Finite element study on the micromechanics of cement-augmented proximal femoral nail anti-rotation (PFNA) for intertrochanteric fracture treatment.

Blade cut-out is a common complication when using proximal femoral nail anti-rotation (PFNA) for the treatment of intertrochanteric fractures. Although cement augmentation has been introduced to overcome the cut-out effect, the micromechanics of this approach remain to be clarified. While previous studies have developed finite element (FE) models based on lab-prepared or cadaveric samples to study the cement-trabeculae interface, their demanding nature and inherent disadvantages limit their application. The aim of this study was to develop a novel 'one-step forming' method for creating a cement-trabeculae interface FE model to investigate its micromechanics in relation to PFNA with cement augmentation. A human femoral head was scanned using micro-computed tomography, and four volume of interest (VOI) trabeculae were segmented. The VOI trabeculae were enclosed within a box to represent the encapsulated region of bone cement using ANSYS software. Tetrahedral meshing was performed with Hypermesh software based on Boolean operation. Finally, four cement-trabeculae interface FE models comprising four interdigitated depths and five FE models comprising different volume fraction were established after element removal. The effects of friction contact, frictionless contact, and bond contact properties between the bone and cement were identified. The maximum micromotion and stress in the interdigitated and loading bones were quantified and compared between the pre- and post-augmentation situations. The differences in micromotion and stress with the three contact methods were minimal. Micromotion and stress decreased as the interdigitation depth increased. Stress in the proximal interdigitated bone showed a correlation with the bone volume fraction (R2 = 0.70); both micromotion (R2 = 0.61) and stress (R2 = 0.93) at the most proximal loading region exhibited a similar correlation tendency. When comparing the post- and pre-augmentation situations, micromotion reduction in the interdigitated bone was more effective than stress reduction, particularly near the cement border. The cementation resulted in a significant reduction in micromotion within the loading bone, while the decrease in stress was minimal. Noticeable gradients of displacement and stress reduction can be observed in models with lower bone volume fraction (BV/TV). In summary, cement augmentation is more effective at reducing micromotion rather than stress. Furthermore, the reinforcing impact of bone cement is particularly prominent in cases with a low BV/TV. The utilization of bone cement may contribute to the stabilization of trabecular bone and PFNA primarily by constraining micromotion and partially shielding stress.

Controllable Adaptive Molybdate-Oligosaccharide Nanoparticles Regulate M2 Macrophage Mitochondrial Function and Promote Angiogenesis via PI3K/HIF-1α/VEGF Pathway to Accelerate Diabetic Wound Healing.

The complex wound environment of diabetic wounds leads to poor treatment efficacy, and the inflammatory disorders and vascular injury are the primary causes of death in such patients. Herein, a sprayable, controllable adaptive, pH-responsive nanosystem of molybdate and oligosaccharide (CMO) is specially developed as an immunomodulatory and angiogenesis-promotion material for diabetic wound healing. CMO exhibited pH-responsive release of Mo2+ and oligosaccharide (COS), specifically in response to the alkalescent environment observed in diabetic wounds. CMO provide an anti-inflammatory environment by promoting M2 polarization through significantly stimulating macrophage mitochondrial function. Specifically, CMO with a certain concentration reduce reactive oxygen species (ROS) and tumor necrosis factor α (TNF-α) expression, and upregulated mitochondrial membrane potential (MMP), superoxide dismutase (SOD), and interleukin 10 (IL-10) expression in macrophages. Moreover, CMO facilitate angiogenesis via upregulating the PI3K/HIF-1α/VEGF pathway-a critical process for the formation of new blood vessels that supply nutrients and oxygen to the healing tissue. Remarkably, CMO promote cell viability and migration of endothelial cells, and enhance the expression of angiogenic genes. In vitro and in vivo studies suggest this simple but powerful nanosystem targeting mitochondrial function has the potential to become an effective treatment for diabetic wound healing.

Agreement Between Single Raters and Team Rating When Applying the International Classification of Functioning, Disability and Health's Rehabilitation Set.

