Microfractures Research Articles

Microfractures, autologous matrix-induced chondrogenesis, osteochondral autograft transplantation and autologous chondrocyte implantation for knee chondral defects: a systematic review and network meta-analysis of randomized controlled trials.

Despite the publication of several randomized controlled trials (RCTs), it is not clear which technique for the treatment of focal chondral and osteochondral defects of the knee grants the best clinical outcome. The aim of this network meta-analysis (NMA) was to compare the efficacy and safety of microfractures (MF), autologous chondrocyte implantation (ACI), autologous matrix-induced chondrogenesis (AMIC), osteochondral autograft transplantation (OCT) at short (< 1 year), intermediate (1-5 years) and long-term (> 5 years). We carried out an NMA with Bayesian random-effect model, according to PRISMA guidelines. The search was performed in MEDLINE, EMBASE, Web of Science, CENTRAL, CINAHL, SPORTDiscus, clinicaltrials.gov, WHO ICTRP, from inception to November 2022. The eligibilities were randomized controlled trials on patients with knee chondral and osteochondral defects, undergoing microfractures, OCT, AMIC, ACI, without restrictions for prior or concomitant surgery on ligaments, menisci or limb alignment, prior surgery for fixation or ablation of osteochondritis dissecans fragments, and prior cartilage procedures as microfractures, drilling, abrasion, or debridement. Nineteen RCTs were included. No difference among treatments was shown in the pooled comparison of patient reported outcome measures (PROMs) at any timepoint. Safety data were not available for all trials due to the heterogeneity of reporting, but chondrospheres seemed to have lower failure and reoperation rates. This NMA showed no difference for PROMs with any technique. The lower failure and reoperation rates with chondrospheres must be interpreted with caution since adverse event data was heterogenous among trials. The standardization of the efficacy and safety outcome measures for future trials on knee cartilage repair and regeneration is necessary.

HWJMSC-EVs promote cartilage regeneration and repair via the ITGB1/TGF-β/Smad2/3 axis mediated by microfractures

The current first-line treatment for repairing cartilage defects in clinical practice is the creation of microfractures (MF) to stimulate the release of mesenchymal stem cells (MSCs); however, this method has many limitations. Recent studies have found that MSC-derived extracellular vesicles (MSC-EVs) play an important role in tissue regeneration. This study aimed to verify whether MSC-EVs promote cartilage damage repair mediated by MFs and to explore the repair mechanisms. In vitro experiments showed that human umbilical cord Wharton’s jelly MSC-EVs (hWJMSC-EVs) promoted the vitality of chondrocytes and the proliferation and differentiation ability of bone marrow-derived MSCs. This was mainly because hWJMSC-EVs carry integrin beta-1 (ITGB1), and cartilage and bone marrow-derived MSCs overexpress ITGB1 after absorbing EVs, thereby activating the transforming growth factor-β/Smad2/3 axis. In a rabbit knee joint model of osteochondral defect repair, the injection of different concentrations of hWJMSC-EVs into the joint cavity showed that a concentration of 50 µg/ml significantly improved the formation of transparent cartilage after MF surgery. Extraction of regenerated cartilage revealed that the changes in ITGB1, transforming growth factor-β, and Smad2/3 were directly proportional to the repair of regenerated cartilage. In summary, this study showed that hWJMSC-EVs promoted cartilage repair after MF surgery.Graphical abstract

EFFECTS OF THE MICRO FRACTURES ON THE SHALE MECHANICS BASED ON INDENTATION SIMULATION METHOD

With methods of nanoindentation and dimensional analysis applied, mechanical properties can be determined and evaluated through small debris. In this paper, the results of dimensional analysis and mechanical parameters are presented based on the finite element method and mathematical statistics method. The indentation of shale is simulated to investigate the influence of the fracture within the sample on the mechanical parameter. Five different factors of fracture are researched in this paper. The investigation shows that the development of fracture and pore is correlated with the deviation of points to the theoretical curve based on dimensional analysis, corresponding to the experimental results of shale, i.e., the lager the deviation, the better the fractures within the sample develop. By analyzing the deviation, the difference values, which represent the influence of each factor, rank as follows in a descending manner: depth (0.01555), shape (0.00765), count (0.00757), eccentricity (0.00319 or 0.00238), angle (0.0044). It shows that the depth of the fracture exerts greater influence on rock mechanics than the eccentricity and the size of the fracture (count and shape), and the influence of the angle is minimum. This paper is of great significance for the shale in evaluating the micro-mechanics of shale and assessing fractures through dimensional analysis.

