Low impact injury resulting in a Schenck type IV classified anterior knee dislocation as well as biceps femoris rupture: A Case Report.

Introduction: Dislocations of the knee joint represent very rare injuries in the literature, accounting for less than 0.02% of all musculoskeletal injuries. Case Report: This report describes a patient suffered a knee joint dislocation of the knee joint caused by a low impact injury following a stumbling trauma during volunteer of a sport competition. Anterior knee joint dislocation with incipient compartment syndrome was clinically prognosed. Vascular and nerve injuries were radiologically examined. Taken together the injury was classified as Schenck type IV CN, and surgical management of the current knowledge was pursued. A satisfying range of motion was examined during surgery next to solid vascular und nerve conditions post-surgery. Conclusion: In case of severe knee joint dislocations, the current standard of a closed reduction with subsequent diagnostic is recommended. Compartment syndrome, nerve, and vascular tears indicate emergency surgery.

Retrospective Analysis of Bone Substitute Material for Traumatic Long Bone Fractures: Sex-Specific Outcomes.

Male patients often experience increased bone and muscle loss after traumatic fractures. This study aims to compare the treatment outcomes of male and female patients with large bone defects. A total of 345 trauma patients underwent surgery, with participants divided into two groups: one receiving bone substitute material (BSM) for augmented defects (n = 192) and the other without augmentation (empty defects = ED, n = 153). Outcome parameters were assessed among female (n = 184) and male (n = 161) patients. Descriptive statistics revealed no significant differences between male and female patients. Approximately one-half of the fractures resulted from high-energy trauma (n = 187). The BSM group experienced fewer complications (p = 0.004), including pseudarthrosis (BSM: n = 1, ED: n = 7; p = 0.02). Among female patients over 65, the incidence of pseudarthrosis was lower in the BSM group (p = 0.01), while younger females showed no significant differences (p = 0.4). Radiologically, we observed premature bone healing with subsequent harmonization. Post hoc power analysis demonstrated a power of 0.99. Augmenting bone defects, especially with bone substitute material, may reduce complications, including pseudarthrosis, in female patients. Additionally, this material accelerates bone healing. Further prospective studies are necessary for confirmation.

Early osteoimmunomodulatory effects of magnesium-calcium-zinc alloys.

Today, substantial attention is given to biomaterial strategies for bone regeneration, and among them, there is a growing interest in using immunomodulatory biomaterials. The ability of a biomaterial to induce neo vascularization and macrophage polarization is a major factor in defining its success. Magnesium (Mg)-based degradable alloys have attracted significant attention for bone regeneration owing to their biodegradability and potential for avoiding secondary removal surgeries. However, there is insufficient evidence in the literature regarding the early inflammatory responses to these alloys in vivo. In this study, we investigated the early body responses to Mg-0.45wt%Zn-0.45wt%Ca pin-shaped alloy (known as ZX00 alloy) in rat femora 2, 5, and 10 days after implantation. We used 3D micro computed tomography (µCT), histological, immunohistochemical, histomorphometrical, and small angle X-ray scattering (SAXS) analyses to study new bone formation, early macrophage polarization, neo vascularization, and bone quality at the implant bone interface. The expression of macrophage type 2 biological markers increased significantly after 10 days of Mg alloy implantation, indicating its potential in stimulating macrophage polarization. Our biomineralization results using µCT as well as histological stained sections did not indicate any statistically significant differences between different time points for both groups. The activity of alkaline phosphatase (ALP) and Runt-related transcription factor 2 (Runx 2) biological markers decreased significantly for Mg group, indicating less osteoblast activity. Generally, our results supported the potential of ZX00 alloy to enhance the expression of macrophage polarization in vivo; however, we could not observe any statistically significant changes regarding biomineralization.

The heparan sulfate proteoglycan Syndecan-1 influences local bone cell communication via the RANKL/OPG axis.

The heparan sulfate proteoglycan Syndecan-1, a mediator of signals between the extracellular matrix and cells involved is able to interact with OPG, one of the major regulators of osteoclastogenesis. The potential of osteoblasts to induce osteoclastogenesis is characterized by a switch of OPG (low osteoclastogenic potential) towards RANKL production (high osteoclastogenic potential). In the present study, we investigated the influence of endogenous Syndecan-1 on local bone-cell-communication via the RANKL/OPG-axis in murine osteoblasts and osteoclasts in wild type and Syndecan-1 lacking cells. Syndecan-1 expression and secretion was increased in osteoblasts with high osteoclastogenic potential. Syndecan-1 deficiency led to increased OPG release by osteoblasts that decreased the availability of RANKL. In co-cultures of Syndecan-1 deficient osteoblasts with osteoclast these increased OPG in supernatant caused decreased development of osteoclasts. Syndecan-1 and RANKL level were increased in serum of aged WT mice, whereas Syndecan-1 deficient mice showed high serum OPG concentration. However, bone structure of Syndecan-1 deficient mice was not different compared to wild type. In conclusion, Syndecan-1 could be regarded as a new modulator of bone-cell-communication via RANKL/OPG axis. This might be of high impact during bone regeneration or bone diseases like cancer where Syndecan-1 expression is known to be even more prevalent.

