The Impact of Defect Size on Bone Healing in Critical-Size Bone Defects Investigated on a Rat Femur Defect Model Comparing Two Treatment Methods.

Critical-size bone defects up to 25 cm can be treated successfully using the induced membrane technique established by Masquelet. To shorten this procedure, human acellular dermis (HAD) has had success in replacing this membrane in rat models. The aim of this study was to compare bone healing for smaller and larger defects using an induced membrane and HAD in a rat model. Using our established femoral defect model in rats, the animals were placed into four groups and defects of 5 mm or 10 mm size were set, either filling them with autologous spongiosa and surrounding the defect with HAD or waiting for the induced membrane to form around a cement spacer and filling this cavity in a second operation with a cancellous bone graft. Healing was assessed eight weeks after the operation using µ-CT, histological staining, and an assessment of the progress of bone formation using an established bone healing score. The α-smooth muscle actin used as a signal of blood vessel formation was stained and counted. The 5 mm defects showed significantly better bone union and a higher bone healing score than the 10 mm defects. HAD being used for the smaller defects resulted in a significantly higher bone healing score even than for the induced membrane and significantly higher blood vessel formation, corroborating the good results achieved by using HAD in previous studies. In comparison, same-sized groups showed significant differences in bone healing as well as blood vessel formation, suggesting that 5 mm defects are large enough to show different results in healing depending on treatment; therefore, 5 mm is a viable size for further studies on bone healing.

Impact of scaffold granule size use in Masquelet technique on periosteal reaction: a study in rat femur critical size bone defect model.

PURPOSE: The Masquelet technique for the treatment of large bone defects is a two-stage procedure based on an induced membrane. Compared to mature periosteum, the induced membrane differs significantly. However, both play a crucial role in bone regeneration. As part of a histological and radiological post-evaluation of an earlier project, we analyzed the influence of the granule size of the bone void filler Herafill® on development of periosteum regrowth in a critical size defect. METHODS: We compared three different sizes of Herafill® granules (Heraeus Medical GmbH, Wehrheim) in vivo in a rat femoral critical size defect (10 mm) treated with the induced membrane technique. After 8 weeks healing time, femurs were harvested and taken for histological and radiological analysis. RESULTS: A significantly increased regrowth of periosteum into the defect was found when small granules were used. Large granules showed significantly increased occurrence of bone capping. Small granules lead to significant increase in callus formation in the vicinity to the membrane. CONCLUSION: The size of Herafill® granules has significant impact on the development of periosteal-like structures around the defect using Masquelet's induced membrane technique. Small granules show significantly increased regrowth of periosteum and improved bone formation adjacent to the induced membrane.

Falls from Great Heights: Risk to Sustain Severe Thoracic and Pelvic Injuries Increases with Height of the Fall.

Falls from a height are a common cause of polytrauma care in Level I Trauma Centers worldwide. The expected injury consequences depend on the height of the fall and the associated acceleration, as well as the condition of the ground. In addition, we further hypothesize a correlation between the cause of the fall, the age of the patient, and the patient's outcome. A total of 178 trauma patients without age restriction who were treated in our hospital after a fall >3 m within a 5-year period were retrospectively analyzed. The primary objective was a clinically and radiologically quantifiable increase in the severity of injuries after falls from different relevant heights (>3 m, >6 m, and >9 m). The cause of the fall, either accidental or suicidal; age and duration of intensive care unit stay, including duration of ventilation; and total hospital stay were analyzed. Additionally, the frequency of urgent operations, such as, external fixation of fractures or hemi-craniectomies, laboratory parameters; and clinical outcomes were also among the secondary objectives. Sustaining a thoracic trauma or pelvis fractures increases significantly with height, and vital parameters are significantly compromised. We also found significant differences in urgent pre- and in-hospital emergency interventions, as well as organ complications and outcome parameters depending on the fall's height.

The Influence of Alcohol on the Base Excess Parameter in Trauma Patients.

