surgery.
Centrifugation led to a concentration of leukocytes by factor 8.1 ± 7.5. Full weight bearing was achieved 11.3 ± 5.0 weeks after surgery. PET analysis showed an increased influx of fluoride by factor 8.3 ± 6.4 compared with the contralateral side (p < 0.01). Bone density in the cortical area was 75 ± 16 % of the contralateral side (p < 0.03). The patient with the largest defect sustained an implant failure in the distal femur and finally accomplished therapy by segmental transport. He also had the lowest uptake of fluoride of the patient collective (2.2-fold increase).
Stem cell concentrates can be an alternative to segmental bone transport. Further studies are needed to compare this method with autologous bone grafting and segmental transport.
PMCID: PMC3824887  PMID: 24013459
Segmental bone defect; Scaffold; Mesenchymal stem cells (MSC); Stem cell concentrate
6.  Improvement in the workflow efficiency of treating non-emergency outpatients by using a WLAN-based real-time location system in a level I trauma center 
Patient localization can improve workflow in outpatient settings, which might lead to lower costs. The existing wireless local area network (WLAN) architecture in many hospitals opens up the possibility of adopting real-time patient tracking systems for capturing and processing position data; once captured, these data can be linked with clinical patient data.
To analyze the effect of a WLAN-based real-time patient localization system for tracking outpatients in our level I trauma center.
Outpatients from April to August 2009 were included in the study, which was performed in two different stages. In phase I, patient tracking was performed with the real-time location system, but acquired data were not displayed to the personnel. In phase II tracking, the acquired data were automatically collected and displayed. Total treatment time was the primary outcome parameter. Statistical analysis was performed using multiple linear regression, with the significance level set at 0.05. Covariates included sex, age, type of encounter, prioritization, treatment team, number of residents, and radiographic imaging.
1045 patients were included in our study (540 in phase I and 505 in phase 2). An overall improvement of efficiency, as determined by a significantly decreased total treatment time (23.7%) from phase I to phase II, was noted. Additionally, significantly lower treatment times were noted for phase II patients even when other factors were considered (increased numbers of residents, the addition of imaging diagnostics, and comparison among various localization zones).
WLAN-based real-time patient localization systems can reduce process inefficiencies associated with manual patient identification and tracking.
PMCID: PMC3822105  PMID: 23676246
Real time location system ; WLAN; patient tracking ; hospital
7.  Different thermal conductivity in drilling of cemented compared with cementless hip prostheses in the treatment of periprosthetic fractures of the proximal femur—an experimental biomechanical analysis 
International Orthopaedics  2013;37(10):1885-1889.
The purpose of this study was to evaluate the different temperature levels whilst drilling cemented and cementless hip prostheses implanted in bovine femora, and to evaluate the insulating function of the cement layer.
Standard hip prostheses were implanted in bovine donor diaphyses, with or without a cement layer. Drilling was then performed using high-performance-cutting drills with a reinforced core, a drilling diameter of 5.5 mm and cooling channels through the tip of the drill for constantly applied internal cooling solution. An open type cooling model was used in this setup. Temperature was continuously measured by seven thermocouples placed around the borehole. Thermographic scans were also performed during drilling.
At the cemented implant surface, the temperature never surpassed 24.7 °C when constantly applied internal cooling was used. Without the insulating cement layer (i.e. during drilling of the cementless bone–prosthesis construct), the temperature increased to 47 °C.
Constantly applied internal cooling can avoid structural bone and soft tissue damage during drilling procedures. With a cement layer, the temperatures only increased to non-damaging levels. The results could be useful in the treatment of periprosthetic fractures with intraprosthetic implant fixation.
PMCID: PMC3779579  PMID: 23775453
8.  Does Additional Head Trauma Affect the Long-term Outcome After Upper Extremity Trauma in Multiple Traumatized Patients: Is There an Additional Effect of Traumatic Brain Injury? 