Investigation of the mechanism of secondary microcrack growth in rocks with native microdefects

Exploring secondary microcracks (SMC) growth during hydraulic fracturing in rocks with native microdefects is a challenging task in unconventional oil and gas exploitation. The effect of native microdefects on the SMC growth currently remains unclear. In this study, conceptual models by discrete element method (DEM) are established for rocks with the native microdefects assuming to be micropores (MP) and microfractures (MF), respectively. Based on the benchmark simulation, the influence of oriental relationship between microdefects and tensile stress on the cracking process is summarized. Furthermore, we investigate the effects of MP and MF on the growth of SMC during the Brazilian splitting loading. The results show that the cluster trend of SMC in the spindle-shaped zone becomes more significant with increasing microdefect densities. Torsion SMC appear outside the zone in the highly dense MP model, which does not occur in the MF model. The central part of MF model induces more SMC than the MP model under the same horizontal tensile stress. The SMC growth is controlled by both microdefect densities and spring stiffness ratios, but the latter could be ignored for the microdefect density over 0.041 (MP) and 0.324 (MF), respectively. The numerical experiments reveal the mechanism of SMC growth in rocks with native microdefects under the tensile stress.

Effects of adipose tissue-derived stromal vascular fraction on osteochondral defects treated by hyaluronic acid-based scaffold: An experimental study.

Objectives This study aims to evaluate the effect of adipose-derived stromal vascular fraction (SVF) on osteochondral defects treated by hyaluronic acid (HA)-based scaffold in a rabbit model.Materials and methods Eighteen white New Zealand rabbits were randomly grouped into the experimental group (n=9) and control group (n=9). In all groups, osteochondral defects were induced on the weight-bearing surfaces of the right femoral medial condyles, and a HA-based scaffold was applied to the defect area with microfractures (MFs). In this study, 1 mL of adipose-derived SVF was injected into the knee joints of the rabbits in the experimental group. For histological and macroscopic evaluation, four rabbits were randomly selected from each group at Week 4, and the remaining rabbits were sacrificed at the end of Week 8. Macroscopic assessments of all samples were performed based on the Brittberg scoring system, and microscopic evaluations were performed based on the O’Driscoll scores.Results Samples were taken at Weeks 4 and 8. At Week 4, the O’Driscoll scores were significantly higher in the control group than the experimental group (p=0.038), while there was no significant difference in the Brittberg scores between the two groups (p=0.108). At Week 8, the O’Driscoll score and Brittberg scores were statistically higher in the experimental group than in the control group (p=0.008 and p=0.007, respectively). According to the microscopic evaluation, at the end of Week 8, the cartilage thickness was greater in the experimental group, and nearly all of the defect area was filled with hyaline cartilage.Conclusion Application of adipose-derived SVF with MF-HA-based scaffold was better than MF-HA-based scaffold treatment in improving osteochondral regeneration. Therefore, it can be used in combination with microfracture and scaffold to accelerate cartilage regeneration, particularly in the treatment of secondary osteoarthritis.

A new treatment of genito-urinary post-menopausal atrophy with autologous micro-fragmented fat tissue: a thirty-six months follow up case series.

Genitourinary atrophy is a menopausal pathological change determined by the definitive drop of ovarian hormones' production that can impact heavily on the health status of women, with important direct and indirect social costs. Unfortunately, available treatments are only symptomatic, and they are not able to reverse the atrophy and other related symptoms. Regenerative medicine, with single local injection of autologous micro-fractured fat tissue, could represent a viable new solution for these patients as it not only helps to relieve symptoms, but it also counteracts the mechanisms that lead to the menopausal genitourinary atrophy. The objective of this paper is to evaluate the long-term effectiveness of micro-fractured fat vulvar injection for genito-urinary atrophy in patients, affected by severe genitourinary atrophy (at least 4 symptoms lasting for at least 4 years). We present a case series of 35 patients followed for 36 months to evaluate the effectiveness and safety of a single subcutaneous vulvar injection of autologous micro-fragmented fat tissue (MFAT). We have not observed any adverse effects in any patients. All symptoms, and especially pelvic pain and dyspareunia, improved in almost half of patients within 3 months. Ninety-nine percent of patients recovered completely from all symptoms after 9-12 months, reporting no relapse of the symptoms up to the third year of follow up. Our case series is the first case series, evaluating the long-term (3 years) safety and effectiveness of micro-fragmented adipose tissue graft for urogenital atrophy.

