Evaluation of two different semi-automated homogenization techniques in microbiological diagnosis of periprosthetic joint infection: disperser vs. bead milling method.

BACKGROUND: In microbiological diagnosis of periprosthetic joint infection (PJI) there is no consensus regarding the most suitable and optimal number of specimens to be cultured or the most effective technique of tissue processing. This comparative study analysed the accuracy of two semi-automated homogenization methods with special focus on the volume and exact origin of each sample. METHODS: We investigated a total of 722 periprosthetic tissue samples. PJI was defined according to the new scoring system for preoperative and intraoperative criteria. We compared the performance of our routinely used single tissue processing by disposable high-frequency disperser with the bead milling method. RESULTS: Eighty patients were included. Among forty classified PJIs, 34 patients yielded positive culture results. In 23 cases (68%) exact concordant results were generated with both techniques. However, in seven cases (20%) processing by the disperser and in four cases (12%) by bead milling provided additional positive samples, but without significant difference since the major definition criteria were met in all cases. The percentage of positive results was influenced by the volume and origin of the tissue samples. Results for small tissue samples tended to be better using the bead milling method. This might lead to improved preoperative arthroscopic diagnosis, as the volume of biopsies is generally limited. Six patients had negative results due to previous antimicrobial therapy. Forty other patients were classified as aseptic failures. Neither procedure resulted in any contamination. CONCLUSION: Both methods enable reliable processing of tissue samples for diagnosis of PJI and are suitable for routine use.

Standards for external fixation application: national survey under the auspices of the German Trauma Society.

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.

Return to Sports After Multiple Trauma: Which Factors Are Responsible?-Results From a 17-Year Follow-up.

OBJECTIVE: We hypothesize that the majority of polytraumatised patients are unable to maintain their preinjury level of sporting activity, and that musculoskeletal injuries are a major contributing factor. We assessed the impact of such injuries on sporting prowess, with a focus on isolating, particularly debilitating musculoskeletal trauma. METHODS: We conducted a cohort study of 637 patients at a level 1 trauma centre, to assess the long-term outcome of severe trauma on return to sporting activities (RTS). Data collated on the multiply injured patient included preinjury physical activity, standardized outcome scores (SF-12, GOS, HASPOC), and clinical follow-up of at least 10 years duration. The return to preinjury sports participation was defined as a primary outcome parameter. Regression analyses were performed to identify specific injuries interfering with the RTS. STUDY DESIGN: Prognostic study; Level of evidence, II. RESULTS: Mean follow-up was 17 ± 5 years. We included 465 patients, including 207 athletic and 258 nonathletic individuals. Mean age at the time of injury was 26 ± 11.5 years and injury severity was comparable between the 2 cohorts. The deleterious effects on quality of life and the total duration of the rehabilitation process were also similar in athletes and nonathletes. Athletes were more likely to be unable to return to preinjury activities, or to return to a lower level of sporting prowess posttrauma. We identified knee injuries as the type of musculoskeletal trauma most likely to be career ending for the athlete (odds ratio 3.4, 95% confidence interval, 1.4-8.3; P = 0.008). CONCLUSION: Our results demonstrate an enforced shift from high-impact and team sports to low-impact activities after multiple trauma. Injuries of the lower extremities, especially around the knee joint, seem to have the highest lifechanging potential, preventing individuals from returning to their previous sporting activities.

Assessment of pelvic injuries treated with ilio-sacral screws: injury severity and accuracy of screw positioning.

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.

Is percutaneous suturing superior to open fibrin gluing in acute Achilles tendon rupture?

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.

Models of hemorrhagic shock: differences in the physiological and inflammatory response.