Musculoskeletal injuries are common in patients with multiple trauma resulting in pain, functional deficits, and disability. Traumatic brain injuries (TBIs) are common in severely injured patients potentially resulting in neurological impairment and permanent disability that would add to that from the musculoskeletal injuries. However, it is unclear to what degree the combination affects impairment.
We therefore asked whether added upper extremity injuries or TBI worsened the functional, psychological, and vocational status in multiple trauma patients.
We retrospectively reviewed 281 patients with multiple trauma: 229 with upper extremity injuries but without TBI (Group I), 32 with concomitant upper extremity injuries and TBI (Group II), and 20 with TBI but no upper extremity injuries (Group III). We assessed patients with the Glasgow Outcome Score (GOS), Hannover Score for Polytrauma Outcome, SF-12 (Physical Component Summary Score and Mental Component Summary Score), medical aid requirements, need of psychological support, and vocational living circumstances. The minimum followup was 10 years (median, 17.5 years; range, 10–28 years).
Additional TBI in multiple trauma patients led to reduced function (GOS: Group I: 4.9 ± 0.2, Group II: 4.5 ± 0.7, Group III: 4.5 ± 0.8) resulting in vocational restrictions (job change: Group I: 74%, Group II: 91%, Group III: 90%). The combination of upper extremity and TBIs did not result in worse long-term scores compared with TBI alone.
Rehabilitation and social reintegration in multiple trauma patients with TBI requires particular emphasis to minimize disability and vocational isolation. Musculoskeletal injuries should not be neglected to ensure the maximum extremity function given the impaired cognitive functions after TBI.
Level of Evidence
Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
PMCID: PMC3734407  PMID: 23657878
9.  Enhanced migration of human bone marrow stromal cells in modified collagen hydrogels 
International Orthopaedics  2013;37(8):1605-1611.
Collagen I hydrogels are widely used as scaffolds for regeneration of articular cartilage defects. We hypothesised that ingrowth might be improved by removing the superficial layer of a compressed hydrogel. The control group consisted of the original unmodified product.
The migration of human bone marrow stromal cells (hBMSCs) into the hydrogel was evaluated by confocal microscopy. We quantified the DNA concentration of the hydrogel for each group and time point and evaluated the chondrogenic differentiation of cells.
After one week, the detectable amount of cells at the depth of 26–50 μm was significantly higher in the modified matrix (MM) than in the non-modified matrix (NM) (p = 0.011). The maximum depth of penetration was 75 μm (NM) and 200 μm (MM). After three weeks, the maximum depth of penetration was 175 μm (NM) and 200 μm (MM). Likewise, at a depth of 0–25 μm the amount of detectable cells was significantly higher in the MM group (p = 0.003). After 14 days, the concentration of DNA was significantly higher in the samples of the MM than in the control group (p = 0.000). Staining of histological sections and labelling with collagen II antibodies showed that a chondrogenic differentiation of cells in the scaffold can occur during in vitro cultivation.
Removing the superficial layer is essential to ensuring proper ingrowth of cells within the compressed hydrogel. Compressed hydrogels contribute better to cartilage regeneration after surface modification.
PMCID: PMC3728398  PMID: 23645081
10.  Temperature control with internally applied cooling in solid material drilling: an experimental, biomechanical study 
International Orthopaedics  2013;37(7):1355-1361.
The purpose of this study was to evaluate the different temperature levels while drilling solid materials and to compare different cooling solutions for possible temperature control. An additional purpose was to develop an internal cooling device which can be connected to routinely used manual drilling devices in trauma surgery.
Drilling was performed on a straight hip stem implanted in bovine femora without cooling, with externally applied cooling and with a newly developed internal cooling device. Temperature changes were measured by seven thermocouples arranged near the borehole. Additionally, thermographic scans were performed during drilling.
