Bone Interface Research Articles

To evaluate and compare the effect of stresses in peri implant bone after offset placement of implant in edentulous posterior mandible using

Background: In the present era, when it comes to oral rehabilitation, a wide array of options are available to restore missing teeth using fixed and removable prostheses, however, advances in dental implant surgery offer viable option to provide improved functional efficiency, appearance, comfort and speech2 . The desired position of the artificial teeth is determined by aesthetic and functional requirements. Lack of bone volume always results in exposure of implant surface, reduced bone implant contact and finally implant failure. Aim: The aim of this study is to evaluate and compare the effect of stresses in peri implant bone after offset placement of implant in edentulous posterior mandible using: - “3D finite element analysis (FEA).” Objectives: 1. To evaluate the effect of stresses in peri implant bone after offset placement of dental implant using 3D finite element analysis. 2. To analyze the stress distribution patterns in the implant and the peri implant bone interface. 3. To evaluate and compare the stress in peri implant bone after placing the implant in different implant configurations – straight and offset.

Histomorphometry of Ossification in Functionalised Ceramics with Tripeptide Arg-Gly-Asp (RGD): An In Vivo Study.

The present study investigated the osseointegration promoted by functionalised ceramics with peptide Arg-Gly-Asp (RGD) in a rabbit model in vivo. Histomorphometry of the RGD functionalised ceramic implants was conducted by a trained pathologist to quantify the amount of mature and immature ossification at the bone interface, and then compared to titanium alloy implants. The region of interest was the area surrounding the implant. The percentage of ROI covered by osteoid implant contact and mature bone implant contact were assessed. The presence of bone resorption, necrosis, and/or inflammation in the areas around the implant were quantitatively investigated. All 36 rabbits survived the experimental period of 6 and 12 weeks. All implants remained in situ. No necrosis, bone resorption, or inflammation were identified. At 12 weeks follow-up, the overall mean bone implant contact (p = 0.003) and immature osteoid contact (p = 0.03) were improved compared to the mean values evidenced at 6 weeks. At 6 weeks follow-up, the overall osteoid implant contact was greater in the RGD enhanced group compared to the titanium implant (p = 0.01). The other endpoints of interest were similar between the two implants at all follow-up points (p ≥ 0.05). Functionalised ceramics with peptide RGD promoted ossification in vivo. The overall osteoid and bone implant contact improved significantly from 6 to 12 weeks. Finally, RGD enhanced ceramic promoted faster osteoid implant contact in vivo than titanium implants. Overall, the amount of ossification at 12 weeks is comparable with the titanium implants. No necrosis, bone resorption, or inflammation were observed in any sample.

Densification of cancellous bone with autologous particles can enhance the primary stability of uncemented implants by increasing the interface friction coefficient

Sufficient primary stability is one of the most important prerequisites for successful osseointegration of cementless implants. Bone grafts, densification and compaction methods have proven clinically successful, but the related effects and causes have not been systematically investigated. Postoperatively, the frictional properties of the bone-implant interface determine the amount of tolerable shear stress. Frictional properties of different implant surfaces have been widely studied. Less attention has been paid to the influence of host bone modifications. The purpose of this study was to investigate the influence of densification of cancellous bone with bone particles on the interface friction coefficient.Cancellous bone samples from femoral heads were densified with bone particles obtained during sample preparation. The densification was quantified using micro-Ct. Friction coefficients of the densified and paired native samples were determined.Densification increased the BV/TV in the first two millimeters of the bone samples by 10.5 ± 2.7% to 30.5 ± 2.7% (p < 0.001). The static friction coefficient was increased by 10.5 ± 6.1% to 0.43 ± 0.03. The static friction coefficient increased with higher BV/TV of the bone interface, which is represented by the top 2 mm of the bone.The increase in contact area, intertrabecular anchorage and particle bracing could be responsible for the increase in friction. Optimization of particle shape and size based on the patient’s individual bone microstructure could further increase frictional resistance. Bone densification has the potential to improve the primary stability of uncemented implants.

