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The bistable deployable composite boom (Bi-DCB) can achieve bistable function by storing and releasing strain energy, which has a good application prospect in space field. For example, it serves as the main support section of deployable structures (e.g., solar arrays and antennas). This paper investigates the folding stable state of the Bi-DCB through the analytical method. Based on the classical Archimedes' helix, the geometrical model of the Bi-DCB was established. Using energy principle, an analytical model for predicting the folding stable state of the Bi-DCB was presented. The failure indices of six Bi-DCBs in the folding stable state were calculated using the Tsai-Hill criterion and the maximum stress criterion. To validate the analytical model proposed in this paper, the prediction results were compared with the results of two Finite Element Models (FEMs) and experimental results, and the four were in good agreement. Finally, the effect of geometric parameters (i.e., radius of cross-section, thickness and length) on the folding stable state of the Bi-DCB was further investigated with the aid of the analytical model. It is shown that geometric parameters are one of the key factors affecting the folding stable state of the Bi-DCB., Comment: arXiv admin note: substantial text overlap with arXiv:2305.05289

Background Adhesion after tendon injury is a common complication in clinical practice. The lack of effective prevention mechanisms seriously affects the functional rehabilitation of patients. This research aimed to optimise the amniotic membrane and explain the mechanism of tendon-amniotic membrane by imitating the tendon sheath to construct a multilayer electrospun polycaprolactone (PCL) nanofibre membrane. Materials and methods Fresh amnions were subjected to freezing and vacuum drying. The two surfaces of freeze-dried amnions were coated with PCL nanofibres by electrospinning, thereby forming a multilayer composite membrane and constructing a growth factor-sustained release system conforming to the tendon-healing cycle. The new materials were characterised, and the biological effects on tenocytes and fibroblasts were evaluated. The tendon injury model of New Zealand rabbits was constructed to observe the effects on tendon adhesion and healing. Results After freezing and vacuum drying, fresh amnions were found to effectively remove most of the cell components but retained the active components TGF-β1, bFGF, VEGF, and PDGF, as well as the fibrous reticular structure of the basement membrane. After coating with PCL nanofibres, a composite membrane mimicking the structure of the tendon sheath was constructed, thereby strengthening the tensile strength of the amnion. By up-regulating the phosphorylation of ERK1/2 and SMAD2/3, the adhesion and proliferation of tenocytes and fibroblasts were promoted, and collagen synthesis was enhanced. In the rabbit tendon repair model, the composite membrane effectively isolated the exogenous adhesion tissue and promoted endogenous tendon healing. Conclusion The composite membrane mimicking the structure of tendon sheath effectively isolated the exogenous adhesion tissue and achieved good tendon slip. By slowly releasing the growth factors TGF-β1, bFGF, VEGF and PDGF, the ERK1/2 and SMAD2/3 pathways were regulated. Consequently, endogenous tendon healing was promoted. This strategy can alternatively address the clinical problem of tendon adhesion.

A full-scale model for predicting low-velocity impact (LVI) damage and compression after impact (CAI) strength was established based on a subroutine of the material constitutive relationship and the cohesive elements. The dynamic responses of the laminate under impact load and damage propagation under a compressive load were presented. The influences of impact energy and ply thickness on the impact damage and the CAI strength were predicted. The predicted results were compared with the experimental ones. It is shown that the predicted value of the CAI strength is in good agreement with the experimental result. As the impact energy reaches a certain value, the CAI strength no longer decreases with the increase in the impact energy. Decreasing the ply thickness can effectively improve the damage resistance and CAI strength.

BACKGROUND The aim of this study was to explore the effect of metformin by inducing autophagy for enhancing functional recovery of peripheral nerve in rats with sciatic nerve crush injury. MATERIAL AND METHODS Autophagy was determined by electron microscopy, immunofluorescence, and Western blot analysis. Motor function recovery was studied by the footprint intensity method. Axonal growth and regeneration were detected through Western blot while axonal remyelination was analysed through immunocytochemistry. Sensory and functional recovery were assessed by reflexive motor function analysis. RESULTS The present study deciphered the role of autophagy induction by metformin in motor functions and peripheral nerve regeneration following sciatic nerve crush injury in rats. The process was detected by measuring autophagosomes and the expression of microtubule-associated protein 1A/1B-light chain 3 upon metformin treatment of sciatic nerve crush-injured rats. Neurobehavioral recovery by metformin was tested by CatWalk gait analysis, and we quantified expression of myelin basic protein MBP and neurofilament NF200 at the damage sight by immunoblotting. In metformin-treated injured rats, autophagy was upregulated, by which the number of dead cells was decreased. Motor function was also recovered after metformin treatment, which was accompanied by upregulation of MBP and NF200 through autophagy induction. Surprisingly, the motor regenerative capability was reduced by treatment with 3-methyl adenine (an autophagy inhibitor) in nerve-injured rats. CONCLUSIONS Our study revealed that pharmacological induction of autophagy has an important and active role in the regeneration of nerve and motor function regain.

This paper seeks to present a semi-analytical model for predicting the nonlinear tensile properties of corrugated flexible composite skin (FCS) within large deformation range based on iterative integration procedure. The FCS is constructed with two thin-walled curved fibre-reinforced-plastics (FRP) composite shells with a biaxially symmetrical lenticular cross-section, which can be stretched largely along the corrugated direction through pure elastic deformation. Analytical formulations for tensile stiffness of the FCS are derived based on the unit virtual load method, and geometrical equations are established to describe tensile deformation of the FCS. By means of linear elastic and strain energy theory, new geometry and tensile force increment of extended FCS are calculated at a given small increment of tensile displacement. In order to obtain the tensile behaviour of the FCS within large deformation range, semi-analytical model is presented by using the iterative calculation, and then is verified from experiments. Finally, the effect of the geometry on tensile behaviour of the FCS is analyzed numerically.

