Intact Bone Research Articles

Progress in the treatment of giant cell tumors of extremities with pathological fracture

Giant cell tumor of bone (GCTB) is a common locally aggressive junctional primary bone tumor, whose clinical treatment becomes more difficult once combined with pathological fracture. Extended curettage and en-bloc resection are common surgical procedures for treating GCTB, and drugs such as receptor activator of nuclear factor-κB ligand(RANKL) inhibitors and bisphosphonates have been successfully used. Curettage is recommended for patients with Campanaccigrade Ⅱor Campanaccigrade Ⅲ with localized soft tissue invasion only and simple fractures with intact bone structure. Resection may be considered for Campanaccigrade Ⅲ with extensive soft tissue invasion or complex fractures with incomplete bone structure. RANKL inhibitors such as denosumab may be recommended if surgery is not possible or before performing resection. This article summarizes the common treatment modalities of pathological fractures combined with giant cell tumors of extremities, including the current status of surgical and pharmacological treatments, analyzing the choice of surgical modalities in different clinical situations, in order to provide clinical inspirations for diagnosis and treatment.

The role of vitamin D metabolism in regulating bone turnover in adolescents with perinatally-acquired HIV in southern Africa: a cross-sectional study in Zimbabwe and Zambia.

Vitamin D dysregulation can occur in people living with HIV, disrupting calcium homeostasis and bone turnover. We aimed to investigate the potential mechanisms by which vitamin D regulates bone turnover in adolescents living with perinatally-acquired HIV (ALWH) in southern Africa. A pre-planned secondary analysis was performed of baseline data from the VITALITY trial [PACTR20200989766029] which enrolled ALWH (11-19years) taking antiretroviral therapy for ≥6months, and recorded socio-demographic, clinical and dietary data. After over-night fasting, vitamin D metabolites [25(OH)D, 1,25(OH)2D, 24,25(OH)2D], intact parathyroid hormone (PTH) and bone turnover markers (BTMs) [CTX and P1NP] were measured. Tandem Mass Spectrometry measured vitamin D metabolites, whilst intact PTH and BTMs were analysed by electrochemiluminescence immunoassay. Stratified by 25(OH)D [<75 vs ≥75nmol/L], associations between standardized concentrations (β = standard deviations) of vitamin D metabolites, intact PTH and BTMs were assessed using structural equations modelling (SEM) adjusted for age, sex and country (Zimbabwe/Zambia). Among the 842 ALWH enrolled, the median dietary calcium intake was 100mg [IQR:55-145]. The SEM showed PTH was positively associated [β 0.21, 95%CI: 0.1,0.32] with 1,25(OH)2D, only when 25(OH)D was <75nmol/L vs ≥75nmol/L [β 0.23, 95%CI: -0.13,0.59], with evidence of an interaction [β -0.11, 95%CI: -0.20,-0.02]. A positive relationship between 25(OH)D and 24,25(OH)2D was seen irrespective of 25(OH)D concentration. 24,25(OH)2D was inversely related to BTMs, particularly when 25(OH)D was <75nmol/L [CTX: β -0.15, 95%CI: -0.24,-0.06, and P1NP: β -0.14, 95%CI: -0.22,-0.06]. There was interaction between dietary calcium and 25(OH)D on PTH [β -0.15, 95% CI: -0.22,-0.07] suggesting an interaction between low 25(OH)D and low dietary calcium which increases PTH. In conclusion, associations between 25(OH)D, PTH, 1,25(OH)2D and BTMs in ALWH appear dependent upon 25(OH)D concentrations <75nmol/L and calcium intake. A novel, potentially causal pathway between 25(OH)D, 24,25(OH)2D and BTMs was seen. Findings enhance understanding of vitamin D metabolism in people living with HIV.