Drilling without cooling leads to an immediate increase in temperature to levels of thermal osteonecrosis (over 200 °C). With externally applied cooling temperatures were decreased, but were still up to a tissue damaging 85 °C. Internally applied cooling led to a temperature decrease to tissue-preserving levels during the drilling procedure (24.7 °C).
Internal cooling with HPC-drillers lowered the measured temperatures to non-tissue damaging temperatures and should avoid structural tissue damage.
PMCID: PMC3685654  PMID: 23512602
11.  Two-stage multilevel en bloc spondylectomy with resection and replacement of the aorta 
European Spine Journal  2012;22(Suppl 3):363-368.
We report a case of multilevel spondylectomy in which resection and replacement of the adjacent aorta were done. Although spondylectomy is nowadays an established technique, no report on a combined aortic resection and replacement has been reported so far.
The case of a 43-year-old man with a primary chondrosarcoma of the thoracic spine is presented. The local pathology necessitated resection of the aorta. We did a two-stage procedure with resection and replacement of the aorta using a heart–lung machine followed by secondary tumor resection and spinal reconstruction.
The procedure was successful. A tumor-free margin was achieved. The patient is free of disease 48 months after surgery.
En bloc spondylectomy in combination with aortic resection is feasible and might expand the possibility of producing tumor-free margins in special situations.
PMCID: PMC3641252  PMID: 22972602
Chondrosarcoma; Spondylectomy; Resection of the aorta; Multilevel
12.  Elective thoracotomy for pedicle screw removal to prevent severe aortic bleeding 
We present a case of a 33-year-old female who sustained multiple injuries of her spine, including spinous process fractures of C5 to C7 and a lamina fracture of C6 and C7. Her thoracic spine showed transverse process fractures of T4 to T10, a compression fracture and lamina fracture of T3, spinous process and transverse process fractures of T4 and T5, a rotation injury of T6, as well as a compression fracture of L1. Thirteen months after posterior thoracic spinal instrumentation, a pedicle screw was suspected to be in contact with the aorta, which was proved by computed tomography angiograms. Consequently, implant removal was planned with direct exposure of the aorta in order to allow for immediate repair if needed. So far, studies that compare different techniques to remove pedicle screws that are suspected to penetrate the aorta are missing. However, different techniques have been described in case reports, mainly minimally invasive endovascular techniques vs open techniques such as thoracotomy.
PMCID: PMC3985037  PMID: 24749121
Spine; Pedicle screw; Aorta; Bleeding; Implant removal; Hemorrhage
14.  Physical and psychological long-term outcome after traumatic brain injury in children and adult patients 
Several studies have indicated that younger age is associated with worse recovery after pediatric traumatic brain injury (TBI) compared to elder children. In order to verify this association between long-term outcome after moderate to severe TBI and patient’s age, direct comparison between different pediatric age groups as well as an adult population was performed.
This investigation represents a retrospective cohort study at a level I trauma center including patients with moderate to severe, isolated TBI with a minimum follow-up of 10 years. According to their age at time of injury, patients were divided in pre-school (0–7 years), school (8–17 years) and adult (18–65 years) patients. Physical examination and standardized questionnaire on physical and psychological aspects (Glasgow Outcome Scale, Barthel Index, Impact of Event Scale, Hospital Anxiety and Depression Scale, short form 12) were performed.
135 traumatized patients were included. Physical and psychological long-term outcome was associated with injury severity but not with patients’ age at time of injury. Outcome recovery measured by Glasgow Outcome Scale was demonstrated with best results for pre-school aged children (p = 0.009). According to the Hospital Anxiety and Depression Scale an increased incidence of anxiety (p = 0.010) and depression (p = 0.026) was evaluated in older patients.
Long-term outcome perceptions after moderate to severe TBI presented in this study question current views of deteriorated recovery for the immature brain. The sustained TBI impact seemed not to reduce the child’s ability to overcome the suffered impairment measured by questionnaire based psychological, physical and health related outcome scores. These results distinguish the relevance of rehabilitation and family support in the long term.