Thin-walled deployable composite structures with high strain ability are of considerable interest and increasingly used in aerospace field due to their superior mechanical behaviour and folding function. This paper seeks to investigate large folding deformation behaviour of a thin-walled deployable composite boom (DCB) made of high strain carbon-fibre-reinforced-plastics fabricated by vacuum-bag and co-bonding technologies. Large deformation function tests are conducted to determine tensile, compression and folding behaviours of the DCB. Geometrically nonlinear, explicit and standard, finite element models and an analytical model are implemented to characterize the tensile and compression behaviours of the DCB, and the deviations of predictions from experiments are in an acceptable scatter. Furthermore, a geometrically nonlinear and explicit finite element model is also generated for folding analysis of the DCB, and a good correlation between predictions and experiments has been achieved.

Adhesion and scarring after neural surgery are detrimental to nerve regeneration and functional recovery. Amniotic membranes have been used in tissue repair due to their immunogenicity and richness in cytokines. In this study, an electrospun polycaprolactone (PCL)-amnion nanofibrous membrane was prepared for the treatment of sciatic nerve compression in a rat model. The effects of the PCL-amnion nanofibrous membrane on the prevention of adhesion formation and nerve regeneration were evaluated using electrophysiology and histological analyses. Compared with the medical chitosan hydrogel dressing, the PCL-amnion nanofibrous membrane significantly reduced peripheral nerve adhesion and promoted the rapid recovery of nerve conduction. Moreover, the immunohistochemical analysis identified more Schwann cells and less pro-inflammatory M1 macrophages in the PCL-amnion group. Western blot and RT-PCR results showed that the expression levels of type-Ⅰ and Ⅲ collagen in the PCL-treated rats were half of those in the control group after 12 weeks, while the expression level of nerve growth factor was approximately 3.5 times that found in the rats treated with medical chitosan hydrogel. In summary, electrospun PCL-amnion nanofibrous membranes can effectively reduce adhesion after neural surgery and promote nerve repair and regeneration. The long-term retention in vivo and sustained release of cytokines make PCL-amnion a promising biomaterial for clinical application.

Background Most of the acute scaphoid fractures have been treated nonoperatively in a cast or by open surgery. Percutaneous screw fixation was introduced for acute scaphoid fractures through K-wire-assisted reduction and maintenance, and the effectiveness of the methods was evaluated. Methods From January 2015 to December 2018, a total of 20 patients were recruited to the study and 10 patients were randomly allocated to the open reduction and percutaneous groups respectively. Different groups received open reduction and internal fixation or percutaneous screw fixation. Function outcomes including the range of motion and grip strength were assessed according to the modified Mayo wrist scoring system. Results Final follow-up examination was performed on an average of 12 months after surgery. No immediate postoperative complication occurred. All patients achieved solid union as confirmed by CT scans. A significant increase in the functional recovery of the injured wrist in the percutaneous group than they were in the open reduction group. Conclusions Our novel percutaneous screw fixation method is beneficial to minimise injury to the blood supply of the scaphoid. Primary percutaneous screw fixation for acute scaphoid fractures is a superior method with reduced time to bony union, early return to daily activity or employment and predictably lessened complications of wrist stiffness, diminished grip strength, delayed union, non-union and osteonecrosis.

Background: Percutaneous screw fixation was introduced for acute scaphoid fractures through K-wire-assisted reduction and maintenance, and the effectiveness of the methods was evaluated.Methods: Ten patients with acute scaphoid fractures were consecutively treated with the proposed technique from January 2015 to December 2018. With the wrist placed in ulnar deviation, one K-wire was introduced perpendicularly through the styloid process of radius into the proximal pole of scaphoid under fluoroscopic guidance. The scaphoid fragment was reduced by dorsiflexing the wrist and translating the distal pole into an extended position. A headless compression screw was then inserted in a standardised manner. Operation time, time to union, time to return to previous activity and complication were recorded. Function outcomes including pain, work status, range of motion (ROM) and grip strength were assessed according to the modified Mayo wrist scoring system.Results: Final follow-up examination was performed on an average of 12 months (range, 10–15 months) after surgery. No immediate postoperative complication occurred. All scaphoid fractures united at an average of 9.2 weeks (range, 7–11.4 weeks). The following average values were achieved: operation time was 48.2 minutes (range, 38–65 minutes), the time that patients returned to previous activity levels was 9.4 weeks (range, 7–11 weeks) and function scores were 92.5 (range, 80–100). At 3 months post-operation, the wrist range of motion was generally 62.5° wrist extension (range, 50°–70°) and 68.2° wrist flexion (range, 55°–75°). Grip strength was approximately 40.1 kg (range, 28–45 kg) and 83.5% (range, 85%–100%) of the contralateral sides. The mean post-operative height-to-length ratio was 0.61.Conclusions: Our novel percutaneous screw fixation method is beneficial to minimise injury to the blood supply of the scaphoid. Primary percutaneous screw fixation for acute scaphoid fractures is a superior method with reduced time to bony union, early return to daily activity or employment and predictably lessened complications of wrist stiffness, diminished grip strength, delayed union, non-union and osteonecrosis.Trial registration: Clinicaltrials.gov; NCT04482868; Registered 19 July 2020-Retrospectively registered.

Triaxial weave fabrics are increasingly used in ultralight structures, such as the wings of unmanned aerial vehicles (UAVs) and deployable antenna on spacecraft. The tensile strength to stiffness ratio for these applications is important, requiring an optimal weave pattern; in this paper Genetic Algorithms are used to improve these designs. The mechanical response is obtained using the minimum total complementary potential energy principle where the yarns are approximated as curved beams in a micromechanical unit cell. Leading Genetic Algorithms are benchmarked to determine which perform best. The results form a disconnected Pareto front where the left hand part can be used for flexible structures but is difficult to find. An overall improvement in strength to stiffness ratio of 1191% is made with 643 designs found better than a current example. The selection of the Genetic Algorithm is shown to be crucial with only MLSGA-NSGAII regularly finding the entire Pareto front.