Strain As An Indicator For Stress Fractures In Racehorses

Abstract The horse racing industry, despite its financial significance, grapples with significant welfare issues, particularly stress fractures in racehorses. Third metacarpal (MC3) bone fractures, constituting about one-third of all limb fractures, severely impact horse health and performance. The frequent occurrence of condylar fractures in the MC3, often resulting in bone comminution, poses high risks-sometimes necessitating euthanasia, and complicates the management and recovery processes for the rest. Comprehensive methods for quantitatively determining fracture risks in horses are lacking, with strain measurements on the MC3 during racing conditions showing promise as an indicator of high loads and potential fracture risks. This study investigated the mechanical properties of MC3 under high compressive loads. Six MC3 bones from euthanized horses were instrumented with strain gauge rosettes at four key locations: Lateral Condyle (CondL), Medial Condyle (CondM), Dorsal DistoLateral (DisL) and Dorsal DistoMedial (DisM). Each bone underwent a pre-loading phase and five cycles of 12kN sinusoidal loading to replicate galloping forces. Strain patterns were observed before and after introducing an artificial slot in the lateral condylar groove to simulate a fatigue crack. A strong correlation was found between load and minimum principal strain in both intact and fatigue crack-induced (FCI) bones, with R-squared values over 0.99. Post-FCI, 83% of bones exhibited an increase in the minimum principal strain-load response slope, indicating uniform changes in material behavior. Additionally, a rise in post-FCI y-intercept values across MC3 locations indicated higher initial strain and possible changes in bone properties.

Prosthetic Soft Tissue Management in Esthetic Implant Restorations, Part I: Presurgical Planning, Implant Placement, and Restoration Timing. A Narrative Review.

This two-part review article delineates various techniques to enhance esthetic outcomes in anterior implant treatments. Part I concentrates on presurgical measures, case selection, implant placement, and restoration timing. Part II discusses post-surgical steps, the temporary restoration phase, the emergence profile contour, abutment types, and impression techniques. A comprehensive search was conducted using Medline/PubMed, Embase, Scopus, and the Cochrane Library. The primary keywords included were "Dental Implants," "Dental Prosthesis, Implant-Supported," "Esthetics, Dental," "Dental Impression Techniques," and "Tissue Management." Initially, 1472 studies were identified, from which 187 were selected based on publication year and title relevance. After removing duplicates, 84 abstracts were reviewed in full text, culminating in 59 studies being thoroughly analyzed. Optimal esthetics in implant restorations are attainable through meticulous treatment planning, precise surgical execution, and systematic restorative steps, ensuring predictable outcomes. Factors such as a thick gingival biotype, an intact facial bone wall, and atraumatic extraction significantly contribute to superior esthetic results. Immediate implant placement combined with immediate provisionalization provides the most predictable outcomes by supporting and maintaining soft tissue architecture. Conversely, delayed implant placement and provisionalization often require extensive manipulation of collapsed soft tissues to achieve desired esthetics.

Effects of Aging on the Immune and Periosteal Response to Fracture in Mice.

Aging predisposes individuals to reduced bone mass and fragility fractures, which are costly and linked to high mortality. Understanding how aging affects fracture healing is essential for developing therapies to enhance bone regeneration in older adults. During the inflammatory phase of fracture healing, immune cells are recruited to the injury site as periosteal skeletal stem/progenitor cells (pSSPCs) rapidly proliferate and differentiate into osteochondral lineages, allowing for fibrocartilaginous callus formation and complete bone healing. Irrespective of age, how periosteal mesenchymal and immune cells interact during early fracture healing is incompletely understood, limiting our ability to potentially modulate these processes. To address this, we directly analyzed, in parallel, at a single-cell level, isolated murine CD45(+) and CD45(-) periosteal cells dissected from intact and fractured bones, collected three days after injury. Through comprehensive analysis, corroborated by bulk RNA-sequencing, flow cytometry, and histology, we found aging decreases pSSPCs proliferative, marked by a reduced expression of genes required for callus formation and an increased senescence signature. We found that the chemokine Cxcl9 was highly upregulated in aged intact Prrx1+ pSSPCs, predicted to interact with other pSSPCs directly, and associated with increased recruitment of CD8+ T cells at the fracture site three days after injury. Cell-to-cell communication analysis provided insight into the complexity of interactions among the many cell types regulating fracture healing and the impact of aging on these processes. Together, these results provide insight into age-induced alterations in fracture healing, informing the development of improved therapeutic approaches for fragility fractures.

