Explainable Deep Learning and Biomechanical Modeling for TMJ Disorder Morphological Risk Factors.

Clarifying multifactorial musculoskeletal disorder etiologies supports risk analysis and development of targeted prevention and treatment modalities. Deep learning enables comprehensive risk factor identification through systematic analysis of disease datasets but does not provide sufficient context for mechanistic understanding, limiting clinical applicability for etiological investigations. Conversely, multiscale biomechanical modeling can evaluate mechanistic etiology within the relevant biomechanical and physiological context. We propose a hybrid approach combining 3D explainable deep learning and multiscale biomechanical modeling; we applied this approach to investigate temporomandibular joint (TMJ) disorder etiology by systematically identifying risk factors and elucidating mechanistic relationships between risk factors and TMJ biomechanics and mechanobiology. Our 3D convolutional neural network recognized TMJ disorder patients through subject-specific morphological features in condylar, ramus, and chin. Driven by deep learning model outputs, biomechanical modeling revealed that small mandibular size and flat condylar shape were associated with increased TMJ disorder risk through increased joint force, decreased tissue nutrient availability and cell ATP production, and increased TMJ disc strain energy density. Combining explainable deep learning and multiscale biomechanical modeling addresses the "mechanism unknown" limitation undermining translational confidence in clinical applications of deep learning and increases methodological accessibility for smaller clinical datasets by providing the crucial biomechanical context.

Viable Vitreous Grafts of Whole Porcine Menisci for Transplant in the Knee and Temporomandibular Joints.

The shortage of suitable donor meniscus grafts from the knee and temporomandibular joint (TMJ) impedes treatments for millions of patients. Vitrification offers a promising solution by transitioning these tissues into a vitreous state at cryogenic temperatures, protecting them from ice crystal damage using high concentrations of cryoprotectant agents (CPAs). However, vitrification's success is hindered for larger tissues (>3 mL) due to challenges in CPA penetration. Dense avascular meniscus tissues require extended CPA exposure for adequate penetration; however, prolonged exposure becomes cytotoxic. Balancing penetration and reducing cell toxicity is required. To overcome this hurdle, a simulation-based optimization approach is developed by combining computational modeling with microcomputed tomography (µCT) imaging to predict 3D CPA distributions within tissues over time accurately. This approach minimizes CPA exposure time, resulting in 85% viability in 4-mL meniscal specimens, 70% in 10-mL whole knee menisci, and 85% in 15-mL whole TMJ menisci (i.e., TMJ disc) post-vitrification, outperforming slow-freezing methods (20%-40%), in a pig model. The extracellular matrix (ECM) structure and biomechanical strength of vitreous tissues remain largely intact. Vitreous meniscus grafts demonstrate clinical-level viability (≥70%), closely resembling the material properties of native tissues, with long-term availability for transplantation. The enhanced vitrification technology opens new possibilities for other avascular grafts.

Three-dimensional finite element modeling of glenoid bone loss and baseplate fixation in reverse total shoulder arthroplasty.