INTRODUCTION: The hemorrhagic shock (HS) model is commonly used to initiate a systemic post-traumatic inflammatory response. Numerous experimental protocols exist and it is unclear how differences in these models affect the immune response making it difficult to compare results between studies. The aim of this study was to compare the inflammatory response of different established protocols for volume-controlled shock in a murine model. METHODS: Male C57/BL6 mice 6-10 weeks and weighing 20-25 g were subjected to volume-controlled or pressure-controlled hemorrhagic shock. In the volume-controlled group 300 µl, 500 µl, or 700 µl blood was collected over 15 min and mean arterial pressure was continuously monitored during the period of shock. In the pressure-controlled hemorrhagic shock group, blood volume was depleted with a goal mean arterial pressure of 35 mmHg for 90 min. Following hemorrhage, mice from all groups were resuscitated with the extracted blood and an equal volume of lactated ringer solution. Six hours from the initiation of hemorrhagic shock, serum IL-6, KC, MCP-1 and MPO activity within the lung and liver tissue were assessed. RESULTS: In the volume-controlled group, the mice were able to compensate the initial blood loss within 30 min. Approximately 800 µl of blood volume was removed to achieve a MAP of 35 mmHg (p<0.001). No difference in the pro-inflammatory cytokine (IL-6 and KC) profile was measured between the volume-controlled groups (300 µl, 500 µl, or 700 µl). The pressure-controlled group demonstrated significantly higher cytokine levels (IL-6 and KC) than all volume-controlled groups. Pulmonary MPO activity increased with the severity of the HS (p<0.05). This relationship could not be observed in the liver. CONCLUSION: Volume-controlled hemorrhagic shock performed following current literature recommendations may be insufficient to produce a profound post-traumatic inflammatory response. A decrease in the MAP following blood withdrawal (300 µl, 500 µl or 700 µl) was usually compensated within 30 min. Pressure-controlled hemorrhagic shock is a more reliable for induction of a systemic inflammatory response.

Do parameters used to clear noncritically injured polytrauma patients for extremity surgery predict complications?

BACKGROUND: In multiply injured patients, definitive stabilization of major fractures is performed whenever feasible, depending on the clinical condition. QUESTIONS/PURPOSES: We therefore asked whether (1) any preoperative indicators predict major complications after major extremity surgery; (2) perioperative routine parameters other than those indicative of hemorrhagic shock predict postoperative complications; and (3) any postoperative clinical findings can predict major complications in the further course of the patient. METHODS: We prospectively followed patients with femoral midshaft fracture, Injury Severity Score (ISS) > 16 points, or three fractures and Abbreviated Injury Scale (AIS) ≥ 2 points and another injury (AIS ≥ 2 points), and age 18 to 65 years. We recorded multiple clinical parameters. End points were pneumonia, sepsis, acute respiratory distress syndrome, acute lung injury, and multiple organ failure. RESULTS: Forty-three of 165 patients developed complications. (1) Patients with complications had a decreased initial Glasgow Coma Scale and tended to have a lower ISS. (2) None of the assessed perioperative parameters was able to sufficiently predict postoperative complications. (3) The presence of a lung contusion and ventilation > 48 hours were associated with complications in the further course. CONCLUSIONS: In stable multiply injured patients, none of the individual routine clinical parameters was able to predict complications. Severe head and thoracic injuries seem to be important drivers for the development postoperative complications.

Trauma care in Germany: an inclusive system.

BACKGROUND: Development of trauma systems is a demanding process. The United States and Germany both have sophisticated trauma systems. This manuscript is a summary of political, economic, and medical changes that have led to the development of both trauma systems and the current high-quality standards. QUESTIONS/PURPOSES: We specifically asked three questions: (1) What tasks are involved in developing a modern trauma system? (2) What is the approach to achieve this task? (3) Do these systems work? METHODS: We conducted a systematic review of relevant articles by searching electronic databases (PubMed, Embase, Cochrane library) using the following search terms: "trauma system", "polytrauma", "trauma networks", and "trauma registry". Of 2573 retrieved manuscripts, the authors made a personal selection of studies. A personal study selection from our experiences was added when their contribution to the topic was judged important. RESULTS: Worldwide, similar tasks concerning trauma care have to be addressed. In most societies, traffic accidents and firearm-related injuries contribute to a high number of trauma victims. The German approach has been to decrease the number of accidents through injury prevention and to provide better care by establishing an emergency medical system. For in-hospital treatment, clinical care has constantly improved and a close interaction with members from the American Association for the Surgery of Trauma and the Orthopaedic Trauma Association has helped a great deal to achieve these improvements. The German healthcare system was developed as a powerful healthcare tool covering patients from injury to rehabilitation. In addition, trauma and injury research has been strengthened to deal with various questions of trauma care. CONCLUSIONS: Organized injury prevention programs and systematized professional patient care can address the issues associated with the global burden of trauma. These trauma systems require constant monitoring and improvement.