Plating after tumor curettage in human femora does not efficiently improve torsional stability ex vivo

BackgroundSurgical treatments of benign primary bone tumors of the femur face the challenge of limiting tissue damage and contamination while providing sufficient stabilization to avoid fracture. While no clear treatment guidelines exist, surgical treatment commonly consists of femoral fenestration and curettage with optional filling and plating of the defect. Mono- or bicortical plating of distal femoral defects aim to reduce fracture risk and have been shown to increase axial stability. However, it remains unclear whether plating increases torsional stability of the affected femur. Questions/purposesThis biomechanical study aimed to determine how much additional stability can be achieved by mono- or bicortical plating of femoral defects after fenestration. The following hypotheses were investigated: 1. Preventive plating of distal femur bone defects enhances torsional stability when compared to femoral fenestration alone. 2. A condition close to the intact (nonpathological) bone can be achieved by bone plating. 3. Defect shape influences torsional stability. Patients and methodsThiel embalmed human femora (n = 24) were left intact or subjected to the following surgical treatments (A) defect creation via fenestration, (B) defect with short monocortical plating, (C) defect with long bicortical plating. All femora were torsion tested in midstance position using pre-cycling and testing until failure. Quantitative computed tomography pre and post testing allowed bone mineral density calculation and crack path analysis. Finite element analysis provided insight into defect shape variations. ResultsTorsion experiments showed no relevant enhancement of torsional stability due to mono- or bicortical plating. There were no significant differences in maximum torque between unplated and plated femora with defect (defect: 35.38 ± 7.53 Nm, monocortical plating: 37.77 ± 9.82 Nm, bicortical plating: 50.27 ± 9.72 Nm, p > 0.05). Maximum torque for all treatment groups was significantly lower compared to intact femora (155–200 Nm, p < 0.001). Cracks originated predominantly from the proximal posterior corner of the defect and intersected with screw holes in plated femora. The influence of variations of the defect corner shapes had no significant influence on maximum torque and angle. ConclusionThis biomechanical study shows that mono- or bicortical plating is not an effective preventive treatment against torsional failure of femora with distal defects as the resulting maximum torque was drastically reduced compared to intact femora. Thus, the initial hypotheses have to be rejected. As habitual loading of the femur includes a combination of axial and torsional loading, the observed lack of prevention against torsional failure might help to explain the occurrence of fractures despite plating. Future research towards ameliorating clinical outcome should address the role of defect filling with bone cement or bone grafts regarding the improvement of torsional stability after primary bone tumor treatment in the femur.

A Customized Distribution of the Coefficient of Friction of the Porous Coating in the Short Femoral Stem Reduces Stress Shielding

Stress shielding and aseptic loosening have been identified as adverse effects of short-stem total hip arthroplasty resulting in hardware failure. However, there is a gap in research regarding the impact of stress shielding in customized porous coatings. The purpose of this study was to optimize the distribution of the coefficients of friction in the porous coating of a metaphyseal femoral stem to minimize stress shielding. Static structural analysis of an implanted short, tapered-wedge stem with a titanium porous coating was performed with the use of Analysis System Mechanical Software under axial loading. To limit computational time, we randomly sampled only 500 of the possible combinations of coefficients of friction. Results indicate that the coefficient of friction in the distal lateral porous coating significantly affected the mid-distal medial femoral surface and lateral femoral surface. The resultant increased proximal strains resulted from an increased coefficient of friction in lateral porous coating and a reduction in the coefficient of friction in medial mid-distal coating. These findings suggest that a customized porous coating distribution may produce strain patterns that are biomechanically closer to intact bone, thereby reducing stress shielding in short femoral stems.

Optimizing surgical approaches for lacrimal gland adenoid cystic carcinoma to minimize cross-organ invasion.