Background: Posterior glenoid bone loss is frequently observed in patients with osteoarthritis undergoing reverse total shoulder arthroplasty. Glenoid bone loss can reduce the baseplate back support area and the number of screws for fixation. The purpose of this study is to determine how initial baseplate fixation is affected by biomechanical factors introduced by glenoid bone loss such as reduced baseplate back support area and reduced screw number using three-dimensional finite element analysis. Methods: Computerized tomography images of a healthy shoulder were selected and segmented to obtain the solid geometry. Solid models were generated with 100%, 75%, 67%, 50%, and 25% glenoid baseplate back support. With these geometries, two groups of finite element models were then built. In the bone loss areas, screws were maintained in one group of models but were removed in the other group of models. 750N compressive loading was applied along the direction parallel to the scapula axis. Maximum von Mises stress and maximum micromotion between the bone and implant were recorded and evaluated for each glenoid bone model. Results: In the group of models where all screws remained in place, the maximum stress and maximum micromotion between the bone and implant exhibited minimal variation. The maximum stresses were 21.10MPa and the maximum micromotions were between 2-3 µm. However, in the group of models removing screws in the bone loss areas, maximum stress increased from 20MPa to 45MPa and maximum micromotion increased from 2 µm to 85 µm as the backside support area decreased from 100% to 25%. Discussion: In conclusion, this three-dimensional finite element analysis study demonstrates that initial fixation can be achieved with approximately 1/3 posterior glenoid bone deficiency even without screw placement in the area of bone loss. Glenoid bone loss affects baseplate fixation mainly by reducing the screw numbers for fixation. If screws can be placed in the bone loss area, the decreased baseplate back support area will not result in increased stresses or micromotion leading to baseplate failure. This study suggests that surgeons should consider applying screws to the bone loss area if the remaining bone is able to hold the screw. Level of evidence: Computer Modeling Study.

Effects of Increased Retroversion Angle on Glenoid Baseplate Fixation in Reverse Total Shoulder Arthroplasty: A Finite Element Analysis.

BACKGROUND: Increased glenoid retroversion occurs in patients with severe arthritis but its effect on baseplate fixation of a reverse total shoulder arthroplasty (rTSA) is not clear. The purpose of this study is to determine the effects of increasing glenoid retroversion on baseplate fixation in rTSA using finite element analysis (FEA) modelling. METHODS: Five sets of computerized tomographic (CT) images of healthy normal shoulders were selected and segmented with Amira (Thermo Fisher Scientific) to obtain the solid geometries. Scapula FEA models with 5°, 10°, 15°, 20° and 25° retroversion angles were generated for each healthy scapula geometry and a rTSA glenoid baseplate was implanted on each model. Maximum stress at the anterior and posterior portions of the glenoid and the micromotion between the bone and baseplate were recorded. After simulation with normal scapular bone material properties (Young's modulus 4GPa and Poisson's ratio 0.3), another set of simulations was run on each subject with a 25° retroversion angle and poor bone quality (Young's modulus 500 MPa and Poisson's ratio 0.3) to study a worst-case scenario. Micromotions in each model were also recorded. All statistical analysis was done with SPSS. RESULTS: Simulation results of models generated from the same subject but with different retroversion angles showed a clear pattern: as retroversion angle increased, the stresses increased posteriorly and decreased anteriorly. Also, micromotion between the bone and the baseplate increased with the increase of retroversion angle. With analysis of variance (ANOVA), we found that all three values change significantly as the retroversion angle increases (p < 0.001). The simulation results also showed that micromotion was large in shoulders with small glenoid size and poor bone quality. However, even in the model with the worst-case scenario (smallest glenoid size, poorest bone quality and 25° retroversion angle), the maximum micromotion and the maximum stresses are still within the safe range. DISCUSSION: In all cases with both normal and poor bone quality, the stresses and micromotion stayed below the threshold to allow for bone ingrowth of the glenoid baseplate to occur. Based on these results, for glenoid baseplates with a central peg/post and 4 screws for fixation, rTSA baseplate retroversion does not need to be corrected to less than 10° to provide good initial fixation as has been recommended for a cemented glenoid component and can withstand the initial stresses and micromotion up to 25° of retroversion. LEVEL OF EVIDENCE: Basic Science Study; Computer Modeling.

Sexual dimorphisms in three-dimensional masticatory muscle attachment morphometry regulates temporomandibular joint mechanics.

