Effects of Vergence Eye Movement Planning on Size Perception and Early Visual Processing.

Our perception of objects depends on non-oculomotor depth cues, such as pictorial distance cues and binocular disparity, and oculomotor depth cues, such as vergence and accommodation. Although vergence eye movements are always involved in perceiving real distance, previous studies have mainly focused on the effect of oculomotor state via "proprioception" on distance and size perception. It remains unclear whether the oculomotor command of vergence eye movement would also influence visual processing. To address this question, we placed a light at 28.5 cm and a screen for stimulus presentation at 57 cm from the participants. In the NoDivergence condition, participants were asked to maintain fixation on the light regardless of stimulus presentation throughout the trial. In the WithDivergence condition, participants were instructed to initially maintain fixation on the near light and then turn their two eyes outward to look at the stimulus on the far screen. The stimulus was presented for 100 msec, entirely within the preparation stage of the divergence eye movement. We found that participants perceived the stimulus as larger but were less sensitive to stimulus sizes in the WithDivergence condition than in the NoDivergence condition. The earliest visual evoked component C1 (peak latency 80 msec), which varied with stimulus size in the NoDivergence condition, showed similar amplitudes for larger and smaller stimuli in the WithDivergence condition. These results show that vergence eye movement planning affects the earliest visual processing and size perception, and demonstrate an example of the effect of motor command on sensory processing.

A Novel Internal Fixation Design for the Treatment of AO/OTA-31A3.3 Intertrochanteric Fractures: Finite Element Analysis.

OBJECTIVE: AO/OTA 31-A3.3 intertrochanteric fracture is the most unstable type of intertrochanteric fracture, with a high rate of postoperative complications and implant failure. We have designed a new intramedullary fixation, proximal femoral totally bionic nail (PFTBN), for the treatment of A3.3 intertrochanteric fracture. To test its biomechanical performance, we adopted the method of finite element analysis and compared PFTBN with proximal femoral nail antirotation (PFNA) and proximal femoral bionic nail (PFBN, another internal fixation we previously designed for stable intertrochanteric fractures). METHODS: Mimics, 3-matic, ANSYS, and other software were used to construct a highly precise and realistic 3D digital model of the human femur. An AO/OTA 31-A3.3 intertrochanteric fracture of the femur was constructed according to the 2018 classification of AO/OTA, and then assembled with PFNA, PFBN and PFTBN models, respectively. The stress distribution and displacement distribution of the three groups of constructs were tested under three times the body weight load and one-foot standing configuration. RESULTS: In terms of maximum stress and maximum displacement, the PFTBN group outperforms the PFBN group, and the PFBN group, in turn, surpasses the PFNA group. The maximum stress of PFTBN group was 408.5 Mpa, that of PFBN group was 525.4 MPa, and that of PFNA group was 764.3 Mpa. Comparatively, the maximum stress in the PFTBN group was reduced by 46.6% when contrasted with the PFNA group. Moreover, the stress dispersion within the PFTBN group was more evenly distributed than PFNA group. Regarding maximum displacement, the PFTBN group displayed the least displacement at 5.15 mm, followed by the PFBN group at 7.32 mm, and the PFNA group at 7.73 mm. Notably, the maximum displacement of the PFTBN group was 33.4% less than that observed in the PFNA group. Additionally, the relative displacement between the fragment and implant at the tip of pressure screw or helical blade was 0.22 mm in the PFTBN group, 0.34 mm in the PFBN group, and substantially higher 0.51 mm in the PFNA group. CONCLUSION: The "lever-reconstruction-balance" theory provides a new perspective for us to understand the mechanical conduction of the proximal femur. Compared with PFNA, in treating A3.3 intertrochanteric fractures PFTBN can better reconstruct the function of lateral wall, restore physiological mechanical conduction, increase postoperative stability, and finally reduce the risk of postoperative cut-out and implant failure. It might be a better alternative for the treatment of A3.3 intertrochanteric fracture.

Strategies for Treating Traumatic Neuromas with Tissue-Engineered Materials.