BACKGROUND: The base excess (BE) parameter can be used as an indicator of mortality. However, study results on the influence of alcohol on the validity of BE as a prognostic parameter in alcohol-intoxicated patients are controversial. Thus, this study examined the hypothesis: An increasing blood alcohol level reduces the prognostic value of the BE parameter on mortality. PATIENTS AND METHODS: In a retrospective analysis of the multicenter database of the TraumaRegister DGU, patients from 2015 to 2017 were grouped depending on their blood alcohol level (BAL) into a BAL+ and BAL- group. The hypothesis was verified using logistic regression with an assumed significance level of 1% (P < 0.01). RESULTS: Eleven thousand eight hundred eighty-nine patients were included; 9,472 patients in the BAL- group and 2,417 patients in the BAL+ group. Analysis of the BE showed lower values in the BAL+ group (BAL-: -1.8 ±â€Š4.4 mmol/L vs. BAL+: -3.4 ±â€Š4.6 mmol/L). There is a trend toward lower BE levels when BAL increases. Assuming a linear relationship, then BE decreases by 0.6 points per mille alcohol (95% CI: 0.5-0.7; P < 0.001). The mortality rate was significantly lower in the BAL+ group (BAL-: 11.1% vs. BAL+: 7.9%). The logistic regression analysis showed a significant beneficial influence of BAL+ on the mortality rate (OR 0.706, 95% CI 0.530-0.941, P = 0.018). To analyze whether a low BE (≤-6 mmol/L) has different prognostic effects in patients with and without alcohol, logistic regression models were calculated. However, the effect of BE ≤ -6 mmol/L was similar in both models (regression coefficients in BAL-/+ patients: 0.379/0.393). CONCLUSIONS: The data demonstrate an existing influence of alcohol on the BE parameter; however, this does not negatively affect the BE as a prognostic parameter at a threshold of ≤ -6 mmol/L.

Clostridial Gas Gangrene - A Rare but Deadly Infection: Case series and Comparison to Other Necrotizing Soft Tissue Infections.

OBJECTIVE: Clostridial gas gangrene (GG) or clostridial myonecrosis is a very rare but life-threatening necrotizing soft tissue infection (NSTI) caused by anaerobic, spore-forming, and gas-producing clostridium subspecies. It is the most rapidly spreading and lethal infection in humans, also affecting muscle tissue. The high mortality, of up to 100%, in clostridial GG is mediated by potent bacterial exotoxins. Necrotizing fasciitis (NF) is an important differential diagnosis, most often caused by group A streptococci, primarily not affecting musculature but the subcutaneous tissue and fascia. In the early stages of the infection, it is difficult to distinguish between GG and NF. Therefore, we compare both infection types, identify relevant differences in initial clinical presentation and later course, and present the results of our patients in a retrospective review. METHODS: Patients diagnosed with GG from 2008 to 2018 in our level one trauma center were identified. Their charts were reviewed retrospectively and data analyzed in terms of demographic information, microbiological and histological results, therapeutic course, outcome, and mortality rates. The laboratory risk indicator for NF (LRINEC) score was applied on the first blood work acquired. Results were compared to those of a second group diagnosed with NF. RESULTS: Five patients with GG and nine patients with NF were included in the present study. Patients with GG had a mortality rate of 80% compared to 0% in patients with NF. In eight patients with NF, affected limbs could be salvaged; one NF underwent amputation. LRINEC did not show significant differences between the groups; however, C-reactive protein was significantly increased (P = 0.009) and hemoglobin (Hb) was significantly decreased (P = 0.02) in patients with GG. Interleukin-6 and procalcitonin levels did not show significant difference. Patients with GG were older (70.2 vs 50 years). Of the isolated bacteria, 86% were sensitive to the initial calculated antibiotic treatment with ampicillin-sulbactam or imipenem plus metronidazole plus clindamycin. CONCLUSION: Both GG and NF need full-scale surgical, antibiotic, and intensive care treatment, especially within the first days. Among patients with NSTI, those with clostridial GG have a significantly increased mortality risk due to early septic shock caused by clostridial toxins. In the initial stages, clinical differences are hardly detectable. Immediate surgical debridement is the key to successful therapy for NSTI and needs to be performed as early as possible. However, patients should be treated in a center with an experienced interdisciplinary intensive care team based on a predetermined treatment plan.

First Human Leucocyte Antigen (HLA) Response and Safety Evaluation of Fibrous Demineralized Bone Matrix in a Critical Size Femoral Defect Model of the Sprague-Dawley Rat.

