The tendon-bone interface is where the tendons or ligaments are connected with the bones. A spectrum of injuries may happen to the "soft-to-hard" tissue interface, including those to the rotator cuff-bone and cruciate ligament-bone interfaces, which are often precipitated by a combination of degenerative changes on the tendon-bone interface and acute or chronic injuries, thus severely impairing the patients′ motor function. In recent years, with the deepening of the interdisciplinary researches in biomechanics, mechanobiology, and sports medicine, the role of mechanical factors in the repair of tendon-bone interface injuries has attracted more and more attention and becomes a focus of the edge-cutting researches on the tendon-bone interface injuries. To this end, the authors proposed the concept of "tendon-bone interface mechanomedicine" based on an overview of the relevant researches at home and abroad. The mechanical properties of the tendon-bone interface and the effects of mechanical stimuli on its biological behavior were elucidated from the four aspects: biomechanics, mechanobiology, mechanodiagnostics, and mechanotherapy, aiming to explore the diagnostic and therapeutic strategies for tendon-bone interface injuries from the angle of mechanics and provide new perspectives and methodologies for the field of tendon-bone interface injury repair.

Rotator cuff injury often leads to shoulder pain and dysfunction. For the injured rotator cuff tendon without continuous interruption, conservative treatment is often used. However, the shoulder is used frequent in daily life, which makes that the rotator cuff injury generally shows gradual aggravation and eventually progresses to complete tear due to poor blood supply of the rotator cuff tendon tissue and weak repair ability. In order to reverse the pathophysiological changes after rotator cuff injury and promote the repair of injured rotator cuff tendon, a series of conservative treatments for rotator cuff injury have been explored. Extracorporeal shock wave therapy (ESWT) is one of the representative treatments, but its molecular biological mechanism in promoting rotator cuff repair is still unclear. Therefore, the authors review the progress of ESWT for rotator cuff injury from aspects of the molecular biological mechanism and clinical application status, so as to provide a reference for future researches and clinical application of ESWT.

Objective:To investigate the risk factors of refracture of the injured vertebrae after percutaneous vertebral augmentation for acute symptomatic thoracolumbar osteoporotic compression fractures (ASTOCFs).Methods:A case-control study was conducted to analyze the clinical data of 2 237 ASTOCFs patients admitted to three hospitals from January 2010 to January 2019. There were 569 males and 1 668 females, with age range of 50-85 years [(66.7±4.8)years]. The patients underwent percutaneous vertebroplasty (PVP) or percutaneous kyphoplasty (PKP). According to the radiographic outcomes, the patients were divided into refracture group ( n=315) and non-refracture group ( n=1 922). Data were recorded for the two groups, including basic demographics (gender, age, height and weight), personal habits (smoking and alcohol consumption), basic diseases (diabetes, hypertension, coronary heart disease and chronic obstructive pulmonary disease), preoperative bone mineral density, fracture segment, number of injured vertebrae, surgical method (PVP or PKP), surgical approach, bone cement viscosity, distance from cement to the upper and lower endplate, cement volume in injured vertebrae, cement leakage, postoperative exercise, and postoperative anti-osteoporosis treatment. The above data were analyzed to identify their correlation with postoperative refracture of the injured vertebrae by univariate analysis. The independent risk factors for postoperative refracture of the injured vertebrae were determined by multivariate Logistic regression analysis. Results:Univariate analysis showed that refracture of injured vertebrae was correlated with gender, age, diabetes, fracture segment, surgical method, distance from cement to the upper and lower endplate, postoperative exercise, and postoperative anti-osteoporosis treatment ( P<0.05 or 0.01), but there was no correlation with height, weight, smoking, alcohol consumption, hypertension, coronary heart disease, chronic obstructive pulmonary disease, preoperative bone mineral density, number of fractured vertebrae, surgical approach, bone cement viscosity, cement volume in injured vertebrae or cement leakage (all P>0.05). Multivariate Logistic regression analysis showed that female ( OR=1.92, 95% CI 1.34-2.64, P<0.01), age ≥80 years ( OR=1.21, 95%CI 1.17-1.25, P<0.01), diabetes ( OR=1.92, 95% CI 0.44-2.55, P<0.01), thoracolumbar fracture ( OR=1.46, 95% CI 1.82-7.51, P<0.05), PKP ( OR=4.56, 95% CI 0.86-1.44, P<0.05), no postoperative exercise ( OR=2.14,95% CI 0.27-0.38, P<0.01), and no postoperative anti-osteoporosis treatment ( OR=2.36,95% CI 0.13-0.47, P<0.05) were positively correlated with refracture of injured vertebrae. Conclusion:Female, age ≥80 years, diabetes, thoracolumbar fracture, PKP, no postoperative exercise, and no postoperative anti-osteoporosis treatment are independent risk factors for refracture of injured vertebrae after percutaneous vertebral augmentation for ASTOCFs.