Temporomandibular joint (TMJ) disorders disproportionally affect females, with female to male prevalence varying from 3:1 to 8:1. Sexual dimorphisms in masticatory muscle attachment morphometry and association with craniofacial size, critical for understanding sex-differences in TMJ function, have not been reported. The objective of this study was to determine sex-specific differences in three-dimensional (3D) TMJ muscle attachment morphometry and craniofacial sizes and their impact on TMJ mechanics. Human cadaveric TMJ muscle attachment morphometry and craniofacial anthropometry (10Males; 11Females) were determined by previously developed 3D digitization and imaging-based methods. Sex-differences in muscle attachment morphometry and craniofacial anthropometry, and their correlation were determined, respectively using multivariate general linear and linear regression statistical models. Subject-specific musculoskeletal models of the mandible were developed to determine effects of sexual dimorphisms in mandibular size and TMJ muscle attachment morphometry on joint loading during static biting. There were significant sex-differences in craniofacial size (p = 0.024) and TMJ muscle attachment morphometry (p < 0.001). TMJ muscle attachment morphometry was significantly correlated with craniofacial size. TMJ contact forces estimated from biomechanical models were significantly, 23% on average (p < 0.001), greater for females compared to those for males when generating the same bite forces. There were significant linear correlations between TMJ contact force and both 3D mandibular length (R2 = 0.48, p < 0.001) and muscle force moment arm ratio (R2 = 0.68, p < 0.001). Sexual dimorphisms in masticatory muscle morphology and craniofacial sizes play critical roles in subject-specific TMJ biomechanics. Sex-specific differences in the TMJ mechanical environment should be further investigated concerning mechanical fatigue of TMJ discs associated with TMJ disorders.

MicroRNA-455-5p exerts inhibitory effect in cervical carcinoma through targeting S1PR1 and blocking mTOR pathway.

BACKGROUND: MicroRNAs (miRNAs) have been increasingly exploited in human malignancies. The regulation of microRNA-455-5p (miR-455-5p) has been shown in several cancers, except for cervical carcinoma. Therefore, the role of miR-455-5p was exploited in cervical carcinoma. METHODS: The qRT-PCR experiment was used to assess miR-455-5p and S1PR1 expression levels. We explored the function of miR-455-5p through MTT and Transwell assays. The mTOR pathway and cell apoptosis were detected by Western blot assays. The relationship between miR-455-5p and S1PR1 was testified by dual-luciferase reporter assay. RESULTS: MiR-455-5p expression was decreased in cervical carcinoma, which was related to poor clinical outcome in cervical carcinoma patients. MiR-455-5p inhibited cell viability and metastasis in cervical carcinoma. Further, S1PR1 is a direct target of miR-455-5p. S1PR1 recovered the inhibition of cell viability and metastasis induced by miR-455-5p in cervical carcinoma. In addition, miR-455-5p induced cell apoptosis and inactivated the mTOR pathway in cervical carcinoma. CONCLUSION: MiR-455-5p exerts inhibitory effect in cervical carcinoma through targeting S1PR1 and blocking the mTOR pathway.

Effect of supplemetation of Zebularine and Scriptaid on efficiency of in vitro developmental competence of ovine somatic cell nuclear transferred embryos.

Somatic cell nuclear transfer (SCNT) technology has been applied in the construction of disease model, production of transgenic animals, therapeutic cloning, and other fields. However, the cloning efficiency remains limited. In our study, to improve SCNT efficiency, brilliant cresyl blue (BCB) staining were chosen to select recipient oocytes. In addition, DNA methyltransferase inhibitor Zebularine (5 nmol/L) and histone deacetylase inhibitor Scriptaid (0.2 µmol/L) were jointly used to treat sheep donor cumulus cells and reconstructed embryo. Moreover, the expression levels of embryonic development-related genes (OCT4, SOX2, H19, IGF2 and Dnmt1) of reconstructed embryo were also detected. Using BCB + oocytes as recipient cell, donor cumulus cells and reconstructed embryos were treated with 5 nmol/L Zebularine and 0.2 µmol/L Scriptaid, the blastocyst rate in Zeb + SCR-SCNT group (28.25%) was significantly higher than SCNT (21.16%) (p < 0.05). Furthermore, results showed that expression levels of OCT4, SOX2, H19, IGF2 and Dnmt1 genes in Zeb + SCR-SCNT embryos were more similar to IVF embryos. Our study proved that 5 nmol/L Zebularine and 0.2 µmol/L Scriptaid treating with sheep donor cumulus cells and reconstructed embryos improved SCNT blastocyst rate and relieve the abnormal expression of embryonic developmental related genes.