PMCID: PMC3941774  PMID: 24571742
Traumatic brain injury; Long-term outcome; Morbidity; Children
15.  Near-Infrared Spectroscopy Correlates with Established Histological Scores in a Miniature Pig Model of Cartilage Regeneration 
Near-Infrared Spectroscopy (NIRS) could be of clinical relevance in modern cartilage regeneration.In a miniature pig model correlation of measurements and histologic scores have never been used before. The data analysis was part of an animal project that investigated the effects of seeding a chondrogenic and osteogenic scaffold with a bone-marrow-derived cell concentrate and reports the histological and mechanical properties. We created 20 osteochondral defects in the femoral condyles of 10 miniature pigs.The defects were left empty (E), filled with the grafted cylinder upside down (U), or with a combined scaffold (S) containing a spongy bone cylinder covered with a collagen membrane. In the fourth group, the same scaffolds were implanted but seeded with a stem cell concentrate (S+BMCC). The animals were euthanized after 3 months, and histologic and spectrometric analyses were performed. NIRS measurements were significantly higher in the central area of the defects of group S+BMCC compared to the central area of the defects of group U. In all groups, a correlation between NIRS and the histologic scores could be demonstrated though on different levels. In the central area, a good NIRS measurement correlates with low (good) histologic scores. In group E and group S, this negative correlation was significant (p=0.01). For the first time, NIRS was successfully used to evaluate osteochondral constructs in a miniature pig model.
PMCID: PMC4040933  PMID: 24895022
Cartilage; miniature pig; near-infrared spectroscopy; NIRS; steochondral lesion; Pineda; Wakitani.
16.  Tibial Inlay Press-fit Fixation Versus Interference Screw in Posterior Cruciate Ligament Reconstruction 
Orthopedic Reviews  2013;5(4):e35.
Reconstruction of the posterior cruciate ligament (PCL) by a tibial press-fit fixation of the patellar tendon with an accessory bone plug is a promising approach because no foreign materials are required. Until today, there is no data about the biomechanical properties of such press-fit fixations. The aim of this study was to compare the biomechanical qualities of a bone plug tibial inlay technique with the commonly applied interference screw of patellar tendon PCL grafts. Twenty patellar tendons including a bone block were harvested from ten human cadavers. The grafts were implanted into twenty legs of adult German country pigs. In group P, the grafts were attached in a press-fit technique with accessory bone plug. In group S, the grafts were fixed with an interference screw. Each group consisted of 10 specimens. The constructs were biomechanically analyzed in cyclic loading between 60 and 250 N for 500 cycles recording elongation. Finally, ultimate failure load and failure mode were analyzed. Ultimate failure load was 598.6±36.3 N in group P and 653.7±39.8 N in group S (not significant, P>0.05). Elongation during cyclic loading between the 1st and the 20th cycle was 3.4±0.9 mm for group P and 3.1±1 mm for group S. Between the 20th and the 500th cycle, elongation was 4.2±2.3 mm in group P and 2.5±0.9 mm in group S (not significant, P>0.05). This is the first study investigating the biomechanical properties of tibial press-fit fixation of the patellar tendon with accessory bone plug in posterior cruciate ligament reconstruction. The implant-free tibial inlay technique shows equal biomechanical characteristics compared to an interference screw fixation. Further in vivo studies are desirable to compare the biological behavior and clinical relevance of this fixation device.
PMCID: PMC3883076  PMID: 24416479
posterior cruciate ligament reconstruction; tibial press-fit fixation; interference screw; biomechanical properties
17.  Tip apex distance, hip screw placement, and neck shaft angle as potential risk factors for cut-out failure of hip screws after surgical treatment of intertrochanteric fractures 
International Orthopaedics  2012;36(11):2347-2354.