The spatiotemporal distribution of growth factors in bone tissue-engineered repair and reconstruction is critical. Growth factors can be used in bone tissue engineering through different encapsulation methods. Different encapsulation methods make growth factors have different release kinetics. At present, the common physical entrapment, easily degradable carrier and simple spatial structure usually result in poor sustained release of growth factors by burst release. The optimization of release methods of growth factors enables their release at different times and spaces in a biomimetric manner, which is conducive to improving the effect of tissue repair and avoiding the adverse effects of excessive factors. Starting from the necessity of spatiotemporal sustained release of growth factors, the authors summarize growth factors can attain spatiotemporal sustained release by being directly immobilized on the surface of the carrier, encapsulated in the carrier, encapsulated in the microparticles and encapsulated in the carrier by the microparticles and review the spatiotemporal sustained release of growth factors in different encapsulation methods, so as to provide a reference for optimizing spatiotemporal release of growth factor in bone tissue engineering.

Objective:To investigate the clinical effect of early arthroscopic shoulder treatment of moderate full-thickness tear of the supraspinatus tendon.Methods:A retrospective case control study was conducted to analyze the clinical data of 43 patients with moderate full-thickness supraspinatus tendon tear admitted to First Affiliated Hospital of Xi 'an Jiaotong University from January 2018 to June 2020，including 17 males and 26 females，aged from 41 to 68 years［（55.9±8.2）years］. All patients had arthroscopic shoulder supraspinatus tendon suture and acromioplasty，including 22 patients underwent surgery within 1 month after persistent shoulder pain and motion limitation in early group and 21 patients between 1 month and 3 months in late group. The duration of operation and intraoperative blood loss were recorded. The visual analogue scale（VAS），American Shoulder and Elbow Society（ASES）score and Constant-Murley score were assessed before operation and at postoperative 3 weeks，6 weeks，3 months and 6 months. The complications were detected with 6 months after operation. Results:All patients were followed up for 6-7 months［（6.4±0.4）months］. There was no statistical significance in operation duration and intraoperative blood loss between the two groups（ P>0.05）. At 3 weeks，6 weeks，3 months and 6 months after operation，there showed significant decrease of VAS but significant increase of ASES and Constant-Murley scores compared to preoperation（ P<0.05）. At 3 weeks and 6 weeks after operation，the VAS in early group［（4.4±0.9）points，（3.7±0.8）points］was lower than that in late group［（5.5±1.0）points，（4.8±1.1）points］；while the ASES score［（49.1±4.6）points，（56.8±4.1）points］and Constant-Murley score［（54.1±4.8）points，（64.1±4.4）points］in early group were higher than those in late group［ASES score：（45.2±5.4）points，（50.3±5.4）points；Constant-Murley score：（50.5±3.3）points，（58.2±3.9）points］（ P<0.05）. At 3 months and 6 months after operation，the two groups showed no statistical significance in these scores. There were no postoperative complications such as infection or nerve injury in both group within 6 months. Conclusion:For moderate full-thickness tear of the supraspinatus tendon，arthroscopic shoulder surgery performed within 1 month after persistent shoulder pain and motion limitation can achieve better pain relief and faster functional rehabilitation in the short term compared with surgery performed 1-3 months later.

The rotator cuff injury is a kind of chronic tendon disease related to overuse injury. The main clinical manifestations of this disease include shoulder pain and dysfunction，which seriously affects people 's life quality and work capability. Although previous studies have shown that inflammation and de- generation of collagen matrix are closely related to the occurrence and development of this disease，the pathogenesis of the disease is still unclear. In this study，the authors review the pathologic mechanisms of rotator cuff injuries from aspects of oxidative stress，inflammation，macrophage and non-coding RNA so as to provide a reference for subsequent research and treatment.

Massive rotator cuff tears often destroy equilibrium of couples of the shoulder joints,whichlead toshoulder pain and functional incapacitation.At present,there is a great controversy about the best treatment strategy for the massive rotator cuff tear,nevertheless surgery has been proved to have more satisfactory results than non-operative treatment.It has been confirmed by numerous studies that cuff repair could prevent loss of shoulder strength and glenohumeral osteoarthritis.However,it is impossible to suture tendon to bone directly due to retraction of tendon stump,fat infiltration of rotator cuff and prominent tear size in massive rotator cuff tear.Muscular flap transfer procedures have played important roles in the treatment of massive rotator cuff tears.Compared with other tendon transposition procedures,such as latissimus dorsi transfer,the deltoid muscular flap may be an optimal method as it works synergistically with the infraspinatus and supraspinatus muscle,and presses down the humeral head potentially.Cuff repair in open operation with tendon stump re-attachment to the deltoid muscle flap,aims to reconstruct the cuff continuity and cover the humeral head toform a new cuff.The deltoid muscle flap,also acting as a muscle cushion,is expected to reduce impingement between the humeral head and the acromion and get better results of pain relief and improvement of shoulder function.However,it is still controversial about the efficacy of deltoid muscle flap transfer in reconstructing a new balance of couple with better shoulder strength,alleviating glenohumeral arthritis and preventing tendon retears.This article reviews the advances in the treatment of chronic massive rotator cuff tears with deltoid flap transfer.

OBJECTIVETo evaluate the effects of Icariin (ICA) on the proliferation and osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs) in vitro and in vivo.

