Ligament Bone Research Articles

A Polyphenol–Metal Network of Propyl Gallate Gallium/Hafnium Oxide on Polyimide Fibers for Facilitating Ligament–Bone Healing

A Polyphenol–Metal Network of Propyl Gallate Gallium/Hafnium Oxide on Polyimide Fibers for Facilitating Ligament–Bone Healing

Application of multiplanar reconstruction and 3D printing in anterior cruciate ligament revision.

Anterior cruciate ligament injury is the most common type of knee joint ligament injury. Anterior cruciate ligament reconstruction has a high failure rate, with bone tunnel abnormalities as the most significant factor in these failures. Digital orthopedic technology can effectively develop implementation plans for the revision, thus increasing the success rate. This study aims to develop a surgical plan for anterior cruciate ligament revision by employing multiplanar reconstruction (MPR) for measuring bone tunnel position and diameter, and simulating bone tunnel creation via 3D printing preoperatively. A total of 12 patients who underwent anterior cruciate ligament revision at the Third Xiangya Hospital of Central South University between 2014 and 2021 were retrospectively studied. The data included patient demographics, preoperative formulated knee joint 3D printing models, and preoperative knee CT scans. The study measured the bone tunnel's diameter and position to guide the establishment of revision bone tunnels during surgery, reassessed the postoperative bone tunnels, and evaluated knee joint functional scores [including International Knee Documentation Committee Knee Evaluation Form (IKDC) score, Lysholm score, and Tegner exercise level score]. Preoperative measurements revealed suboptimal femoral tunnels positions in 4 patients and tibial tunnels positions in 2 patients. MPR and 3D printing technology were used to guide the establishment of a new bone canal during surgery, and postoperative measurements were satisfactory for all patients. Preoperative measurements demonstrated the interclass correlation coefficient for femoral tunnels and tibial tunnels diameters were 0.843 (P<0.05) and 0.889 (P<0.001), respectively. Meanwhile, the intraclass correlation coefficient were 0.811 (P<0.05) and 0.784 (P<0.05), respectively. The intraoperative diameter of femoral and tibial tunnels showed excellent correlation with postoperative CT measurements, with intraclass correlation coefficient values of 0.995 (P<0.001) and 0.987 (P<0.001), respectively. All bone tunnel positions were within the normal range. At the final follow-up, knee joint function scores in all 12 patients improved significantly compared to pre-surgery (P<0.001), and the reoperation rate was zero. MPR and 3D printing technology can accurately measure the parameters of reconstructed anterior cruciate ligament bone tunnels. Personalized revision plans for patients with reconstruction failure enhances the success rate of revision surgery and improves patient prognosis.

A morphological study on the sphenoid bone ligaments’ ossification pattern

PurposeThe sphenoid bone (SB) extracranial ligaments (ECRLs) are the pterygoalar and pterygospinous ligaments (PTAL and PTSL) that are located at the SB lateral pterygoid plate, and inferior to the foramen ovale (FO). Their ossification may affect the mandibular nerve’s distribution. The intracranial ligaments’ (ICRLs) ossification (the caroticoclinoid ligament—CCLL, the anterior and posterior interclinoid ligaments—AICLL and PICLL) may impede the approaches to the sella.This study highlights the incidence of the ossified ECRLs and ICRLs location, their type (partial, or complete), considering laterality, gender, age, and ligaments’ simultaneous presence.MethodsThe sample consisted of 156 Greek adult dried skulls of both genders and variable age.ResultsOssified ligaments were identified in 57.05%, predominantly extracranially (42.31%, P = 0.003). ECRLs were predominantly identified unilaterally (30.13%, P < 0.001). The majority of the ossified ICRLs were predominantly identified in male skulls (31.1%, P = 0.048) and the majority of the ECRLs (52.8%, P = 0.028) were predominantly identified at the age of 60 years and above. The PTAL was the most ossified (32.69%), followed by the CCLL (24.36%), the PTSL (16.03%), the PICLL (6.41%), and the AICLL (4.49%).ConclusionsDetailed knowledge of the SB morphology and ligaments’ ossification extent is essential to improve the technique of the FO percutaneous approach, and sellar approaches, to minimize complications.