Research progress on subchondral bone lesions in degenerative knee osteoarthritis

The role of the subchondral bone in the pathophysiological processes of knee osteoarthritis(KOA)is receiving increasing attention.During the early stages of KOA, micro-fractures due to stress occurr with increased subchondral bone remodeling and decreased subchondral bone structural parameters, promoting the development of local microcirculatory disorders and atypical bone marrow lesions(BMLs). The micro-pores in cartilage provide pathways for blood vessel invasion into the deep layers of articular cartilage and subsequently bring in cartilage-degrading enzymes.With the pathogenesis of KOA, the loss of proteoglycans, which resist pressure to maintain the integrity of articular cartilage, results in stress overloading and then metabolic imbalances, leading to decreased bone resorption and increased bone formation.In the late stages of KOA, significant subchondral bone sclerosis further obstructs local blood microcirculation, which manifests as extended BMLs or increased signal intensity and even subchondral bone cysts.The acidic local environment impairs osteoblast function and erodes bone strength, contributing to subchondral bone collapse.Consequently, there is continued loss of the attached articular cartilage because of the positive feedback.Drug or surgical treatment aimed at cartilage protection should focus on functional modulation of osteoblasts and/or osteoclasts in the subchondral bone and the internal environment at different stages, instead of merely on the protection of articular cartilage. Key words: Cartilage; Osteoarthritis; Knee

Safety and Efficacy of Percutaneous Injection of Lipogems Micro-Fractured Adipose Tissue for Osteoarthritic Knees.

The aim of this study was to evaluate the safety and efficacy of using autologous, micro-fractured, minimally manipulated adipose tissue in patients with refractory knee osteoarthritis (OA). A total of 17 subjects (26 knees) with a median age of 72 years (range: 54-78 years) and a history of knee OA (Kellgren-Lawrence, grade of 3 or 4) underwent treatment with ultrasound-guided injection of micro-fractured adipose tissue. Micro-fractured fat was obtained using a minimal manipulation technique in a closed system (Lipogems), without the addition of enzymes or any other additives. The study subjects were clinically evaluated using the numerical pain rating scale (NPRS), the 100-point Knee Society Score (KSS) with its functional component (FXN), and the lower extremity activity scale (LEAS) at 6 weeks, 6 months, and 12 months following this procedure. When compared with baseline, significant improvements were noted in the mean values of NPRS, FXN, and LEAS at 6 weeks, 6 months, and 12 months. The mean KSS significantly improved at 6 weeks and 12 months. In particular, the average KSS score improved from 74 to 82, the FXN score improved from 65 to 76, and the LEAS score improved from 36 to 47. These values were significantly greater than the previously published minimal clinically important difference described for KSS and FXN in patients who underwent total knee arthroplasty for primary OA. No serious adverse events were reported. The injection of autologous, micro-fractured, minimally manipulated adipose tissue appears to be a safe and effective treatment option for patients with refractory, severe (grade 3 or 4) knee OA. This study demonstrated significant improvements in pain, quality of life, and function for at least 12 months in this study population. This intervention may represent a nonsurgical treatment option to avoid knee joint replacement in this population; however, further investigation is needed.