Hongfang Zhao,* Siyu Tian,* Lingde Kong,* Jiangbo Bai,* Jian Lu, Bing Zhang, Dehu Tian Department of Orthopedics, The Third Hospital of Hebei Medical University, Shijiazhuang, Hebei 050051, People’s Republic of China *These authors contributed equally to this work Background: The aim of this study was to investigate the union time of acute middle-third scaphoid fractures following treatments and to analyze the effect of different factors on late union.Patients and methods: We retrospectively reviewed patients with acute middle-third scaphoid fracture at our institution between January 2013 and December 2017. Patient demographics, fracture characteristics, and treatment strategy, such as age, gender, body mass index, habit of smoking, sides of injury, dominant hand, ulnar variance, multiple fractures, and treatment methods, were investigated. Univariate and multivariate analyses were used to identify possible predictive factors.Results: A total of 132 patients with scaphoid fracture were included in our study. Operation was performed in 67 patients (50.8%), and conservative treatment was performed in the other 65 patients (49.2%). The union time was 7.2±0.5 weeks. In the multivariate logistic regression analysis, late diagnosis (odds ratio, 1.247; 95% CI, 1.022–1.521) and conservative treatment method (odds ratio, 1.615; 95% CI, 1.031–2.528) were identified as 2 independent predictors of late union in scaphoid fractures patients. Other parameters were not demonstrated to be predictive factors.Conclusion: Late diagnosis and conservative treatment were two factors associated with late union. Long time of follow-up is necessary for patient with these factors. Keywords: predictive factors, union time, nonunion, scaphoid fractures, multivariable analysis

Lingde Kong,* Jiangbo Bai,* Kunlun Yu, Bing Zhang, Jichun Zhang, Dehu Tian Department of Hand Surgery, The Third Hospital of Hebei Medical University, Shijiazhuang, People’s Republic of China *These authors contributed equally to this work Background: In the treatment of cubital tunnel syndrome (CuTS), in situ ulnar nerve decompression is commonly used. This study aims to investigate predictive factors for poor recovery and ulnar nerve instability following this procedure. Methods: We enrolled 235 patients who underwent in situ ulnar nerve decompression for the treatment of CuTS from January 2010 to December 2014. All patients underwent >2 years’ follow-up. The primary outcome was postoperative recovery, which was assessed by Messina’s criteria, and the secondary outcome was postoperative ulnar nerve instability. Potential risk factors were collected from demographic data and electrodiagnostic test, which included age, gender, body mass index, history of tobacco or alcohol use, history of major medical comorbidities, disease duration, preoperative severity, motor conduction velocity, and sensory conduction velocity. Results: A total of 208 patients (88.5%) had satisfactory outcomes, while the other 27 patients (11.5%) had not. There were 25 patients (10.6%) showing postoperative ulnar nerve instability during follow-up. The multivariate analysis showed that only severe preoperative symptom (odds ratio [OR], 3.06; 95% confidence interval [CI], 2.16–4.32) was associated with unsatisfactory postoperative outcomes in patients with CuTS (P

Composite helical structures (CHSs) can store and release strain energy through elastic deformation , which have been used in automobile and aerospace structures. The compressive stiffness to weight ratio is the core in the design of these structures, requiring an optimal geometric configuration . Seven state-of-the-art Genetic Algorithms were employed and benchmarked to optimise two conflicting objectives, maximising the compressive stiffness while minimising the weight. All design variables that having effects on the compressive stiffness and weight of CHSs had been considered, which are the helix angle , the number of active coils , the helix diameter, the outer and inner diameter of cross-section, and the ply angle . A quantitative analysis method, mimicked inverted generational distance (mIGD), was used to determine the best practice of Genetic Algorithms. This study shows the selection of the Genetic Algorithm is crucial and multi-objective evolutionary algorithm based on decomposition (MOEA/D) is the best solver on searching the designs of the maximum compressive stiffness and the minimum weight.

This paper deals with a novel corrugated flexible composite skin (FCS) for morphing application. The FCS is constructed with two thin-walled curved fibre-reinforced-plastics (FRP) composite shells which can be extended through pure elastic deformation during a large deformation process. Thus, the area of the FCS can be changed significantly. Geometrical equations are established for describing the extensional deformation of the FCS. Based on equilibrium equations and laminate theory, analytical solutions are derived for calculating the mechanical properties of the FCS in an extensional deformation process. In order to validate the FCS design and the analytical model, FCS specimens made from T300/5228 prepreg were fabricated using vacuum bag and co-bonding methods. Tensile tests on the FCS specimens were successfully carried out. Load versus displacement curves, tensile stiffness versus tensile load curves and relative deformation versus tensile load curves were measured. Comparisons between the theoretical predictions and the experiments were conducted. It is shown that the predictions using the new model correlates well with the experiments. The theoretical analysis and experimental validation thus show that the new FCS design was effective and feasible.

This paper proposes a new analytical model to predict plastic deformation and strain distributions in aluminium-alloy plates under low velocity impact loading. The low velocity impact load on the fully clamped circular plate was idealized as a quasi-static normal point force acting at the centre of plate. Based on apt geometrical approximation and assumptions, governing equations were established to predict the out-of-plane deflection and the radial tensile, radial and circumferential flexure strains in fully clamped conditions. From the deformation theory of plasticity, a new formula was derived to estimate the impact load by incorporating strain-energy approach, bilinear strain-hardening constitutive model and the one-dimensional Tresca yield criterion. Low velocity impact tests were performed to confirm the proposed model and good correlation was achieved between the predictions and actual experiments, demonstrating the practical and effective use of the proposed model.

This paper deals with new analytical solutions to predict tensile and in-plane shear strengths of triaxial weave fabric (TWF) composites accounting for the interaction between angularly interlacing yarns. The triaxial yarns in three directions of 0° and ±60° in micromechanical unit cell (UC) are idealized as the curved beams with a path depicted by using sinusoidal shape functions. The tensile and in-plane shear strengths of TWF composites are derived by means of the minimum total complementary potential energy principle founded on micromechanics. In order to validate the new model, the predictions are compared with experimental data in prior literatures. It is shown that the predictions from the new model agree well with experimental results.