Upregulation of Runt related transcription factor 1 (RUNX1) contributes to tendon–bone healing after anterior cruciate ligament reconstruction using bone mesenchymal stem cells

BackgroundAnterior cruciate ligament (ACL) injury could lead to functional impairment along with disabilities. ACL reconstruction often fails owing to the regeneration failure of tendon–bone interface. Herein, we aimed to investigate the effects of Runt related transcription factor 1 (RUNX1) on tendon–bone healing after ACL reconstruction using bone mesenchymal stem cells (BMSCs).MethodsBMSCs were isolated from the marrow cavity of rat femur, followed by the modification of RUNX1 with lentiviral system. Then, an ACL reconstruction model of rats was established with autografts.ResultsResults of flow cytometry exhibited positive-antigen CD44 and CD90, as well as negative-antigen CD34 and CD45 of the BMSCs. Then, we found that RUNX1-upregulated BMSCs elevated the decreased biomechanical strength of the tendon grafts after ACL reconstruction. Moreover, based on the histological observation, upregulation of RUNX1 was linked with better recovery around the bone tunnel, a tighter tendon–bone interface, and more collagen fibers compared to the group of BMSCs infected with LV-NC. Next, RUNX1-upregulated BMSCs promoted osteogenesis after ACL reconstruction, as evidenced by the mitigation of severe loss and erosion of the cartilage and bone in the tibial and femur area, as well as the increased number of osteoblasts identified by the upregulation of alkaline phosphatase, osteocalcin, and osteopontin in the tendon–bone interface.ConclusionElevated expression of RUNX1 contributed to tendon–bone healing after ACL reconstruction using BMSCs.

3D cell-printing of gradient multi-tissue interfaces for rotator cuff regeneration.

Owing to the prevalence of rotator cuff (RC) injuries and suboptimal healing outcome, rapid and functional regeneration of the tendon–bone interface (TBI) after RC repair continues to be a major clinical challenge. Given the essential role of the RC in shoulder movement, the engineering of biomimetic multi-tissue constructs presents an opportunity for complex TBI reconstruction after RC repair. Here, we propose a gradient cell-laden multi-tissue construct combined with compositional gradient TBI-specific bioinks via 3D cell-printing technology. In vitro studies demonstrated the capability of a gradient scaffold system in zone-specific inducibility and multi-tissue formation mimicking TBI. The regenerative performance of the gradient scaffold on RC regeneration was determined using a rat RC repair model. In particular, we adopted nondestructive, consecutive, and tissue-targeted near-infrared fluorescence imaging to visualize the direct anatomical change and the intricate RC regeneration progression in real time in vivo. Furthermore, the 3D cell-printed implant promotes effective restoration of shoulder locomotion function and accelerates TBI healing in vivo. In summary, this study identifies the therapeutic contribution of cell-printed constructs towards functional RC regeneration, demonstrating the translational potential of biomimetic gradient constructs for the clinical repair of multi-tissue interfaces.

Impact of patient, surgical, and implant design factors on predicted tray-bone interface micromotions in cementless total knee arthroplasty.

Micromotion magnitudes exceeding 150 µm may prevent bone formation and limit fixation after cementless total knee arthroplasty (TKA). Many factors influence the tray-bone interface micromotion but the critical parameters and sensitivities are less clear. In this study, we assessed the impacts of surgical (tray alignment, tibial coverage, and resection surface preparation), patient (bone properties and tibiofemoral kinematics), and implant design (tray feature and surface friction) factors on tray-bone interface micromotions during a series of activities of daily living. Micromotion was estimated via three previously validated implant-bone finite element models and tested under gait, deep knee bending, and stair descent loads. Overall, the average micromotion across the tray-bone cementless contact interface ranged from 9.3 to 111.4 µm, and peak micromotion was consistently found along the anterior tray edge. Maximizing tibial coverage above a properly sized tibial tray (an average of 12.3% additional area) had minimal impact on micromotion. A 1 mm anterior tray alignment change reduced the average micromotion by an average of 16.1%. Two-degree tibial angular resection errors reduced the area for bone ingrowth up to 48.1%. Differences on average micromotion from ±25% changes in bone moduli were up to 75.5%. A more posterior tibiofemoral contact due to additional 100 N posterior force resulted in an average of 79.3% increase on average micromotion. Overall, careful surgical technique, patient selection, and controlling kinematics through articular design all contribute meaningfully to minimizing micromotion in cementless TKA, with centralizing the load transfer to minimize the resulting moment at the anterior tray perimeter a consistent theme.