Effects of TLR4 overexpression on sperm quality, seminal plasma biomarkers, sperm DNA methylation and pregnancy rate in sheep.

Genetic modification provides a means to enhancing disease resistance in animals. In this study, the first generation of genetically modified (GM) sheep overexpressing TLR4 was produced by microinjection for better disease resistance. To compare semen characteristics including sperm quality, seminal plasma biochemical index, sperm DNA methylation and pregnancy rate of three-year old transgenic sheep with TLR4 overexpressed (toll like receptor 4, TLR4) and non-transgenic ram. Sixteen transgenic ram of F0 generation were produced by microinjection of the TLR4 plasmid into the pronucleus of fertilized ova. Seven transgenic sheep of F1 generation was produced by breeding F0 transgenic founders with non-transgenic sheep of the same breed. There were no significant differences between transgenic and control rams for all semen quality parameters, including semen volume, sperm concentration, sperm viability, and percentages of sperm with an intact plasma membrane, acrosomal integrity, and viable sperm with high mitochondrial membrane potential in both F0 and F1 generation. Furthermore, no significant differences were found for seminal plasma concentrations of zinc, neutral alpha-glucosidase, acid phosphatase or fructose, nor for levels of H19 and IGF2R methylation in sperm DNA. In addition, pregnancy rate was also similar between these two groups. In conclusion, there was no evidence that TLR4 overexpression altered the sperm quality, seminal plasma or sperm DNA of transgenic sheep.

Zebularine significantly improves the preimplantation development of ovine somatic cell nuclear transfer embryos.

Aberrant DNA methylation reduces the developmental competence of mammalian somatic cell nuclear transfer (SCNT) embryos. Thus, hypomethylation-associated drugs are beneficial for improving reprogramming efficiency. Therefore, in the present study we investigated the effect of zebularine, a relatively novel DNA methyltransferase inhibitor, on the developmental potential of ovine SCNT embryos. First, reduced overall DNA methylation patterns and gene-specific DNA methylation levels at the promoter regions of pluripotency genes (octamer-binding transcription factor 4 (Oct4), SRY (sex determining region Y)-box 2 (Sox2) and Nanog) were found in zebularine-treated cumulus cells. In addition, the DNA methylation levels in SCNT embryos derived from zebularine-treated cumulus cells were significantly reduced at the 2-, 4-, 8-cell, and blastocyst stages compared with their corresponding controls (P<0.05). The blastocyst rate was significantly improved in SCNT embryos reconstructed by the cumulus donor cells treated with 5nM zebularine for 12h compared with the control group (25.4±1.6 vs 11.8±1.7%, P<0.05). Moreover, the abundance of Oct4 and Sox2 mRNA was significantly increased during the preimplantation stages after zebularine treatment (P<0.05). In conclusion, the results indicate that, in an ovine model, zebularine decreases overall DNA methylation levels in donor cumulus cells and reconstructed embryos, downregulates the DNA methylation profile in the promoter region of pluripotency genes in donor cells and ultimately elevates the expression of pluripotency genes in the reconstructed embryos, which can lead to improved development of SCNT embryos.

[Case-control study on clinical effects of squeezing and clapping manipulation for treating the postpartum pubic symphysis separation].