Short-term results of arthroscopic micro-fracture and autologous osteochondralplasty for osteochondritis dissecans of elbow

Objective To evaluate the short-term results of arthroscopic treatment including micro-fractures and autologous osteochondralplasty for osteochondritis dissecans (OCD) of elbow. Methods Data of 30 OCD patients who were treated by arthroscopic micro-fracture or autologous osteochondralplasty from January 2012 to December 2014 were retrospectively analyzed. 22 of them were followed-up for more than one year. Among them, there were 20 males and 2 females. All had OCD lesion on dominated side. The average age was 15 years old (range, 12-19 years old). All patients suffered from pain and limitation on the range of motion at different level. Arthroscopic micro-fracture was performed if the diameter of the lesion was less than 1 cm, otherwise, autologous osteochondralplasty was performed. 16 cases received arthroscopic micro-fracture and 6 cased received autologous osteochondralplasty. 6 patients were athletes who received micro-fracture. 16 patients were non-athletes and 10 of them received micro-fractures. The flexion-extension range of motion(ROM), Mayo elbow performance score (MEPS), visual analog scale for pain (VAS) were recorded preoperatively and at the final follow-up for comparison. Results Patients were followed up for 13 month on average (range, 12-18 months) without any complications. All patients got improvement significantly with 100% good or excellent rate. For patients receiving arthroscopic micro-fracture, the preoperative ROM, MEPS and VAS was 101.88°±14.82°, 64.38±4.79 and 5.13±1.09, which was improved to 114.38°±11.53°, 88.75±8.06 and 0.88±1.02 respectively. There were significant differences between preoperative and postoperative ROM, MEPS and VAS. Among these 16 patients, 13 were excellent and 3 were good. For 6 patients who received arthroscopic autologous osteochondralplasty, the preoperative ROM, MEPS and VAS was 105.00°±11.83°, 60.83±6.11 and 5.67±1.37, which was improved to 120.83°±6.11°, 87.50±5.24 and 1.17±0.56 at the final follow up respectively. There were significant differences between preoperative and postoperative ROM, MEPS and VAS. Among these 6 patients, 4 were excellent and 2 were good. Conclusion For elbow OCD, satisfied result can be expected by arthroscopic micro-fracture and autologous osteochondralplasty because both are effective procedures to improve the elbow function. Key words: Arthroscopy; Elbow joint; Transplantation, autologous

Fault detection based on microseismic events

In unconventional reservoirs, small faults allow the flow of oil and gas as well as act as obstacles to exploration; for, (1) fracturing facilitates fluid migration, (2) reservoir flooding, and (3) triggering of small earthquakes. These small faults are not generally detected because of the low seismic resolution. However, such small faults are very active and release sufficient energy to initiate a large number of microseismic events (MEs) during hydraulic fracturing. In this study, we identified microfractures (MF) from hydraulic fracturing and natural small faults based on microseismicity characteristics, such as the time–space distribution, source mechanism, magnitude, amplitude, and frequency. First, I identified the mechanism of small faults and MF by reservoir stress analysis and calibrated the ME based on the microseismic magnitude. The dynamic characteristics (frequency and amplitude) of MEs triggered by natural faults and MF were analyzed; moreover, the geometry and activity types of natural fault and MF were grouped according to the source mechanism. Finally, the differences among time–space distribution, magnitude, source mechanism, amplitude, and frequency were used to differentiate natural faults and manmade fractures.

مطالعه کانی شناسی و فرآیندهای اسکارنی شدن در اسکارن مس- آهن آوان، شمالخاور خاروانا، شمال باختر ایران

اسکارن مس- آهن آوان در نتیجه نفوذ باتولیت گرانیتوئیدی قره داغ به‌ داخل سنگهای کربناته ناخالص کرتاسه بالایی تشکیل شده است. اسکارن آوان متشکل از پهنه های مرمر، اگزواسکارن و اندواسکارن بوده و بخش اصلی آن پهنه اگزواسکارن، است. بررسیهای کانی شناسی بیانگر آن است که پهنه اگزواسکارن شامل زیرپهنه های گارنت اسکارن، پیروکسن- گارنت اسکارن و کانه اسکارن است. مهمترین کانی کالک سیلیکاته بی آب در پهنه اگزواسکارن، گارنت و ترکیب آن اوگراندیتی (Ad53-89) است. برخی بلورهای گارنت، منطقه‌بندی دارد و ترکیب آنها به طرف حاشیه‌ها به آندرادیت خالص (Ad99) میل می‌کند. کلینوپیروکسن موجود در زیرپهنه پیروکسن- گارنت اسکارن از نوع دیوپسید (Di75-96) است. زیرپهنه کانه اسکارن از کانه‌های مگنتیت، هماتیت، پیریت، کالکوپیریت، بورنیت، مالاکیت و گوتیت تشکیل شده است. وجود میزان محدود ولاستونیت در مجموعه کانی شناسی اسکارن آوان، هم‌رشدی بلورهای گارنت و کلینوپیروکسن و نبود هاله واکنشی بین این دو کانی و نبود بافتهای جانشینی نشان‌دهنده آن است که این کانیها به‌صورت هم‌زمان در محدوده دمایی C°600- 430 و فوگاسیته اکسیژن بیشتر از 10-26 تشکیل شده‌اند.