Skeletally Immature Patients With Classic Anterior Cruciate Ligament Bone Bruise Patterns Have a Higher Likelihood of Having an Intact Anterior Cruciate Ligament Compared With Skeletally Mature Patients.

The incidence of anterior cruciate ligament (ACL) tears in skeletally immature patients with an ACL bone contusion pattern has been sparsely investigated. The purpose of this study is to investigate whether physeal status has an influence on the likelihood of sustaining an ACL tear when classic bipolar ACL bone bruising pattern is present. Magnetic resonance imaging reports were queried for "contusion" on all patients between 6 and 22 years between 2015 and 2019. Images were reviewed to denote all intra-articular pathology and the physeal status of the femur and tibia. The primary outcome was the incidence of ACL tears in patients with the presence of bipolar bone contusions. Fischer exact testing was used to determine associations. Of 499 patients included, 269 of those had bipolar bone contusions. Patients with bipolar bone contusions and ACL tears had a shorter duration between injury and imaging date compared with patients with ACL tears without bipolar bone contusions (6.9 vs. 38.6d, P =0.05). Patients with an open femoral physis had a higher likelihood of having an intact ACL despite the presence of bipolar bone contusions than patients with a closed femoral physis (10.8% vs. 1.0%, P <0.001). Of patients with bipolar bone contusions, those with an intact ACL were younger than patients with an ACL tear (14.6 vs. 16.4, P =0.017). Although bipolar bone contusions of the central lateral femoral condyle and posterior lateral tibial plateau are typically found after ACL injury, these bipolar contusions can be found concomitantly with an intact ACL and were more often found in relatively younger patients. Patients who have an open femoral physis have a higher likelihood to have an intact ACL despite the presence of bipolar bone contusions compared with patients who have a closed femoral physis. Level IV-cross-sectional.

Shared ACL Bone Tunnel Technique for Repair of Lateral Meniscus Posterior Root Tears Combined With ACL Reconstruction.

Background:Independent transtibial pullout repair is a common surgical technique for repairing lateral meniscus posterior root tears (LMPRTs). The shared anterior cruciate ligament (ACL) bone tunnel technique is an alternative technique for LMPRT repair combined with ACL reconstruction (ACLR) to avoid the establishment of additional bone tunnels.Purpose:To compare the clinical outcomes of the shared ACL bone tunnel versus the independent transtibial pullout techniques for LMPRT repair combined with ACLR.Study Design:Cohort study; Level of evidence, 3.Methods:Between March 2014 and February 2018, a total of 48 patients were diagnosed with ACL injury with concomitant LMPRT; 22 patients underwent independent transtibial pullout repair (group T), and 26 patients underwent the shared ACL bone tunnel technique (group S). At a follow-up of >2 years, we compared knee functional recovery using the Lysholm, Tegner, and International Knee Documentation Committee scores and the pivot-shift test. Lateral meniscal extrusion, and cartilage degeneration on magnetic resonance imaging (MRI) scans were also compared. The healing status of the lateral meniscus posterior root was compared using second-look arthroscopy and MRI.Results:The duration of surgery was significantly shorter in group S compared with group T (98.3 ± 11.1 vs 127.9 ± 17.5 min; P = .001). At final follow-up, there were no significant differences between the 2 groups in knee functional scores, pivot shift, or grade of cartilage degeneration. Lateral meniscal extrusion was decreased in group S compared with group T (2.41 ± 0.61 vs 1.59 ± 1.35 mm; P = .014). Second-look arthroscopy revealed stable healing in 16 of 18 patients (88.9%) in group S and 10 of 15 patients (66.7%) in group T (P = .38).Conclusion:Both the shared ACL bone tunnel and the independent transtibial pullout techniques led to satisfactory clinical outcomes. The shared ACL bone tunnel technique is the simpler of the 2 procedures for combined LMPRT repair with ACLR.

