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Purpose: We evaluated the biomechanical characteristics of the transiliac internal fixator (TIFI) as compared to two well-established methods of internal posterior pelvic ring fixation.Methods: Six freshly frozen human pelves were used for simulated single-leg stance loading of an AO type C injury model (pubic symphysis diastasis and unilateral sacroiliac joint disruption). The symphysis rupture was stabilized with a dynamic compression plate. Afterwards the three internal stabilization systems (TIFI, iliosacral screws and ventral plate osteosynthesis) were analysed. Fragment movement was measured in a contact-free manner with a stereophotometric infrared system.Results: No significant differences in the three-dimensional deformation tolerated by the TIFI as compared to the other internal fixation systems were found.Conclusions: The transiliac internal fixator provides the same biomechanical stability as the other reference implants tested. We suggest the use of this device as a suitable alternative to the other implants. [ABSTRACT FROM AUTHOR]

Introduction: External fixation is widely accepted as a provisional or sometimes definitive treatment for long-bone fractures. Indications include but are not limited to damage control surgery in poly-traumatized patients as well as provisional bridging to definite treatment with soft tissue at risk. As little is known about surgeon's habits in applying this treatment strategy, we performed a national survey., Methods: We utilized the member database of the German Trauma Society (DGU). The questionnaire encompassed 15 questions that addresses topics including participants' position, experience, workplace, and questions regarding specifics of external fixation application in different anatomical regions. Furthermore, we compared differences between trauma centre levels and surgeon-related factors., Results: The participants predominantly worked in level 1 trauma centres (42.7%) and were employed as attendings (54.7%). There was widespread consensus for planning and intra-operative radiographical control of external fixation. Surgeons appointed at a level I trauma centre preferred significantly more often supra-acetabular pin placement in external fixation of the pelvis rather than the utilization of iliac pins (75.8%, p = 0.0001). Moreover, they were more likely to favor a mini-open approach to insert humeral pins (42.4%, p = 0.003). Overall, blunt dissection and mini-open approaches seemed equally popular (38.2 and 34.1%). Department chairmen indicated more often than their colleagues to follow written pin-care protocols for minimization of infection (16.7%, p = 0.003)., Conclusion: Despite the fact that external fixation usage is widespread and well established among trauma surgeons in Germany, there are substantial differences in the method of application.

Purpose: The aim of this study was to analyse possible indicative parameters for percutaneous ilio-sacral stabilisation and to identify parameters associated with screw misplacement., Methods: Cohort study, level I trauma centre., Inclusion Criteria: (1) unstable pelvic injury, (2) percutaneous ilio-sacral screws placement., Exclusion Criteria: (1) sacral dysmorphy, (2) failed closed reduction, (3) navigated techniques. Indicative parameters were age, gender, body mass index, number of screws, screw angulation, fracture type and injury severity. End points were ilio-sacral screw position and associated complications. Screw placement accuracy was graded as follows: grade 0, no perforation; grade 1, perforation <2 mm; grade 2, perforation from 2 to 4 mm; grade 3, ≥4 mm perforation., Results: Between March 2008 and March 2013, 102 (53 women) patients were included (mean age, 48.5 ± 21.4 years). The Injury Severity Score (ISS) and New Injury Severity Score (NISS) were 18.9 ± 9.9 and 22.3 ± 22.3, respectively. The positions of 137 ilio-sacral screws were analysed. Of all screws, 87.6 % (120) were placed satisfactory (<2 mm perforation). The incidence of screw misplacement was significantly higher in the case of two unilateral S1 screws compared with a single screw (failure rate: two unilateral screws 23.1 % vs single screw 7.0 %; p < 0.05). Screw perforation anterior to the lateral mass (in-out-in) represented the most frequent malposition. Revision was necessary in three cases due to malpositioning. Furthermore, no major complication occurred., Conclusions: We conclude, that twofold ilio-sacral screw positioning from one side increases the risk for screw misplacement. In this case, alternative techniques like navigation should be considered. Anterior screw perforation represents a common problem with a high incidence and warrants particular attention.

Purpose: Open fibrin gluing is reported to enable anatomical reconstruction with less soft tissue compromise than suture repair. Our main objective was to compare the complication rate, function, pain and disability of the two operative approaches of percutaneous suture using the Paessler technique and open fibrin gluing., Methods: Sixty-four patients (two centres, retrospective cohort study, 2000-2009) who had undergone acute Achilles tendon repair with either percutaneous suture (n = 27; 44 years) or open fibrin glue (n = 37; 45 years) took part in a follow-up examination after a median of 63 months (range, six to 180). Ankle range of motion, calf and ankle circumferences and return to work and sports activities were evaluated. Isokinetic und sonographic evaluation results were retrieved., Results: Complications were noted in 22 patients (34 %). Delayed wound healing without evidence of surgical site infection was found in three patients in the fibrin group and two patients in the suture group. Postoperative scar tenderness described as pain at the rim of the shoe was significantly more frequent in the suture group (p = 0.03). Re-rupture requiring re-operation occurred in one patient. Transient paresthesia of the heel occurred in 12 patients. No sural nerve lesions were reported. There was no significant difference between groups regarding lower leg circumference, disability, or function. Ultrasound and isokinetic measurements did not reveal a significant difference between the two methods., Conclusions: The present study suggests that open fibrin gluing is a reasonable alternative to percutaneous repair of acute ruptures of the Achilles tendon and both techniques can yield reliably good results.

