Minimal-invasive anterior approach to the hip provides a better surgery-related and early postoperative functional outcome than conventional lateral approach after hip hemiarthroplasty following femoral neck fractures.

INTRODUCTION: Femoral neck fractures (FNF) are one of the most frequent fractures among elderly patients and commonly require surgical treatment. Bipolar hip hemiarthroplasty (BHHA) is mostly performed in these cases. MATERIAL AND METHODS: In the present retrospective study geriatric patients with FNF (n = 100) treated either by anterior minimal-invasive surgery (AMIS; n = 50) or lateral conventional surgery (LCS; n = 50) were characterized (age at the time of surgery, sex, health status/ASA score, walking distance and need for walking aids before the injury) and intraoperative parameters (duration of surgery, blood loss, complications), as well as postoperative functional performance early (duration of in-patient stay, radiological leg length discrepancy, ability to full weight-bearing, mobilization with walking aids) and 12 months (radiological signs of sintering, clinical parameters, complication rate) after surgery were analyzed. RESULTS: Patients in the AMIS group demonstrated a reduced blood loss intraoperatively, while the duration of surgery and complication rates did not differ between the two groups. Further, more patients in the AMIS group achieved full weight-bearing of the injured leg and were able to walk with a rollator or less support during their in-patient stay. Of interest, patients in the AMIS group achieved this level of mobility earlier than those of the LCS group, although their walking distance before the acute injury was reduced. Moreover, patients of the AMIS group showed equal leg lengths postoperatively more often than patients of the LCS group. No significant differences in functional and surgery-related performance could be observed between AMIS and LCS group at 12 months postoperatively. CONCLUSIONS: In conclusion, geriatric patients treated by AMIS experience less surgery-related strain and recover faster in the early postoperative phase compared to LCS after displaced FNF. Hence, AMIS should be recommended for BHHA in these vulnerable patients.

Effects of locally applied adipose tissue-derived microvascular fragments by thermoresponsive hydrogel on bone healing.

Insufficient vascularization is a major cause for the development of non-unions. To overcome this problem, adipose tissue-derived microvascular fragments (MVF) may serve as vascularization units. However, their application into bone defects needs a carrier system. Herein, we analyzed whether this is achieved by a thermoresponsive hydrogel (TRH). MVF were isolated from CD-1 mice and cultivated after incorporation into TRH, while non-incorporated MVF served as controls. Viability of MVF was assessed immunohistochemically over a 7-day period. Moreover, osteotomies were induced in femurs of CD-1 mice. The osteotomy gaps were filled with MVF-loaded TRH (TRH + MVF), unloaded TRH (TRH) or no material (control). Bone healing was evaluated 14 and 35 days postoperatively. MVF incorporated into TRH exhibited less apoptotic cells and showed a stable vessel morphology compared to controls. Micro-computed tomography revealed a reduced bone volume in TRH + MVF femurs. Histomorphometry showed less bone and more fibrous tissue after 35 days in TRH + MVF femurs compared to controls. Accordingly, TRH + MVF femurs exhibited a lower osseous bridging score and a reduced bending stiffness. Histology and Western blot analysis revealed an increased vascularization and CD31 expression, whereas vascular endothelial growth factor (VEGF) expression was reduced in TRH + MVF femurs. Furthermore, the callus of TRH + MVF femurs showed increased receptor activator of NF-κB ligand expression and higher numbers of osteoclasts. These findings indicate that TRH is an appropriate carrier system for MVF. Application of TRH + MVF increases the vascularization of bone defects. However, this impairs bone healing, most likely due to lower VEGF expression during the early course of bone healing. STATEMENT OF SIGNIFICANCE: In the present study we analyzed for the first time the in vivo performance of a thermoresponsive hydrogel (TRH) as a delivery system for bioactive microvascular fragments (MVF). We found that TRH represents an appropriate carrier for MVF as vascularization units and maintains their viability. Application of MVF-loaded TRH impaired bone formation in an established murine model of bone healing, although vascularization was improved. This unexpected outcome was most likely due to a reduced VEGF expression in the early phase bone healing.

[A new continuous gait analysis system for ankle fracture aftercare]. / Ein neues, kontinuierliches Ganganalysesystem zur Nachbehandlung von Sprunggelenkfrakturen.