Epigallocatechin gallate Mucoadhesive Gingival Patch as Potential Biomaterial to Regulate Macrophage and Lymphocyte Cells in Periodontitis: A Review

Background: Periodontitis is a periodontal disease that affects more than 743 million peopleworldwide and causes damage to the periodontal ligament and alveolar bone. One of the bacteriathat can cause periodontitis is Porphyromonas gingivalis (P.gingivalis). P. gingivalis has virulence factors that can damage the periodontal tissue. Treatment of periodontitis is in the form of non- surgical therapy such as scaling and root planning and some cases, doxycycline can be given as adjunctive therapy after scaling and root planing. Epigallocatechin gallate (EGCG) is one of the catechins found in green tea and has anti-bacterial properties. Purpose: The study aimed to describe the potency of the mucoadhesive gingival patch with EGCG green tea against the number of macrophage cells and lymphocyte cells during periodontitis through narrative review. Review: Mucoadhesive gingiva patch loaded with EGCG has the advantages such as maintaining drug bioavailability, non-invasive, and optimizing drug distribution. Using a mucoadhesive gingiva patch with EGCG can reduce macrophage and lymphocyte cells by inhibiting lipopolysaccharide, a virulence factor of P. gingivalis. Inhibited lipopolysaccharide will inhibit pro-inflammatory cytokines such as TNF-α and IL-6. Macrophage and lymphocyte cells will reduce due to the inhibition of pro inflammatory cytokines. Conclusion: Mucoadhesive gingiva patch with EGCG green tea potentially to decreased macrophage and lymphocyte cells in periodontitis.

Stem Cell with a Peri-implant Defects

Periodontal regeneration aims are restoring of the destructed bone, cementum and periodontal ligament. The new strategies of regeneration is very challenging, one of these strategies is tissue engineering, including stem cells and it's considered very promising solution. This paper aims to review the use of stem cells for the treatment of peri-implant defects. Nowadays, many types of mesenchymal stem cells (MSCs) have the ability of periodontal regeneration in animal studies. The bone marrow MSCs (BMMSCs), dental pulp stem cell (DPSC), periodontal ligament stem cells (PDLSCs), and gingival mesenchymal stem cells (GMSCs) are the most types that give very promising results in animal models.

Socket Preservation Using Bovine Bone Graft and Pericardium Membrane: A Case Report

Background: Tooth extraction is followed by a resorption of the bone in the buccal or facial portion, up to 50% in the first six months after the extraction. Bone loss mainly results from damage to the periodontal bone ligament complex. Socket preservation is a surgical procedure aimed to maintain an alveolar ridge after extraction, eliminating or minimizing the need for future augmentation in implant-prosthetic rehabilitation. Socket preservation techniques use some regenerative material such as bone graft and membrane.&#x0D; Objective: To discuss socket preservation procedures using bovine bone graft and pericardium membrane.&#x0D; Method: A 48-year-old woman presented to the Dental and Oral Hospital of Hasanuddin University to have tooth 47, which was mobile and extruded, extracted. Patient had no systemic disease and did not use any drugs. Clinical and radiograph examinations showed bone resorption in the surrounding edentulous area. The patient wanted to wear prosthesis but the bone resorption showed that socket preservation was needed to maintain the alveolar ridge high. The case was diagnosed as chronic periodontitis. Atraumatic extraction was done and bovine bone graft was placed in the socket, followed by the placement of pericardium membrane. Soft tissue healing was clinically evaluated.&#x0D; Results: Control period after one week showed apparent uneventful clinical healing in the socket. Patient was satisfied with the treatment.&#x0D; Conclusion: The socket preservation procedure is an effective treatment for maintaining the alveolar ridge high from excessive resorption, especially for prosthesis treatment.&#x0D; Keywords: alveolar ridge, bone bovine, pericardium membrane, socket preservation

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.