Purpose: The benefits of minimally invasive surgical techniques in total hip arthroplasty (THA) are well known, but concerns about applying those techniques in obese patients are controversial. We prospectively compared patients with increased body mass index (BMI ≥ 30) undergoing THA with normal weight patients., Methods: A total of 134 patients admitted for unilateral THA were randomised to have surgery through either a transgluteal or a minimally invasive approach (MicroHip). In each group a BMI ≥ 30 was used to define obese patients. Pre- and early post-operative demographics, intraoperative data, baseline haematological values, hip function (Harris Hip Score, Oxford Hip Score) and quality of life (EQ-5D) were assessed with follow-up at three months., Results: Duration of surgery, blood loss, C-reactive protein levels, radiographic measurements and complication rates were comparable in all groups. There was a tendency for lower serum creatine kinase levels in the MicroHip group. Intraoperative fluoroscopic time and dose area products were significantly elevated in patients with a BMI exceeding 30 regardless of the approach used. Time points of mobilisation, length of hospital stay and functional outcome measurements were similar in the different weight groups., Conclusions: Our data suggest that obese patients gain similar benefit from MicroHip THA as do non-obese patients. The results of this study should be further investigated to assess long-term survivorship.

Purpose: Mesenchymal stem cells (MSCs) express markers of hypertrophic chondrocytes during chondrogenic differentiation. We tested the suitability of parathyroid hormone-related protein (PTHrP), a regulator of chondrocyte hypertrophy in embryonic cartilage development, for the suppression of hypertrophy in an in vitro hypertrophy model of chondrifying MSCs., Methods: Chondrogenesis was induced in human MSCs in pellet culture for two weeks and for an additional two weeks cultures were either maintained in standard chondrogenic medium or transferred to a hypertrophy-enhancing medium. PTHrP(1-40) was added to the medium throughout the culture period at concentrations from 1 to 1,000 pM. Pellets were harvested on days one, 14 and 28 for biochemical and histological analysis., Results: Hypertrophic medium clearly enhanced the hypertrophic phenotype, with increased cell size, and strong alkaline phosphatase (ALP) and type X collagen staining. In chondrogenic medium, 1-100 pM PTHrP(1-40) did not inhibit chondrogenic differentiation, whereas 1,000 pM PTHrP(1-40) significantly reduced chondrogenesis. ALP activity was dose-dependently reduced by PTHrP(1-40) at 10-1,000 pM in chondrogenic conditions. Under hypertrophy-enhancing conditions, PTHrP(1-40) did not inhibit the induction of the hypertrophy. At the highest concentration (1,000 pM) in the hypertrophic group, aggregates were partially dedifferentiated and differentiated areas of these aggregates maintained their hypertrophic appearance., Conclusions: PTHrP(1-40) treatment dose-dependently reduced ALP expression in MSC pellets cultured under standard chondrogenic conditions and is thus beneficial for the maintenance of the chondrogenic phenotype in this medium condition. When cultured under hypertrophy-enhancing conditions, PTHrP(1-40) could not diminish the induced enhancement of hypertrophy in the MSC pellets.

Purpose: Percutaneous reduction and periarticular screw implantation techniques have been successfully introduced in acetabular surgery. The advantages of this less invasive approach are attenuated by higher risks of screw misplacement. Anatomical landmarks are strongly needed to prevent malplacement. This cadaver study was designed to identify reliable anatomical osseous landmarks in the pelvic region for screw placement in acetabular surgery. Gender differences were specifically addressed., Methods: Twenty-seven embalmed cadaveric hemipelvic specimens (13 male, 14 female) were used. After soft-tissue removal, anterior and posterior column acetabular screw placement was conducted by one orthopaedic trauma surgeon under direct vision. Each column was addressed by antegrade and retrograde screw insertion. Radiographic verification of ideal screw placement was followed by assessment of the distance from the different entry points to adjoining anatomical osseous structures., Results: For anterior column screw positioning, the posterior superior iliac spine (PSIS), posterior inferior iliac spine (PIIS), iliopectineal eminence and centre of the symphysis were most reliable regarding gender differences. For posterior column screw positioning, the distance to the anterior superior iliac spine (ASIS) and the ischial tuberosity showed the lowest deviation between the different gender specimens. Highest gender differences were seen in relation to the cranial rim of the superior pubic ramus in retrograde anterior column screw positioning (p = 0.002). Most landmarks could be targeted within a 2.5-cm range in all specimens., Conclusions: The findings emphasise the relevance of osseous landmarks in acetabular surgery. By adhering to easily identifiable structures, screw placement can be safely performed. Significant gender differences must be taken into consideration during preoperative planning.

Mesenchymal stromal cells have the potential to differentiate into a variety of mesenchymal tissues such as bone, cartilage and ligaments. The potential for the regeneration of bone with cartilage coverage has still not been achieved. We evaluated the ability of bone marrow mesenchymal stromal cells to regenerate osteochondral defects in the cavity of the lunate in an animal model. Autologous mesenchymal stromal cells were harvested from the iliac crest of New Zealand white rabbits and expanded in vitro. Total lunate excision was performed in 24 animals and the isolated cells were loaded onto scaffolds. Cell-free scaffolds were implanted in the lunate space of the right wrists of all animals, and the left lunate spaces were filled with predifferentiated, cell-loaded scaffolds. Radiographic and histological analyses were performed after two, six and 12 weeks. In addition, the animals were injected with a fluorescent agent every five days, starting at day 30. After two and six weeks there was no radiographic evidence of ossification, whereas after 12 weeks all animals showed radiographic evidence of ossification. Histological sections showed increasing evidence of cartilage-like cell formation at the edges and new bone tissue in the centre of the newly formed tissue in all groups. The histological examinations showed that bone tissue was located around the newly incorporated vascularisation. This study demonstrated that newly formed vascularisation is necessary for the regeneration of bone tissue with cell-loaded scaffolds.