BACKGROUND: Correct aftercare following lower extremity fractures remains a controversial issue. Reliable, clinically applicable weight-bearing recommendations have not yet been defined. The aim of the current study was to establish a new gait analysis insole during physical therapy aftercare of ankle fractures to test patients' continuous, long-term compliance to partial weight-bearing restrictions and investigate whether patients can estimate their weight-bearing compliance. MATERIALS AND METHODS: The postoperative gait of 14 patients after operative treatment of Weber B-type ankle fractures was monitored continuously for six weeks (OpenGO, Moticon GmbH, Munich). All patients were instructed and trained by physical therapists on how to maintain partial weight-bearing for this time. Discontinuous (three, six and twelve weeks) clinical (patient questionnaire, visual analogue pain score [VAS]) and radiographic controls were performed. RESULTS: Despite the set weight-bearing limits, individual ranges for overall weight-bearing (range 5-107% of the contralateral side) and patient activity (range 0-366 min/day) could be shown. A good correlation between weight-bearing and pain was seen (rs = -0.68; p = <0.0001). Patients significantly underestimated their weight-bearing time over the set limit (2.3 ± 1.4 min/day vs. real: 12.6 ± 5.9 min/day; p < 0.01). CONCLUSIONS: Standardized aftercare protocols and repeated training alone cannot ensure compliance to postoperative partial weight-bearing. Patients unconsciously increased weight-bearing based on their pain level. This study shows that new, individual and possibly technology-assisted weight-bearing regimes are needed. The introduced measuring device is feasible to monitor and steer patient weight-bearing during future studies.

[Periprosthetic acetabular fractures in geriatric patients]. / Die periprothetische Azetabulumfraktur des geriatrischen Patienten.

Periprosthetic acetabular fractures in geriatric patients are rare injuries; however, the incidence is increasing because of the current demographic developments. For diagnosis of periprosthetic acetabular fractures, conventional X­ray images are regularly complemented by computed tomography (CT). For exclusion of loosening of the prosthesis more advanced techniques, such as single photon emission CT (SPECT/CT) are applied. In addition to classification of periprosthetic acetabular fractures by the traditional system of Letournel there are several other classification systems, which take into account the etiology of the fracture and the stability of the prosthesis. While, under certain circumstances conservative treatment of periprosthetic acetabular fractures is possible, operative treatment often requires extensive surgical procedures to restore the stability of the acetabulum as a support for the cup of the prosthesis. Besides the traditional techniques of acetabular osteosynthesis, special revision systems, augmentations and allografts are used for the reconstruction of periprosthetic acetabular fractures. To determine a therapeutic regimen patient-specific preconditions as well as fracture pattern and type of prosthesis need to be taken into account. In the literature there are several algorithms, which are aimed at supporting the attending physician in making the correct decision for the treatment of periprosthetic acetabular fractures. In cases of periprosthetic acetabular fractures even experienced surgeons are faced with great challenges. Thus, treatment should be carried out in specialized centers.

BMP-2-coated mineral coated microparticles improve bone repair in atrophic non-unions.

Atrophic non-unions are a major clinical problem. Mineral coated microparticles (MCM) are electrolyte-coated hydroxyapatite particles that have been shown in vitro to bind growth factors electrostatically and enable a tuneable sustained release. Herein, we studied whether MCM can be used in vivo to apply Bone Morphogenetic Protein-2 (BMP-2) to improve bone repair of atrophic non-unions. For this purpose, atrophic non-unions were induced in femurs of CD-1 mice (n = 48). Animals either received BMP-2-coated MCM (MCM + BMP; n = 16), uncoated MCM (MCM; n = 16) or no MCM (NONE; n = 16). Bone healing was evaluated 2 and 10 weeks postoperatively by micro-computed tomographic (µCT), biomechanical, histomorphometric and immunohistochemical analyses. µCT revealed more bone volume with more highly mineralised bone in MCM + BMP femurs. Femurs of MCM + BMP animals showed a significantly higher bending stiffness compared to other groups. Histomorphometry further demonstrated that the callus of MCM + BMP femurs was larger and contained more bone and less fibrous tissue. After 10 weeks, 7 of 8 MCM + BMP femurs presented with complete osseous bridging, whereas NONE femurs exhibited a non-union rate of 100 %. Of interest, immunohistochemistry could not detect macrophages within the callus, indicating a good biocompatibility of MCM. In conclusion, the local application of BMP-2-coated MCM improved bone healing in a challenging murine non-union model and, thus, should be of clinical interest in the treatment of non-unions.