Neuroma, a pathological response to peripheral nerve injury, refers to the abnormal growth of nerve tissue characterized by disorganized axonal proliferation. Commonly occurring after nerve injuries, surgeries, or amputations, this condition leads to the formation of painful nodular structures. Traditional treatment options include surgical excision and pharmacological management, aiming to alleviate symptoms. However, these approaches often offer temporary relief without addressing the underlying regenerative challenges, necessitating the exploration of advanced strategies such as tissue-engineered materials for more comprehensive and effective solutions. In this study, we discussed the etiology, molecular mechanisms, and histological morphology of traumatic neuromas after peripheral nerve injury. Subsequently, we summarized and analyzed current nonsurgical and surgical treatment options, along with their advantages and disadvantages. Additionally, we emphasized recent advancements in treating traumatic neuromas with tissue-engineered material strategies. By integrating biomaterials, growth factors, cell-based approaches, and electrical stimulation, tissue engineering offers a comprehensive solution surpassing mere symptomatic relief, striving for the structural and functional restoration of damaged nerves. In conclusion, the utilization of tissue-engineered materials has the potential to significantly reduce the risk of neuroma recurrence after surgical treatment.

Conductive Hydrogel Restores Electrical Conduction to Promote Neurological Recovery in a Rat Model.

Spinal cord injury (SCI), caused by significant physical trauma, as well as other pathological conditions, results in electrical signaling disruption and loss of bodily functional control below the injury site. Conductive biomaterials have been considered a promising approach for treating SCI, owing to their ability to restore electrical connections between intact spinal cord portions across the injury site. In this study, we evaluated the ability of a conductive hydrogel, poly-3-amino-4-methoxybenzoic acid-gelatin (PAMB-G), to restore electrical signaling and improve neuronal regeneration in a rat SCI model generated using the compression clip method. Gelatin or PAMB-G was injected at the SCI site, yielding three groups: Control (saline), Gelatin, and PAMB-G. During the 8-week study, PAMB-G, compared to Control, had significantly lower proinflammatory factor expression, such as for tumor necrosis factor -α (0.388 ± 0.276 for PAMB-G vs. 1.027 ± 0.431 for Control) and monocyte chemoattractant protein (MCP)-1 (0.443 ± 0.201 for PAMB-G vs. 1.662 ± 0.912 for Control). In addition, PAMB-G had lower astrocyte and microglia numbers (35.75 ± 4.349 and 40.75 ± 7.890, respectively) compared to Control (50.75 ± 6.5 and 64.75 ± 10.72) and Gelatin (48.75 ± 4.787 and 71.75 ± 7.411). PAMB-G-treated rats also had significantly greater preservation and regeneration of remaining intact neuronal tissue (0.523 ± 0.059% mean white matter in PAMB-G vs 0.377 ± 0.044% in Control and 0.385 ± 0.051% in Gelatin) caused by reduced apoptosis and increased neuronal growth-associated gene expression. All these processes stemmed from PAMB-G facilitating increased electrical signaling conduction, leading to locomotive functional improvements, in the form of increased Basso-Beattie-Bresnahan scores and steeper angles in the slope test (76.667 ± 5.164 for PAMB-G, vs. 59.167 ± 4.916 for Control and 58.333 ± 4.082 for Gelatin), as well as reduced gastrocnemius muscle atrophy (0.345 ± 0.085 for PAMB-G, vs. 0.244 ± 0.021 for Control and 0.210 ± 0.058 for Gelatin). In conclusion, PAMB-G injection post-SCI resulted in improved electrical signaling conduction, which contributed to lowered inflammation and apoptosis, increased neuronal growth, and greater bodily functional control, suggesting its potential as a viable treatment for SCI.

The Relationship Between Shoulder Impingement Syndrome and Coracoacromial Ligament Degeneration a Predictive Factor for Shoulder Acromioplasty.

Objective: The coracoacromial ligament (CAL) connects the acromion and coracoid process of the scapula. This study aimed to explore the correlation between CAL degeneration and shoulder pathology, specifically focusing on the efficacy of acromioplasty in treating shoulder impingement in patients with varying degrees of CAL degeneration. Methods: 49 patients diagnosed with bursal-side partial rotator cuff tear were assessed for CAL degeneration and categorized into three grades. They were then randomized into acromioplasty and non-acromioplasty groups to compare the outcomes. Acromiohumeral distance (AHD) and fatty infiltration was evaluated on imaging examinations. American Shoulder and Elbow Score (ASES) and Visual Analogue Scale (VAS) was recorded to evaluate the shoulder function before and two years after surgery. Results: Grade III CAL patients demonstrated significantly reduced AHD and increased VAS scores compared to Grades I and II. Post-acromioplasty, Grade III patients showed a statistically significant improvement in ASES scores compared to the non-acromioplasty group. Conclusion: The study indicates that CAL degeneration is a significant indicator of shoulder impingement. Notably, acromioplasty significantly improves shoulder function in patients with severe CAL degeneration, suggesting its potential as a targeted treatment in managing shoulder impingement.