OBJECTIVE: To study the clinical effect of squeezing and clapping bone setting manipulation in treating the postpartum pubis symphysis separation. METHODS: From June 2015 to March 2017, 80 patients with postpartum pubic symphysis separation were randomly divided into treatment group and control group, 40 patients in each group. In treatment group, the patients' reproductive age ranged from 26 to 40 years old with an average of (30.61±5.94) years old and the neonatal weight ranged from 3.2 to 4.52 kg with an average of (3.59±0.13) kg. In control group, patients' reproductive age ranged from 22 to 37 years old with an average age of (27.51±4.57) years old and the neonatal weight ranged from 3 to 5.8 kg with an average of (3.81±0.63) kg. The patients in the treatment group were treated with the squeezing and clapping manipulation, once a week for 3 weeks. The patients in the control group were treated with pelvic bandage immobilization, and the immobilization of the pelvis was not less than 8 hours per day, 3 weeks for 1 course. The VAS pain score, Oswestry dysfunction index (ODI) and separation distance of pubis were clinical observed and evaluated on the first day of treatment, 1, 2, 3 weeks and 1 months after treatment. RESULTS: The pubic symphysis VAS score was compared with that before treatment, in the treatment group, the difference was statistically significant at 1 week(P=0.013); the difference was statistically significant in the control group for 1 month (P=0.042). The two groups were less than those of the control group after treatment (P<0.05). The ODI score was compared with that before the treatment, in the treatment group, the difference was statistically significant at 1 week (P=0.009), the difference was statistically significant in the control group for 1 month(P=0.013), the two groups were less than those before treatment(P<0.05). The pubic symphysis distance was compared with that before treatment, the treatment group decreased significantly after treatment (P<0.05), there was no significant difference in the control group after treatment (P>0.05), the two groups were compared, the difference was statistically significant at first weeks(P=0.042) and third weeks (P=0.005). CONCLUSIONS: The "squeezing and clapping" manipulation can quickly restore the distance between pubic symphysis separation, relieve local pain and improve lumbosacral function, and is better than pelvic bandage fixation treatment.

[Application of finite element method in spinal biomechanics].

The finite element model is one of the most important methods in study of modern spinal biomechanics, according to the needs to simulate the various states of the spine, calculate the stress force and strain distribution of the different groups in the state, and explore its principle of mechanics, mechanism of injury, and treatment effectiveness. In addition, in the study of the pathological state of the spine, the finite element is mainly used in the understanding the mechanism of lesion location, evaluating the effects of different therapeutic tool, assisting and completing the selection and improvement of therapeutic tool, in order to provide a theoretical basis for the rehabilitation of spinal lesions. Finite element method can be more provide the service for the patients suffering from spinal correction, operation and individual implant design. Among the design and performance evaluation of the implant need to pay attention to the individual difference and perfect the evaluation system. At present, how to establish a model which is more close to the real situation has been the focus and difficulty of the study of human body's finite element.Although finite element method can better simulate complex working condition, it is necessary to improve the authenticity of the model and the sharing of the group by using many kinds of methods, such as image science, statistics, kinematics and so on.

The histone deacetylase inhibitor Scriptaid improves in vitro developmental competence of ovine somatic cell nuclear transferred embryos.

Although the success rate of sheep cloning remains extremely low, using a histone deacetylase (HDAC) inhibitor to increase histone acetylation in SCNT embryos has significantly enhanced developmental competence in several species. The objective was to determine whether HDAC inhibitors trichostatin A (TSA) and the novel inhibitor Scriptaid enhance cloning efficiency in sheep cumulus cell (passage 2) reconstructed embryos. In this study, 0.2 µmol/L Scriptaid yielded a high blastocyst development rate, almost twice that of the untreated group (25/103 [24.3%] vs. 12/101 [11.9%]; P < 0.05). Furthermore, 0.2 µmol/L Scriptaid was more effective than 0.05 µmol/L TSA in terms of the blastocyst percentage for cloned ovine embryos in vitro (17/66 [25.7%] vs. 11/65 [16.8%]; P < 0.05). Furthermore, treatment with Scriptaid increased acetylation (compared with the Control, P < 0.05) at lysine residue 12 of histone H4 (acH4K12) and lysine residue 9 of histone H3 (acH3K9) in one-, two-, four-, and eight-cell stages, as well as blastocyst stages, in cloned embryos. In conclusion, Scriptaid was more effective than TSA to enhance in vitro developmental competence in ovine SCNT embryos; furthermore, Scriptaid improved epigenetic status.