[Talus Fractures - an Update]. / Talusfrakturen ­ ein Update.

Background: Talus fractures are rare and often result from axial trauma. As most of the talus surface is covered by cartilage, the blood supply is limited. Thus talus fractures are seen as one of the most severe fractures and often lead to significant long-term complications. Several studies suggest that the initial fracture classification can lead to correct treatment and that this can influence the long-term outcome. The aim of the current study was to investigate the importance of the initial fracture classification in respect to the radiological outcome in a large patient cohort. Patients and Methods: Over a span of 12 years, 61 patients with talus fractures were treated at our institution. Overall 45 patients were available for a retrospective analysis. Correlation analysis was performed between the initial fracture severity and the radiological outcome. Results: The average follow-up was 17.3 months (range 6-68). Significant correlations were found between the Marti-Weber Classification and Bargon Score (rs = 0.78; p < 0.0001), as well as between the Hawkins Classification and the Bargon Score (rs = 0.80; p < 0.0001). Conclusions: Precise prediction of the expected radiological outcome of talar neck and body fractures is possible through the initial fracture classification alone. Computed tomography is the accepted standard to determine the exact diagnosis and extent of injury.

[Influence of the pelvic trauma registry of the DGU on treatment of pelvic ring fractures]. / Einfluss des Beckenregisters der DGU auf die Versorgung von Beckenringfrakturen.

Fractures of the pelvic ring are comparatively rare with an incidence of 2-8 % of all fractures depending on the study in question. The severity of pelvic ring fractures can be very different ranging from simple and mostly "harmless" type A fractures up to life-threatening complex type C fractures. Although it was previously postulated that high-energy trauma was necessary to induce a pelvic ring fracture, over the past decades it became more and more evident, not least from data in the pelvic trauma registry of the German Society for Trauma Surgery (DGU), that low-energy minor trauma can also cause pelvic ring fractures of osteoporotic bone and in a rapidly increasing population of geriatric patients insufficiency fractures of the pelvic ring are nowadays observed with no preceding trauma.Even in large trauma centers the number of patients with pelvic ring fractures is mostly insufficient to perform valid and sufficiently powerful monocentric studies on epidemiological, diagnostic or therapeutic issues. For this reason, in 1991 the first and still the only registry worldwide for the documentation and evaluation of pelvic ring fractures was introduced by the Working Group Pelvis (AG Becken) of the DGU. Originally, the main objectives of the documentation were epidemiological and diagnostic issues; however, in the course of time it developed into an increasingly expanding dataset with comprehensive parameters on injury patterns, operative and conservative therapy regimens and short-term and long-term outcome of patients. Originally starting with 10 institutions, in the meantime more than 30 hospitals in Germany and other European countries participate in the documentation of data. In the third phase of the registry alone, which was started in 2004, data from approximately 15,000 patients with pelvic ring and acetabular fractures were documented. In addition to the scientific impact of the pelvic trauma registry, which is reflected in the numerous national and international publications, the dramatically changing epidemiology of pelvic ring fractures, further developments in diagnostics and the changes in operative procedures over time could be demonstrated. Last but not least the now well-established diagnostic and therapeutic algorithms for pelvic ring fractures, which could be derived from the information collated in registry studies, reflect the clinical impact of the registry.

Obesity does not affect the healing of femur fractures in mice.

Obesity is reported to be both protective and deleterious to bone. Lipotoxicity and inflammation might be responsible for bone loss through inhibition of osteoblasts and activation of osteoclasts. However, little is known whether obesity affects the process of fracture healing. Therefore, we studied the effect of high fat diet-induced (HFD) obesity on callus formation and bone remodelling in a closed femur fracture model in mice. Thirty-one mice were fed a diet containing 60kJ% fat (HFD) for a total of 20 weeks before fracture and during the entire postoperative observation period. Control mice (n=31) received a standard diet containing 10kJ% fat. Healing was analyzed using micro-CT, biomechanical, histomorphometrical, immunohistochemical, serum and protein biochemical analysis at 2 and 4 weeks after fracture. HFD-fed mice showed a higher body weight and increased serum concentrations of leptin and interleukin-6 compared to controls. Within the callus tissue Western blot analyses revealed a higher expression of transcription factor peroxisome proliferator-activated receptor y (PPARy) and a reduced expression of runt-related transcription factor 2 (RUNX2) and bone morphogenetic protein (BMP)-4. However, obesity did not affect the expression of BMP-2 and did not influence the receptor activator of nuclear factor κB (RANK)/RANK ligand/osteoprotegerin (OPG) pathway during fracture healing. Although the bones of HFD-fed animals showed an increased number of adipocytes within the bone marrow, HFD did not increase callus adiposity. In addition, radiological and histomorphometric analysis could also not detect significant differences in bone formation between HFD-fed animals and controls. Accordingly, HFD did not affect bending stiffness after 2 and 4 weeks of healing. These findings indicate that obesity does not affect femur fracture healing in mice.