A 3D Network of Nanochannels for Possible Ion and Molecule Transit in Mineralizing Bone and Cartilage

During crucial growth stages of vertebrate long bones, calcified cartilage beneath the growth plate is anchored to bone by a third mineralized component, the cement line. Proper skeletal development is contingent on the interplay of these three constituents, yet their mineralization processes and structural interactions are incompletely understood, in part from limited knowledge of their meso‐ and nanoscale features. Herein, focused ion beam‐scanning electron microscopy (FIB‐SEM) with serial surface imaging is applied to examine the cartilage–bone interface of mouse femoral heads at an unprecedented scale: FIB‐SEM provides 3D, nanometer resolution of structural details for volumes encompassing metaphyseal calcified cartilage, bone, and the intervening cement line. A novel and complex structural network is revealed, comprising densely packed nanochannels smaller than bone canaliculi (≈10–50 nm diameter) within the calcified cartilage and bone extracellular matrices, but absent in the cement line. A structural correlation is demonstrated between the nanochannels and ellipsoidal mineral domains, which appear to coalesce during mineralization in a process analogous to powder sintering in metallurgy. A mineralization process is proposed, supported by energy‐dispersive X‐Ray spectroscopy of nanochannel contents, in which these unreported structures offer ion and molecule conduits to access the extracellular matrices of calcified cartilage and bone.

Peri-Implantitis: A New Definition Proposal Based on Unnatural Spatial Arrangement and Late Mechanical Coupling between Two Cortical Bone Layers during Osseointegration Phase: Part I

Scientists have been speculating for three decades about the reasons for the occurrence of peri-implantitis around dental implants. Many theories have been proposed since the beginning of 1990. Since then, the dental profession has been exposed to a vast number of peri-implantitis cases, whereas the “disease” had been unknown before this time. However, the situation has not improved because we focus more on how to treat the problem instead of trying to understand it completely. The aim of this paper is to present a purely bone-based explanation for the beginning of the “bone loss” process around already “osseointegrated” implants. Conclusion: There are a number of possible chain reactions of physiological bone response to dental implants which may explain the occurrence of peri-implantitis. Bacteria and “immunological reactions” may not be the main causes of this disease. In the first part, the authors present the principles of bone biology and physiology based on the theories of Donath, Jansen and Frost and transfer them to the field of implantology. They describe the stages of “osseointegration”, explaining the subsequent changes in the bone at the implant–bone interface.

Influence of a remelt scan strategy on the microstructure and fatigue behaviour of additively manufactured biomedical Ti65Ta efficiently assessed using small scale specimens

Due to its high cost and demanding characteristics, Tantalum requires unique processing techniques and is restricted to small parts. In the present work, Ti65Ta was additively manufactured as a new potential material for small biomedical implants. Assessment of the effects of a remelt scanning strategy was solely accomplished by testing of small mechanical specimens. Yield strength was achieved superior to either L-PBF pure Ti or Ta and low-cycle fatigue behaviour was similar to that of L-PBF Ti-6Al-4 V. The Ti65Ta alloy is a good candidate for a new gold standard alloy for small bone interfacing implants.

Effect of Diabetes Mellitus on Implant Osseointegration of Titanium Screws: An Animal Experimental Study.