This study aimed to evaluate the results of volar locking plate for treatment of type B distal radius fractures involving the lunate facet and compare them with those without involvement in lunate facet.s: This was a retrospective study. A total of 93 patients with type B distal radius were treated by single volar locking plate between January 2014 and December 2015. Preoperative digital radiographs were used to initially diagnose and further classify this injury according to AO/OTA classification system. CT scanning or reconstruction was used to diagnose the complex or suspicious cases. Patients with lunate facet involvement were defined as group 1 (n = 21) and the remaining without luante facet involvement as group 2 (n = 72). Postoperative immediate radiographs and radiographs at last visit were analyzed. We evaluated clinical outcomes at minimum of 12 months and performed statistical analysis using the SPSS 19.0 software package.Bony union was reached in all participants, at the median time of 8 weeks. At the final follow-up, there were no significant difference observed in term of volar tilt and radial inclination between both groups (P, 0.172; 0.514). Articular step-off in group 1 was significantly greater than those of group 2 (P, 0.016). Significant articular step-off (2 mm) occurred in 4 patients (19.0%) in group 1 and 3 (4.2%) in group 2 (P = 0.044). At 3-months postoperatively, group 1 showed worse results than group 2 for most variables (P 0.05). At 6-months postoperatively, the differences for wrist flexion, supination, ulnar deviation and VAS in motion remained significant between both groups (P 0.05). At the last follow-up, no significant differences were observed for any variable (P 0.05). Five minor complications occurred in group 1 and 11 in group 2, and the difference was not significant (P = 0.346).Patients with distal radius fractures involving lunate facet would obtain more slow recovery, especially for wrist flexion, supination, ulnar deviation and VAS in motion. In addition, patients with lunate facet fractures would be at higher risk of loss of reduction and final articular step-off.

This article presents a new micromechanical model to predict biaxial tensile moduli of plain weave fabric composites by considering the interaction between the orthogonal interlacing strands. The two orthogonal yarns in micromechanical unit cell were idealized as curved beams with a path depicted using sinusoidal shape functions. The biaxial tensile moduli of plain weave fabric composites were derived by means of the minimum total complementary potential energy principle founded on micromechanics. Biaxial tensile tests were conducted on the resin transfer molding–made EW220/5284 plain weave fabric composites at five biaxial loading ratios of 0, 1, 2, 3 and ∞ to validate the new model. Predictions from the new model were compared with experimental data. Good correlation was achieved between the predictions and actual experiments, demonstrating the practical and effective use of the proposed model. Using the new model, the biaxial tensile moduli of plain weave fabric composites can be predicted based only on the properties of basic woven fabric.

Background: Carpal tunnel syndrome is a common compressive neuropathy of the median nerve. Compared with standard release, the efficacy, safety, and postoperative complications of limited carpal tunnel release remain controversial. The purpose of this study was to compare the effects of the 2 treatments. Methods: The English-language literature was searched using MEDLINE, Web of Science, and Embase. Randomized controlled trials that compared standard and limited incision for carpal tunnel release were included in the meta-analysis. Strength, interval to return to activities, the rate of adverse events, effectiveness, and operative time were compared. Results: Thirteen randomized controlled trials (RCTs) containing 1020 patients were included. Limited incision treated patients showed better early recovery of grip strength (mean difference [MD], 4.25 [0.86–7.65]; P = .01) and pinch strength (MD, 1.37 [0.24–2.51]; P = .02) but no advantage after more than 6 months. Patients treated with limited incision showed an earlier return to activities (MD,−8.80 [−9.21 to −8.39]; P

Introduction. Tendon adhesion to surrounding tissues is the most common complication reported after tendon repair. To date, effective solutions to prevent tendon injury are still lacking. Materials and Methods. A total of 89 patients with flexor tendon injury in zone II were recruited. The patients were divided into a control group, a poly-DL-lactic acid (PDLLA) group, and an amnion group according to the different tendon treatments applied. The control group was not subjected to other treatments. PDLLA and bioamniotic membranes were, respectively, used to wrap broken ends in the PDLLA and amnion membrane groups. The patients were followed at 1, 2, 3, 6, and 12 months after surgery and the ranges of active flexion and extension lag in the proximal and distal interphalangeal joints were evaluated. Results. The means of total active ranges of motion of the interphalangeal joints (excluding rupture cases) in the PDLLA and amnion groups did not significantly differ between each other but significantly differed from that of the control group. Statistical analysis showed a significant difference in the clinical grades of the outcomes among the control, PDLLA, and amnion groups. The incidence of complications in the control and PDLLA groups was found to be significantly higher than that in the amniotic membrane group; no significant difference was observed between the control and PDLLA groups. Conclusion. In this study, freeze-dried amniotic membrane transplantation was applied to promote healing of the flexor tendon in zone II and prevent adhesion. This technique presents a new method to solve the issue of tendon adhesion after repair. Clinical Trial Registration. The trial was registered by identifier ChiCTR1900021769.

The biaxial properties of plain weave fabric composites are important as they are more representative of the performance under complex loading conditions. Experimental determination of these properties is difficult and Finite Element Analysis provides accurate prediction but is computationally expensive and requires skilled users. To provide a simple and rapid prediction of the strength of plain weave fabric composites under biaxial tension a novel micromechanical model is proposed in this paper. To predict the biaxial tensile strengths the minimum total complementary potential energy principle is used on a micromechanical unit cell where the orthogonally interlaced yarns are idealised as curved beams. The new model is verified with a finite element method model on three warp/weft biaxial loading ratios: 1:1, 2:1 (1:2) and 3:1 (1:3) and uniaxial experimental data. The model is verified on four types of material, ranging in mechanical properties from carbon to glass fibres, and 11 yarn specifications, including five cases compared to experimental results and six cases compared to the FE model, giving a mean error of 9.85% and a maximum error of 16.74% compared to experimental results and a mean error of 10.71% and a maximum error of 14.67% compared to the FE model, which demonstrates the effectiveness of the model. The standard deviation of prediction errors among the 11 cases is 2.66%, which demonstrates the robustness of the model for a range of applications. The proposed model is able to predict the uniaxial and biaxial tensile strengths without experimental investigations at the fabric and laminate level and only requires the yarn mechanical properties and specifications.