Characterization of the healing process in non-stabilized and stabilized femur fractures in mice.

BACKGROUND: Although a variety of suitable fracture models for mice exist, in many studies bone healing was still analyzed without fracture stabilization. Because there is little information whether the healing of non-stabilized fractures differs from that of stabilized fractures, we herein studied the healing process of non-stabilized compared to stabilized femur fractures. MATERIALS AND METHODS: Twenty-one CD-1 mice were stabilized after midshaft fracture of the femur with an intramedullary screw allowing micromovements and endochondral healing. In another 22 mice the femur fractures were left unstabilized. Bone healing was studied by radiological, biomechanical, histomorphometric and protein expression analyses. RESULTS: Non-stabilized femur fractures revealed a significantly lower biomechanical stiffness compared to stabilized fractures. During the early phase of fracture healing non-stabilized fractures demonstrated a significantly lower amount of osseous tissue and a higher amount of cartilage tissue. During the late phase of fracture healing both non-stabilized and stabilized fractures showed almost 100 % osseous callus tissue. However, in stabilized fractures remodeling was almost completed with lamellar bone while non-stabilized fractures still showed large callus with great amounts of woven bone, indicating a delay in bone remodeling. Of interest, western blot analyses of callus tissue demonstrated in non-stabilized fractures a significantly reduced expression of vascular endothelial growth factor and a slightly lowered expression of bone morphogenetic protein-2 and collagen-10. CONCLUSION: Non-stabilized femur fractures in mice show a marked delay in bone healing compared to stabilized fractures. Therefore, non-stabilized fracture models may not be used to analyze the mechanisms of normal bone healing.

[The Biological Knife II - Fracture Healing and Pharmacological Interactions]. / Das biologische Skalpell II - Frakturheilung und pharmakologische Einflussfaktoren.

The reasons for delayed fracture healing or non-union formation are multifactorial. Mechanical factors are well known to influence the process of fracture healing. However, there is a lack of knowledge about the biological conditions that have to be achieved for adequate bone healing. Treatment of non-unions is still demanding and we have only poor options to stimulate the bone healing process. Therefore, it is important to optimise the biological conditions to avoid non-union formation. Beside patient-related factors, pharmacological drugs are able to impede or stimulate fracture healing. Especially geriatric patients show a pre-existing drug medication due to different co-morbidities. However, also younger patients are frequently treated with different drugs for infection prophylaxis, analgesia or thrombosis prophylaxis. The aim of the current review article is to give an overview about the influence of different pharmacological agents on the process of fracture healing. A deeper understanding of a drug-related influence on fracture healing could help the medical practitioner to optimise the general conditions for adequate fracture healing, i.e., by avoiding specific pharmacological agents. Vice versa some drugs could be used to stimulate fracture healing in the future.

[Complex pelvic traumas : data linkage of the German Pelvic Injury Register and the TraumaRegister DGU®]. / Das komplexe Beckentrauma : Matching des Beckenregisters DGU mit dem TraumaRegister DGU®.