ObjectiveTo explore the effect of diabetes mellitus (DM) on implant osseointegration of titanium screws.MethodsSixty rats were randomly divided into a DM group and a control group (each group, n = 30). DM group rats were injected with 1% Streptozotocin solution at 65 mg/kg to establish a DM model. Titanium screws were implanted into the rats' distal femurs in both groups. The rats were sacrificed for micro‐CT scanning, micro‐indentation, biomechanical detection, confocal Raman microspectroscopy, and histological and histomorphometric analysis at 4, 8, and 12 weeks post‐implantation, respectively. Messenger RNA (mRNA) expression and protein expression of the related growth factors around the implant were analyzed using real‐time polymerase chain reaction and Western blots.ResultsAt 4, 8 and 12 weeks, micro‐CT scanning, hematoxylin‐eosin (HE) staining, Gieson's acid‐magenta staining, and fluorescent labeled staining showed disorder in the bone tissue arrangement, a lack of new bone tissue, poor maturity and continuity, and poor trabecular bone parameters around the implant in the DM group. At 4, 8, and 12 weeks, the interfacial bone binding rate in the DM group was significantly lower (16.2% ± 4.8%, 25.7% ± 5.7%, 42.5% ± 5.8%, respectively) than that in the control group (23.6% ± 5.2%, 40.8% ± 6.3%, 64.2% ± 7.3%, respectively; P < 0.05). At 8 and 12 weeks, the elastic modulus (17.0 ± 1.8 and 15.1 ± 1.5 GPa, respectively) and trabecular bone hardness (571 ± 39 and 401 ± 37 MPa, respectively) in the DM group were significantly lower than the elastic modulus (23.4 ± 2.3 and 23.8 ± 1.8 GPa, respectively) and trabecular bone hardness (711 ± 45 and 719 ± 46 MPa, respectively) in the control group (P < 0.05). The maximum load required for the prosthesis pull‐out experiment in the DM group at 4, 8, and 12 weeks (55.14 ± 6.74 N, 73.34 ± 8.43 N, and 83.45 ± 8.32 N, respectively) was significantly lower than that in the control group (77.45 ± 7.48 N, 93.28 ± 8.29 N, and 123.62 ± 9.43 N, respectively, P < 0.05). At 8 and 12 weeks, the mineral‐to‐collagen ratio in the DM group (6.56 % ± 1.35% and 4.45%± 1.25%, respectively) was significantly higher than that in the control group (5.31% ± 1.42% and 3.62% ± 1.33%, respectively, P < 0.05). At 12 weeks, mRNA and protein expression levels of bone morphogenetic protein 2, transforming growth factor‐β1, vascular endothelial growth factor, osteopontin, osteocalcin, and runt‐related transcription factor 2 in the DM group were significantly lower than that in the control group.ConclusionsDM can negatively affect bone osseointegration, manifesting as disorder in bone tissue arrangement around the implant, a lack of new bone tissue, poor maturity and continuity, poor trabecular bone parameters and lower expression of the related growth factors.

High-purity magnesium screws modulate macrophage polarization during the tendon-bone healing process in the anterior cruciate ligament reconstruction rabbit model.

Magnesium (Mg) screws perform clinical potential in anterior cruciate ligament (ACL) reconstruction, and promote fibrocartilaginous entheses regeneration at the femoral entrance. We aim to prove that high-purity Magnesium (HP Mg) screws modulate macrophage polarization in fibrocartilage interface regeneration both in vitro and in vivo. HP Mg extracts performed good cytocompatibility and significantly promoted M2 macrophage polarization in the flow cytometry and ELISA assays. M2 macrophages stimulated fibrochondrocyte differentiation of co-cultured hBMSCs, and HP Mg extracts had synergistic effect on the process. Then we applied HP Mg screws, with Ti screws as control, in the ACL reconstruction rabbit model. In the histological and immunofluorescence analysis, HP Mg screws inhibited M1 polarization at 2 weeks and highly promoted M2 polarization at 2 and 4 weeks at the tendon–bone interface. Furthermore, regeneration of fibrocartilaginous entheses, rather than the fibrovascular scar interface, was detected in the HP Mg group at 12 weeks. For further mechanism study via RNA-seq detection and WB assays, we found that AKT1 was highly activated in M2 polarization, and HP Mg could stimulate AKT1 expression, rather than AKT2, in the early phase of tendon–bone healing. Our study elucidated macrophage polarization during tendon–bone healing process and emphasized HP Mg on M2 polarization and fibrocartilage interface regeneration via the selective activation of AKT1 and PI3K/AKT pathway.

A Three – Dimensional Finite Element Analysis of Polyetheretherketone PEEK in Dental Implant Prosthesis: A Novel Implant System

Purpose: This current numerical investigation aim to evaluate the benefits of substituting Titanium with CRF- PEEK for better stress distribution in implant- bone interface. Methods: 3D models of a dental implant for the first mandibular molar were constructed using the computed tomography (CT) scan. Four distinct models using a combination of titanium, carbon reinforced polyetheretherketone (CRF- PEEK), and zirconia for implant /abutment materials were studied. A three- dimensional finite element simulation was used to evaluate the stress distribution at the implant – bone interface under a compressive axial load of magnitude 120 N. A spherical indenter was used to simulate occlusal load. Results: Mesh independent study was converged for a very large number of elements. Finite element analysis showed: 1) there was no significant difference in the distribution pattern of stress at the implant – bone interface in the different material models studied, 2) the stress values for all prosthetic implant parts were well below the yield strength, 3) a larger deformation of PEEK implant versus titanium. Conclusion: The substitution of titanium with PEEK for the implant does not provide any better stress distribution and may lead to problems from the deformation of the implant.