The different subtalar ligaments show significant differences in their mechanical properties

BackgroundToday, the relative contribution of each ligamentous structure in the stability of the subtalar joint is still unclear. The purpose of this study is to assess the material properties of the different ligamentous structures of the subtalar joint. MethodsEighteen paired fresh-frozen cadaveric feet were used to obtain bone–ligament–bone complexes of the calcaneofibular ligament (CFL), the cervical ligament (CL) and the anterior capsular ligament-interosseous talocalcaneal ligament complex (ACaL-ITCL). The samples were subjected to uniaxial testing to calculate their respective stiffness and failure load. ResultsThe stiffness of ACaL-ITCL complex (mean: 150 ± 51 N/mm, 95% confidence interval (CI): 125.0–176.6 N/mm) was significantly higher than both CFL (mean: 55.8 ± 23.0 N/mm, CI: 43.8–67.7 N/mm) and CL (mean: 63.9 ± 38.0 N/mm, CI: 44.4–83.3 N/mm). The failure load of both the ACaL-ITCL complex (mean:382.5 ± 158 N, CI: 304.1–460.8 N) and the CFL (mean:320.4 ± 122.0 N, CI: 257.5–383.2 N) were significantly higher than that of the CL (mean:163.5 ± 58.0 N, CI: 131.3–195.7 N). The injury pattern demonstrated a partial rupture in all CFL and ACaL-ITCL specimens and in 60% of the CL specimens. ConclusionThe CFL, CL and ACaL-ITCL show significant differences in their intrinsic mechanical properties. Both the CFL and CL are more compliant ligaments and seem to be involved in the development of subtalar instability. Based on the material properties, a gracilis tendon graft seems more appropriate than a synthetic ligament to reconstruct a CL or CFL. A partial rupture was the most commonly seen injury pattern in all ligaments. A fibular avulsion of the CFL was only rarely seen. The injury patterns need further investigation as they are important to optimize diagnosis and treatment.

Fabrication of bioinspired grid-crimp micropatterns by melt electrospinning writing for bone–ligament interface study

Many strategies have been adopted to engineer bone–ligament interface, which is of great value to both the tissue regeneration and the mechanism understanding underlying interface regeneration. However, how to recapitulate the complexity and heterogeneity of the native bone–ligament interface including the structural, cellular and mechanical gradients is still challenging. In this work, a bioinspired grid-crimp micropattern fabricated by melt electrospinning writing (MEW) was proposed to mimic the native structure of bone–ligament interface. The printing strategy of crimped fiber micropattern was developed and the processing parameters were optimized, which were used to mimic the crimp structure of the collagen fibrils in ligament. The guidance effect of the crimp angle and fiber spacing on the orientation of fibroblasts was studied, and both of them showed different levels of cell alignment effect. MEW grid micropatterns with different fiber spacings were fabricated as bone region. Both the alkaline phosphatase activity and calcium mineralization results demonstrated the higher osteoinductive ability of the MEW grid structures, especially for that with smaller fiber spacing. The combined grid-crimp micropatterns were applied for the co-culture of fibroblasts and osteoblasts. The results showed that more cells were observed to migrate into the in-between interface region for the pattern with smaller fiber spacing, suggested the faster migration speed of cells. Finally, a cylindrical triphasic scaffold was successfully generated by rolling the grid-crimp micropatterns up, showing both structural and mechanical similarity to the native bone–ligament interface. In summary, the proposed strategy is reliable to fabricate grid-crimp triphasic micropatterns with controllable structural parameters to mimic the native bone-to-ligament structure, and the generated 3D scaffold shows great potential for the further bone–ligament interface tissue engineering.

Tissue Engineering Properties of Nanomaterials and Their Performance Evaluation for Repairing Athletic Ligament Injuries in Sports Dance