To describe the quality of osteosynthesis after intertrochanteric fractures evaluation of tip apex distance (TAD) and position of the hip screw have been established. Furthermore, a slightly valgus fracture reduction has been suggested to reduce the risk of cut-out failure. However, uniform recommendations for optimal screw positioning and fracture reduction are still missing. The purpose of our study was to confirm potential risk factors for cut-out of hip screws of intertrochanteric fractures and to provide recommendations for practical clinical use.
A retrospective analysis of all patients with intertrochanteric fractures treated with a DHS or a gamma nail between January of 2007 and May of 2010 was performed at a level I trauma center.
Two hundred thirty-five patients with intertrochanteric fractures after intra- and extramedullary stabilization were analyzed. A TAD of more than 25 mm was demonstrated to be the most important factor for cut-out in stable and unstable fractures. Fracture reduction with a valgus NSA of 5–10° was associated with a trend towards a lower rate of screw cut-out while an anterior placement of the screw (Parker’s ratio index of <40) significantly increased cut-out incidence.
According to our results, the TAD should not exceed 25 mm in stable (AO/OTA A1) as well as unstable (AO/OTA A2) fractures. An increased anterior hip screw placement should be avoided while fracture reduction with a slight valgus Neck Shaft seems favorable.
PMCID: PMC3479298  PMID: 23011721
18.  Simultaneous Bilateral Transitional Fractures of the Proximal Tibia after Minor Sports Trauma 
Case Reports in Orthopedics  2013;2013:724802.
We report a very rare case of a 16-year-old healthy athletic boy who sustained simultaneous bilateral transitional fractures of the proximal tibia after kicking a football with his right leg during a soccer game. Following minimal invasive plate osteosynthesis with bridging of the growth plate, the patient recovered rapidly without any growth disturbances.
PMCID: PMC3804443  PMID: 24191212
19.  Emergency Closed Reduction of a C4/5 Fracture Dislocation with Complete Paraplegia Resulting in Profound Neurologic Recovery 
Case Reports in Orthopedics  2013;2013:272865.
Introduction. Cervical spinal cord injuries due to traumatic fractures are associated with persistent neurological deficits. Although clinical evidence is weak, early decompression, defined as <24–72 h, has been frequently proposed. Animal studies show better outcomes after early decompression within one hour or less, which can hardly ever be achieved in clinical practice. Case Presentation. A 37-year-old patient was hospitalized after being hit by a shying horse. After diagnosis of C4/5 fracture dislocation and complete paraplegia, she was intubated and sedated with deep relaxation. Emergency reduction was performed at approximately 120 minutes after trauma. Subsequently, a standard anterior decompression, discectomy, and fusion were carried out. She was then transferred to a specialized rehabilitation hospital. Her neurologic function improved from AIS grade A on admission to grade B postoperatively and grade D after four months of rehabilitation. One year after the accident, she was ambulatory without walking aids and restarted horse riding. Discussion and Conclusion. Rarely in clinical practice, decompression of the spine canal can be performed as early as in this case. This case highlights the potential benefit of utmost early reduction in cervical fracture dislocations with compression of the spinal cord.
PMCID: PMC3789362  PMID: 24151573
20.  Simultaneous Bilateral Quadriceps Tendon Rupture following Long-Term Low-Dose Nasal Corticosteroid Application 
Case Reports in Orthopedics  2013;2013:657845.
Simultaneous bilateral quadriceps tendon rupture is a very rare injury, which was previously only described in slightly more than 100 cases in the English literature. Occurrence after minor trauma is predominantly associated with certain medical conditions including chronic diseases and long-term use of certain drugs. We report the case of a 61-year-old healthy patient who sustained a simultaneous bilateral quadriceps tendon rupture following minor trauma. Medical history was completely clear except of a long-term nasal corticosteroid medication due to allergic rhinitis.
PMCID: PMC3747487  PMID: 23984143
21.  Survival benefit of helicopter emergency medical services compared to ground emergency medical services in traumatized patients 
Critical Care  2013;17(3):R124.