Treatment of large bone defects is one of the great challenges in contemporary orthopedic and traumatic surgery. Grafts are necessary to support bone healing. A well-established allograft is demineralized bone matrix (DBM) prepared from donated human bone tissue. In this study, a fibrous demineralized bone matrix (f-DBM) with a high surface-to-volume ratio has been analyzed for toxicity and immunogenicity. f-DBM was transplanted to a 5-mm, plate-stabilized, femoral critical-size-bone-defect in Sprague-Dawley (SD)-rats. Healthy animals were used as controls. After two months histology, hematological analyses, immunogenicity as well as serum biochemistry were performed. Evaluation of free radical release and hematological and biochemical analyses showed no significant differences between the control group and recipients of f-DBM. Histologically, there was no evidence of damage to liver and kidney and good bone healing was observed in the f-DBM group. Reactivity against human HLA class I and class II antigens was detected with mostly low fluorescence values both in the serum of untreated and treated animals, reflecting rather a background reaction. Taken together, these results provide evidence for no systemic toxicity and the first proof of no basic immunogenic reaction to bone allograft and no sensitization of the recipient.

Introduction of a New Surgical Method to Improve Bone Healing in a Large Bone Defect by Replacement of the Induced Membrane by a Human Decellularized Dermis Repopulated with Bone Marrow Mononuclear Cells in Rat.

The Masquelet technique for the treatment of large bone defects is a two-stage procedure based on an induced membrane. We eliminate the first surgical step by using a decellularized dermal skin graft (Epiflex®) populated with bone marrow mononuclear cells (BMC), as a replacement for the induced membrane. The aim of this study was to demonstrate the feasibility of this technology and provide evidence of equivalent bone healing in comparison to the induced membrane-technique. Therefore, 112 male Sprague-Dawley rats were allocated in six groups and received a 10 mm femoral defect. Defects were treated with either the induced membrane or decellularized dermis, with or without the addition of BMC. Defects were then filled with a scaffold (ß-TCP), with or without BMC. After a healing time of eight weeks, femurs were taken for histological, radiological and biomechanical analysis. Defects treated with Epiflex® showed increased mineralization and bone formation predominantly in the transplanted dermis surrounding the defect. No significant decrease of biomechanical properties was found. Vascularization of the defect could be enhanced by addition of BMC. Considering the dramatic reduction of a patient's burden by the reduced surgical stress and shortened time of treatment, this technique could have a great impact on clinical practice.

From two stages to one: acceleration of the induced membrane (Masquelet) technique using human acellular dermis for the treatment of non-infectious large bone defects.

INTRODUCTION: The induced membrane technique for the treatment of large bone defects is a two-step procedure. In the first operation, a foreign body membrane is induced around a spacer, then, in the second step, several weeks or months later, the spacer is removed and the Membrane pocket is filled with autologous bone material. Induction of a functional biological membrane might be avoided by initially using a biological membrane. In this study, the effect of a human acellular dermis (hADM, Epiflex, DIZG gGmbH) was evaluated for the treatment of a large (5 mm), plate-stabilised femoral bone defect. MATERIAL AND METHODS: In an established rat model, hADM was compared to the two-stage induced membrane technique and a bone defect without membrane cover. Syngeneous spongiosa from donor animals was used for defect filling in all groups. The group size in each case was n = 5, the induction time of the membrane was 3-4 weeks and the healing time after filling of the defect was 8 weeks. RESULTS: The ultimate loads were increased to levels comparable with native bone in both membrane groups (hADM: 63.2% ± 29.6% of the reference bone, p < 0.05 vs. no membrane, induced membrane: 52.1% ± 25.8% of the reference bone, p < 0.05 vs. no membrane) and were significantly higher than the control group without membrane (21.5%). The membrane groups were radiologically and histologically almost completely bridged by new bone formation, in contrast to the control Group where no closed osseous bridging could be observed. CONCLUSION: The use of the human acellular dermis leads to equivalent healing results in comparison to the two-stage induced membrane technique. This could lead to a shortened therapy duration of large bone defects.

Do antiosteoporotic drugs improve bone regeneration in vivo?