Type I collagen nerve conduits for median nerve repairs in the forearm.

PURPOSE: To evaluate patients with median nerve damage in the distal forearm treated with type 1 collagen nerve conduits. METHODS: Nine patients with damage to the median nerve in the distal forearm underwent treatment with a type 1 collagen nerve conduit. The nerve gaps ranged between 1 and 2 cm. An independent observer reexamined patients after treatment at a minimal follow-up of 14 months and a mean follow-up of 21 months. Residual pain was evaluated using a visual analog scale. Functional outcome was quantified by assessing static 2-point discrimination, nerve conduction velocity relative to the uninjured limb, and Disabilities of the Arm, Shoulder, and Hand outcome measure scoring. We also recorded quality of life measures including patients' perceived satisfaction with the results and return to work latency. RESULTS: We observed no implant-related complications. Of 9 patients, 7 were free of pain, and the mean visual analog scale was 0.6. The mean Disabilities of the Arm, Shoulder, and Hand score was 6. The static 2-point discrimination was less than 6 mm in 3 patients, between 6 and 10 mm in 4 patients, and over 10 mm in 2 patients. Six patients reached a status of M4 or higher. Eight patients were satisfied with the procedure and would undergo surgery again. CONCLUSIONS: This study indicates that purified type 1 bovine collagen conduits are a practical and efficacious method for the repair of median nerves in the distal forearm. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

A minimally invasive approach for total hip arthroplasty does not diminish early post-operative outcome in obese patients: a prospective, randomised trial.

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.

Screw placement in percutaneous acetabular surgery: gender differences of anatomical landmarks in a cadaveric study.

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.

Effect of parathyroid hormone-related protein in an in vitro hypertrophy model for mesenchymal stem cell chondrogenesis.

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.

Radiographic changes in the operative treatment of acute acromioclavicular joint dislocation - tight rope technique vs. K-wire fixation.

BACKGROUND: Operative treatment of higher degree acromioclavicular joint luxation is common. A new option is made available by the tight rope technique. It claims to provide adequate outcome with the use of a minimally invasive technique. First clinical studies justified its medical use, but the equivalence to established surgical methods remains unclear. We therefore analyzed radiographic data from patients that were treated with the tight rope system (TR) and compared them to those treated with K-wires (KW) fixation. MATERIAL/METHODS: RETROSPECTIVE STUDY WITH INCLUSION CRITERIA: surgery for acromioclavicular joint luxation between 2004 and 2011, classified as Rockwood type III, no concomitant injury, first event injury. We compared pre- and post-operative X-rays with those taken at the end of treatment. Clinical data from follow-ups and radiographic data were evaluated. The main outcome variable was the remaining distance between the acromion and clavicle (ACD), as well as the coracoid process and clavicle (CCD). RESULTS: 27 patients (TR: n=16; KW: n=11) with comparable demographics and injury severity were included. Surgery reduced ACD (TR: p=0.002; KW: p<0.001) and CCD (TR: p=0.001; KW: p=0.003). Heterotopic ossification or postoperative osteolysis was not significantly associated with either one of the procedures. Three patients (18.75%) in the TR group showed impaired wound healing, migrating K-wires were recorded in 2 patients (18.2%) and impingement syndrome occurred in 1 patient (9.1%) with K-wires. Posttraumatic arthritis was not seen. There was a loss of reduction in 2 cases within the TR-group (12.51%) and 1 in the KW-group (9.1%). At last follow up, ACD and CCD were wider in both groups compared to the healthy side. CONCLUSIONS: This study shows that the Tight rope system is an effective alternative in the treatment of higher degree acromioclavicular luxation and comparable to the established methods.