Physician-staffed helicopter emergency medical services (HEMS) are a well-established component of prehospital trauma care in Germany. Reduced rescue times and increased catchment area represent presumable specific advantages of HEMS. In contrast, the availability of HEMS is connected to a high financial burden and depends on the weather, day time and controlled visual flight rules. To date, clear evidence regarding the beneficial effects of HEMS in terms of improved clinical outcome has remained elusive.
Traumatized patients (Injury Severity Score; ISS ≥9) primarily treated by HEMS or ground emergency medical services (GEMS) between 2007 and 2009 were analyzed using the TraumaRegister DGU® of the German Society for Trauma Surgery. Only patients treated in German level I and II trauma centers with complete data referring to the transportation mode were included. Complications during hospital treatment included sepsis and organ failure according to the criteria of the American College of Chest Physicians/Society of Critical Care Medicine (ACCP/SCCM) consensus conference committee and the Sequential Organ Failure Assessment (SOFA) score.
A total of 13,220 patients with traumatic injuries were included in the present study. Of these, 62.3% (n = 8,231) were transported by GEMS and 37.7% (n = 4,989) by HEMS. Patients treated by HEMS were more seriously injured compared to GEMS (ISS 26.0 vs. 23.7, P < 0.001) with more severe chest and abdominal injuries. The extent of medical treatment on-scene, which involved intubation, chest and treatment with vasopressors, was more extensive in HEMS (P < 0.001) resulting in prolonged on-scene time (39.5 vs. 28.9 minutes, P < 0.001). During their clinical course, HEMS patients more frequently developed multiple organ dysfunction syndrome (MODS) (HEMS: 33.4% vs. GEMS: 25.0%; P < 0.001) and sepsis (HEMS: 8.9% vs. GEMS: 6.6%, P < 0.001) resulting in an increased length of ICU treatment and in-hospital time (P < 0.001). Multivariate logistic regression analysis found that after adjustment by 11 other variables the odds ratio for mortality in HEMS was 0.75 (95% CI: 0.636 to 862).
Afterwards, a subgroup analysis was performed on patients transported to level I trauma centers during daytime with the intent of investigating a possible correlation between the level of the treating trauma center and posttraumatic outcome. According to this analysis, the Standardized Mortality Ratio, SMR, was significantly decreased following the Trauma Score and the Injury Severity Score (TRISS) method (HEMS: 0.647 vs. GEMS: 0.815; P = 0.002) as well as the Revised Injury Severity Classification (RISC) score (HEMS: 0.772 vs. GEMS: 0.864; P = 0.045) in the HEMS group.
Although HEMS patients were more seriously injured and had a significantly higher incidence of MODS and sepsis, these patients demonstrated a survival benefit compared to GEMS.
PMCID: PMC4056624  PMID: 23799905
22.  The Phosphate Source Influences Gene Expression and Quality of Mineralization during In Vitro Osteogenic Differentiation of Human Mesenchymal Stem Cells 
PLoS ONE  2013;8(6):e65943.
For in vitro differentiation of bone marrow-derived mesenchymal stem cells/mesenchymal stromal cells into osteoblasts by 2-dimensional cell culture a variety of protocols have been used and evaluated in the past. Especially the external phosphate source used to induce mineralization varies considerably both in respect to chemical composition and concentration. In light of the recent findings that inorganic phosphate directs gene expression of genes crucial for bone development, the need for a standardized phosphate source in in vitro differentiation becomes apparent. We show that chemical composition (inorganic versus organic phosphate origin) and concentration of phosphate supplementation exert a severe impact on the results of gene expression for the genes commonly used as markers for osteoblast formation as well as on the composition of the mineral formed. Specifically, the intensity of gene expression does not necessarily correlate with a high quality mineralized matrix. Our study demonstrates advantages of using inorganic phosphate instead of β-glycerophosphate and propose colorimetric quantification methods for calcium and phosphate ions as cost- and time-effective alternatives to X-ray diffraction and Fourier-transform infrared spectroscopy for determination of the calcium phosphate ratio and concentration of mineral matrix formed under in vitro-conditions. We critically discuss the different assays used to assess in vitro bone formation in respect to specificity and provide a detailed in vitro protocol that could help to avoid contradictory results due to variances in experimental design.