PURPOSE: Treatment of complex fractures in the elderly is a challenge for operative reconstruction due to degraded bone structure. Early peri-operative bone anabolic treatment could improve new bone formation, avoid implant loosening and accelerate fracture healing. METHODS: To compare the osteoanabolic potential of different drugs after distraction osteogenesis, 168 female Sprague-Dawley rats underwent lengthening of the right femur using a monolateral external fixator. Animals were randomly divided into six groups: vehicle-injected group, PTH(1-34), raloxifen, strontium ranelate, alendronate and simvastatin. Histomorphometry, CT-scanning, DEXA- and biomechanical analysis were performed to evaluate new bone formation, callus volume, mineralisation and biomechanical strength. Expression of bone metabolic mediators and differentiation indicators of distracted and intact bone were examined by RT-PCR and western blot. RESULTS: Histological analysis showed significant increase of the bone mass after treatment with PTH(1-34), raloxifen and strontium ranelate (p = 0.02). Raloxifen increased bone mineral content (BMC) of the whole distracted femur significantly (p = 0.007). Callus volume was significantly larger in the PTH(1-34), raloxifen and simvastatin groups (p = 0.001) compared to control. Ultimate load of distracted new formed bone was increased in PTH(1-34) and raloxifen groups. It seems that PTH(1-34) and raloxifen have a stronger effect on bone where a repair response is activated. Strontium ranelate demonstrates similar effects to PTH regarding new bone formation but shows low values for mineralisation and biomechanical strength. CONCLUSION: This study suggests that peri-operative treatment of complex and/or osteoporotic fractures with PTH(1-34) and raloxifen might be useful as a stimulator of bone formation and mineralisation to shorten the consolidation time in humans.

Increased extracellular ubiquitin in surgical wound fluid provides a chemotactic signal for myeloid dendritic cells.

PURPOSE: Myeloid dendritic cells (MDC) decline significantly after multiple traumas which might be due to an increased migration into injured regions. Ubiquitin is released from dying cells and is increased in serum after trauma. Ubiquitin can bind to the chemokine receptor CXCR4. Thus, we hypothesized that elevated ubiquitin provides a chemotactic signal for MDC to injured regions. METHODS: Surgical wound fluid (SWF) and serum from patients with mono-trauma (n = 20) were used to simulate the humoral situation in injured tissue. MDC were identified by flow cytometry. Chemotaxis was measured using transwell migration assays. Ubiquitin and CXCL12 (natural CXCR4 ligand) were determined by ELISA. RESULTS: MDC express CXCR4 and fluorescence-labeled ubiquitin binds to MDC. Ubiquitin exerts a dose-dependent chemotactic effect (fourfold at 100 ng/mL, p < 0.05). Ubiquitin concentration was sixfold higher in SWF (p < 0.05), whereas CXCL12 was increased in serum. MDC migration towards SWF was significantly reduced (- 40%, p < 0.05), if ubiquitin was neutralized by specific antibodies. CONCLUSIONS: Ubiquitin is increased in SWF and exerts a significant chemotactic effect on MDC. This mechanism might play a role in attraction of immune cells to injured regions and might contribute to the decline of circulating MDC in multiple traumas.

Epidemiology and treatment of distal radius fractures: current concept based on fracture severity and not on age.

PURPOSE: A shift towards surgical treatment of distal radius fractures seems to be apparent. The purpose of the present study was to assess current epidemiological data, the fracture severity according to the AO classification and the changing trend in the treatment. METHODS: This study presents a retrospective review of 268 patients ≥ 18 years of age admitted to our level I trauma center with distal radius fractures between 2013 and 2015. The data were obtained from the hospital inpatient enquiry system and review of the radiological examinations. RESULTS: The ratio between males and females was 87:181. The average age of the patients was 56.9 (18-99) years. A fall from standing position was the most common mechanism of injury. According to the AO classification, 43.3% were type A fractures, 13.1% type B, and 43.7% type C. As the intensity of the injury mechanism increased, the percentage of type C fractures also increased. A total of 61.9% of patients underwent surgery with open reduction and internal fixation with volar locking plates used as the preferred surgical treatment. Fracture severity correlated well with surgical decision. Elderly patients were just as likely to get surgical treatment as adult patients. CONCLUSIONS: Our findings confirmed the increasing popularity of surgical intervention with open reduction and internal fixation. Contrary to previous studies, the fracture type profile showed an equal proportion of type A and C fractures and the indication for surgical treatment correlated with fracture severity and not age.

Size matters: Effect of granule size of the bone graft substitute (Herafill®) on bone healing using Masquelet's induced membrane in a critical size defect model in the rat's femur.