Internal representations of the canonical real-world distance of objects.

In the real world, every object has its canonical distance from observers. For example, airplanes are usually far away from us, whereas eyeglasses are close to us. Do we have an internal representation of the canonical real-world distance of objects in our cognitive system? If we do, does the canonical distance influence the perceived size of an object? Here, we conducted two experiments to address these questions. In Experiment 1, we first asked participants to rate the canonical distance of objects. Participants gave consistent ratings to each object. Then, pairs of object images were presented one by one in a trial, and participants were asked to rate the distance of the second object (i.e., a priming paradigm). We found that the rating of the perceived distance of the target object was modulated by the canonical real-world distance of the prime. In Experiment 2, participants were asked to judge the perceived size of canonically near or far objects that were presented at the converging end (i.e., far location) or the opening end (i.e., near location) of a background image with converging lines. We found that regardless of the presentation location, participants perceived the canonically near object as smaller than the canonically far object even though their retinal and real-world sizes were matched. In all, our results suggest that we have an internal representation of the canonical real-world distance of objects, which affects the perceived distance of subsequent objects and the perceived size of the objects themselves.

Live cell pool and rare cell isolation using Enrich TROVO system.

Although several technologies have been developed to isolate cells of interest from a heterogenous sample, clogging and impaired cell viability limit such isolation. We have developed the Enrich TROVO system as a novel, nonfluidic technology to sort live cells. The TROVO system combines imaging-based cell selection and photo-crosslinking of (gelatin methacrylate) gelMA-hydrogel to capture cells. After capture, cells are released by enzymatic digestion of the hydrogel and then retrieved for downstream analysis or further cell culturing. The system can capture cells with a recovery rate of 48% while maintaining 90% viability. Moreover, TROVO can enrich rare cells 506-fold with 93% efficiency using single step isolation from a 1:104 cell mixture, and can also capture one target cell from 1 million cells, reaching an enrichment ratio of 9128. In addition, 100% purity and 49% recovery rate can be achieved by a following negative isolation process. Compared to existing technologies, the TROVO system is clog-resistant, highly biocompatible, and can process a wide range of sample sizes.

Uterine Immunoprivileged Cells Restore Cardiac Function of Male Recipients After Myocardial Infarction.

It has been documented that the uterus plays a key cardio-protective role in pre-menopausal women, which is supported by uterine cell therapy, to preserve cardiac functioning post-myocardial infarction, being effective among females. However, whether such therapies would also be beneficial among males is still largely unknown. In this study, we aimed to fill in this gap in knowledge by examining the effects of transplanted uterine cells on infarcted male hearts. We identified, based on major histocompatibility complex class I (MHC-I) expression levels, 3 uterine reparative cell populations: MHC-I(neg), MHC-I(mix), and MHC-I(pos). In vitro, MHC-I(neg) cells showed higher levels of pro-angiogenic, pro-survival, and anti-inflammatory factors, compared to MHC-I(mix) and MHC-I(pos). Furthermore, when cocultured with allogeneic mixed leukocytes, MHC-I(neg) had lower cytotoxicity and leukocyte proliferation. In particular, CD8+ cytotoxic T cells significantly decreased, while CD4+CD25+ Tregs and CD4-CD8- double-negative T cells significantly increased when cocultured with MHC-I(neg), compared to MHC-I(mix) and MHC-I(pos) cocultures. In vivo, MHC-I(neg) as well as MHC-I(mix) were found under both syngeneic and allogeneic transplantation in infarcted male hearts, to significantly improve cardiac function and reduce the scar size, via promoting angiogenesis in the infarcted area. All of these findings thus support the view that males could also benefit from the cardio-protective effects observed among females, via cell therapy approaches involving the transplantation of immuno-privileged uterine reparative cells in infarcted hearts.

State transition and intercellular communication of synovial fibroblasts in response to chronic and acute shoulder injuries unveiled by single-cell transcriptomic analyses.