Treatment of complicated tibial plateau fractures: strategy and development

Tibial plateau fracture, one of the most common fractures, includes simple and complicated fractures. Inappropriate treatment could result in pain and deformity, which has a bad effect on patient life. With the development of the surgical technique, a lot of methods could be selected when an orthopedist deals with these fractures. X-ray, one of the most common assistant examination, is the preferred method for tibial plateau fracture and could diagnose most of these fractures. Due to high resolution, CT scan could find these micro-fractures which X-ray cannot find and it could supplement the Schatzker type. MRI could find ligament, meniscus and arthrodial cartilage injury. Surgical approach includes anterolateral approach, medial approach, posteromedial approach, post approach, anterior approach. Anterolateral approach could be used for most of tibial plateau fractures. Posteromedial approach is used for medial plateau fracture involving post plateau fracture or post plateau fracture alone. Common plate, locking plate, dual plate and external fixation are commonly used fixation method. Dual plate is often used for complicated tibial plateau fracture. However, how to make accurate diagnosis and choose appropriate fixation is crucial for patients. We will summarize the application of X-ray, CT scan and MRI in diagnosis of tibial plateau fracture. Commonly used approaches to the proximal tibia, which together allow for the treatment of any proximal tibia fracture, will be described in this article.

Influence of magnitude and permeability of fracture networks on behaviors of vertical shale gas wells by a free-simulator approach

After stimulated reservoir volume (SRV), complex fracture networks can be generated around shale gas (SG) vertical wells. Due to intricate flow characteristics, performance forecasts of those wells highly depend on numerical simulators. To lighten the burden of numerical computation work, a free-simulator approach was proposed in this work.To facilitate methodology development, the SG formation was assumed to be made up of two systems (reservoir/fracture system) and four media (shale matrix, unreacted nature fractures, reacted nature fractures or micro fractures (MF), and hydraulic fractures (HF)). Based on that, a mathematical model comprised of reservoir equations, fracture equations, and mass balance equations was developed for vertically fracture-network wells (VFNW). Using Laplace transformation and Pedrosa's substitution, equations in the mathematical model were solved. Type curves were generated and flow regimes were identified. Case study and sensitivity analysis were also conducted.Results from this study show that the possible flow regimes for a VFNW in SG reservoirs includes (1) wellbore storage and skin effect, (2) bilinear flow, (3) formation linear flow, (4) pseudo boundary-dominated flow, (5) bi-radial flow, (6) Knudsen diffusion flow, and (7) pseudo radial flow. As the magnitude of fracture networks increases, the formation linear flow lasts longer and the pseudo boundary-dominated flow occurs later. As the permeability of fracture networks increases, the pseudo boundary-dominated flow becomes more obvious. Additionally, it is found that pressure depletion in the SG reservoir decreases with the increase of magnitude or permeability of fracture networks.This work provides a novel respective on performance forecast on vertical wells with fracture networks, which has considerable significances on fracturing optimization as well as productivity estimation for SRV.