Composite helical structures (CHS) can store and release strain energy through elastic deformation, which has a good application prospect in automobile, aerospace and other fields, such as shock-absorbing spring, deployable antenna, etc. Compressive behaviour (i.e. stiffness, strength and load–displacement relationship) is one of the most important basic mechanical properties of CHS. In order to accurately predict the compressive behaviour of CHS, this paper proposes a new analytical model considering geometric nonlinearity effect. In the geometric model, the geometric parameters of CHS change continuously with the increase of compressive load. The load–displacement relationship considering geometric nonlinearity is deduced by accumulative compressive load increment and accumulative compressive deformation increment. The compressive stiffness of CHS is obtained using linear fitting with least square method. On this basis, the analytical expression of compressive strength of CHS is derived. The predicted results are compared with experimental data from literatures. It is shown that predictions using the new analytical model correlated well with experimental results. Considering geometric nonlinearity effect in the analytical model can predict the compressive behaviour of CHS more accurately. The analytical model is used to further analyze influences of helix angle and helix diameter on the compressive behaviour of CHS.

Jian Lu,1,*Changjun Sun,2,* Jiangbo Bai,1,* Siyu Tian,1,* Bing Zhang,1 Dehu Tian,1 Lingde Kong1 1Department of Orthopedics, The Third Hospital of Hebei Medical University, Shijiazhuang, Hebei 050051, China; 2Department of Emergency, The Second Hospital of Tangshan City, Tangshan, Hebei 063000, China *These authors contributed equally to this work Background: This study was conducted to determine whether sagittal lordotic alignment and clinical outcomes could be improved by the correction of segmental kyphosis after single-level anterior cervical discectomy and fusion (ACDF) surgery.Patients and methods: We retrospectively reviewed patients who underwent single-level ACDF surgery in our hospital between January 2014 and February 2017. Basic characteristics of patients included age at surgery, gender, diagnosis, duration of symptoms, and location of target level. Pre- and postoperative radiographs at the 6-month follow-up were used to evaluate the following parameters, such as segmental angle, C2–C7 angle, T1 slope, and C2–C7 sagittal vertical axis (SVA). Postoperative clinical outcomes were assessed by the Neck Disability Index and VAS. According to the segmental angle of postoperative radiographs, patients were divided into noncorrection group and correction group.Results: A total of 181 patients (99 males and 82 females) were analyzed in our study. There were 32 patients in the noncorrection group and 149 patients in the correction group. There was no significant difference in demographic and clinical data between the two groups before surgery. However, patients in the correction group showed larger C2–C7 angle and lower C2–C7 SVA after surgery in comparison with those in the noncorrection group. Besides, changes in the segmental angle were positively correlated with changes in C2–C7 angle and negatively correlated with changes in C2–C7 SVA.Conclusion: Surgical correction of segmental kyphosis in single-level cervical surgery contributed to balanced cervical alignment in comparison with those without satisfactory correction. However, we could not demonstrate that the correction of segmental alignment is associated with a better recovery in clinical outcomes. Keywords: segmental kyphosis, sagittal alignment, single level, cervical spine, anterior cervical discectomy and fusion

The adhesion of tendon and surrounding tissue is the most common complication after repairing an injured tendon. The injured flexor tendons in zone II are frequently accompanied by tendon sheath defects, which lead to poor recovery. A variety of biological and non-biological materials have been recently used for repair or as substitute for tendon sheaths to prevent tendon adhesion. However, non-biological materials, such as polyethylene films, have been used to prevent tendon adhesions by mechanical isolation. The possibility of tendon necrosis and permanent foreign body remains due to the lack of permeability and the obstruction of nutrient infiltration. The natural macromolecule amniotic membrane derived from organisms is a semi-permeable membrane with the following characteristics: smooth; without vascular, nerve, and lymphatic; and rich in matrix, cytokines, enzymes, and other active ingredients. The unique structure of this membrane makes it an ideal biomaterial. In the experiment in Henry chicken, the model of tendon sheath defect and the flexor digitorum tendon in zone II was established and randomly divided into control group, medical membrane group, and decellularized amniotic membrane group. Samples were obtained at the 2nd, 4th, 8th, and 12th week after operation. General, histological, and biomechanical tests were performed to investigate the preventive effect of repaired tendon sheath by decallularized amniotic membrane. Experimental results showed the following: the amniotic membrane group and the medical membrane group had mild inflammatory reaction and tissue edema, and nearly no adhesion was observed in the surrounding tissue; the fibroblast-like cells were distributed in layers under the light microscope; the amniotic membrane group was denser than the medical membrane group cells, and numerous fibroblasts were disorganized in the control group. Biomechanical measurements showed that the sliding distance of tendon, the total flexion angle of the toes, and the tendon maximum tensile breaking strength at the early postoperative were significantly better than in the control group. Through this experiment, the amniotic membrane, as a natural biological substitute material in the construction of tendon sheath, can effectively inhibit exogenous healing and promote endogenous healing to prevent tendon adhesion.

Lingde Kong,* Jiangbo Bai,* Bing Zhang, Yong Shen, Dehu Tian Department of Orthopedics, The Third Hospital of Hebei Medical University, Shijiazhuang, Hebei, People’s Republic of China *These authors contributed equally to this work Background: The aim of this study was to determine the incidence of coexisting symptomatic lumbar canal stenosis (LCS) in patients after surgery for cervical spondylotic myelopathy (CSM) and identify possible predictive factors associated with it.Materials and methods: We retrospectively reviewed patients with CSM at our institution between January 2005 and December 2015. Clinical and radiographic factors including age, gender, body mass index, Japanese Orthopedic Association scores, cervical alignment, anteroposterior diameter of cervical canal, number of levels with CSM, and percentage of cervical cord compression were investigated. Symptomatic LCS was defined as leg symptoms and a narrowing of the lumbar spinal canal at one level at least, which is confirmed by magnetic resonance images of the lumbar spine. Univariate and multivariate analyses were used to identify possible predictive factors. Pearson correlation analysis was also conducted to analyze the association between cervical parameters and percentage of LCS.Results: A total of 317 patients with CSM met the criteria for inclusion. There were 39 patients (12.3%) with LCS after cervical surgery during a mean of 7.3 years’ follow-up. In the multivariate logistic regression analysis, narrow diameter of cervical canal (OR, 3.96; 95% CI, 1.20–13.04) was identified as the only independent predictor of symptomatic LCS in CSM patients. The correlation coefficient between anteroposterior diameter of cervical canal and severity of LCS indicated a significantly positive linear relationship with 0.536 (P