With the fast growth of nanotechnology, the usage of nuclear materials is becoming increasingly widespread, and the exposure of people, plants, and fauna to nanomaterials has become unavoidable. As scaffolds of biomaterials, nanomaterials are widely used in tissue engineering because of their good biocompatibility, noncytotoxicity, and noninflammatory reaction. In this paper, the tissue engineering properties of nanomaterials and their performance evaluation for repairing sports ligament injuries in dance sports were investigated. Sports ligament injury is a common sports disease, and ligament injury has a very serious impact on sports performance and sports life of athletes. In this paper, we takes football as an example, establishes a human body model of tendon‐bone repair after anterior cruciate ligament reconstruction, evaluated the effect of injectable rhBMP‐2 nanocontrolled release capsule on ligament bone tunnel interface repair, and evaluated from the scientific and biomechanical point of view. In addition, human ligament research and rabbit ligament supplementary experiment were carried out. In the study of human ligament, we selected 30 patients with unilateral polyarticular ligament injury caused by sports dance as the research subjects and randomly divided them into control group, experimental group, and blank group. The experimental group underwent the repair and reconstruction of rhBMP‐2 nanocontrolled release capsule ligament. The results of human ligament study showed that the injectable rhBMP‐2 nanocontrolled release capsules showed positive staining and uniform staining for ligament repair. The stiffness of the tender bony temple junction was 11.73%, 15.65%, and 50.59% greater in the test group than in the control group at 2, 4, and 8 weeks postoperatively, respectively.

Anatomical, morphometric and radiographic study of the humerus in lesser anteater (Tamandua mexicana Saussure, 1860): terminological and functional analyses.

Tamandua is a neotropical mammal genus that belongs to the superorder Xenarthra. The thoracic limbs of Tamandua have anatomical adaptations that widely differ from other mammals, and there are frequently specimens in wildlife care centers with traumas in their limbs. However, there are few studies describing the radiographic and morphometric anatomy of the humerus in Tamandua, or describing partially the bone reliefs. Thus, the main objective of this study was to describe the characteristics of the humerus of Tamandua mexicana based on gross dissections, radiographies and measurements comparing with other studies in the three Vermilingua genera, and establishing more suitable terminology. Twelve thoracic limbs of six death specimens of Tamandua mexicana were analyzed. The bone reliefs, ligaments, muscles and neurovascular structures related to the humerus were identified, and the suitable terminology to the humerus of Tamandua was established. Morphometric measurements of each bone relief were taken, and the data were statistically analyzed with the Wilcoxon non-parametric test for functional proposes. The humerus of Tamandua has anatomical characteristics mainly to offer greater areas to the muscles that act on the shoulder flexion and hand movements. Even the articular reliefs are lesser than the adjacent non-articular reliefs, the muscles and ligaments are the anatomical structures that give more stabilization to the shoulder and elbow joints. The deltosupracondylar ligament can be partially ossified in older adult specimens, and neurovascular structures pass through the supracondylar foramen. These anatomical characteristics must be accounted for in the radiological diagnosis and surgical approaches.

Nanometer materials and the repairing function of ligament injury in basketball

Basketball has always been a favorite sport for many young people, but ligament injuries often occur during basketball, which will also affect the progress of many sports games. This study focuses on the effects of nanomaterials on the repair of basketball ligament injuries, mainly through tissue engineering to repair ligaments. First, HA nanocomposites are prepared by dissolving P (LLA-Cl) and collagen in hexagonal fluoropropanol. Samples were scanned and analyzed using a high-resolution micro-CT system. Scanning electron microscope (SEM) was used to examine the microstructure, chemical structure and thermal stability of the composite biomaterial. The ligament maturity is evaluated by measuring ligament growth (Tb.N). In vitro cell culture technique was used to inoculate bone marrow mesenchymal stem cells on the cultured nanomaterials, and the adhesion and proliferation of cells were observed with confocal microscope and SEM. The ability of bone marrow mesenchymal stem cells to secrete extracellular calcium matrix is determined by alcohol phosphatase (ALP) and calcium ion content. Using RT-PCR and immunohistology, bone formation and ligament differentiation of bone marrow mesenchymal stem cells were detected. Nanomaterials show extremely high compatibility with damaged ligament tissue, Lysholm score increased from 43.2 ± 2.4 points (30–88 points) before surgery to 96 ± 2.0 points (72–100 points) after surgery (p < 0.001). The research results show that nanocomposite materials combined with tissue engineering can obviously promote the repair of ligaments.

Consequences of ankle joint immobilisation: insights from a morphometric analysis about fibre typification, intramuscular connective tissue, and muscle spindle in rats.