PURPOSE: We aimed to investigate the heterogeneity of synovial fibroblasts and their potential to undergo cell state transitions at the resolution of single cells. MATERIALS AND METHODS: We employed the single-cell RNA sequencing (scRNA-seq) approach to comprehensively map the cellular landscape of the shoulder synovium in individuals with chronic rotator cuff tears (RCTs) and acute proximal humerus fractures (PHFs). Utilizing unbiased clustering analysis, we successfully identified distinct subpopulations of fibroblasts within the synovial environment. We utilized Monocle 3 to delineate the trajectory of synovial fibroblast state transition. And we used CellPhone DB v2.1.0 to predict cell-cell communication patterns within the synovial microenvironment. RESULTS: We identified eight main cell clusters in the shoulder synovium. Unbiased clustering analysis identified four synovial fibroblast subpopulations, with diverse biological functions associated with protein secretion, ECM remodeling, inflammation regulation and cell division. Lining, mesenchymal, pro-inflammatory and proliferative fibroblasts subsets were identified. Combining the results from StemID and characteristic gene features, mesenchymal fibroblasts exhibited characteristics of fibroblast progenitor cells. The trajectory of synovial fibroblast state transition showed a transition from mesenchymal to pro-inflammatory and lining phenotypes. In addition, the cross talk between fibroblast subclusters increased in degenerative shoulder diseases compared to acute trauma. CONCLUSION: We successfully generated the scRNA-seq transcriptomic atlas of the shoulder synovium, which provides a comprehensive understanding of the heterogeneity of synovial fibroblasts, their potential to undergo state transitions, and their intercellular communication in the context of chronic degenerative and acute traumatic shoulder diseases.

Treatment of Distal Third Humeral Shaft Fracture with Intramedullary Nail Combined with Anterior Minimally Invasive Plate Osteosynthesis.

OBJECTIVE: The treatment of distal third humeral shaft fracture is difficult. Studies have shown that anterior minimally invasive plate has lower probability of complication and higher healing rate. However there is no applicable anatomical plate at present. This study is to investigate the clinical effect of intramedullary nail combined with anterior minimally invasive plate in the treatment of distal humeral shaft fractures. METHODS: The data of 83 patients with lower humerus shaft fracture treated from September 2015 to January 2020 were analyzed. According to different treatment methods, they were divided into two groups: 40 patients were treated with intramedullary nailing combined with minimally invasive anterior plate fixation (group A), and 43 patients were treated with double plate fixation through posterior approach (group B). General preoperative data, operative time, intraoperative blood loss, total incision length, fracture healing time, shoulder and elbow visual analogue scale (VAS) score, Constant-Murley shoulder function score, Mayo elbow function score, and complications were recorded and compared between the two groups. Two independent sample t-tests was used for follow-up, age, BMI, operation time, intraoperative bleeding, total incision length, fracture healing time, Constant-Murley score and Mayo score, and rank sum test was used for VAS score of shoulder and elbow. RESULTS: There was no significant difference in preoperative general data between the two groups (p > 0.05), indicating comparability. There were no significant differences in operation time, total incision length, fracture healing time, Constant-Murley shoulder function score at the last follow-up, Mayo elbow function score, and shoulder and elbow VAS pain score between 2 groups (p > 0.05). The amount of intraoperative blood loss in observation group was 76.98 ± 16.46, which was significantly less than that in control group, and the difference was statistically significant (p < 0.01). There were no radial nerve injury, musculocutaneous nerve injury, incision infection and fracture nonunion in the observation group. In the control group, four cases of iatrogenic radial nerve injury, three cases of incision infection and three cases of fracture nonunion were found. The complication rate was 23.3% (10/43). There was statistical difference in the incidence of complications between the two groups (p < 0.01). CONCLUSION: A humeral intramedullary nail combined with an anterior minimally invasive plate in the treatment of distal humeral shaft fracture has the advantages of less soft tissue damage, less blood transfusion, high fracture healing rate and low risk of iatrogenic radial nerve injury, which is an effective method for clinical treatment of this type of fracture.

Multifunctional wet-adhesive chitosan/acrylic conduit for sutureless repair of peripheral nerve injuries.