Jiangbo Bai,* Kunlun Yu,* Yaning Sun, Lingde Kong, Yong Shen Department of Orthopedics, The Third Hospital of Hebei Medical University, Shijiazhuang, Hebei, People’s Republic of China *These authors contributed equally to this work Background: The aim of this study was to assess the prevalence of cervical Modic change (MC) in patients with cervical spondylosis and to develop a better understanding of the possible risk factors for the prevalence of MC.Methods: Between January 2014 and April 2017, patients with cervical spondylosis were included in our study. All patients underwent magnetic resonance imaging (MRI) to evaluate the presence of MC. The MC was classified into three types according to the Modic classification. Potential risk factors were collected from demographic data, lifestyle variables, laboratory tests, and radiographic images. Both univariate and multivariate analysis were used to detect factors associated with MC. We further compared several variables related to fat metabolism between patients with Type 1 and Type 2 MC.Results: The prevalence of MC in patients with cervical spondylosis was 9.24%. The MC was most frequent at C5–6, followed by C6–7, C4–5, and C3–4. The proportion of Type 1 MC in patients with neck pain was significantly higher than that in patients without neck pain (46.2% vs 13.6%, P=0.027). However, none of the variables associated with fat metabolism showed a significant difference between Type 1 and Type 2 MC. Multivariate logistic analysis showed that age ≥55 years (odds ratio [OR], 1.91; 95% confidence interval [CI], 1.22–2.98) and body mass index (BMI) ≥25 kg/m2 (OR, 2.41; 95% CI, 1.62–3.59) were two significant independent factors that are associated with cervical MC in patients with cervical spondylosis (P

This paper seeks to investigate thermal behaviour of a thin-walled deployable composite boom (DCB) in a space environment using ground thermal-vacuum test and FEA methods. Thermal tests simulating a space environment include three key conditions, namely ultra-high level of vacuum (lower than 10 −5 Pa), heat sink (−180 °C) that is realized using black panels with the liquid-nitrogen cooling system and thermal loading that is achieved through infrared lamps. The thermal tests of the DCB under seven typical heat fluxes were conducted to characterize heat transfer mechanisms and to obtain temperature fields. The basic heat transfer methods for the DCB in a space environment were surface radiation, cavity radiation and heat conduction. These led to significant temperature difference and gradient occurring on the irradiated and shadowed parts of the DCB at nighttime and daytime. FE models were established to predict temperature fields and thermally induced deformation. Good correlation was achieved between experimental and numerical results.

This paper outlines an analytical model to predict the temperature of fully-inflated balloon on float at high altitude in stratosphere. Simplified radiative and convective heat transfer models are developed to estimate absorption and emission heat of balloon film and lifting gas within balloon. Thermal equilibrium equations for the balloon system in the day time and night time are derived by incorporating radiative and convective heat transfer models. The new model is applied to calculate the day and night temperatures of the balloon system on float at a high-altitude in stratosphere and reasonable correlation is achieved between the predictions obtained from new models and from prior flight testing data, demonstrating the effective use of the proposed models.

Background Platelet-rich plasma (PRP) is used as an alternative therapy to reduce pain and improve functional restoration in patients with Achilles tendinopathy (AT). We evaluated the current evidence for the efficacy of PRP as a treatment for chronic AT. Methods The PubMed, Embase, Web of Science, and The Cochrane Library databases were searched for articles on randomized controlled trials (RCTs) that compared the efficacy of PRP with that of with placebo injections plus eccentric training as treatment for AT. The articles were uploaded over the establishment of the databases to May 01, 2018. The Cochrane risk of bias (ROB) tool was used to assess methodological quality. Outcome measurements included the Victorian Institute of Sports Assessment-Achilles (VISA-A), visual analog scale (VAS) and Achilles tendon thickness. Statistical analysis was performed with RevMan 5.3.5 software. Results Five RCTs (n = 189) were included in this meta-analysis. Significant differences in the VISA-A were not observed between the PRP and placebo groups after 12 weeks [standardized mean difference (SMD) = 0.2, 95% confidence interval (95% CI): 0.36 to 0.76, I = 71%], 24 weeks (SMD = 0.77, 95% CI: -0.10-1.65, I = 85%) and 1 year (SMD = 0.83, 95% CI: -0.76-2.42, I = 72%) of treatment. However, PRP exhibited better efficacy than the placebo treatment after 6 weeks (SMD = 0.46, 95% CI: 0.15-0.77, I = 34%). Two studies included VAS scores and tendon thickness. VAS scores after 6 weeks (SMD = 1.35, 95% CI: -0.1.04-3.74, I = 93%) and 24 weeks (SMD = 1.48, 95% CI: -0.1.59-4.55, I = 95%) were not significantly different. However, VAS scores at the 12th week (SMD = 1.10, 95% CI: 0.53-1.68, I = 83%) and tendon thickness (SMD = 1.51, 95% CI: 0.39-2.63, I = 53%) were significantly different. Conclusion PRP injection around the Achilles tendon is an option for the treatment of chronic AT. Limited evidence supports the conclusion that PRP is not superior to placebo treatment. These results still require verification by a large number of well designed, heterogeneous RCT studies.