Treatment of long bone defects and non-unions: from research to clinical practice.

The treatment of long bone defects and non-unions is still a major clinical and socio-economical problem. In addition to the non-operative therapeutic options, such as the application of various forms of electricity, extracorporeal shock wave therapy and ultrasound therapy, which are still in clinical use, several operative treatment methods are available. No consensus guidelines are available and the treatments of such defects differ greatly. Therefore, clinicians and researchers are presently investigating ways to treat large bone defects based on tissue engineering approaches. Tissue engineering strategies for bone regeneration seem to be a promising option in regenerative medicine. Several in vitro and in vivo studies in small and large animal models have been conducted to establish the efficiency of various tissue engineering approaches. Neverthelsss, the literature still lacks controlled studies that compare the different clinical treatment strategies currently in use. However, based on the results obtained so far in diverse animal studies, bone tissue engineering approaches need further validation in more clinically relevant animal models and in clinical pilot studies for the translation of bone tissue engineering approaches into clinical practice.

Estradiol inhibits chondrogenic differentiation of mesenchymal stem cells via nonclassic signaling.

OBJECTIVE: We undertook this study to examine the effects of estradiol on chondrogenesis of human bone marrow-derived mesenchymal stem cells (MSCs), with consideration of sex-dependent differences in cartilage repair. METHODS: Bone marrow was obtained from the iliac crest of young men. Density-gradient centrifugation-separated human MSCs proliferated as a monolayer in serum-containing medium. After confluence was achieved, aggregates were created and cultured in a serum-free differentiation medium. We added different concentrations of 17beta-estradiol (E2) with or without the specific estrogen receptor inhibitor ICI 182.780, membrane-impermeable E2-bovine serum albumin (E2-BSA), ICI 182.780 alone, G-1 (an agonist of G protein-coupled receptor 30 [GPR-30]), and G15 (a GPR-30 antagonist). After 21 days, the aggregates were analyzed histologically and immunohistochemically; we quantified synthesized type II collagen, DNA content, sulfated glycosaminoglycan (sGAG) concentrations, and type X collagen and matrix metalloproteinase 13 (MMP-13) expression. RESULTS: The existence of intracellular and membrane-associated E2 receptors was shown at various stages of chondrogenesis. Smaller aggregates and significantly lower type II collagen and sGAG content were detected after treatment with E2 and E2-BSA in a dose-dependent manner. Furthermore, E2 enhanced type X collagen and MMP-13 expression. Compared with estradiol alone, the coincubation of ICI 182.780 with estradiol enhanced suppression of chondrogenesis. Treatment with specific GPR-30 agonists alone (G-1 and ICI 182.780) resulted in a considerable inhibition of chondrogenesis. In addition, we found an enhancement of hypertrophy by G-1. Furthermore, the specific GPR-30 antagonist G15 reversed the GPR-30-mediated inhibition of chondrogenesis and up-regulation of hypertrophic gene expression. CONCLUSION: The experiments revealed a suppression of chondrogenesis by estradiol via membrane receptors (GPR-30). The study opens new perspectives for influencing chondrogenesis on the basis of classic and nonclassic estradiol signaling.

A minimally invasive stabilizing system for dorsal pelvic ring injuries.