Orthosis immobilisations are routinely used in orthopaedic procedures. This intervention is applicable in bone fractures, ligament injuries, and tendonitis, among other disorders of the musculoskeletal system. We aimed to evaluate the effects of ankle joint functional immobilisation on muscle fibre morphology, connective tissue, muscle spindle and fibre typification triggered by a novel metallic orthosis. We developed a rodent-proof experimental orthosis able to hold the tibiotalar joint in a functional position for short and long terms. The tibialis anterior muscles of free and immobilised legs were collected and stained by histology and histochemistry techniques to investigate general muscle morphology, connective tissue and muscle fibre typification. Morphometric analysis of muscle cross-section area, fibre type cross-section area, fibre type density, percentage of intramuscular connective tissue, and thickness of the muscle spindle capsule were obtained to gain insights into the experimental protocol. We found that short- and long-term immobilisation decreased the cross-section area of the muscles and induced centralisation of myonuclei. The connective tissue of immobilised muscle increased after 2 and 4weeks mainly by deposition of type III and type I collagen fibres in the perimysium and endomysium, respectively, in addition to muscle spindle capsule thickening. Type IIB muscle fibre was severely affected in our study; the profile assumed odd shapes, and our data suggest interconversion of these fibre types within long-term immobilisation. In conclusion, our protocol has produced structural and histochemical changes in muscle biology. This method might be applied to various rodent models that enable genetic manipulation for the investigation of muscle degeneration/regeneration processes.

Application of Ozonated Olive Oil as Adjunctive Therapy after Periodontal Pocket Curettage towards Collagen Density of Alveolar Bone in Periodontitis Healing Process (In Vivo Study with Sprague dawley)

Periodontitis is an inflammatory disease of the supporting tissue of the teeth caused by specific microorganisms or groups of specific microorganisms, resulting in progressive destruction of the periodontal ligament and alveolar bone with periodontal pocket formation. Application of ozonated olive oil in dentistry is based on the actions such as antimicrobial and therapeutic agent, needed as adjunctive therapy after periodontal pocket curretage. Collagen is the main constituent of alveolar bone extracellular matrix and needed as a scaffold in the formation of mineralized matrix. The aim of this study was to determine the density of collagen in alveolar bone on periodontitis healing process after adjunctive topical application of ozonated olive oil in periodontal pocket curretage. In this study, 32 Sprague dawley rats were randomly divided into two groups: curetted-topical application of ozonated olive oil as treatment groups and curetted-topical application of 1% CMC-Na as placebo group. Periodontitis induced by placing silk-ligature around submandibular incisors for 7 days. Subsequently, the rats were sacrificed on days 3, 5, 7, and 14 after curetted and topical application, and each group was represented by four rats. The staining was done using Mallory staining method. All the results were statistically analyzed using Kruskal-Wallis and Mann-Whitney tests. The results showed that there were significant differences (p&lt;0,05) in the density of collagen between two groups. The study concluded that adjunctive topical application of ozonated olive oil after periodontal pocket curretage significantly increase the density of collagen in alveolar bone on periodontitis healing process in Spraque dawley.

Advanced biofabrication strategies for biomimetic composite scaffolds to regenerate ligament‐bone interface

The natural ligament–bone interface features gradient changes in matrix composition, architecture and cell phenotype, which play critical roles in reliable ligament fixation and smooth loading transfer. Mimicking such organisations in artificial composite tissue-engineering scaffolds is important for realising functional fixation between ligament implants and host bones. Here, the authors aim to provide a comprehensive review on the latest strategies to fabricate biomimetic composite scaffolds for the regeneration of ligament-to-bone interface. The biomimetic composite scaffolds are divided into stratified and gradient scaffolds, which are characterised as layer-specific and continuous changes, respectively, in scaffold materials and/or microstructures. Biofabrication strategies for different types of composite scaffolds are summarised. The effects of material/structural changes on cellular morphology, cell differentiation, in vivo osteointegration and multi-tissue interface regeneration are highlighted. Finally, the potential challenges and future perspectives in engineering biomimetic composite scaffolds for ligament–bone interface regeneration are discussed.