BACKGROUND: Complex pelvic traumas, i.e., pelvic fractures accompanied by pelvic soft tissue injuries, still have an unacceptably high mortality rate of about 18 %. PATIENTS AND METHODS: We retrospectively evaluated an intersection set of data from the TraumaRegister DGU® and the German Pelvic Injury Register from 2004-2009. Patients with complex and noncomplex pelvic traumas were compared regarding their vital parameters, emergency management, stay in the ICU, and outcome. RESULTS: From a total of 344 patients with pelvic injuries, 21 % of patients had a complex and 79 % a noncomplex trauma. Complex traumas were significantly less likely to survive (16.7 % vs. 5.9 %). Whereas vital parameters and emergency treatment in the preclinical setting did not differ substantially, patients with complex traumas were more often in shock and showed acute traumatic coagulopathy on hospital arrival, which resulted in more fluid volumes and transfusions when compared to patients with noncomplex traumas. Furthermore, patients with complex traumas had more complications and longer ICU stays. CONCLUSION: Prevention of exsanguination and complications like multiple organ dysfunction syndrome still pose a major challenge in the management of complex pelvic traumas.

[Fractures of the acetabulum: complications and joint replacement]. / Azetabulumfrakturen: Komplikationen und Endoprothetik.

Acetabular fractures assume a special role amongst the fractures of the pelvis, because they involve a major weight-bearing joint. As those fractures mostly result from exposure to great force, and because of their location in an anatomically complex region, a high rate of complications has to be anticipated. Besides general and perioperative complications long-term consequences, especially post-traumatic arthrosis, are relevant problems when it comes to treating fractures of the acetabulum. The primary reconstruction of the acetabulum, as well as a possibly necessary prosthetic replacement of the hip joint, makes high demands on the diagnostic and operative capabilities of the attending physician. Exact knowledge of the specific risks and pitfalls for each type of fracture and for the specific surgical techniques is crucial for a successful treatment. Due to the much worse long-term outcome when compared to primary total hip replacement in patients with osteoarthritis, acetabular fractures should, regardless of the patient's age, whenever possible be treated by operative reconstruction.

Biomechanical methods for the assessment of fracture repair.

The progress of fracture healing is directly related to an increasing stiffness and strength of the healing fracture. Similarly the weight bearing capacity of a bone directly relates to the mechanical stability of the fracture. Therefore, assessing the progress of fracture repair can be based on the measurement of the mechanical stability of the healing fracture. However, fracture stability is difficult to assess directly due to various obstacles of which shielding of the mechanical properties by the fracture fixation construct is the most relevant one. Several assessment methods have been proposed to overcome these obstacles and to obtain some sort of mechanical surrogate describing the stability of the fracture. The most direct method is the measurement of the flexibility of a fracture under a given external load, which comprises the challenge of accurately measuring the deformation of the bone. Alternative approaches include the measurement of load share between implant and bone by internal or by external sensors. A direct 3 dimensional measurement of bone displacement is provided by radiostereometric analysis which can assess fracture migration and can detect fracture movement under load. More indirect mechanical methods induce cyclic perturbations within the bone and measure the response as a function of healing time. At lower frequencies the perturbations are induced in the form of vibration and at higher frequencies in the form of ultrasonic waves. Both methods provide surrogates for the mechanical properties at the fracture site. Although biomechanical properties of a healing fracture provide a direct and clinically relevant measure for fracture healing, their application will in the near future be limited to clinical studies or research settings.

[Quality of life after multiple trauma]. / Lebensqualität nach Polytrauma.

BACKGROUND: Multiple trauma is an independent injury pattern which, because of its complexity, is responsible for 25 % of the costs for the treatment of all injured patients. Because of the often long-lasting physical impairment and the high incidence of residual permanent handicaps, it is apparent that multiple trauma can lead to a reduction in patient quality of life. OBJECTIVES: The aim of this study was to give an overview of the known data concerning the change in quality of life for multiple trauma patients. Furthermore, predictors for the reduction of quality of life after multiple trauma will be identified. MATERIALS AND METHODS: A MedLine search was performed to identify studies dealing with the outcome after multiple trauma. RESULTS: In addition to functional outcome parameters, the term quality of life has become more important in recent years when it comes to evaluating the outcome following injury. While the mortality after multiple trauma could be significantly reduced over the years, there is no comparable effect on the quality of life. Predictors for a worse quality of life after multiple trauma are female gender, high age, low social status, concomitant head injuries and injury to the lower extremities. CONCLUSION: The fact that mortality after multiple trauma has decreased but not impairment of the quality of life makes it clear that in addition to the acute medical treatment, a follow-up treatment including not only physiotherapy but also psychotherapy is crucial for multiple trauma patients.

Proper coding of the Abbreviated Injury Scale: can clinical parameters help as surrogates in estimating blood loss?

