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Christian Kaps - One of the best experts on this subject based on the ideXlab platform.
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formation of cartilage repair tissue in articular cartilage defects pretreated with Microfracture and covered with cell free polymer based implants
Journal of Orthopaedic Research, 2009Co-Authors: Christoph Erggelet, Michaela Endres, Katja Neumann, L Morawietz, Jochen Ringe, Kathrin Haberstroh, Michael Sittinger, Christian KapsAbstract:The aim of our study was to evaluate the mid-term outcome of a cell-free polymer-based cartilage repair approach in a sheep cartilage defect model in comparison to Microfracture treatment. Cell-free, freeze-dried implants (chondrotissue 1 ) made of a poly-glycolic acid (PGA) scaffold and hyaluronan were immersed in autologous serum and used for covering Microfractured full-thickness articular cartilage defects of the sheep (n ¼4). Defects treated with Microfracture only served as controls (n ¼4). Six months after implantation, cartilage implants and controls were analyzed by immunohistochemical staining of type II collagen, histological staining of proteoglycans, andhistologicalscoring.Histologicalanalysisshowedtheformationofacartilaginousrepairtissuerichinproteoglycans.Histologicalscoring documented significant improvement of repair tissue formation when the defects were covered with the cell-free implant, compared to controlstreatedwithMicrofracture.Immunohistochemistryshowedthatthecell-freeimplantinducedcartilaginousrepairtissueandtypeII collagen.ControlstreatedwithMicrofractureshowedmarginalformationofamixed-typerepairtissueconsistingofcartilaginoustissueand
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regeneration of ovine articular cartilage defects by cell free polymer based implants
Biomaterials, 2007Co-Authors: Christoph Erggelet, Michaela Endres, Katja Neumann, Kathrin Haberstroh, Michael Sittinger, Christian KapsAbstract:The aim of our study was the evaluation of a cell-free cartilage implant that allows the recruitment of mesenchymal stem and progenitor cells by chemo-attractants and subsequent guidance of the progenitors to form cartilage repair tissue after Microfracture. Chemotactic activity of human serum on human mesenchymal progenitors was tested in 96-well chemotaxis assays and chondrogenic differentiation was assessed by gene expression profiling after stimulating progenitors with hyaluronan in high-density cultures. Autologous serum and hyaluronan were combined with polyglycolic acid (PGA) scaffolds and were implanted into full-thickness articular cartilage defects of the sheep pre-treated with Microfracture. Defects treated with Microfracture served as controls. Human serum was a potent chemo-attractant and efficiently recruited mesenchymal progenitors. Chondrogenic differentiation of progenitors upon stimulation with hyaluronan was shown by the induction of typical chondrogenic marker genes like type II collagen and aggrecan. Three months after implantation of the cell-free implant, histological analysis documented the formation of a cartilaginous repair tissue. Controls treated with Microfracture showed no formation of repair tissue. The cell-free cartilage implant consisting of autologous serum, hyaluronan and PGA utilizes the migration and differentiation potential of mesenchymal progenitors for cartilage regeneration and is well suited for the treatment of cartilage defects after Microfracture.
Matthew S Shive - One of the best experts on this subject based on the ideXlab platform.
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novel scaffold based bst cargel treatment results in superior cartilage repair compared with Microfracture in a randomized controlled trial
Journal of Bone and Joint Surgery American Volume, 2013Co-Authors: William D Stanish, Robert G Mccormack, Francisco Forriol, Nicholas G H Mohtadi, Stephane Pelet, Jacques Desnoyers, Alberto Restrepo, Matthew S ShiveAbstract:Background: Microfracture, the standard of care, is recognized to be an incomplete solution for cartilage damage. BST-CarGel, a chitosan-based medical device, is mixed with autologous whole blood and is applied to a Microfractured cartilage lesion in which it physically stabilizes the clot and guides and enhances marrow-derived repair. An international, multicenter, randomized controlled trial was conducted to evaluate BST-CarGel treatment compared with Microfracture alone in the repair of cartilage lesions in the knee. Methods: Eighty patients between the ages of eighteen and fifty-five years with a single, symptomatic focal lesion on the femoral condyles were randomized to BST-CarGel and Microfracture treatment (n = 41) or Microfracture treatment alone (n = 39). The primary end points of repair tissue quantity and quality at twelve months were assessed by quantitative three-dimensional magnetic resonance imaging measuring the degree of lesion filling and T2 relaxation time with use of standardized one and twelve-month posttreatment scans. The secondary end point at twelve months was clinical benefit determined with the Western Ontario and McMaster Universities Osteoarthritis Index. The tertiary end point was quality of life determined by the Short Form-36. Safety was assessed through the recording of adverse events. Results: Patient baseline characteristics were similar in the two groups, although baseline lesion areas were slightly larger on quantitative magnetic resonance imaging for the BST-CarGel group compared with the Microfracture group. Blinded quantitative magnetic resonance imaging analysis demonstrated that, at twelve months, when compared with Microfracture treatment alone, BST-CarGel treatment met both primary end points by achieving statistical superiority for greater lesion filling (p = 0.011) and more hyaline cartilage-like T2 values (p = 0.033). The lesion filling values were 92.8% ± 2.0% for the BST-CarGel treatment group and 85.2% ± 2.1% for the Microfracture treatment group, and the mean T2 values were 70.5 ± 4.5 ms for the BST-CarGel treatment group and 85.0 ± 4.9 ms for the Microfracture treatment group. Western Ontario and McMaster Universities Osteoarthritis Index subscales for pain, stiffness, and function yielded equivalent improvement for both groups at twelve months, which were significant (p < 0.0001) from baseline. Treatment safety profiles were considered comparable. Conclusions: At twelve months, BST-CarGel treatment resulted in greater lesion filling and superior repair tissue quality compared with Microfracture treatment alone. Clinical benefit was equivalent between groups at twelve months, and safety was similar. Level of Evidence: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.