OBJECTIVE: To quantify the agreement between functional assessments by a single rater and a team using the Chinese version of the International Classification of Functioning, Disability and Health Rehabilitation Set in a clinical situation. DESIGN: Inter-rater, multi-centre agreement study. SUBJECTS: A total of 193 adult inpatients admitted to 5 rehabilitation centres at 5 hospitals in China Methods: The Chinese version of the International Classification of Functioning, Disability and Health Rehabilitation Set was used by either a single rater or a team to assess 193 patients at 5 Chinese hospitals. Percentage of agreement and quadratic-weighted kappa coefficients were computed. Evaluation times were compared with paired t-tests. RESULTS: The mean team and individual evaluation times were not significantly different. The percentage of agreement ranged from 46.1% to 94.2% depending on the item, and the quadratic-weighted kappas ranged from 0.43 to 0.92. Eight categories (26.6%) showed a weighted kappa exceeding 0.4, 11 others (36.7%) exceeded 0.6, and another 11 (36.7%) produced kappas of more than 0.8. CONCLUSION: Either a single rater or a team of raters can produce valid and consistent ratings when using the Chinese version of the International Classification of Functioning, Disability and Health Rehabilitation Set to assess patients in a rehabilitation department. The team rating approach is suitable for clinical application.

Studying trabecular bone samples demonstrates a power law relation between deteriorated structure and mechanical properties - a study combining 3D printing with the finite element method.

Introduction: The bone volume fraction (BV/TV) significantly contributes to the mechanical properties of trabecular bone. However, when studies compare normal trabeculae against osteoporotic trabeculae (in terms of BV/TV decrease), only an "average" mechanical result has been determined because of the limitation that no two trabecular structures are the same and that each unique trabecular structure can be mechanically tested only once. The mathematic relation between individual structural deterioration and mechanical properties during aging or the osteoporosis process has yet to be further clarified. Three-dimensional (3D) printing and micro-CT-based finite element method (µFEM) can assist in overcoming this issue. Methods: In this study, we 3D printed structural-identical but BV/TV value-attenuated trabecular bones (scaled up ×20) from the distal femur of healthy and ovariectomized rats and performed compression mechanical tests. Corresponding µFEM models were also established for simulations. The tissue modulus and strength of 3D printed trabecular bones as well as the effective tissue modulus (denoted as Ez) derived from µFEM models were finally corrected by the side-artifact correction factor. Results: The results showed that the tissue modulus corrected, strength corrected and Ez corrected exhibited a significant power law function of BV/TV in structural-identical but BV/TV value-attenuated trabecular samples. Discussion: Using 3D printed bones, this study confirms the long-known relationship measured in trabecular tissue with varying volume fractions. In the future, 3D printing may help us attain better bone strength evaluations and even personal fracture risk assessments for patients who suffer from osteoporosis.

Combined computational analysis and cytology show limited depth osteogenic effect on bone defects in negative pressure wound therapy.

Background: The treatment of bone defects remains a clinical challenge. The effect of negative pressure wound therapy (NPWT) on osteogenesis in bone defects has been recognized; however, bone marrow fluid dynamics under negative pressure (NP) remain unknown. In this study, we aimed to examine the marrow fluid mechanics within trabeculae by computational fluid dynamics (CFD), and to verify osteogenic gene expression, osteogenic differentiation to investigate the osteogenic depth under NP. Methods: The human femoral head is scanned using micro-CT to segment the volume of interest (VOI) trabeculae. The VOI trabeculae CFD model simulating the bone marrow cavity is developed by combining the Hypermesh and ANSYS software. The effect of trabecular anisotropy is investigated, and bone regeneration effects are simulated under NP scales of -80, -120, -160, and -200 mmHg. The working distance (WD) is proposed to describe the suction depth of the NP. Finally, gene sequence analysis, cytological experiments including bone mesenchymal stem cells (BMSCs) proliferation and osteogenic differentiation are conducted after the BMSCs are cultured under the same NP scale. Results: The pressure, shear stress on trabeculae, and marrow fluid velocity decrease exponentially with an increase in WD. The hydromechanics of fluid at any WD inside the marrow cavity can be theoretically quantified. The NP scale significantly affects the fluid properties, especially those fluid close to the NP source; however, the effect of the NP scale become marginal as WD deepens. Anisotropy of trabecular structure coupled with the anisotropic hydrodynamic behavior of bone marrow; An NP of -120 mmHg demonstrates the majority of bone formation-related genes, as well as the most effective proliferation and osteogenic differentiation of BMSCs compared to the other NP scales. Conclusion: An NP of -120 mmHg may have the optimal activated ability to promote osteogenesis, but the effective WD may be limited to a certain depth. These findings help improve the understanding of fluid mechanisms behind NPWT in treating bone defects.