To evaluate the outcomes of eye-sparing surgery for lacrimal gland adenoid cystic carcinoma and the impact on tumor recurrence and orbital integrity. The study enrolled four patients with recurrent lacrimal gland adenoid cystic carcinoma. The outcome focused on the relevance of the integrity of the lateral orbital wall to the occurrence of extraorbital metastasis in the local recurrence of lacrimal gland adenoid cystic carcinoma. Three patients underwent eye-sparing surgery via lateral orbitotomy without postoperative radiotherapy, and one patient who underwent eye-sparing surgery via sub-brow approach. These four patients all demonstrated a recurrence involving the invasion of extraorbital tissues as metastatic form through surgical bone seams. Preserving intact orbital bone tissue is crucial for mitigating direct cross-organ metastasis of lacrimal gland adenoid cystic carcinoma. The findings suggest avoiding the lateral orbitotomy approach with no or limited orbital bone wall invasion.

Healing sequelae following tooth extraction and dental implant placement in an aged, ovariectomy model.

At present, a lack of consensus exists regarding the clinical impact of osteoporosis on alveolar bone metabolism during implant osseointegration. While limited preclinical and clinical evidence demonstrates a negative influence of osteoporosis on dental extraction socket healing, no preclinical studies offer data on the results of implant placement in 6-mo-old, ovariectomized (OVX) Sprague-Dawley rats. This study aimed to investigate the outcomes of dental tooth extraction socket healing and implant placement in a rodent model of osteoporosis following daily vehicle (VEH) or abaloparatide (ABL) administration. Micro-CT and histologic analysis demonstrated signs of delayed wound healing, consistent with alveolar osteitis in extraction sockets following 42d of healing in both the VEH and ABL groups. In a semiquantitative histological analysis, the OVX-ABL group demonstrated a tendency for improved socket regeneration with a 3-fold greater rate for moderate socket healing when compared to the OVX-VEH group (43% vs 14%), however, this finding was not statistically significant (p=.11). No significant differences were observed between vehicle and test groups in terms of implant outcomes (BMD and bone volume/total volume) at 14- and 21-d post-implant placement. Abaloparatide (ABL) significantly increased BMD of the femoral shaft and intact maxillary alveolar bone sites in OVX animals, demonstrating the therapeutic potential for oral hard tissue regeneration. The present model involving estrogen-deficiency-induced bone loss demonstrated an impaired healing response to dental extraction and implant installation.

Greenstick fractures of the forearm shaft-Is it obligatory or facultative to break the cortex?

To break or not to break-That is the question that has been asked in pediatric traumatology for many years regarding the treatment of greenstick fractures of the diaphyseal forearm shaft. The frequency of greenstick fractures of the forearm shaft in children and adolescents; the influence of breaking the fracture on the refracture rate. Analysis and discussion of relevant articles, analysis of the refracture rate of pediatric greenstick fractures of the forearm shaft in our own patient population. Greenstick fractures frequently occur in the area of the forearm shaft and incomplete consolidation leads to an increased refracture rate. In the patient collective of the authors of 420 children with greenstick fractures of the diaphyseal forearm, there was arefracture rate of 9.5%; however, the rate for non-completed fractures was significantly higher compared to the group with completed fractures (15.2% vs.3%). While in the subgroup of conservatively treated fractures (n = 234), breaking the intact cortex significantly reduced the refracture rate, breaking the intact cortical bone during surgical treatment with elastic stable intramedullary nailing (ESIN) did not change the refracture rate. As part of the conservative treatment of greenstick fractures of the diaphyseal forearm, completing the fracture can be recommended in order to lower the refracture rate. Completing the fracture does not appear to be necessary during surgical treatment using ESIN.

A Randomized Controlled Trial on the Timing of Soft-Tissue Augmentation in Immediate Implant Placement: Hard-Tissue Changes and Clinical Outcome.