Effects of 3D printed surface topography and normal force on implant expulsion

3D printing is a critical method for manufacturing metallic implants as it enables direct fabrication of intricate geometries and porous structures inaccessible to other manufacturing methods. Some common 3D printed porous structures are strut based (e.g. octet truss), triply periodic minimal surfaces (TPMS) (e.g. gyroid) or randomized (e.g. stochastic). When designed to be on the surface of bone interfacing implants, the surface porous region impacts short-term adhesion and friction, ultimately affecting implant stability prior to and during long-term osseointegration. In many orthopedic procedures, expulsion resistance is an essential design requirement, to prevent the risk of the implant migrating from the implantation site. While expulsion tests are universal, they are a poorly understood method to examine the bone-implant interface in determining the performance of an orthopedic implant. In this foundational study, we examine the expulsion behavior of metallic samples in synthetic Sawbone with systematically varied surface topography at increasing applied normal forces. The applied normal force and size of the sample were shown to have the strongest influence on expulsion force followed by surface structure. Compared to a polished sample control, certain 3D printed surface structures are up to 10x more expulsion resistant and should be considered in implants where prevention of implant migration before and during osseointegration is critical. Nonlinear relationships were discovered that reveal “crossover” in expulsion resistance as a function of applied load revealing that the ranking of the relative expulsion resistance of different samples can depend on the normal force selected. This new fundamental understanding has broad implications on both the design and potential standardized regulatory testing of textured orthopedic implants with tailored topologies.

Multiscale Sensing of Bone-Implant Loosening for Multifunctional Smart Bone Implants: Using Capacitive Technologies for Precision Controllability.

The world population growth and average life expectancy rise have increased the number of people suffering from non-communicable diseases, namely osteoarthritis, a disorder that causes a significant increase in the years lived with disability. Many people who suffer from osteoarthritis undergo replacement surgery. Despite the relatively high success rate, around 10% of patients require revision surgeries, mostly because existing implant technologies lack sensing devices capable of monitoring the bone–implant interface. Among the several monitoring methodologies already proposed as substitutes for traditional imaging methods, cosurface capacitive sensing systems hold the potential to monitor the bone–implant fixation states, a mandatory capability for long-term implant survival. A multifaceted study is offered here, which covers research on the following points: (1) the ability of a cosurface capacitor network to effectively monitor bone loosening in extended peri-implant regions and according to different stimulation frequencies; (2) the ability of these capacitive architectures to provide effective sensing in interfaces with hydroxyapatite-based layers; (3) the ability to control the operation of cosurface capacitive networks using extracorporeal informatic systems. In vitro tests were performed using a web-based network sensor composed of striped and interdigitated capacitive sensors. Hydroxyapatite-based layers have a minor effect on determining the fixation states; the effective operation of a sensor network-based solution communicating through a web server hosted on Raspberry Pi was shown. Previous studies highlight the inability of current bone–implant fixation monitoring methods to significantly reduce the number of revision surgeries, as well as promising results of capacitive sensing systems to monitor micro-scale and macro-scale bone–interface states. In this study, we found that extracorporeal informatic systems enable continuous patient monitoring using cosurface capacitive networks with or without hydroxyapatite-based layers. Findings presented here represent significant advancements toward the design of future multifunctional smart implants.

Bioactive Film-Guided Soft-Hard Interface Design Technology for Multi-Tissue Integrative Regeneration.

Control over soft‐to‐hard tissue interfaces is attracting intensive worldwide research efforts. Herein, a bioactive film‐guided soft–hard interface design (SHID) for multi‐tissue integrative regeneration is shown. Briefly, a soft bioactive film with good elasticity matchable to native ligament tissue, is incorporated with bone‐mimic components (calcium phosphate cement, CPC) to partially endow the soft‐film with hard‐tissue mimicking feature. The hybrid film is elegantly compounded with a clinical artificial ligament to act as a buffer zone to bridge the soft (ligament) and hard tissues (bone). Moreover, the bioactive film‐decorated ligament can be rolled into a 3D bio‐instructive implant with spatial‐controllable distribution of CPC bioactive motifs. CPC then promotes the recruitment and differentiation of endogenous cells in to the implant inside part, which enables a vascularized bone growth into the implant, and forms a structure mimicking the biological ligament–bone interface, thereby significantly improving osteointegration and biomechanical property. Thus, this special design provides an effective SHID‐guided implant‐bioactivation strategy unreached by the traditional manufacturing methods, enlightening a promising technology to develop an ideal SHID for translational use in the future.