PURPOSE: The Abbreviated Injury Scale (AIS) requires the estimation of the lost blood volume for some severity assignments. This study aimed to develop a rule of thumb for facilitating AIS coding by using objective clinical parameters as surrogate markers of blood loss. METHODS: Using the example of pelvic ring fractures, a retrospective analysis of TraumaRegister DGU(®) data from 2002 to 2011 was performed. As potential surrogate markers of blood loss, we recorded the hemoglobin (Hb) level, systolic blood pressure (SBP), base excess (BE), Quick's value, units of packed red blood cells (PRBCs) transfused before intensive care unit (ICU) admission, and mortality within 24 h. RESULTS: We identified 11,574 patients with pelvic ring fractures (Tile/OTA classification: 39 % type A, 40 % type B, 21 % type C). Type C fractures were 73.1 % AISpelvis 4 and 26.9 % AISpelvis 5. Type B fractures were 47 % AISpelvis 3, 47 % AISpelvis 4, and 6 % AISpelvis 5. In type C fractures, cut-off values of <7 g/dL Hb, <90 mmHg SBP, <-9 mmol/L BE, <35 % Quick's value, >15 units PRBCs, and death within 24 h had a positive predictive value of 47 % and a sensitivity of 62 % for AISpelvis 5. In type B fractures, these cut-off values had poor sensitivity (48 %) and positive predictive value (11 %) for AISpelvis 5. CONCLUSIONS: We failed to develop a rule of thumb for facilitating a proper future AIS coding using the example of pelvic ring fractures. The estimation of blood loss for severity assignment still remains a noteworthy weakness in the AIS coding of traumatic injuries.

Emergency stabilization of the pelvic ring: Clinical comparison between three different techniques.

BACKGROUND: Emergency devices for pelvic ring stabilization include circumferential sheets, pelvic binders, and c-clamps. Our knowledge of the outcome of these techniques is currently based on limited information. METHODS: Using the dataset of the German Pelvic Trauma Registry, demographic and injury-associated characteristics as well as the outcome of pelvic fracture patients after sheet, binder, and c-clamp treatment was compared. Outcome parameters included transfusion requirement of packed red blood cells, length of hospital stay, mortality, and incidence of lethal pelvic bleeding. RESULTS: Two hundred seven of 6137 (3.4%) patients documented in the German Pelvic Trauma Registry between April 30th 2004 and January 19th 2012 were treated by sheets, binders, or c-clamps. In most cases, c-clamps (69%) were used, followed by sheets (16%), and binders (15%). The median age was significantly lower in patients treated with binders than in patients treated with sheets or c-clamps (26 vs. 47 vs. 42 years, p=0.01). Sheet wrapping was associated with a significantly higher incidence of lethal pelvic bleeding compared to binder or c-clamp stabilization (23% vs. 4% vs. 8%). No significant differences between the study groups were found in sex, fracture type, blood haemoglobin concentration, arterial blood pressure, Injury Severity Score, the incidence of additional pelvic packing and arterial embolization, need of red blood cell transfusion, length of hospitalisation, and mortality. CONCLUSIONS: The data suggest that emergency stabilization of the pelvic ring by binders and c-clamps is associated with a lower incidence of lethal pelvic bleeding compared to sheet wrapping. LEVEL OF EVIDENCE: Level III.

Rodent animal models of delayed bone healing and non-union formation: a comprehensive review.

Despite the growing knowledge on the mechanisms of fracture healing, delayed healing and non-union formation remain a major clinical challenge. Animal models are needed to study the complex process of normal and impaired fracture healing and to develop new therapeutic strategies. Whereas in the past mainly large animals have been used to study normal and impaired fracture healing, nowadays rodent models are of increasing interest. New osteosynthesis techniques for rat and mice have been developed during the last years, which allowed for the first time stable osteosynthesis in these animals comparable to the standards in large animals and humans. Based on these new implants, different models in rat and mice have been established to study delayed healing and non-union formation. Although in humans the terms delayed union and non-union are well defined, in rodents definitions are lacking. However, especially in scientific studies clear definitions are necessary to develop a uniform scientific language and allow comparison of the results between different studies. In this consensus report, we define the basic terms "union", "delayed healing" and "non-union" in rodent animal models. Based on a review of the literature and our own experience, we further provide an overview on available models of delayed healing and non-union formation in rats and mice. We further summarise the value of different approaches to study normal and delayed fracture healing as well as non-union formation, and discuss different methods of data evaluation.