To assess the impact of the timing of soft-tissue augmentation (STA) on mean buccal bone changes following immediate implant placement (IPP) in the anterior maxilla. Patients with a failing tooth and intact buccal bone wall in the anterior maxilla (15-25) were enrolled in this randomized controlled trial. Following single IIP and socket grafting, they were randomly allocated to the control group (immediate STA performed during the same surgical procedure) or the test group (delayed STA performed 3 months later). Implants were placed with a surgical guide and immediately restored with an implant-supported provisional crown. Changes in bone dimensions were assessed using superimposed CBCT images taken prior to surgery and at 1-year follow-up. Clinical outcomes were registered at 1-year follow-up. Twenty patients were randomized to each group (control: 16 females, 4 males, mean age 57.6; test: 9 females, 11 males, mean age 54.2). Ten patients in the control group and 13 patients in the test group had a thick bone wall phenotype. Estimated marginal mean horizontal buccal bone loss at 1 mm below the implant shoulder was -0.553 and -0.898 mm for the control and test group, respectively. The estimated mean difference of 0.344 mm in favour of the control group was not significant (95% CI: -0.415 to 1.104; p = 0.363). Also at all other horizontal and vertical levels, no significant differences could be observed between the groups. The combination of socket grafting and STA enabled counteraction of any buccal soft-tissue loss (≥ 0 mm) at 1 mm below the implant shoulder in 82% of the patients in the control group and in 75% of the patients in the test group (p = 1.000). The clinical outcome was favourable in both groups, yet implants in the control group demonstrated slightly less marginal bone loss (median difference 0.20 mm; 95% CI: 0.00-0.44; p = 0.028). In patients with an intact and mainly thick buccal bone wall in the anterior maxilla, the timing of STA following IIP had no significant impact on mean buccal bone loss. ClinicalTrials.gov identifier: NCT05537545.

Immediate single-tooth implant placement in bony defect sites: A 10-year randomized controlled trial.

It is unclear whether an intact buccal bony plate is a prerequisite for immediate implant placement in postextraction sockets. The aim of this 10-year randomized controlled trial was to compare peri-implant soft and hard tissue parameters, esthetic ratings of, and patient-reported satisfaction with immediate implant placement in postextraction sockets with buccal bony defects ≥5mm in the esthetic zone versus delayed implant placement after alveolar ridge preservation. Patients presenting a failing tooth in the esthetic region and a buccal bony defect ≥5mm after an extraction were randomly assigned to immediate (Immediate Group, n=20) or delayed (Delayed Group, n=20) implant placement. The second-stage surgery and provisional restoration placement occurred 3months after implant placement in both groups, followed by definitive restorations 3months thereafter. During a 10-year follow-up period, marginal bone levels (primary outcome), buccal bone thickness, soft tissue parameters, esthetics, and patient-reported satisfaction were recorded. The mean marginal bone level change was -0.71±0.59mm and -0.36±0.39mm in the Immediate Group and the Delayed Group after 10years (p=0.063), respectively. The secondary outcomes were not significantly different between both groups. Marginal bone level changes, buccal bone thickness, clinical outcomes, esthetics, and patients' satisfaction following immediate implant placement, in combination with bone augmentation in postextraction sockets with buccal bony defects ≥5mm, were not statistically different to those following delayed implant placement after ridge preservation in the esthetic zone. Immediate implant placement in case of a failing tooth is a favorable treatment option for patients because it considerably shortens treatment time and the number of surgical treatments. The question is if an intact buccal bone wall is necessary for immediate implant placement. A 10-year study was performed in which 20 patients with a failing tooth in the frontal region of the upper jaw were treated with immediate implant placement and were compared with 20 patients in whom a more conventional treatment strategy was followed in which the failing tooth was first removed and the bone gap restored and the implant placed in a second step. After a 10-year follow-up period, it appeared that the bone around the implant was very stable, gums were healthy, and patients were very satisfied with the result. There was no difference between the two treatment procedures. Such results mean that professionals can discuss the procedure with the patient and apply the individual's preference.

Mass Spectrometry Imaging of the Subchondral Bone in Osteoarthritis Reveals Tissue Remodeling of Extracellular Matrix Proteins that Precede Cartilage Loss.