Constitutive modeling of the anterior cruciate ligament bundles and patellar tendon with full-field methods

Anterior cruciate ligament (ACL) injury rates are rising, and there is little consensus about what puts someone at risk for an ACL injury. Finite element models provide an effective platform for systemically determining the effect of possible injury risk factors on ACL strain concentrations. However, the accuracy of a finite element model relies on the accuracy of the material models used in its construction. Standard material characterization methods require an assumption of both deformation and material homogeneity, but our recent work has demonstrated that structural features like the shape of the ligament–bone attachment (enthesis) and collagen fiber splay (material direction heterogeneity) create unavoidable deformation heterogeneity. Hence, in this study, full-volume, full-field, finite deformation methods were used to build material models for the ovine ACL bundles and patellar tendon. Specifically, displacement-encoded magnetic resonance imaging (MRI) was used to measure five full-volume deformation fields of each ligament (n=5 specimens of each) under tension, and the virtual fields method (VFM) was used to determine material model parameters with these data. This method accounts for strain heterogeneity, principal material direction heterogeneity (fiber splay), and enthesis shape. While most constitutive parameters were consistent among all specimen groups, parameters describing the degree of anisotropy, or collagen fiber alignment, showed statistically significant differences between groups. This work demonstrates that (when strain heterogeneity and structural properties are accounted for) ligament material properties are deterministic and ligament material microstructure is detectable with mesoscale measures of mechanical function.

Comparison of one versus two maxillary molars distalization with iPanda: a finite element analysis

BackgroundThe purpose of this study was to compare the stress distribution and displacement patterns of the one versus two maxillary molars distalization with iPanda and to evaluate the biomechanical effect of distalization on the iPanda using the finite element method.MethodsThe finite element models of a maxillary arch with complete dentition, periodontal ligament, palatal and alveolar bone, and an iPanda connected to a pair of midpalatal miniscrews were created. Two models were created to simulate maxillary molar distalization. In the first model, the iPanda was connected to the second molar to simulate a single molar distalization. In the second model, the iPanda was connected to the first molar to simulate “en-masse” first and second molar distalization. A varying force from 50 to 200 g was applied. The stress distribution and displacement patterns were analyzed.ResultsFor one molar, the stress was concentrated at the furcation and along the distal surface in all roots with a large amount of distalization and distobuccal crown tipping. For two molars, the stress in the first molar was 10 times higher than in the second molar with a great tendency for buccal tipping and a minimal amount of distalization. Moreover, the stress concentration on the distal miniscrew was six times higher than in the mesial miniscrew with an extrusive and intrusive vector, respectively.ConclusionsIndividual molar distalization provides the most effective stress distribution and displacement patterns with reduced force levels. In contrast, the en-masse distalization of two molars results in increased force levels with undesirable effects in the transverse and vertical direction.

The effect of high concentration of zoledronic acid on tooth induced movement and its repercussion on root, periodontal ligament and alveolar bone tissues in rats

Zoledronic acid (ZA) is often prescribed for osteoporosis or resorptive metabolic bone disease. This study aims to evaluate the effect of ZA on orthodontic tooth movement (OTM) and root and bone resorption and its repercussion on root, periodontal ligament and alveolar bone tissues. The experimental group consisted of 72 Wistar rats divided in four subgroups: Naive, Saline and Zoledronic Acid groups at the concentration of 0.2 mg/kg [ZA (0.2)] or 1.0 mg/kg [ZA (1.0)]. The animals were subjected to i.v (dorsal penile vein) administrations of ZA or saline solution, on days 0, 7, 14 and 42. Under anesthesia, NiTi springs were installed in the first left maxillary molar with 50gf allowing the OTM, except for the negative control group (N) for mesial movement of the left first maxillary teeth. The animals were sacrificed and maxillae were removed for macroscopic and histopathological analyzes, scanning electron microscopy, computerized microtomography and confocal microscopy. Treatment with ZA decreased the OTM and the number of osteoclasts and loss of alveolar bone when compared to the naive and saline groups. Reduction of radicular resorption, increased necrotic areas and reduced vascularization in the periodontal ligament were observed in the ZA groups. ZA interferes with OTM and presents anti-resorptive effects on bone and dental tissues associated with a decreased vascularization, without osteonecrosis.