PMCID: PMC3688813  PMID: 23823126
23.  Pectus excavatum in blunt chest trauma: a case report 
Blunt cardiac rupture is an exceedingly rare injury.
Case presentation
We report a case of blunt cardiac trauma in a 43-year-old Caucasian German mother with pectus excavatum who presented after a car accident in which she had been sitting in the front seat holding her two-year-old boy in her arms. The mother was awake and alert during the initial two hours after the accident but then proceeded to hemodynamically collapse. The child did not sustain any severe injuries. Intraoperatively, a combined one-cm laceration of the left atrium and right ventricle was found.
Patients with pectus excavatum have an increased risk for cardiac rupture after blunt chest trauma because of compression between the sternum and spine. Therefore, patients with pectus excavatum and blunt chest trauma should be admitted to a Level I Trauma Center with a high degree of suspicion.
PMCID: PMC3567954  PMID: 23320897
Blunt cardiac rupture; Pectus excavatum; Seatbelt injury
24.  The role of stem cells in fracture healing and nonunion 
International Orthopaedics  2011;35(11):1587-1597.
Nonunion and large bone defects present a therapeutic challenge to the surgeon and are often associated with significant morbidity. These defects are expensive to both the health care system and society. However, several surgical procedures have been developed to maximise patient satisfaction and minimise health-care-associated and socioeconomic costs. Integrating recent evidence into the diamond concept leads to one simple conclusion that not only provides us with answers to the “open questions” but also simplifies our entire understanding of bone healing. It has been shown that a combination of neo-osteogenesis and neovascularisation will restore tissue deficits, and that the optimal approach includes a biomaterial scaffold, cell biology techniques, a growth factor and optimisation of the mechanical environment. Further prospective, controlled, randomised clinical studies will determine the effectiveness and economic benefits of treatment with mesenchymal stem cells, not in comparison to other conventional surgical approaches but in direct conjunction with them.
PMCID: PMC3193959  PMID: 21863226
25.  Intraprosthetic fixation techniques in the treatment of periprosthetic fractures-A biomechanical study 
World Journal of Orthopedics  2012;3(10):162-166.
AIM: To develop new fixation techniques for the treatment of periprosthetic fractures using intraprosthetic screw fixation with inserted threaded liners.
METHODS: A Vancouver B1 periprosthetic fracture was simulated in femur prosthesis constructs using sawbones and cemented regular straight hip stems. Fixation was then performed with either unicortical locked-screw plating using the less invasive stabilization system-plate or with intraprosthetic screw fixation using inserted liners. Two experimental groups were formed using either prostheses made of titanium alloy or prostheses made of cobalt chrome alloy. Fixation stability was compared in an axial load-to-failure model. Drilling was performed using a specially invented prosthesis drill with constantly applied internal cooling.
RESULTS: The intraprosthetic fixation model with titanium prostheses was superior to the unicortical locked-screw fixation in all tested devices. The intraprosthetic fixation model required 10 456 N ± 1892 N for failure and the unicortical locked-screw plating required 7649 N ± 653 N (P < 0.05). There was no significant difference between the second experimental group and the control group.
CONCLUSION: Intraprosthetic screw anchorage with special threaded liners enhances the primary stability in treating periprosthetic fractures by internal fixation.
PMCID: PMC3536858  PMID: 23326763
Periprosthetic fracture; Less invasive stabilization system; Plate fixation; Intraprosthetic screw fixation; Material science; Biomechanical testing; Axial load-to-failure

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