The incidence of peripheral nerve injury (PNI) is high worldwide, and a poor prognosis is common. Surgical closure and repair of the affected area are crucial to ensure the effective treatment of peripheral nerve injuries. Despite being the standard treatment approach, reliance on sutures to seal the severed nerve ends introduces several limitations and restrictions. This technique is intricate and time-consuming, and the application of threading and punctate sutures may lead to tissue damage and heightened tension concentrations, thus increasing the risk of fixation failure and local inflammation. This study aimed to develop easily implantable chitosan-based peripheral nerve repair conduits that combine acrylic acid and cleavable N-hydroxysuccinimide to reduce nerve damage during repair. In ex vivo tissue adhesion tests, the conduit achieved maximal interfacial toughness of 705 J m-2 ± 30 J m-2, allowing continuous bridging of the severed nerve ends. Adhesive repair significantly reduces local inflammation caused by conventional sutures, and the positive charge of chitosan disrupts the bacterial cell wall and reduces implant-related infections. This promises to open new avenues for sutureless nerve repair and reliable medical implants.

The Porous Structure of Peripheral Nerve Guidance Conduits: Features, Fabrication, and Implications for Peripheral Nerve Regeneration.

Porous structure is an important three-dimensional morphological feature of the peripheral nerve guidance conduit (NGC), which permits the infiltration of cells, nutrients, and molecular signals and the discharge of metabolic waste. Porous structures with precisely customized pore sizes, porosities, and connectivities are being used to construct fully permeable, semi-permeable, and asymmetric peripheral NGCs for the replacement of traditional nerve autografts in the treatment of long-segment peripheral nerve injury. In this review, the features of porous structures and the classification of NGCs based on these characteristics are discussed. Common methods for constructing 3D porous NGCs in current research are described, as well as the pore characteristics and the parameters used to tune the pores. The effects of the porous structure on the physical properties of NGCs, including biodegradation, mechanical performance, and permeability, were analyzed. Pore structure affects the biological behavior of Schwann cells, macrophages, fibroblasts, and vascular endothelial cells during peripheral nerve regeneration. The construction of ideal porous structures is a significant advancement in the regeneration of peripheral nerve tissue engineering materials. The purpose of this review is to generalize, summarize, and analyze methods for the preparation of porous NGCs and their biological functions in promoting peripheral nerve regeneration to guide the development of medical nerve repair materials.

Tissue-Engineered Nanomaterials Play Diverse Roles in Bone Injury Repair.

Nanomaterials with bone-mimicking characteristics and easily internalized by the cell could create suitable microenvironments in which to regulate the therapeutic effects of bone regeneration. This review provides an overview of the current state-of-the-art research in developing and using nanomaterials for better bone injury repair. First, an overview of the hierarchical architecture from the macroscale to the nanoscale of natural bone is presented, as these bone tissue microstructures and compositions are the basis for constructing bone substitutes. Next, urgent clinical issues associated with bone injury that require resolution and the potential of nanomaterials to overcome them are discussed. Finally, nanomaterials are classified as inorganic or organic based on their chemical properties. Their basic characteristics and the results of related bone engineering studies are described. This review describes theoretical and technical bases for the development of innovative methods for repairing damaged bone and should inspire therapeutic strategies with potential for clinical applications.

Biomechanical Properties of Bionic Collum Femoris Preserving Hip Prosthesis: A Finite Element Analysis.