The paper deals with the analytical solutions on geometrical and mechanical properties of ultra-thin-walled lenticular collapsible composite tube (LCCT) in fold deformation for understanding the phenomenon of actual fold deformation and for improving the structural behaviours in engineering application. The LCCT in fold deformation was idealized as the curved thin-walled beam with a biaxisymmetrical lenticular cross-section described by concave and convex tangential circular arcs and with a longitudinal path depicted by using multinomial shape function. New geometrical equations were established for predicting the in-plane strain of the LCCT in fold deformation (consisting of flattening and curling deformation modes) based on apt geometrical approximations and deformation assumptions, and analytical solution was derived for calculating the interlaminar shear stress on the bonding interface of the LCCT by means of equilibrium equation and linear-elastic constitutive equation founded on micromechanics. In order to validate the model, experiments were performed to determine respectively the load–displacement and in-plane strains of the ultra-thin-walled LCCT in the flattening and curling deformation modes and the comparison between the theoretical predictions and the experiments was conducted. It is shown that the predictions from the new models correlate well with the experiments within small deflection range. These efforts are argued to be successful in predicting the fold deformation of ultra-thin-walled LCCT, but limited to small deflection range only.

This study aims to evaluate whether volar locking plate was superior over non-locking plate in the treatment of die-punch fractures of the distal radius.A total of 57 patients with closed die-punch fractures of the distal radius were included and analyzed. Of them, 32 were treated by non-locking plate (NLP) and the remaining 25 were treated by volar locking plate (VLP). Preoperative radiographs, computer tomographs and three-dimensional reconstruction, radiographs taken at immediate postoperation and at last follow-up were extracted and evaluated. Patients' electronic medical records were inquired and related demographic and medical data were documented. The documented contents were volar tilt, radial inclination, ulnar variance, grip strength, Disabilities of the Arm, Shoulder, and Hand (DASH) and visual analog scale (VAS) scores and complications.VLP group demonstrated a significantly reduced radial subsidence of 1.5 mm (0.7 versus 2.2 mm), during the interval of bony union (P 0.001), compared to NLP group. Larger proportion of patients (88% versus 62.5%) in VLP group gained acceptable joint congruity (step-off2 mm) at the final follow-up (P = 0.037). No significant differences were observed between the groups in the measurements of volar tilt, radial inclination, DASH, VAS and grip strength recovery at the last follow-up. There was a trend of fewer overall complications (5/25 versus 10/32) and major complications that required surgery interventions (1/25 versus 4/32) in VLP than NLP groups, although the difference did not approach to significance (P = 0.339, 0.372).VLP leaded to significantly better results of reduction maintainance and the final joint congruity than NLP, while reducing overall and major complications. However, the results should be treated in the context of limitations and the clinical significance of the difference required further studies to investigate.

OBJECTIVE: This study aimed to compare the clinical and radiologic outcomes of AO titanium locking plate and screw (ATLPS) and anterograde intramedullary (AIM) fixation for treating unstable metacarpal and phalangeal fractures. METHODS: Adult patients with isolated fresh unstable metacarpal and phalangeal fractures who met the inclusion criteria were enrolled into this prospective study from July 2013. Patients were divided into ATLPS or AIM groups when they were admitted to our department after considering their work requirement, fracture complexity, and surgeon's experience and were then treated accordingly. Relevant demographic, clinical and preoperative clinical data were collected and analyzed. Clinical examination and radiograph evaluation were performed 1 week and 1, 3, and 6 months postoperatively. Outcome measures were visual analog scale (VAS) scores for pain, total range of motion (ROM) of the injured digit, Quick Disabilities of the Arm, Shoulder, and Hand scores (Quick‐DASH) and grip strength (percentage of the contralateral corresponding digit). RESULTS: From July 2013 to September 2014, 76 patients were treated by AIM and 71 by ATLPS. Age, sex, time from injury to operation, dominant hand, injury mechanism, fracture location, fracture type and participant occupation were similar in both groups (P > 0.05). Operations were all performed well and followed by uneventful postoperative functional recoveries. At 3‐month follow‐up, all clinical outcomes were significantly better in the AIM than ATLPS group (P < 0.05) except for VAS pain scores. However, at 6‐month follow‐up, the differences were no longer significant, indicating similar results for both types of fixation. Patients in the AIM group developed significantly more complications (P = 0.037). Sick leave was significantly longer in the AIM group (P = 0.02). CONCLUSIONS: AIM outperforms ATLPS in the treatment of unstable metacarpal and phalangeal fractures in the early, but not the later, postoperative period; the latter is associated with significantly more complications. Patients treated by ATLPS require shorter sick leave, which is of particular benefit to workers with specialized manual skills.

Few clinical studies investigate risk factors associated with clinical adjacent segment pathology (CASP) following multi-level cervical fusion surgery. The aim is to record the incidence of postoperative CASP in patients after at least 2 years′ follow-up and to identify possible risk factors that may be associated with the CASP after multi-level cervical surgery. We retrospectively reviewed patients who underwent multi-level cervical surgery in our hospital from January 2004 to February 2016. All patients underwent more than 2 years′ follow-up. The diagnosis of CASP is according to clinical symptoms as well as image findings. Potential risk factors were collected from demographic data and radiographic images. A total of 301 patients after multi-level cervical surgery were analyzed. During follow-up, 28 patients (9.3%) were diagnosed as having CASP. Among these patients, 7 showed symptoms of CASP within 3 years after surgery, 6 showed symptoms between 3 and 5 years, 14 showed symptoms between 5 and 10 years, and the last one showed symptoms more than 10 years later. In the multivariate analysis, degeneration of adjacent segment (OR, 1.592; 95% CI, 1.113–2.277), decreased Cobb angle in fused vertebrae (OR, 2.113; 95% CI, 1.338–3.334) and decreased Cobb angle in cervical spine (OR, 1.896; 95% CI, 1.246–2.886) were correlated with the incidence of CASP during follow-up. The incidence of CASP following multi-level cervical surgery was 9.3% with a mean of about 70 months′ follow-up. Patients with preoperative degeneration of adjacent segment and postoperative imbalance of sagittal alignment have a higher risk of developing CASP after multi-level cervical surgery.