Our experience of the management of severe bone defects in primary total knee arthroplasty with cement and screws with undersizing of tibia

&lt;p&gt;&lt;strong&gt;Background: &lt;/strong&gt;There are several options for dealing with tibial bone defects during total knee arthroplasty in severe primary osteoarthritis. The aim of this study was to report the midterm results of TKA with screw and cement augmentation of moderate-sized tibial bone defects.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Methods: &lt;/strong&gt;Patients with osteoarthritis who had posterior stabilised TKA with screw and cement augmentation of the tibia were reviewed retrospectively. Patients were assessed preoperatively and at follow-up using the International knee society knee score and function score, and radiographic analysis of alignment and signs of loosening.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results&lt;/strong&gt;&lt;strong&gt;:&lt;/strong&gt; 60 knee in 60 patients were included in the study. The mean age was 71 years; mean follow-up was 58 months. KS improved from 46 to 76 and FS from 51 to 92. The femorotibial mechanical angle changed from 174 to 178. There were no signs of osteolysis or loosening, and no revisions. Radiolucent lines at the cement bone interface were common but non- progressive.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Conclusions: &lt;/strong&gt;Midterm clinical and radiographic results of TKA with screw and cement augmentation for moderate tibial defects were satisfactory.&lt;/p&gt;

Ultrasound-Guided Injection Approach of Treating Tennis Elbow and Elbow Joint Synovitis Simultaneously Under One Needle Insertion Point.

A 52-yr-old man with right elbow pain for 6 mos visited an outpatient rehabilitation clinic. An obvious tender spot at the lateral epicondyle area was palpated with positive Cohen test.1 The patient had received autologous platelet-rich plasma injection but without much improvement.2 Musculoskeletal ultrasound images revealed thickening of the common extensor tendon, combined with diffuse heterogeneity and focal hypoechogenicity. Bony irregularity was observed at the tendon insertion site. The diagnosis of lateral epicondylitis, also known as “tennis elbow,” is a common cause of elbow pain. The exact pathogenesis remains elusive and is often difficult to treat. Ultrasound-guided injection to the bone and common extensor tendon interface may not be effective as many patients are also bothered with elbow joint synovitis.3 As a result, this article describes an important ultrasound-guided injection approach to treat tennis elbow and joint synovitis simultaneously under one needle insertion point. When applying ultrasound-guided injection to treat tennis elbow, the elbow is flexed at a 90-degree angle. The ultrasound linear probe is placed over the lateral epicondyle, along the longitudinal axis of the common extensor tendon origin. Under this sonographic view, the common extensor tendon, the lateral epicondyle, and the elbow joint can be observed. Conventionally, injection can be done under the longitudinal view, in a distal-to-proximal or proximal-to-distal direction, by guiding the needle to the bone tendon (extensor carpi radialis brevis tendon) interface.4 For patients who are also bothered with elbow joint synovitis, simultaneous injection to the bone-tendon interface, and aspiration of the joint fluid followed by the injection of an injectant may be needed (Figs. 1A, B).3 However, under the in-plane or longitudinal view, needle insertion into the elbow joint can be difficult because of the convex curvature of the radial head (Fig. 1B). Therefore, a different injection approach is recommended. Similar to the conventional method, the linear probe is placed longitudinally on top of the elbow joint. The needle is then inserted in a lateral-to-medial direction under the out-of-plane approach or short-axis view into the elbow joint (Figs. 2A, B). The needle is observed as a hyperechoic dot inside the elbow joint. Aspiration of the joint fluid followed by injection can then be performed. Still under the short-axis view, the needle is retracted and then guided in a slightly obliqued direction to the bone-tendon interface to commence subsequent injection treatment (Figs. 3A, B). Steroid was the injectant used. Elbow pain was greatly improved after the treatment.FIGURE 1: A, The linear ultrasound transducer is placed longitudinally on top of the right elbow to visualize the lateral epicondyle, common extensor tendon, bone-tendon (extensor carpi radialis brevis) interface, and the elbow joint. Conventionally, injection can be done under the longitudinal view and in a distal-to-proximal direction by guiding the needle to the bone-tendon interface. B, The needle is accurately guided to the bone-tendon (extensor carpi radialis brevis) interface (*). Due to synovitis, increased hypoechogenicity (resembling fluid accumulation) can be observed in the elbow joint (+). Using the distal-to-proximal direction needle approach, insertion into the elbow joint can be difficult because of the convex curvature of the radial head.FIGURE 2: A, With the linear ultrasound transducer placed longitudinally on top of the right elbow, the needle is inserted in a short-axis or out-of-plane view relative to the transducer and guided into the elbow joint (pink area). B, Under the short-axis view, the injection needle can be visualized as a hyperechoic dot inside the elbow joint.FIGURE 3: A, After completing elbow joint injection, the needle is then retracted and the syringe is moved slightly in a distal direction to guide the needle to the lateral epicondylar area (curved white arrow). B, Still under the short-axis view or slightly obliqued short-axis view, the needle is guided to the bone-tendon interface.