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drilling and Microfracture lead to different bone structure and necrosis during bone marrow stimulation for cartilage repair
Journal of Orthopaedic Research, 2009Co-Authors: Hongmei Chen, Marc D Mckee, Caroline D Hoemann, Matthew S Shive, V Lascaucoman, Wei Ouyang, Michael D. BuschmannAbstract:Bone marrow stimulation is performed using several surgical techniques that have not been systematically compared or optimized for a desired cartilage repair outcome. In this study, we investigated acute osteochondral characteristics following Microfracture and comparing to drilling in a mature rabbit model of cartilage repair. Microfracture holes were made to a depth of 2 mm and drill holes to either 2 mm or 6 mm under cooled irrigation. Animals were sacrificed 1 day postoperatively and subchondral bone assessed by histology and micro-CT. We confirmed one hypothesis that Microfracture produces fractured and compacted bone around holes, essentially sealing them off from viable bone marrow and potentially impeding repair. In contrast, drilling cleanly removed bone from the holes to provide access channels to marrow stroma. Our second hypothesis that drilling would cause greater osteocyte death than Microfracture due to heat necrosis was not substantiated, because more empty osteocyte lacunae were associated with Microfracture than drilling, probably due to shearing and crushing of adjacent bone. Drilling deeper to 6 mm versus 2 mm penetrated the epiphyseal scar in this model and led to greater subchondral hematoma. Our study revealed distinct differences between Microfracture and drilling for acute subchondral bone structure and osteocyte necrosis. Additional ongoing studies suggest these differences significantly affect long-term cartilage repair outcome. 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:1432-1438, 2009
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drilling and Microfracture lead to different bone structure and necrosis during bone marrow stimulation for cartilage repair
Journal of Orthopaedic Research, 2009Co-Authors: Hongmei Chen, Marc D Mckee, Caroline D Hoemann, Matthew S Shive, Jun Sun, V Lascaucoman, Wei Ouyang, Michael D. BuschmannAbstract:Bone marrow stimulation is performed using several surgical techniques that have not been systematically compared or optimized for a desired cartilage repair outcome. In this study, we investigated acute osteochondral characteristics following Microfracture and comparing to drilling in a mature rabbit model of cartilage repair. Microfracture holes were made to a depth of 2 mm and drill holes to either 2 mm or 6 mm under cooled irrigation. Animals were sacrificed 1 day postoperatively and subchondral bone assessed by histology and micro-CT. We confirmed one hypothesis that Microfracture produces fractured and compacted bone around holes, essentially sealing them off from viable bone marrow and potentially impeding repair. In contrast, drilling cleanly removed bone from the holes to provide access channels to marrow stroma. Our second hypothesis that drilling would cause greater osteocyte death than Microfracture due to heat necrosis was not substantiated, because more empty osteocyte lacunae were associated with Microfracture than drilling, probably due to shearing and crushing of adjacent bone. Drilling deeper to 6 mm versus 2 mm penetrated the epiphyseal scar in this model and led to greater subchondral hematoma. Our study revealed distinct differences between Microfracture and drilling for acute subchondral bone structure and osteocyte necrosis. Additional ongoing studies suggest these differences significantly affect long-term cartilage repair outcome.