Osteoarthritis (OA) of the knee is a degenerative condition of the skeletal extracellular matrix (ECM) marked by the loss of articular cartilage and subchondral bone homeostasis. Treatments for OA in the knee beyond full joint replacement are lacking primarily due to gaps in molecular knowledge of the biological drivers of disease. Here, Mass Spectrometry Imaging (MSI) enabled molecular spatial mapping of the proteomic landscape of human knee tissues. Histologic sections of human tibial plateaus from OA patients and cadaveric controls were treated with collagenase III to target ECM proteins prior to imaging using a timsTOF fleX mass spectrometer (Bruker) for matrix-assisted laser desorption ionization (MALDI)-MSI of bone and cartilage proteins in human knees. Spatial MSI data of the knee, using sections of the tibial plateau from non-arthritic, cadaveric donors or from knee replacement patients with medial OA were processed and automatically segmented identifying distinct areas of joint damage. ECM peptide markers compared either OA to cadaveric tissues or OA medial to OA lateral. Not only did candidate peptides distinguish OA relative to intact cartilage, but also emphasized a significant spatial difference between OA and intact subchondral bone (AUROC >0.85). Overall, 31 peptide candidates from ECM proteins, including COL1A1, COL3A1, and unanticipated detection of collagens COL6A1 and COL6A3 in adult bone, exhibited significantly elevated abundance in diseased tissue. Highly specific hydroxyproline-containing collagens dominated OA subchondral bone directly under regions of lost cartilage revealing dramatic tissue remodeling providing molecular details on the progression of joint degeneration in OA. The identification of specific spatial markers for the progression of subchondral bone degeneration in OA advances our molecular understanding of coupled deterioration of joint tissues.

In Vitro Biomechanical Study of Femoral Neck Fracture Fixation with Two or Three Cannulated Screws in Dogs.

To evaluate the in vitro mechanical properties of basilar fractures of the femoral neck stabilized with two or three titanium-cannulated screws in dogs. Ex vivo study. Cadaveric canine femur (n = 21). The bones were divided as follows: Group 1: control (no osteotomy); Group 2: osteotomy and stabilization with two cannulated screws; and Group 3: osteotomy and stabilization with three cannulated screws. All groups were tested with destructive axial compression with load applied to the femoral head. The stiffness, load, and displacement were evaluated at the failure of Group 1, and the yield load and displacement of Groups 2 and 3. The placement of the three cannulated screws was more demanding than two cannulated screws because of the risk of cortical perforation, especially in the trochanteric fossa area. The smaller the width of the femoral neck, the higher the risk of cortical bone wall perforation. The intact control bones were stiffer (674 N/mm) than both the two-screw repair (90 N/mm) and three-screw repair (120 N/mm) groups (p < 0.05). The failure load was greatest for Group 1 (2692 N). The yield loads for Groups 3 and 2 were 586 and 303 N, respectively. There was no difference between groups for displacement. In vitro cadaveric models of femoral neck basilar fractures repaired with three cannulated screws were significantly stronger than two cannulated screws, but the clinical efficacy must be evaluated by comparing them in vitro with noncannulated stainless steel screws.

Osteogenic potency of dental stem cell-composite scaffolds in an animal cleft palate model

ObjectiveTo evaluate the osteogenic potency of stem cells isolated from human exfoliated deciduous teeth (SHED) in polycaprolactone with gelatin surface modification (PCL-GE) and poly (lactic-co-glycolic acid)-bioactive glass composite (PLGA-bioactive glass (BG)) scaffolds after implantation in a rat cleft model. MethodsCleft palate-like lesions were induced in Sprague-Dawley rats by extracting the right maxillary first molars and drilling the intact alveolar bone. Rats were then divided into five groups: Control, PCL-GE, PCL-GE-SHED, PLGA-BG, and PLGA-BG-SHED, and received corresponding composite scaffolds with/without SHED at the extraction site. Tissue samples were collected at 2, 3, and 6 months post-implantation (4 rats per group). Gross and histological analyses were conducted to assess osteoid or bone formation. Immunohistochemistry for osteocalcin and human mitochondria was performed to evaluate bone components and human stem cell viability in the tissue. ResultsBone tissue formation was observed in the PCL-GE and PLGA-BG groups compared to the control, where no bone formation occurred. PLGA-BG scaffolds demonstrated greater bone regeneration potential than PCL-GE over 2–6 months. Additionally, scaffolds with SHED accelerated bone formation compared to scaffolds alone. Osteocalcin expression was detected in all rats, and positive immunoreactivity for human mitochondria was observed in the regenerated bone tissue with PCL-GE-SHED and PLGA-BG-SHED. ConclusionPCL-GE and PLGA-BG composite scaffolds effectively repaired and regenerated bone tissue in rat cleft palate defects. Moreover, scaffolds supplemented with SHED exhibited enhanced osteogenic potency. Clinical significancePCL-GE and PLGA-BG scaffolds, augmented with SHED, emerge as promising biomaterial candidates for addressing cleft repair and advancing bone tissue engineering endeavors.