3D printed trabeculae conditionally reproduce the mechanical properties of the actual trabeculae - A preliminary study.

Three-dimensional (3D) printing has been used to fabricate synthetic trabeculae models and to test mechanical behavior that cannot be recognized in the actual sample, but the extent to which 3D printed trabeculae replicate the mechanical behavior of the actual trabeculae remains to be quantified. The aim of this study was to evaluate the accuracy of 3D printed trabeculae in reproducing the mechanical properties of the corresponding actual trabeculae. Twelve human trabecular cubes (5 × 5 × 5 mm) were scanned by micro-CT to form the trabecular 3D model. Each trabecular 3D model was scaled ×2-, ×3-, ×4- and ×5-fold and then printed twice at a layer thickness of 60 µm using poly (lactic acid) (PLA). The actual trabecular cubes and the 3D-printed trabecular cubes were first compressed under a loading rate of 1 mm/min; another replicated stack of 3D-printed trabecular cubes was compressed under a strain rate of 0.2/min. The results showed that the stiffness of the printed cubes tended to increase, while the strength tended to converge when the magnification increased under the two loading conditions. The strain rate effect was found in the printed cubes. The correlation coefficient (R2) of the mechanical properties between the printed and actual trabeculae can reach up to 0.94, especially under ×3-, ×4- and ×5-fold magnification. In conclusion, 3D printing could be a potential tool to evaluate the mechanical behavior of actual trabecular tissue in vitro and may help in the future to predict the risk of fracture and even personalize the treatment evaluation for osteoporosis and other trabecular bone pathologies.

Medial tibial plateau sustaining higher physiological stress than the lateral plateau: based on 3D printing and finite element method.

BACKGROUND: Medial compartment knee osteoarthritis (KOA) accounts for most KOA cases, and increased trabecular bone volume fraction (BV/TV) is one of the pathological changes in the tibial plateau of KOA. How BV/TV changes before and after the menopause and its effects on medial compartment KOA are yet to be clarified. METHODS: Twenty femurs from twenty 12-week-old rats were included. The operated group underwent ovariectomy (to represent the osteoporosis condition), called the O group, and the non-operated group was the normal control, called the N group. Micro-CT scans of the femoral condyles were acquired 12 weeks after the surgery, and the volume of interest (VOI) of medial-, inter-, and lateral-condyle trabeculae were three-dimensional (3D) printed for uniaxial compression mechanical test and simulated by the finite element (FE) method. RESULTS: The results demonstrated that the O group indicated poorer trabecular architecture than the N group in three parts of the femoral condyle, especially in the intercondyle. Within the group, the BV/TV, trabecular thickness (Tb.Th), and trabecular number (Tb.N) ratios between the medial and lateral condyles were greater than 1 in both N and O groups. The medial condyle trabeculae's mechanical properties were higher than those of the lateral condyle, and this superiority appears to be broadened under osteoporotic conditions. FE modelling well reproduced these mechanical differentiations. CONCLUSIONS: According to Wolff's law, the higher BV/TV and mechanical properties of the medial femoral condyle may be due to inherent imbalanced loading on the knee component. Alterations in BV/TV and their corresponding mechanical properties may accompany KOA.

Cement augmentation of the proximal femoral nail antirotation for the treatment of two intertrochanteric fractures - a comparative finite element study.

BACKGROUND: There are concerns regarding initial stability and cutout effect in proximal femoral nail antirotation (PFNA) treating intertrochanteric fractures. No study have used finite element analysis (FEA) to investigate the biomechanics. This study aimed to compare the cutout effect, stress and displacement between stable (AO31-A1.3) and unstable (AO31-A2.2) intertrochanteric fractures treated by cement augmented PFNA. METHODS: Four femoral finite element models (FEMs) were constructed and tested under the maximum loading during walking. Non-augmented and augmented PFNA in two different intertrochanteric fractures were respectively simulated, assuming Tip Apex Distance (TAD) < 25 mm within each FEM. The cutout effect, stress and displacement between femur and PFNA were compared in each condition. RESULTS: Cutout effect was observed in both non-augmented femoral head and was more apparently in unstable intertrochanteric fracture model. After reinforced by bone cement, no cutout effect occurred in two models. Stress concentration were observed on medial part of intertrochanteric region and the proximal part of helical blade before augmented while were observed on femoral shaft and the conjunction between blade and nail after augmented in both FEMs. Displacement mainly appeared on femoral head and the helical blade tip before augmented while distributed moderately on intertrochanteric region and the upper part of nail after augmented in both FEMs. The maximum stress and displacement value of femur decreased both in stable and unstable model after augmented but was more significantly in the unstable one. The maximum stress and displacement value of PFNA increased both in stable and unstable model after augmented but was more significantly in the unstable one. CONCLUSION: Our FEA study indicated that the cement augmentation of the PFNA biomechanically enhances the cutout resistance in intertrochanteric fracture, this procedure is especially efficient for the unstable intertrochanteric fracture.