METHODSAn enzymatic digestion block was used in vitro to culture hPDLSCs, which were separated and purified by limited dilution cloning. The hPDLSCs were identified using cell-surface markers and cocultured with 1 x 10(-7) mol.L-1 ICA solution. The proliferation ability of these cells was determined by thiazolyl blue tetrazolium bromide (MTT) assay. After staining with alkaline phosphatase (ALP), osteogenesis was detected by enzyme-linked immunosorbent assay. Osteoblast-related genes were analyzed by reverse transcription-polymerase chain reaction. Alizarin red staining was performed to measure the level of calcium deposition. The hPDLSCs were cocultured with 1 x 10(-7) mol.L-1 ICA and nano-hydroxyapatite scaffolds in vivo before transplantation into subcutaneous tissues of nude mice. Osteogenic abilities were histochemically analyzed after 30 days of induction.

RESULTSThe hPDLSCs were affected by 1 x 10(-7) mol.L-1 ICA, and MTT assay showed that the proliferation of the groups treated with ICA in vitro was better than that of the control groups on the second day. The ALP activity of the treated hPDLSCs was significantly enhanced after cell culture for 3, 5, and 7 days. The gene expression of osteoblastic markers was also significantly enhanced after 7 days. The deposition of mineralization after incubation with 1 x 10(-7) mol.L-1 ICA increased compared with the control after cell culture for 14, 21, and 28 days. Furthermore, the bone expression of the treatment groups in vivo was significantly enhanced compared with that of the control groups.

CONCLUSIONTreatment with 1 x 10(-7) mol.L-1 ICA can significantly promote proliferation and differentiation of hPDLSCs in vitro and in vivo. ICA can effectively function as a bioactive growth factor in periodontal tissue engineering to replace traditional growth factors.

Alkaline Phosphatase ; Animals ; Cell Culture Techniques ; Cell Differentiation ; Cell Proliferation ; Coculture Techniques ; Enzyme-Linked Immunosorbent Assay ; Flavonoids ; Humans ; Mice ; Mice, Nude ; Osteoblasts ; Osteogenesis ; Periodontal Ligament ; Stem Cells

Objective??To?evaluate?the?effects?of?Icariin?(ICA)?on?the?proliferation?and?osteogenic?differentiation?of?human?periodontal?ligament?stem?cells?(hPDLSCs)?in vitro and?in vivo. Methods??An?enzymatic?digestion?block?was?used?in vitro?to?culture?hPDLSCs,?which?were?separated?and?purified?by?limited?dilution?cloning.?The?hPDLSCs?were?identified?using?cell-surface?markers?and?cocultured?with?1×10?7 mol·L?1 ICA?solution.?The?proliferation?ability?of?these?cells?was?determined?by?thiazolyl?blue?tetrazolium?bromide?(MTT)?assay.?After?staining?with?alkaline?phosphatase?(ALP),?osteogenesis?was?detected?by?enzyme-linked?immunosorbent?assay.?Osteoblast-related?genes?were?analyzed?by?reverse?transcription-polymerase?chain?reaction.?Alizarin?red?staining?was?performed?to?measure?the?level?of?calcium?deposition.?The?hPDLSCs?were?cocultured?with?1×10?7 mol·L?1 ICA?and?nano-hydroxyapatite?scaffolds?in vivo?before?transplantation?into?subcutaneous?tissues?of?nude?mice.?Osteogenic?abilities?were?histochemically?analyzed?after?30?days?of?induction.?Results??The?hPDLSCs?were?affected?by?1×10?7 mol·L?1 ICA,?and?MTT?assay?showed?that?the?proliferation?of?the?groups?treated?with?ICA?in vitro?was?better?than?that?of?the?control?groups?on?the?second?day.?The?ALP?activity?of?the?treated?hPDLSCs?was?significantly?enhanced?after?cell?culture?for?3,?5,?and?7?days.?The?gene?expression?of?osteoblastic?markers?was?also?significantly?enhanced?after?7?days.?The?deposition?of?mineralization?after?incubation?with?1×10?7 mol·L?1?ICA?increased?compared?with?the?control?after?cell?culture?for?14,?21,?and?28?days.?Furthermore,?the?bone?expression?of?the?treatment?groups?in vivo?was?significantly?enhanced?com-pared?with?that?of?the?control?groups.?Conclusion??Treatment?with?1×10?7 mol·L?1 ICA?can?significantly?promote?proliferation?and?differentiation?of?hPDLSCs?in vitro?and?in vivo.?ICA?can?effectively?function?as?a?bioactive?growth?factor?in?periodontal?tissue?engineering?to?replace?traditional?growth?factors.

With the development of tissue engineering, a variety of forms of silk fibroin (SF) scaffolds has been applied to research of constructing variety of organization based on cells, which has become scientific focus in recent years. In this paper we introduced the source and structure of SF and the fabrication method of the scaffold, and also address the SF application progress in several relevant fields of tissue engineering, such as bone, cartilage, skin, blood vessel and nerves. Finally, we discuss the future leading prospect of the SF in order to provide reference for subsequent research.
Fibroins ; Humans ; Tissue Engineering ; Tissue Scaffolds