[Anterior approaches to the pelvic ring]. / Anteriore Zugänge zum Beckenring.

Anterior approaches for the stabilization of anterior and also posterior B and C type instability of the pelvic ring were the standard procedures before minimally invasive percutaneous methods supported by image intensifiers or navigation devices were established. Anterior approaches are currently still of high relevance for difficult or impossible closed reductions in multiple trauma surgery where the patient must remain in a supine position. They are also used for stabilization of an increasing number of osteoporotic fractures in the elderly which are no longer only treated in specialized pelvic trauma centres. The anterior as well as the posterior part of the pelvic ring can be stabilized via various anterior approaches. A Pfannenstiel incision is appropriate for plating of ruptures of the pubic symphysis and can be extended to a modified Stoppa approach if necessary. Fractures of the iliac wings can be approached either laterally or less traumatically, via an anterolateral approach. The latter equates the lateral window of the ilioinguinal approach to the acetabulum, allows visualization of the entire sacroiliac joint and therefore stabilization of not only iliosacral luxation but also luxated fractures with a small iliac fragment. By a combination of the different approaches it is possible to simultaneously stabilize ventral and dorsal instabilities in type C fractures of the pelvic ring with a minimal amount of iatrogenic soft tissue trauma. Although the described anterior approaches are considered as simple exact knowledge of the endangered structures and general risks for each approach are essential for a safe exposure of the anatomical region addressed.

Pantoprazole, a proton pump inhibitor, delays fracture healing in mice.

Proton pump inhibitors (PPIs), which are widely used in the treatment of dyspeptic problems, have been shown to reduce osteoclast activity. There is no information, however, on whether PPIs affect fracture healing. We therefore studied the effect of the PPI pantoprazole on callus formation and biomechanics during fracture repair. Bone healing was analyzed in a murine fracture model using radiological, biomechanical, histomorphometric, and protein biochemical analyses at 2 and 5 weeks after fracture. Twenty-one mice received 100 mg/kg body weight pantoprazole i.p. daily. Controls (n = 21) received equivalent amounts of vehicle. In pantoprazole-treated animals biomechanical analysis revealed a significantly reduced bending stiffness at 5 weeks after fracture compared to controls. This was associated with a significantly lower amount of bony tissue within the callus and higher amounts of cartilaginous and fibrous tissue. Western blot analysis showed reduced expression of the bone formation markers bone morphogenetic protein (BMP)-2, BMP-4, and cysteine-rich protein (CYR61). In addition, significantly lower expression of proliferating cell nuclear antigen indicated reduced cell proliferation after pantoprazole treatment. Of interest, the reduced expression of bone formation markers was associated with a significantly diminished expression of RANKL, indicating osteoclast inhibition. Pantoprazole delays fracture healing by affecting both bone formation and bone remodeling.

Increased exercise after stable closed fracture fixation does not affect fracture healing in mice.

PURPOSE: The aim of the present study was to evaluate the systemic biological effect of increased exercise on bone repair after stable fracture fixation. METHODS: Two groups of SKH-1h mice were studied. Animals of the first group (n=36) were housed in cages supplied with a running wheel, while mice of the second group (n=37) were housed in standard cages for control. Using a closed femur fracture model, bone repair was analysed by histomorphometry and biomechanical testing at 2 and 5 weeks. At 2 weeks, we additionally evaluated the expression of the proliferation marker PCNA (proliferating cell nuclear antigen) and the angiogenic and osteogenic growth factor VEGF (vascular endothelial growth factor). To standardise the mechanical conditions in the fracture gap, we used an intramedullary compression screw for stable fracture fixation. RESULTS: Each mouse of the exercise group run a mean total distance of 23.5 km after 2 weeks and 104.3 km after 5 weeks. Histomorphometric analysis of the size and tissue composition of the callus could not reveal significant differences between mice undergoing exercise and controls. Accordingly, biomechanical testing showed a comparable torsional stiffness, peak rotation angle, and load at failure of the healing bones in the two groups. The expression of PCNA and VEGF did also not differ between mice of the exercise group and controls. CONCLUSION: We conclude that increased exercise does not affect bone repair after stable fracture fixation.