[Finite element analysis of different intramedullary fixation methods for the treatment of senile pubic ramus fractures].

OBJECTIVE: To evaluate the biomechanical stability of elastic intramedullary nail in the treatment of pubic ramus fractures by finite element analysis, and to compare the stability of elastic intramedullary nail with cannulated screw intramedullary fixation. METHODS: The CT data of the pelvis of a volunteer were selected, and the three-dimensional model of the pelvis was reconstructed by reverse engineering software and the fracture of the pubic ramus fractures was simulated by osteotomy. The hollow nail model, single elastic nail model and double elastic nailmodel were assembled with different implants respectively. The mesh division, material assignment loading and other steps were carried out in the ANSYS software, and then the calculation was submitted. RESULTS: The overall displacement of the pelvis of the elastic nail model was smaller than that of the cannulated screw model, in which the double elastic nail model had the smallest overall displacement, but the cannulated screw model had the smallest plant displacement and the single elastic nail model had the largest plant displacement. Although the stress of cannulated screw was small, there was obvious stress concentration, the stress of elastic nail was large, but there was no obvious stress concentration, especially the stress distribution of double elastic nail was more uniform and the overall stress of pelvis was the smallest. CONCLUSION: All the three fixation methods can effectively improve the stability of the anterior ring of the pelvis. Among them, there is no significant difference in the overall biomechanical propertiesof hollow nail fixation and double elastic nail fixation, which is better than that of single elastic nail fixation. Elastic nail fixation has the advantages of minimally invasive surgery and good biomechanical stability, so it can be used as a better surgical method for the treatment of pubic ramus fractures.

A team approach to applying the International Classification of Functioning, Disability and Health Rehabilitation set in clinical evaluation.

OBJECTIVE: To develop a team approach to applying the International Classification of Functioning, Disability and Health Rehabilitation Set (ICF-RS) in clinical evaluation. DESIGN: A Delphi study. SUBJECTS: Experts from rehabilitation institutions in China including physicians, nurses, physiotherapists and occupational therapists. METHODS: A 2-round Delphi survey and expert panel discussion were used to generate the team approach. Firstly, the candidate types of professionals for team rating were chosen through expert panel discussion. A carefully selected group of participants was then asked to score the suitability of physicians, nurses, or other candidate therapists for each category's rat-ing, applying the International Classification of Functioning, Disability and Health Rehabilitation Set in clinical evaluation. After initial assignment of cate-gory to types of professionals, a second round Delphi survey was conducted to quantify the professionals' agreement with the category assignments and generate a final team evaluation approach. RESULTS: Thirty of the category assignments achiev-ed consensus. The final team evaluation approach assigned 6 categories to physicians to evaluate, 7 categories to nurses, 9 categories to physiotherapists, and 8 to occupational therapists. CONCLUSION: Such a team evaluation approach could facilitate implementation of the ICF-RS in clinical settings and provide a more convenient assessment tool for professionals.

A mobile app implementing the international classification of functioning, disability and health rehabilitation set.

BACKGROUND: The Chinese assessment standards of the International Classification of Functioning, Disability and Health Rehabilitation Set is available now. It is coming to be used as a basic functional evaluation tool in China. With data accumulating, a mobile application is needed to eliminate the extra cost of data entry, storage, and graphical presentation of trends. This study aimed to design, develop and test a mobile app based on the International Classification of Functioning, Disability and Health Rehabilitation Set Rehabilitation Set. METHODS: The study had three phases. The first involved specifying the functional requirements of the app. Then an app was designed and refined to meet those requirements. In a pilot test, the app was used by rehabilitation professionals in clinical practice and their comments were collected for its further modification in one-on-one interviews. RESULTS: The app met the initial requirements, and the pilot study showed it worked as designed. The pilot study also showed that the app is user-friendly and convenient to use in rehabilitation practice. Some feedback was given to improve the app. CONCLUSION: An Android mobile app implementing the International Classification of Functioning, Disability and Health Rehabilitation Set was successfully developed.