BACKGROUND: Open reduction and stabilization of dorsal pelvic ring injuries is accompanied by a high rate of soft tissue complications. Minimally invasive techniques have the potential to decrease soft tissue trauma, but the risk of iatrogenic nerve and vessel damage through the reduced surgical exposure should be considered. We treated these injuries using a transiliac internal fixator (TIFI) in a minimally invasive technique characterized by implantation of a pedicle screw and rod system, bridging the sacroiliac joints and the sacral area. QUESTIONS/PURPOSES: We asked whether (1) we could achieve anatomic restoration with the device, (2) specific complications were associated with this minimally invasive approach (particularly enhanced intraoperative blood loss, soft tissue complications, and iatrogenic neurovascular damage), and (3) function 3 years after trauma was comparable to that of established methods. METHODS: We retrospectively reviewed 67 patients with dorsal pelvic injuries during a 7-year period. We evaluated the (1) reduction by grading the maximal displacement measured with three radiographic views, (2) the complications during the observation period, and (3) the function with a validated questionnaire (Pelvic Outcome Score) in all but five patients at least 3 years after trauma (mean, 37 months; range, 36-42 months). RESULTS: At last followup we observed a secondary fracture displacement greater than 5 mm in one patient. The intraoperative blood loss was less than 50 mL in all patients. No neurovascular lesions occurred owing to implantation. Four patients had wound infections, one had loosening of a single pedicle screw, and one had an iatrogenic screw malpositioning. Thirty-five of the 62 patients achieved Pelvic Outcome Scores of either a maximum score or 6 of 7 points. CONCLUSION: Our observations suggest TIFI is a reasonable alternative to other established fixation devices for injuries of the dorsal pelvic ring with minor risks of major blood loss or iatrogenic neurovascular damage. LEVEL OF EVIDENCE: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Biomechanical analysis of a transiliac internal fixator.

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.

Arthroplasty of the lunate using bone marrow mesenchymal stromal cells.

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.

Hypertrophy in mesenchymal stem cell chondrogenesis: effect of TGF-beta isoforms and chondrogenic conditioning.

Induction of chondrogenesis in mesenchymal stem cells (MSCs) with TGF-beta leads to a hypertrophic phenotype. The hypertrophic maturation of the chondrocytes is dependent on the timed removal of TGF-beta and sensitive to hypertrophy-promoting agents in vitro. In this study, we have investigated whether TGF-beta3, which has been shown to be more prochondrogenic compared to TGF-beta1, similarly enhances terminal differentiation in an in vitro hypertrophy model of chondrogenically differentiating MSCs. In addition, we tested the impact of the time of chondrogenic conditioning on the enhancement of hypertrophy. MSCs were chondrogenically differentiated in pellet culture in medium containing TGF-beta1 or TGF-beta3. After 2 or 4 weeks, chondrogenic medium was switched to hypertrophy-inducing medium for 2 weeks. Aggregates were analyzed histologically and biochemically on days 14, 28 and 42. The switch to hypertrophy medium after 14 days induced hypertrophic cell morphology and significant increase in alkaline phosphatase activity compared to the chondrogenesis only control using both TGF-beta1 and TGF-beta3. After 28 days predifferentiation, differences between hypertrophic and control groups diminished compared to 14 days predifferentiation. In conclusion, chondrogenic conditioning with both TGF-beta isoforms similarly induced hypertrophy in our experiment and allowed the enhancement of the hypertrophic chondrocyte phenotype by hypertrophic medium. Enhancement of hypertrophy was seen more clearly after the shorter chondrogenic conditioning. Therefore, to utilize this experimental model as a tool to study hypertrophy in MSC chondrogenesis, a predifferentiation period of 14 days is recommended.

Asymptomatic dissection of craniocervical arteries in combination with severe cervical spine fractures.

Cervical spine fractures and traumatic dissection of craniocervical arteries are a common combination after severe trauma to the head and neck. Usually, severe symptoms lead the way to diagnosis. We report the case of a young woman involved in a high-velocity car accident without leading neurological symptoms but the threatening combination of dislocation fractures of the C6th/C7th/Th1th vertebrae and dissections of both carotid arteries and one vertebral artery. This case illustrates the need for quick and sufficient clinical diagnostic workup and evaluation and a well-scheduled treatment plan to combine the management of the spinal column fractures and the vascular injury. A review of the relevant literature and therapeutic approaches is presented.