Effects of macroporous, strontium loaded xerogel-scaffolds on new bone formation in critical-size metaphyseal fracture defects in ovariectomized rats.

New bone formation was studied in a metaphyseal fracture-defect in ovariectomized rats stimulated by a plain and a strontium-enriched macroporous silica/collagen scaffold (ScB30 and ScB30Sr20) and a compact silica/collagen xerogel (B30). 45 female Sprague-Dawley rats were randomly assigned to three different treatment groups: (1) ScB30 (n=15), (2) ScB30Sr20 (n=15), and (3) B30 (n=15). 12 weeks after bilateral ovariectomy and multi-deficient diet, a 4 mm wedge-shaped fracture-defect was created at the metaphyseal area of the left femur. A 7-hole T-shaped plate at the lateral aspect of the femur stabilized the bone and the defect was filled with ScB30, ScB30Sr20 or B30 subsequently. After six weeks, histomorphometrical analysis revealed a statistically significant higher bone volume/tissue volume ratio in the ScB30Sr20 group compared to ScB30 (p=0.043) and B30 (p=0.0001) indicating an improved formation of new bone by the strontium-enriched macroporous silica/collagen scaffold. Furthermore, immunohistochemical results showed increased expression of BMP2 and OPG and a decreased RANKL expression in the ScB30Sr20 group. This was further confirmed with the gene expression analysis where an increase in prominent bone formation markers (ALP, OCN, Runx2, Col1a1 and Col10a1) was seen. No material remnants were found in the scaffold group indicating an almost complete degradation process of the biomaterials. This is confirmed by ToF-SIMS analysis that did not detect any strontium in the ScB30Sr20 group neither in the defect nor in the surrounding tissue. Taken together, this study shows the stimulating effects of strontium through increased bone formation by up regulation of osteoanabolic markers. This work also indicates the importance of material porosity, geometry and biodegradability in bone healing.

Characterization of bone turnover and energy metabolism in a rat model of primary and secondary osteoporosis.

BACKGROUND: An experimental rat model served for evaluation of bone- and energy metabolism in early and late stages of osteoporosis. For the early stage, we hypothesized that bilateral ovariectomy (OVX)+multi-deficiency diet (OVXD; depletion of vitamin D, calcium, vitamin K, phosphorus) would induce increased bone turnover while the late stage would be characterized by enhanced bone catabolism. Obesity, insulin resistance and hyperleptinemia would be seen during the whole course of disease. Healthy female Sprague Dawley rats (n=41) aged 10 weeks were randomly assigned to sham and treatment groups and sacrificed at 3, 12, and 14 months after the study began. RESULTS: In the early phase, OVXD was associated with an increase in body weight, but not, however, in later stages. There was a decrease in bone mineral density and relative bone volume (BV/TV) as assessed by Dual Energy X-ray Absorptiometry and micro computed tomography that was most severe in the later stages of disease, indicating bone catabolism. Osteocalcin limiting bone formation was increased initially, whereas later stages (14 months) were characterized by elevated osteopontin, suggesting bone remodeling. Severe hyperparathyroidism was present during all stages of disease. Only the early phases of disease were characterized by hyperinsulinemia and increased adrenocorticotrophic stimulating hormone, whereas in the late stage hypoleptinemia rather than hyperleptinemia was seen. CONCLUSION: Markers of bone and energy metabolism reflected both an increased bone turn over and ongoing bone remodeling associated with initial hyperinsulinemia. Osteopontin and osteocalcin can be used to differentiate early and late stages of osteoporosis.

Change of mechanical vertebrae properties due to progressive osteoporosis: combined biomechanical and finite-element analysis within a rat model.

For assessing mechanical properties of osteoporotic bone, biomechanical testing combined with in silico modeling plays a key role. The present study focuses on microscopic mechanical bone properties in a rat model of postmenopausal osteoporosis. Female Sprague-Dawley rats were (1) euthanized without prior interventions, (2) sham-operated, and (3) subjected to ovariectomy combined with a multi-deficiencies diet. Rat vertebrae (corpora vertebrae) were imaged by micro-CT, their stiffness was determined by compression tests, and load-induced stress states as well as property changes due to the treatment were analyzed by finite-element modeling. By comparing vertebra stiffness measurements with finite-element calculations of stiffness, an overall microscopic Young's modulus of the bone was determined. Macroscopic vertebra stiffness as well as the microscopic modulus diminish with progression of osteoporosis by about 70 %. After strong initial changes of bone morphology, further decrease in macroscopic stiffness is largely due to decreasing microscopic Young's modulus. The micromechanical stress calculations reveal particularly loaded vertebra regions prone to failure. Osteoporosis-induced changes of the microscopic Young's modulus alter the fracture behavior of bone, may influence bone remodeling, and should be considered in the design of implant materials.