The Masquelet technique for the treatment of large bone defects is a two-stage procedure based on an induced membrane. The size of a scaffold is reported to be a critical factor for bone healing response. We therefore aimed to investigate the influence of the granule size of a bone graft substitute on bone marrow derived mononuclear cells (BMC) supported bone healing in combination with the induced membrane. We compared three different sizes of Herafill® granules (Heraeus Medical GmbH, Wehrheim) with or without BMC in vivo in a rat femoral critical size defect. A 10 mm defect was made in 126 rats and a membrane induced by a PMMA-spacer. After 3 weeks, the spacer was taken out and membrane filled with different granule sizes. After 8 weeks femurs were taken for radiological, biomechanical, histological, and immunohistochemical analysis. Further, whole blood of the rat was incubated with granules and expression of 29 peptide mediators was assessed. Smallest granules showed significantly improved bone healing compared to larger granules, which however did not lead to an increased biomechanical stability in the defect zone. Small granules lead to an increased accumulation of macrophages in situ which could be assigned to the inflammatory subtype M1 by majority. Increased release of chemotactic respectively proangiogenic active factors in vitro compared to syngenic bone and beta-TCP was observed. Granule size of the bone graft substitute Herafill® has significant impact on bone healing of a critical size defect in combination with Masquelet's technique in terms of bone formation and inflammatory potential.

Nonunions of the humerus - Treatment concepts and results of the last five years.

PURPOSE: Fractures of the humerus account for 5%-8% of all fractures. Nonunion is found with an incidence of up to 15%, depending on the location of the fracture. In case of a manifest nonunion the surgeon faces a challenging problem and has to conceive a therapy based on the underlying pathology. The aim of this study was to describe our treatment concepts for this entity and present our results of the last five years. METHODS: Twenty-six patients were treated for nonunion of the humerus between January 2013 and December 2017. Their charts were reviewed retrospectively and demographic data, pathology, surgical treatment and outcome were assessed. RESULTS: The most frequent location for a nonunion was the humeral shaft, with the most common trauma mechanism being multiple falls. Most often atrophic nonunion (n = 14), followed by hypertrophic and infection-caused nonunion (each n = 4), were found. Our treatment concept could be applied in 19 patients, of which in 90% of those who were available for follow-up consolidation could be achieved. CONCLUSION: Humeral nonunion is a heterogeneous entity that has to be analyzed precisely and be treated correspondingly. We therefore present a treatment concept based on the underlying pathology.

Cultivation of EPC and co-cultivation with MSC on ß-TCP granules in vitro is feasible without fibronectin coating but influenced by scaffolds' design.

INTRODUCTION: Meanwhile, the osteoconductive properties of frequently used synthetic bone grafts can be improved by the use of osteoinductive cells and growth factors. Nevertheless, the cultivation of endothelial progenitor cells (EPC) seems to be difficult and requires a pre-conditioning of the scaffolds with fibronectin. Additionally, the influence of the scaffolds' design on cell cultivation is not fully elucidated. METHODS: As scaffold, a commercially available ß-tricalcium phosphate was used. 5 × 105 EPC, or 5 × 105 MSC or a combination of each 2.5 × 105 cells was seeded onto the granules. We investigated seeding efficiency, cell morphology, cell metabolism, adherence, apoptosis and gene expression of EPC and MSC in this in vitro study on days 2, 6 and 10. RESULTS: Total number of adherent cells was higher on the ß-TCP without fibronectin coating. The number of cells in all approaches significantly declined when a solid ß-TCP was used. Metabolic activity of MSC was comparable throughout the scaffolds and increased until day 10. Additionally, the amount of supernatants VEGF was higher for MSC than for EPC. DISCUSSION: Our results demonstrate that a coating of the scaffold for successful cultivation of EPC in vitro is not necessary. Furthermore, our study showed that structural differences of the scaffolds significantly influenced cell adherence and metabolic activity. Thereby, the influence on EPC seems to be higher than on MSC.

Neurovascular complications after supracondylar humerus fractures in children.

BACKGROUND: Supracondylar fractures of the humerus are a common injury in pediatric traumatology. The most common operative therapy is closed reduction and percutaneous pinning using K-wires. Common complications associated with this entity are neurovascular lesions, especially of the brachial artery and the median nerve. METHODS: We report two cases of patients treated in our trauma-center with supracondylar fracture of the humerus (AO IV°) and neurovascular complications. RESULTS: Both patients underwent open revision and recovered completely in their further course. CONCLUSION: We recommend detailed neurovascular examination initially and after reposition of the fracture. The threshold for open reduction in cases of irreducible fractures should be low. In the presence of neurovascular impairment an open revision is mandatory, even months after the initial Trauma.Level of evidence: Level V (case report).