OBJECTIVE: Compared with total hip replacement, conventional collum femoris preserving prosthesis has a better bone retention effect. However, damage to the trabecular bone of the proximal femur leads to inevitable abnormal stress distribution, which leads to increased risks of femoral neck bone absorption, periprosthetic fracture, prosthesis loosening, rotation, and sinking. Thus, we compare the biomechanical properties of collum femoris preserving (CFP) and bionic collum femoris preserving (BCFP) hip prostheses. METHODS: The Sawbone digital model (#3503, left, medium) was selected as the research object. We used the Mimics 21.0 software to reconstruct the digital model of the femur and the SolidWorks 2019 software to build and assemble the three-dimensional models of CFP and BCFP prostheses. With the ANSYS Workbench 2021R1 software, the models were meshed and assigned values to simulate the load of a single foot under slow walking. We measured the mechanical distribution of the whole model and obtained the stress nephogram. RESULTS: For CFP prosthesis, the peak stresses of the medial interface of the stem neck, the lateral interface of the stem neck, and the end of the stem were 64.894, 32.199, and 8.578 MPa, respectively; the peak stresses of the medial surface of the femoral shaft, the lateral surface of femoral shaft, the medial femoral neck bone-prosthesis interface (osteotomy interface), the lateral femoral neck bone-prosthesis interface (basal area), the lateral femoral neck bone-prosthesis interface (osteotomy interface), and the greater trochanter area were 28.093, 24.790, 14.388, 5.118, 4.179, and 8.245 MPa, respectively; the valley stress of the greater trochanter area was 1.134 MPa. For BCFP prosthesis, the peak stresses of the medial interface of the stem neck, the lateral interface of the stem neck, and the end of the stem were 47.015, 26.771, and 47.593 MPa, respectively; the peak stress of tension screw was 15.739 MPa; the peak stresses of the medial surface of the femoral shaft, the lateral surface of femoral shaft, the medial femoral neck bone-prosthesis interface (osteotomy interface), the lateral femoral neck bone-prosthesis interface (basal area), the lateral femoral neck bone-prosthesis interface (osteotomy interface) and the greater trochanter area were 28.581, 25.364, 15.624, 6.434, 4.986, and 8.796 MPa, respectively; the valley stress of the greater trochanter area was 1.419 MPa; the peak stress of bone-metal interface between the tension screw and the lateral surface of the femur was 5.858 MPa. CONCLUSION: Compared with the CFP prosthesis, the design of the BCFP prosthesis is based on the lever balance theory. With the bionic reconstruction of tension trabeculae, BCFP prosthesis makes up for the defects of CFP prosthesis design, optimizes the stress distribution, and reduces the stress shelter effect of the proximal femur, which has better biomechanical properties.

Protocatechuic acid reverses myocardial infarction mediated by ß-adrenergic agonist via regulation of Nrf2/HO-1 pathway, inflammatory, apoptotic, and fibrotic events.

Myocardial infarction (MI) is an instant ischemic death of cardiomyocytes that remains a major global cause of mortalities. MI is accompanied by oxidative, inflammatory, apoptotic, and fibrotic insults. Protocatechuic acid (PCA) is a polyphenolic compound with various potent biological activities. In this study, we explored the possible cardioprotective role of PCA against isoproterenol (ISO)-mediated MI. Rats were either injected with ISO (85 mg/kg, subcutaneously) or pretreated with PCA (100 or 200 mg/kg, orally). PCA supplementation markedly normalized ISO-induced disturbed cardiac function markers (creatine kinase-MB, lactate dehydrogenase, and troponin T). Notably, PCA administration exerted remarkable increases in glutathione and its derived enzymes, superoxide dismutase, and catalase, as well as decreases in malondialdehyde and nitric oxide levels in the injured cardiac tissue. The molecular findings validated the augmented cellular antioxidative capacity by PCA via increasing the gene expressions of nuclear factor erythroid 2-related factor 2 and heme oxygenase-1. The cardioprotective efficacy of PCA extended to suppress cardiac inflammation as demonstrated by the decreased levels of tumor necrosis factor-alpha, interleukin-1 beta, and nuclear factor kappa B. Additionally, PCA prevented cardiomyocyte loss and fibrosis by decreasing Bax, caspase-3, transforming growth factor-ß1 and matrix metalloproteinase-9, and enhancing B-cell lymphoma 2 and tissue inhibitors of metalloproteinase-3. The cardiac histological screening further confirmed the PCA's protective action. The obtained data recommend PCA as an alternative therapeutic agent to attenuate the molecular, biochemical, and histological alterations associated with MI development.

A Transosseous Suture as an Alternative to Suture Anchor on Anterior-Avulsion Greater Tuberosity Fragment Fixation in Neer Three-Part Proximal Humeral Fracture: A Biomechanical Study.