[Observation of clinical curative effect of "oblique-pulling" maneuver in the treatment of lumbar intervertebral disc herniation].

OBJECTIVE: To evaluate the clinical curative effect of "oblique-pulling" maneuver in patients with lumbar intervertebral disc herniation (LIDH). METHODS: Sixty-five LIDH cases were randomly divided into experimental group and control group. In the experimental group 32 patients were treated by "oblique-pulling" maneuver, and 32 patients in the control group were treated by lumbar traction therapy. One case were excluded from the study and another one case were dropped from the study. After one course of treatment, the therapeutic effects of the two groups were compared quantitatively by using the JOA and VAS scores, including the improvement of signs, symptoms, living ability, and low back and leg pain. RESULTS: After one course of treatment, in the experimental group, 7 cases were controlled well, 16 cases were marked effect, 8 cases were effect, 1 case was no effect. In the control group, 4 cases were controlled well, 10 cases were marked effect, 13 cases were effect, 4 cases was no effect in control group. The clinical effective rate of the experimental group was 96.86%, which was higher than 87.10% of the control group (P < 0.05). In the experimental group the scores of JOA and VAS were obviously improved after treatment (P < 0.001) and the improvement was better than that of control group (P < 0.01). CONCLUSION: The "oblique-pulling" maneuver has the characteristics of simple operation, repeatability, good efficiency, high safety.

[The influence of rotary manipulation on the internal pressure of cervical nucleus pulposus].

OBJECTIVE: To measure the pressure changes inside the cervical nucleus pulposus in fresh human cervical specimen by imitating different rotary manipulations. METHODS: The load of 100 N was applied for 5 second on the six fresh male cervical samples by using material test system, which imitated the human head weigh and the strength of cervical extensor muscle. After that, traction, rotation and pulling on the samples were performed in different sequence under the force of 150, 200, 300 N respectively. Three states were included in adding the load state A: samples were loaded with traction and then rotation to the biggest angle, pulling backward for 15 degrees; state B: samples were loaded with rotary stress to the biggest angle and then loaded with traction, pulling backward for 15 degrees; state C: samples were loaded simultaneously with traction and rotary stress to the biggest angle, pulling backward for 15 degrees. The internal pressure of cervical nucleus pulposus at segment of C(3,4), C(4,5), C(5,6), and C7 was measurred by micro-pressure sensors for state A, B, C and for the imitation of head weight and the strength of cervical extensor muscle. RESULTS: The pressure inside the cervical nucleus pulposus at segments C(5,6), C(6,7) was higher than that at segments C(3,4) and C(4,5) (P < 0.05) by loading stress with 100 N for 5 seconds. The internal pressure of the nucleus pulposus decreased with the increase of traction (P < 0.05), and increased when traction and rotary force were loaded. State A, the value of increased pressure within the nucleus pulposus became smaller and smaller while increasing of the traction force loaded (P < 0.05). State B, the increase of internal pressure in nucleus pulposus became obvious as loading pressure increased (P < 0.05). State C, the internal pressure in nucleus pulposus was not increased obviously (P > 0.05). There was a transitional pressure raise inside all cervical nucleus pulposus when pulling added after different sepuence traction and rotary strength was applied, however, the internal pressure of state A was significantly higher than that of state B or C (P < 0.05). There was also a transitional pressure raise inside all cervical nucleus pulposus when pulling added in different strength (P < 0.05),the internal pressure by pulling with 150 N was obviously higher than that with 200 N and 300 N (P < 0.05). CONCLUSION: The order of rotation first and traction second should be avoided when practice of rotary manupuplation in case protrusion of the nucleus pulposus. Meanwhile, proper traction should be applied along with rotary manipulation in order to increase its safety.