Performance of horizontal wells with fracture networks in shale gas formation

Abstract With micro fractures (MF) in shale gas (SG) reservoirs, complex fracture networks can easily develop along horizontal wells after stimulated reservoir volume (SRV) treatments. Due to the intricate flow characteristics, performance investigations for horizontal wells with fracture networks (HWFN) are extreme challenges. Hence, lots of work needs to be done to overcome this difficulty. In this paper, we proposed a semi-analytical method to predict the performance of HWFN in SG formation. First, based on symmetry, the fracture networks were approximated as a mixture of multiple hydraulic fractures (HF) and MF. Then, a new semi-analytical model was proposed by discretizing all these fractures into small segments with consideration of fracture interferences, SG diffusion, SG adsorption, and effect of stress-sensitivity of permeability. By solving this model, the transient pressure performance of HWFN was obtained. To verify the semi-analytical method, both analytical and numerical validations were conducted. After validation, the effects on performance of HWFN were studied including fracture number, fracture length, fracture conductivity, SG diffusion coefficient, SG adsorption index, and stress-sensitivity coefficient. Finally, type-curve matching and parameter estimations for a field case were conducted. Results show the type curves of HWFN have two unique features: (1) a “dip” which occurs by the end of bilinear flow period and (2) a disappearance of early radial flow. The possible flow regimes for HWFN in a finite SG formation are: (a) bilinear flow, (b) “MF-HF support”, (c) first linear flow, (d) bi-radial flow, (e) SG diffusion flow, and (f) boundary-dominated flow. In addition, results of sensitivity analysis indicate that the “MF-HF support” is stronger with the increase of MF number, MF length, and MF conductivity; it is weaker with the increase of HF number, HF length and HF conductivity.

A model for simultaneous matrix depletion into natural and hydraulic fracture networks

Existing transient triple-porosity models for fractured horizontal wells do not converge to linear dual-porosity models (DPM) in the absence of micro-fractures (MF). The reason is the assumption of sequential-depletion from matrix to MF, and from MF to hydraulic-fractures (HF). This can result in unreasonable estimates of MF and/or HF parameters. Hence, a quadrilinear flow model (QFM) is proposed which relaxes the sequential-depletion assumption.To allow simultaneous matrix-MF and matrix-HF depletion, the matrix volume is conceptually divided into two sub-domains; one feeds HF and the other feeds MF. This breaks a single 2-D problem into two 1-D problems. Using Laplace transforms, the flow equations are solved under constant-rate and constant-pressure well constraints. Type-curves are generated by numerically inverting the resulting Laplace-space solutions to time-space using Gaver-Stefhest algorithm. QFM converges to the linear sequential triple-porosity model (STPM) in the absence of matrix-HF communication; and converges to the DPM in the absence of MF. Flow-regimes observed comprise linear, bilinear, and boundary dominated. QFM matches production history of two fractured horizontal wells completed in Bakken and Cardium Formations. This match yields reservoir parameters like half-length and permeability; these parameters are estimated as range of values instead of single values to reflect the non-uniqueness in the match.Results from this study are significant when selecting the appropriate model for interpreting production data from multifractured horizontal wells in formations with/without natural-fracture (NF/MF) reactivation. DPM is appropriate if analog studies (e.g. outcrop, micro-seismic and image log analyses) reveal high spacing aspect ratio (negligible MF) in the reservoir. Spacing aspect ratio is MF spacing divided by HF spacing. STPM is appropriate if analog studies reveal low spacing aspect ratio (e.g. matrix-HF face damage or high MF density within a given HF spacing). QFM is appropriate for all spacing aspect ratios.

IS THAT POSSIBLE TO RESTORE PRE-INJURY PHYSICAL ACTIVITY LEVEL AFTER ONE-STAGE ARTICULAR CARTILAGE AND ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION PROCEDURE

Purposeto compare the concomitant treatment of the articular cartilage damage (ACD) in the knee with three different articular cartilage procedures at the time of anterior cruciate ligament (ACL) reconstruction.Methodsbetween the...

Fluid inclusions in microstructures of shocked quartz from the Keurusselkä impact site, Central Finland

AbstractGranitoid rock samples from the assumed center of the Keurusselkä impact site were subjected to a systematic study of fluid‐inclusion compositions and densities in various microstructures of the shocked quartz. The results are consistent with the following impact‐induced model of formation. After cessation of all major regional tectonic activity and advanced erosional uplift of the Fennoscandian shield, a meteorite impact (approximately 1.1 Ga) caused the formation of planar fractures (PFs) and planar deformation features (PDFs) and the migration of shock‐liberated metamorphic fluid (CO2 ± H2O) to the glass in the PDFs. Postimpact annealing of the PDFs led to the formation of CO2 (±H2O) fluid‐inclusion decorated PDFs. The scarce fluid‐inclusion implosion textures (IPs) suggest a shock pressure of 7.6–10 GPa. The postimpact pressure release and associated heating initiated hydrothermal activity that caused re‐opening of some PFs and their partial filling by moderate‐salinity/high temperature (&gt;200 °C) H2O (+ chlorite + quartz) and moderate‐density CO2. The youngest postimpact endogenic sub‐ and nonplanar microfractures (MFs) are characterized by low‐density CO2 and low‐salinity/low‐temperature (&lt;200 °C) H2O.