OBJECTIVE: Greater tuberosity (GT) fragments were communicated, and additional techniques to increase the GT fragment stability after the locking plate fixation was necessary. This study aimed to analyze the reinforcement effects on the anterior-avulsion GT fragment in Neer three-part proximal humeral fractures (PHFs) using transosseous suture and suture anchor techniques. METHODS: Eighteen fresh-frozen human cadaveric shoulder specimens were used in the study. Standardized fracture of the GT and surgical neck was created in 18 human cadaveric proximal humerus. The GT fragments were reinforced with transosseous suture (TS), suture anchor (SA), and suture in addition to the PHILOS plate fixation. The fixed humerus was tested by applying static loading to the supraspinatus tendon. Load forces and fragment displacement were evaluated by a biomechanical testing machine, and the load to 3- and 5-mm displacements, load to failure, and mode of failure were recorded for all specimens. Nonparametric variables were examined by the Kruskal-Wallis test, and the Bonferroni post hoc test was used to analyze the mean loads to create 3- and 5-mm displacements as well as the failure load. RESULTS: The age, female proportion, and bone mineral density showed no statistically significant differences between the three groups. The mean loading force to create 3-mm and 5-mm displacement in the TS group (254.9 ± 77.4, 309.6 ± 152.7) were significantly higher than those in the suture group (136.1 ± 16.7, 193.4 ± 14.5) (P = 0.024, P = 0.005). For the SA group, the force to create 3- and 5-mm displacement (204.3 ± 60.9, 307.8 ± 73.5) were comparable to those in the TS group (P = 0.236, P = 0.983). Moreover, the loading force to failure in the TS group (508.6 ± 217.7) and SA group (406.6 ± 114.9) was significantly higher than that in the suture group (265.9 ± 52.1) (P = 0.021, P = 0.024). In the TS group, three failed due to tendon-bone junction rupture; bone tunnel broken occurred in two specimens; suture rupture could also be seen in one specimen. All specimens in the suture group failed because of suture rupture. In the SA group, three specimens failed due to suture rupture; two failed secondary to tendon-bone junction rupture; and one failed because of shaft fracture. CONCLUSIONS: Transosseous suture is a new type of reinforcement for GT fragment in Neer-three part PHFs. The transosseous suture was superior to the suture only in the reinforcement of the anterior-avulsion GT fragment of Neer three-part PHFs, and it had comparable biomechanical strength to the suture anchor.

Fracture Line Morphology of Greater Tuberosity Fragments of Neer Three- and Four-Part Proximal Humerus Fractures.

OBJECTIVE: In complicated Neer three- and four-part proximal humerus fracture (PHF), greater tuberosity (GT) fragments are often comminuted, and the currently widely used locking plate may not fix GT fragments effectively. A further understanding of morphological characteristics of the GT fragments may help explore new fixation devices. This study aimed to determine the fracture line morphology of the GT fragment of Neer three- or four-part PHF and analyze the location relationship between the locking plate and the GT fragment. METHODS: Seventy-one three-dimensional computed tomography scans of Neer three- and four-part PHF were retrospectively reviewed between January 2014 and June 2019. Fracture fragments were reconstructed and virtually reduced in the Mimics software, and fracture lines of GT fragments were depicted on a humerus template in the 3-matic software and then were superimposed altogether. The common sites of the GT fracture were identified, and the location relationship between the locking plate and GT fragments was analyzed in a computer-simulated scenario. RESULTS: The fracture line morphology of GT fragments was similar between Neer three- and four-part PHF. The overall morphology of GT fragments was in a fan shape, which could be summarized as anterior, superior, posterior, and middle lines. Of these, we identified 51 split and 29 avulsion type GT fragments based on the Mutch classification, and they could occur simultaneously in a PHF. The overall morphology of split type fragments was in a fan shape, and avulsion type fragments showed a quite distinguishable distribution pattern. A GT fragment could be classified as anterior-split, posterior-split, complete-split, anterior -avulsion, and posterior-avulsion type based on its morphology and location. The median percentage of fragment area covered by the plate was 32.3% in all of the fragments, and it was 69.4%, 23.0%, 37.2%, 21.8%, 0.0% in anterior-split, posterior-split, complete-split, anterior-avulsion, and posterior-avulsion type GT fragments. We defined the posterior-split, anterior-avulsion, and posterior-avulsion type GT fragments as the risky GT fragments, and they occurred in 43 (60.6%) Neer three- and four-part PHFs. CONCLUSION: The fracture line morphology of GT fragments of Neer three- and four-part PHF was in a fan shape. GT fragments could be classified based on their location and morphology. The extent of GT fragment coverage provided by the locking plate differed in various fragment types, and we identified the anterior-avulsion, posterior-avulsion, and posterior-split type fragments as the risky GT fragments with a high incidence rate in Neer three- and four-part PHFs.