223Ra Induces Transient Functional Bone Marrow Toxicity.

223Ra is a bone-seeking, α-particle-emitting radionuclide approved for the treatment of patients with metastatic prostate cancer and is currently being tested in a variety of clinical trials for primary and metastatic cancers to bone. Clinical evaluation of 223Ra hematologic safety showed a significantly increased rate of neutropenia and thrombocytopenia in patients, hinting at myelosuppression as a side effect. Methods: In this study, we investigated the consequences of 223Ra treatment on bone marrow biology by combining flow cytometry, single-cell RNA sequencing, three-dimensional multiphoton microscopy and bone marrow transplantation analyses. Results: 223Ra accumulated in bones and induced zonal radiation damage confined to the bone interface, followed by replacement of the impaired areas with adipocyte infiltration, as monitored by 3-dimensional multiphoton microscopy ex vivo. Flow cytometry and single-cell transcriptomic analyses on bone marrow hematopoietic populations revealed transient, nonspecific 223Ra-mediated cytotoxicity on resident populations, including stem, progenitor, and mature leukocytes. This toxicity was paralleled by a significant decrease in white blood cells and platelets in peripheral blood-an effect that was overcome within 40 d after treatment. 223Ra exposure did not impair full hematopoietic reconstitution, suggesting that bone marrow function is not permanently hampered. Conclusion: Our results provide a comprehensive explanation of 223Ra reversible effects on bone marrow cells and exclude long-term myelotoxicity, supporting safety for patients.

Extramedullary Osseointegration-A Novel Design of Percutaneous Osseointegration Prosthesis for Amputees.

The percutaneous osseointegrated (OI) prostheses have greatly improved the overall quality of life for amputees. However, the long-term maintenance of the OI prostheses is still challenging. A major problem is bone resorption around the bone-implant-skin interface, which might cause implant loosening or osteomyelitis. Another problem is the breakage of connecting components between the intramedullary implant and external prosthesis due to excessive stress. We designed a novel osseointegration implant by changing the bone-implant contact from the inner cortex to the outer surface of cortical bone. In the current study, we compared the extramedullary cap-shaped implants with the intramedullary screw-type implants in rabbits. Osteointegration was confirmed at the interface of bone to implant contact (BIC) in both implant types. The external implant induced intramedullary bone regeneration in the medullary canal and increased the cortical bone density at the end of the stump. This study provides a new perspective on the design of osseointegration implants which might prevent the currently reported complications of the intramedullary OI systems.

Probing the sensitivity of the resonant frequency analysis to the dental implant-bone condition: A numerical study

The resonant frequency analysis (RFA) is a routinely used technique to assess dental implant stability. However, its sensitivity to the condition of the bone-implant interface remains largely unexplored. This paper investigates the RFA by means of numerical (finite element) simulations of short conical implants inserted into realistic jawbone sections.Two cases are examined. The first consists of a systematic variation in the bone-implant contact (BIC) using a random generation of the contact points in the two bone components. The results of the analyses show that beyond a BIC of ca. 20%, the RFA does not vary significantly, indicating a lack of sensitivity to further osseointegration.The next topic concerns peri-implantitis, as simulated firstly by a deterministic progressive detachment of the bone-implant interface. The main result of this simulation is that the RFA-BIC relationship is radically different for the osseointegration and bone recess phases, indicating a sensitivity to the location of the BIC in the bone components (random vs. deterministic). Finally, the simulation of a realistic peri-implantitis cylindrical crater of various depths shows no difference with respect to the previously analyzed interfacial bone detachment, indicating that the exact geometry of the peri-implantitis crater is of little if no influence on the RFA results.