Design and evaluation of mechanical strength of multi-material polymeric implants for mandibular reconstruction.

Reconstruction of mandible implants to address segmental abnormalities is still a challenging task, both in vitro and in vivo. The mechanical strength of the materials used is a critical factor that determines how well bone is regenerated. The reconstruction technique of mandibular abnormalities widely uses polymeric implants. It is critical to evaluate the mechanical resilience under different load cases, including axial, combined, and flexural loading conditions. This study developed implants for mandibular defects using a combination of four materials: polylactic acid (PLA), polyethylene terephthalate glycol (PETG), thermoplastic polyurethane (TPU), and polycaprolactone (PCL), with the aim of mimicking the inherent characteristics of cortical and cancellous bone structures and evaluating their mechanical properties to support bone Osseo integration. The eleven of these combinations of structures result below the micro strain threshold level of <3000 µε, and the five combinations of the structures result in micro strain above the threshold value. The intact bone study results show that the stress under axial, combined, and flexural loading conditions is 27.6, 38.9, and 64.9 MPa, respectively. This study's stress results are lower than those from the intact bone study. The study found that the combinations of PLA and TPU material were most preferred for the cortical and cancellous bone regions of polymeric implants. These materials are also compatible with 3D printing. The results of this study can be used to find multi-material combinations that are strong and flexible.

Bone health in young adults with type 1 diabetes and progressive eGFR decline

BackgroundType 1 Diabetes (T1D) is associated with increased risk of fractures, worsened by presence of microvascular complications. This study’s objective is to determine the impact of progressive decline in estimated glomerular filtration rate (eGFR) on bone biomarkers and bone microarchitecture in youth with T1D.MethodsSlopes of eGFR were calculated using measures obtained at four timepoints from adolescence to young adulthood. Participants were identified as eGFR decliners if eGFR decreased ≥ 3ml/min/1.73m2/year. Bone health was assessed in young adulthood by high resolution peripheral quantitative computed tomography (HRpQCT Xtreme CTII) and bone biomarkers; osteocalcin, procollagen 1 intact n-terminal pro-peptide (P1NP), c-terminal telopeptide (CTX), and bone specific alkaline phosphatase. The relationship between diabetes duration, glycated hemoglobin, body mass index (BMI) and vitamin D level on bone biomarkers and microarchitecture was evaluated. Linear regression analysis was used for the statistical analysis in this study.ResultsNinety-nine study participants were studied with longitudinal evaluation of eGFR over 7.4 ± 1.0 years with mean age of 14.7 ± 1.7 years at baseline. Cross sectional evaluation of bone was performed at 21.3 ± 2.1 years. 44% participants had eGFR decline and showed 5% higher cortical porosity diameter than non-decliners (p = 0.035). Greater diabetes duration was associated with higher trabecular separation (p = 0.004) and lower trabecular number (p = 0.01). Higher level of 25 hydroxy-vitamin D was associated with lower trabecular separation (p = 0.01). Elevated glycated hemoglobin (p = 0.0008) and BMI (p = 0.009), were associated with lower markers of bone formation.ConclusionMild increase in cortical porosity diameter was found in youth with T1D and eGFR decline, however, overall measures of bone microarchitecture on HR-pQCT were similar between both groups and there were no statistically significant changes in bone biomarkers. Hence, skeletal impairments were limited in youth with different eGFR trajectories near peak bone mass. Longitudinal HR-pQCT studies are needed to further understand the impact of eGFR decline on bone microarchitecture. Optimal glycemic control, normal BMI and vitamin D status were supported by this study as important markers for good bone health.