Background In the absence of scientific evidence regarding the effectiveness of shoulder management strategies after stage I of fingertip reconstruction, the purpose of this study was to compare the clinical outcomes of various rehabilitation procedures. Material/Methods Patients who underwent fingertip reconstruction with a random-pattern abdominal skin flap between March 2007 and February 2013 were enrolled in the study (n=95). Thirty performed only active exercise (group A), 29 performed only passive exercise (group B), and 32 received a combination of active exercise and pulsed electromagnetic field (PEMF) (group C). The mean age at the time of treatment was 30.2 years in group A, 29.6 years in group B, and 31.8 years in group C. Results At the final follow-up, there were significant differences between group A and B in terms of Constant score (P=.001), VAS (P=.047), forward flexion of the shoulder (P=0.049), and muscle strength with forward flexion and external rotation (P=0.049 and P=0.042, respectively). A higher Constant score was observed in group C compared to group A, and although there were no differences in the other evaluations between groups A and C, a trend toward better function of the shoulder was demonstrated in group C. Conclusions The most important findings in our study are that a combination of active exercise and PEME produces superior patient-reported outcomes regarding relief of shoulder signs and symptoms. Given the limitations of this study, better-designed studies with large sample sizes and long-term follow-up are required.

The aim of the present study was to treat intraosseous ganglia of the carpal bones with injectable bone cement grafting. Between January 2012 and December 2013, 4 patients (3 men and 1 woman) presenting with wrist pain and activity limitation were diagnosed with intraosseous ganglion of the carpal bones by radiography. The patients were treated with minimal invasive curettage and bone cement injection surgery. All patients were followed up for a mean time of 17 months (range, 12-22 months). The wrist pain was significantly reduced in all patients following surgery. In addition, the activity range and grip strength were also improved compared with the preoperative parameters. Subsequent to treatment, the Mayo wrist score and the Disabilities of the Arm, Shoulder and Hand score presented mean values of 78.8 (range, 75-80) and 11 (range, 7.7-15.0), respectively. These results suggested that the patients showed a good recovery. All patients were satisfied with the postoperative results and returned to work within 4 weeks. In conclusion, bone cement injection is an effective and safe therapeutic strategy for the treatment of intraosseous ganglia of the carpal bone.

Drug treatment, electric stimulation and decimeter wave therapy have been shown to promote the repair and regeneration of the peripheral nerves at the injured site. This study prepared a Mackinnon's model of rat sciatic nerve compression. Electric stimulation was given immediately after neurolysis, and decimeter wave radiation was performed at 1 and 12 weeks post-operation. Histological observation revealed that intraoperative electric stimulation and decimeter wave therapy could improve the local blood circulation of repaired sites, alleviate hypoxia of compressed nerves, and lessen adhesion of compressed nerves, thereby decreasing the formation of new entrapments and enhancing compressed nerve regeneration through an improved microenvironment for regeneration. Immunohistochemical staining results revealed that intraoperative electric stimulation and decimeter wave could promote the expression of S-100 protein. Motor nerve conduction velocity and amplitude, the number and diameter of myelinated nerve fibers, and sciatic functional index were significantly increased in the treated rats. These results verified that intraoperative electric stimulation and decimeter wave therapy contributed to the regeneration and the recovery of the functions in the compressed nerves.

This paper proposes a new analytical solution to predict the shear modulus of a two-dimensional (2D) plain weave fabric (PWF) composite accounting for the interaction of orthogonal interlacing strands with coupled shear deformation modes including not only relative bending but also torsion, etc. The two orthogonal yarns in a micromechanical unit cell are idealized as curved beams with a path depicted by using sinusoidal shape functions. The internal forces and macroscopic deformations carried by the yarn families, together with macroscopic shear modulus of PWFs are derived by means of a strain energy approach founded on micromechanics. Three sets of experimental data pertinent to three kinds of 2D orthogonal PWF composites have been implemented to validate the new model. The calculations from the new model are also compared with those by using two models in the earlier literature. It is shown that the experimental results correlate well with predictions from the new model.

This paper seeks to outline the temperature effect on the buckling properties of ultra-thin-walled lenticular collapsible composite tube (LCCT) subjected to axial compression. The buckling tests of the LCCT specimens subjected to axial compression were carried out on INSTRON-500N servo-hydraulic machine in dry state and at the temperatures of 25 °C, 100 °C and −80 °C. The load–displacement curves and buckling initiation loads were measured and the buckling initiation mechanism was discussed from experimental observations. Experiments show that the buckling initiation load, on average, is only about 2.2% greater at the low temperature of −80 °C than at the room temperature of 25 °C due to the material hardening, demonstrating an insignificant increase in the buckling initiation load, whereas it is about 19.5% lower at the high temperature of 100 °C than at the room temperature owing to the material softening, implying a significant decrease in the buckling initiation load. The failure mode of the LCCT in axial compression tests at three different temperatures can be reckoned to be characteristic of the buckling initiation and propagation around the central region until rupture. The finite element (FE) model is presented to simulate the buckling initiation mechanism based on the eigenvalue-based methodology. Good correlation between experimental and numerical results is achieved.

This work seeks to investigate the notch sensitivity and fracture behaviour of orthogonal Kevlar-plain woven fabric (PWF)- reinforced thermoplastic polyurethanes (TPU) film applied to high altitude balloon. Four types of specimens are implemented to measure notched strength and fracture toughness by conducting static tension and tear tests on an MTS system respectively. The damage and failure mechanisms are discussed and the results for notched strength and tear resistance are evaluated and compared with each other. From the experiments, it is found that the notch sensitivity of the film increases with the increase in the size of the hole, but the notch sensitivity and the stress concentration of the notch are insignificant and there is a decrease of only about 4%-10% in tensile strength for the notched specimens with different hole sizes in diameter compared with the unnotched specimen. In contrast, the tear resistance containing a central slit with only 1 mm length is about half of tensile strength of the unnotched film, which implies that the tear resistance exists an significant notch sensitivity. The results of this study provide an insight into notch sensitivity and fracture behaviour of the Kevlar-PWF-reinforced TPU film and constitute a fundamental basis for the design of high altitude balloon.