Analyzing the Effects of Intrauterine Hypoxia on Gene Expression in Oocytes of Rat Offspring by Single Cell Transcriptome Sequencing.

Intrauterine hypoxia is one of the most frequently occurring complications during pregnancy, and the effects of antenatal hypoxia in offspring are not restricted to the perinatal period. Previous studies have reported on this phenomenon, which is usually described as multigenerational or transgenerational inheritance. However, the exact mechanism of this type of inheritance is still not clear. Therefore, in the present study, we investigated the alteration in the gene expression of oocytes, derived from intrauterine hypoxia rats and their offspring, by transcriptome sequencing. Our results showed that 11 differentially expressed genes were inherited from the F1 to F2 generation. Interestingly, these differentially expressed genes were enriched in processes predominantly involved in lipid and insulin metabolism. Overall, our data indicated that alteration in the gene expression of oocytes may be associated with some metabolic diseases and could potentially be the basis of transgenerational or multigenerational inheritance, induced by an adverse perinatal environment.

Does serum calcium relate to different types of hip fracture? A retrospective study.

PURPOSE: To investigate the potential correlation between two different types of hip fractures and serum calcium levels. METHODS: We consecutively studied 101 cases of femoral neck fracture and 95 cases of femoral inter- trochanteric fracture between January 2011 and December 2013. Fasting blood samples were taken and serum calcium measurements were performed respectively in three periods: the time of admission, postoperation, and discharge. Creatinine, alkaline phosphatase and albumin were also analyzed. RESULTS: Considering the levels of serum calcium between two groups at the time of admission, post- operation and discharge, there was significant difference at admission and discharge (p <0.05), while there was no significant difference at the time of postoperation (p > 0.05). The magnitude of serum calcium fluctuation was larger in femoral neck group than femoral intertrochanteric group. Concerning alkaline phosphatase and albumin levels at admission, there was no significant difference between two groups (p > 0.05). CONCLUSION: The capability of reservation and restoration of serum calcium in patients with femoral neck fracture is better than that in patients with femoral intertrochanteric fracture. A low serum calcium level may be susceptible to femoral intertrochanteric fracture.

Non-traumatic myositis ossificans circumscripta at elbow joint in a 9-year old child.

Myositis ossificans circumscripta (MOC) is a kind of self-localized, benign and tumor-like lesions often seen in adults, with approximately 75% of cases caused by trauma. We reported a case of non-traumatic MOC occurred at the elbow joint in a 9-year old child and it has been excised by surgery. After 18 months follow-up, a favorable outcome has been achieved with the Broberg-Morrey score of 100. We suggest that surgical resection should be done as soon as the diagnosis is confirmed.

Long-term effectiveness of neuromuscular electrical stimulation for promoting motor recovery of the upper extremity after stroke.

OBJECTIVE: To investigate the long-term efficacy of neuromuscular electrical stimulation in enhancing motor recovery in the upper extremities of stroke patients. METHODS: A total of 46 patients with stroke were assigned to a neuromuscular electrical stimulation group or a control group. All patients received a standard rehabilitation programme. Patients in the neuromuscular electrical stimulation group received neuromuscular electrical stimulation for 30 min, 5 days a week for 3 weeks. Measurements were recorded before treatment, at the 2nd and 3rd week of treatment and 1, 3 and 6 months after treatment ended. The Modified Ashworth Scale for spasticity, the upper extremity section of the Fugl-Meyer motor assessment, and the Modified Barthel Index were used to assess the results. RESULTS: Significant improvements were found in both groups in terms of Fugl-Meyer motor assessment, and Modified Ashworth Scale scores after the 3rd week of treatment. The significant improvements persisted 1 month after treatment had been discontinued. At 3 and 6 months after treatment was discontinued the average scores in the neuromuscular electrical stimulation group were significantly better than those in the control group. CONCLUSION: Three weeks of neuromuscular electrical stimulation to the affected upper extremity of patients with stroke improves motor recovery. The effect persists for at least 6 months.