Advances in the application of the bony window technique in endodontic microsurgery

The bony window technique refers to cutting the intact bone plate to form a bone window and a free bone block to get access to lesions under the bone. At the end of the surgery, the dislocated bony lid needs to be repositioned to its original position. In endodontic microsurgery, compared with conventional osteotomy, the bony window technique has the advantages of improving the view of surgery and operability, reducing postoperative bone defects, promoting bone healing, and maintaining the integrity of the jaw outline. Accurate positioning and preparation of the bony window are important prerequisites for subsequent operations during the surgery, but it's difficult in some situations, such as when the operative area is located posteriorly or the bone cortex on the lesion surface is thick and intact. What's more, whether the free bone block can be stabilized in situ after repositioning is closely related to the prognosis of the surgery. The complementary application of digital navigation technology and bone cavity filling materials may help to improve the bony window technique and provide more possibilities for the retention of affected teeth in difficult cases.

COMORBIDITY IN ONCOLOGY: MODERN CHALLENGES AND THE SEARCH FOR WAYS TO SOLVE THE PROBLEM

Introduction. The article is devoted to the current problem of modern oncology – increasing the treatment effectiveness of cancer patients with comorbidities. Comorbidity is accompanied by higher rates of mortality, disability, side effects of treatment, increased use of the patient's body resources, and lower quality of life. The aim of the study. To develop a method of recurrence prevention after bone lesions resection and bone replacement surgery for malignant primary bone tumors, which would ensure a longer duration of the 1st recurrence-free period in patients with comorbidities. Materials and methods. The study included a control group consisting of 27 patients who underwent bone replacement surgery after removal of primary malignant tumors of the pelvis and lower extremities. The study group included 25 patients who underwent biomin bone replacement surgery after removal of malignant primary tumors of the pelvic bones and lower limbs, as well as neuropeptide therapy with the drug dalargin. Results. The obtained data testify to the effectiveness of the proposed method of treatment with the use of dalargin: compaction of the structure of compact and spongy tissues and an increase in their heterogeneity have been established. Under the influence of dalargin, the structure of the interface, characteristic of intact bone tissue, is reorganized, accordingly, the restoration of strength is observed. 12 months after the operation, the bone density in the patients of the main group practically recovered to the values typical for the intact limb (p&lt;0.01). No such recovery was observed in patients of the control group. Within 11 to 23 months, 10 patients of the control group had tumor recurrences. Instead, in the study group, the analysis of the results revealed the following: within 21 months, only 1 patient had a recurrence of the tumor. Conclusions. Neuropeptide Dalargin helps to increase the duration of the 1st relapse-free period in patients with primary malignant bone tumors with polymorbidity. The proposed treatment method with integration into the therapeutic protocol of the neuropeptide dalargin allows to increase the complex therapy effectiveness and improve the prognosis of the course of the disease.

Numerical evaluation of scaffolds as a method to restore continuity of a long bone

PurposeIn case of necessity of removing a bone fragment, the process of restoring bone continuity relies on the use of bone grafts or bone plates as osteosynthesis methods. These approaches are characterised by several disadvantages, such as significant changes in load transfer method through the bone. Recently, scaffolds emerged as potentially more efficient method in restoring bone continuity. In this paper, an attempt was made to validate the correctness of this statement. Materials and methodsThree lengths of bone defects were selected for the analysis: 35, 45 and 55 mm, located in the lower, middle and upper section of femur diaphysis. The following methods of restoring bone continuity were evaluated: 1 plate, 2 parallel plates, 1 plate and scaffold, 2 parallel plates and scaffold. Simulations of the forces generated during human gait cycle were performed. The evaluated parameters obtained were: maximal and average stresses, strain energy density as well as percentage changes in values of these parameters in relation to the values obtained for intact bone in its selected zones. ResultsStudies have shown that the best method of restoring bone continuity is to use a single plate with a scaffold. The stress distribution obtained by this method had the highest similarities to the one obtained for intact bone model in terms of load transfer as well as maximal stresses values obtained. ConclusionsThe study validated the statement that the use of a scaffold to restore bone continuity is potentially more efficient method than conventional approaches.