Defects of porcine articular cartilage of the knee repaired at one stage by autologous adipose-derived stem cells and collagen I scaffolds with slow-release inducing factors

Objective To investigate the feasibility of repairing at one stage defects of porcine articular cartilage of the knee with autologous adipose-derived stem cells (ADSCs) and collagen Ⅰ scaffolds with slow-release inducing factors.Methods We first made collagen Ⅰ scaffolds with slow-release inducing factors using freeze drying technology.The concentrations of slow-release inducing factors(transformation growth factor-β2,insulin-like growth factor-l) were evaluated by Elisa.The porcine ADSCs,obtained by density gradient centrifugation,were seeded onto the collagen Ⅰ scaffolds with slow-release inducing factors for in vitro culture for 3 weeks to observe the cellular distribution and secretion of type Ⅱ collagen and aggrecan within the scaffold.Porcine models of full thickness defects of the knee articular cartilage were created,7 ×7mm in size.ADSCs and collagen Ⅰ scaffolds were implanted into the cartilage defects in the experimental group (3 pigs) while micro-fractures were made in the subchondral bone and treated with absorbable membranes in the control group (3 pigs).Gross observation and histological analyses were conducted 2 and 4months after operation to assess defect healing in the 2 groups.Results The inducing factors were slowly released in the scaffolds with slowly reduced concentrations.The ADSCs distributed extensively and expressions of type Ⅱ collagen and aggrecan were observed in the scaffolds after 3-week in vitro culture.In the experimental group,edges of the articular cartilage defects were filled with reparative hyaline cartilage after 2 months,and the whole defects were repaired by the hyaline cartilage 4 months later.HE staining showed typical cartilaginous structure in the repaired area,though its cellular density was higher than in the normal cartilage.In the control group,defects were not repaired but filled with fibrous tissue.Conclusions Enough autologous porcine ADSCs can be obtained at one stage for implantation.ADSCs seeded onto the collagen Ⅰ scaffolds with slow-release inducing factors may be differentiated into chondrocytes to repair porcine articular cartilage defects. Key words: Knee joint; Cartilage; articular; Stem cell transplantation; Cytoskeleton

Assessment of bone quality. Bone remodeling and bone quality

Bone remodeling is a sequential process consisting of osteoclastic bone resorption and osteoblastic bone formation. Excess bone remodeling reduces bone mass, while suppressed bone remodeling increases it. Bisphosphonate treatment increases bone mass in patients with osteoporosis. However, bone strength is determined not only by mass but also by bone quality, and suppressed bone remodeling may reduce bone quality due to accumulation of micro fractures and to other mechanisms. Therefore understanding the relationship between bone remodeling and bone quality is essential to design interventions to effectively treat osteoporosis.

Treatment and management of severe osteoporosis

Because there is an extremely high probability of new fractures occurring in cases in which there are pre-existing fractures, it is easy for such patients to develop severe osteoporosis. We therefore must correctly ascertain any existence of either vertebral or hip fractures. High values of bone resorption markers reflect the existence of microfractures, so it is necessary to be careful due to the high risk of new fractures. Kinesitherapy for severe osteoporosis focuses on therapeutic exercise, walking, balance drills, and so forth with the aim of maintaining muscular strength and thus preventing falls. For severe osteoporosis such as senile osteoporosis and glucocorticoid-induced osteoporosis, bisphosphonates are currently the only medication that has been proven to be effective for preventing fractures. For the treatment of disuse osteoporosis stemming from paralysis, etc., the intravenous injection of bisphosphonates is able to suppress the decline in bone mass, but there is still very little evidence of its fracture prevention effect.