Tuberosity reconstruction baseplate for shoulder hemiarthroplasty: Morphological design and biomaterial application.

Background: Shoulder hemiarthroplasty is prone to tuberosity malposition and migration, reducing the rate of tuberosity healing. We proposed to design a tuberosity reconstruction baseplate to assist in tuberosity integration and to evaluate the mechanical properties of baseplate made from the novel biomaterial carbon fiber reinforced polymer (CFRP) composites. Methods: The three-dimensional model of native proximal humerus was constructed by computed tomography (CT) data. The morphological design of baseplate was based on the tuberosity contour and rotator cuff footprint. Finite element models were created for different thicknesses of CFRP composites, poly (ether-ether-ketone) (PEEK) and titanium-nickel (TiNi) alloy. The permissible load and suture hole displacements were applied to evaluate the mechanical properties. Results: The structurally optimized model made of CFRP composites provided superior strength and deformability, compared to the PEEK material and TiNi alloy. Its permissible load was above 200 N and the suture hole displacement was between 0.9 and 1.4 mm. Conclusion: This study proposed a method for designing tuberosity reconstruction baseplate based on morphological data and extended the application of biomaterial CFRP composites in orthopedics field. The optimized model made of CFRP composites allowed a certain extent of elastic deformation and showed the possibility for dynamic compression of tuberosity bone blocks.

Designing and validating a comparison card method for quantification of glenoid bone defect.

To design and investigate a comparison card to evaluate the glenoid bone defect compared with Sugaya method. 33 patients with bony Bankart lesions were included. The comparison card and Sugaya method were performed on two occasions by three participants. The intra-group correlation coefficient (ICC) analysis and the inter-group correlation coefficient analysis of two measurements was performed. The concordance of the two methods was assessed using Bland-Altman analysis. Firstly, the percentage of defect measured by Sugaya method was 10.32 ± 8.38, and the comparison card method was 10.26 ± 8.41, 10.15 ± 8.23, and 10.62 ± 8.48, separately. There was no statistically significant difference (P > 0.05). The second measurement showed it was 10.37 ± 8.39 for Sugaya method, and 10.23 ± 8.37, 10.15 ± 8.35, 10.54 ± 8.49 for the comparison card, without a statistically significant difference (P > 0.05). For the comparison card, the intra- and inter-observer ICC values were all > 0.75. In the first measurement, Bland-Altman analysis demonstrated agreement between the two methods (bias, -0.03; SD, 0.48; - 0.97- 0.91; 95% CI, - 0.1999- 0.1413). Agreement was also found between them (bias, 0.07; SD, 0.61; - 1.13- 1.26; 95% CI, - 0.1509- 0.2812) in the second measurement. The comparison card method has similar accuracy with Sugaya method, which is of great reliability and convenience.

Epicardial delivery of a conductive membrane synchronizes conduction to reduce atrial fibrillation.

Conductive polymers have been investigated as a medium for the transmission of electrical signals in biological tissues, but their capacity to rewire cardiac tissue has not been evaluated. Myocardial tissue is unique in being able to generate an electrical potential at a fixed rate; this potential spreads rapidly among cells to trigger muscle contractions. Tissue injuries result in myocardial fibrosis and subsequent non-uniform conductivity, leading to arrhythmia. Atrial fibrillation (AF) is the most common sustained arrhythmia, associated with disruption of atrial electrical signaling, which can potentially be restored by the epicardial delivery of conductive polymers. In this work, poly-3-amino-4-methoxybenzoic acid, conjugated to gelatin, is fabricated as a membrane (PAMB-G) to support conductive velocities that are close to that of the myocardium. A cross-linked gelatin membrane (Gelatin) is used as a control. The as-fabricated PAMB-G has similar tensile elasticities, determined using the Young's modulus, as contracting myocardium; it can also transmit electrical signals to initiate cardiac cell and tissue excitation. Delivering PAMB-G onto the atrium of a rat AF model shortens AF duration and improves post-AF recovery for the duration of a 28-day-long study. Atrial tissue in the PAMB-G-implanted group has lower impedance, higher conduction velocity, and higher field potential amplitude than that in the Gelatin-implanted group. Therefore, the as-proposed PAMB-G is a suitable medium for restoring proper cardiac electrical signaling in AF hearts.