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chitosan glycerol phosphate blood implants improve hyaline cartilage repair in ovine Microfracture defects
Journal of Bone and Joint Surgery American Volume, 2005Co-Authors: Caroline D Hoemann, Mark B Hurtig, Evgeny Rossomacha, Anik Chevrier, Matthew S Shive, Michael D. BuschmannAbstract:Background: Microfracture is a surgical procedure that is used to treat focal articular cartilage defects. Although joint function improves following Microfracture, the procedure elicits incomplete repair. As blood clot formation in the Microfracture defect is an essential initiating event in Microfracture therapy, we hypothesized that the repair would be improved if the Microfracture defect were filled with a blood clot that was stabilized by the incorporation of a thrombogenic and adhesive polymer, specifically, chitosan. The objectives of the present study were to evaluate (1) blood clot adhesion in fresh Microfracture defects and (2) the quality of the repair, at six months postoperatively, of Microfracture defects that had been treated with or without chitosan-glycerol phosphate/blood clot implants, using a sheep model. Methods: In eighteen sheep, two 1-cm2 full-thickness chondral defects were created in the distal part of the femur and treated with Microfracture; one defect was made in the medial femoral condyle, and the other defect was made in the trochlea. In four sheep, Microfracture defects were created bilaterally; the Microfracture defects in one knee received no further treatment, and the Microfracture defects in the contralateral knee were filled with chitosan-glycerol phosphate/autologous whole blood and the implants were allowed to solidify. Fresh defects in these four sheep were collected at one hour postoperatively to compare the retention of the chitosan-glycerol phosphate/blood clot with that of the normal clot and to define the histologic characteristics of these fresh defects. In the other fourteen sheep, Microfracture defects were made in only one knee and either were left untreated (control group; six sheep) or were treated with chitosan-glycerol phosphate/blood implant (treatment group; eight sheep), and the quality of repair was assessed histologically, histomorphometrically, and biochemically at six months postoperatively. Results: In the defects that were examined one hour postoperatively, chitosan-glycerol phosphate/blood clots showed increased adhesion to the walls of the defects as compared with the blood clots in the untreated Microfracture defects. After histological processing, all blood clots in the control Microfracture defects had been lost, whereas chitosanglycerol phosphate/blood clot adhered to and was partly retained on the surfaces of the defect. At six months, defects that had been treated with chitosan-glycerol phosphate/blood were filled with significantly more hyaline repair tissue (p < 0.05) compared with control defects. Repair tissue from medial femoral condyle defects that had been treated with chitosan-glycerol phosphate/blood contained more cells and more collagen compared with control defects and showed complete restoration of glycosaminoglycan levels. Conclusions: Solidification of a chitosan-glycerol phosphate/blood implant in Microfracture defects improved cartilage repair compared with Microfracture alone by increasing the amount of tissue and improving its biochemical composition and cellular organization. Clinical Relevance: The use of chitosan-glycerol phosphate/blood implants in conjunction with Microfracture can improve the structural and compositional properties of repaired cartilage. These effects may result in better integration, improved biomechanical properties, and longer durability of the repair tissue.
Michael D. Buschmann - One of the best experts on this subject based on the ideXlab platform.
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drilling and Microfracture lead to different bone structure and necrosis during bone marrow stimulation for cartilage repair
Journal of Orthopaedic Research, 2009Co-Authors: Hongmei Chen, Marc D Mckee, Caroline D Hoemann, Matthew S Shive, V Lascaucoman, Wei Ouyang, Michael D. BuschmannAbstract:Bone marrow stimulation is performed using several surgical techniques that have not been systematically compared or optimized for a desired cartilage repair outcome. In this study, we investigated acute osteochondral characteristics following Microfracture and comparing to drilling in a mature rabbit model of cartilage repair. Microfracture holes were made to a depth of 2 mm and drill holes to either 2 mm or 6 mm under cooled irrigation. Animals were sacrificed 1 day postoperatively and subchondral bone assessed by histology and micro-CT. We confirmed one hypothesis that Microfracture produces fractured and compacted bone around holes, essentially sealing them off from viable bone marrow and potentially impeding repair. In contrast, drilling cleanly removed bone from the holes to provide access channels to marrow stroma. Our second hypothesis that drilling would cause greater osteocyte death than Microfracture due to heat necrosis was not substantiated, because more empty osteocyte lacunae were associated with Microfracture than drilling, probably due to shearing and crushing of adjacent bone. Drilling deeper to 6 mm versus 2 mm penetrated the epiphyseal scar in this model and led to greater subchondral hematoma. Our study revealed distinct differences between Microfracture and drilling for acute subchondral bone structure and osteocyte necrosis. Additional ongoing studies suggest these differences significantly affect long-term cartilage repair outcome. 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:1432-1438, 2009
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drilling and Microfracture lead to different bone structure and necrosis during bone marrow stimulation for cartilage repair
Journal of Orthopaedic Research, 2009Co-Authors: Hongmei Chen, Marc D Mckee, Caroline D Hoemann, Matthew S Shive, Jun Sun, V Lascaucoman, Wei Ouyang, Michael D. BuschmannAbstract:Bone marrow stimulation is performed using several surgical techniques that have not been systematically compared or optimized for a desired cartilage repair outcome. In this study, we investigated acute osteochondral characteristics following Microfracture and comparing to drilling in a mature rabbit model of cartilage repair. Microfracture holes were made to a depth of 2 mm and drill holes to either 2 mm or 6 mm under cooled irrigation. Animals were sacrificed 1 day postoperatively and subchondral bone assessed by histology and micro-CT. We confirmed one hypothesis that Microfracture produces fractured and compacted bone around holes, essentially sealing them off from viable bone marrow and potentially impeding repair. In contrast, drilling cleanly removed bone from the holes to provide access channels to marrow stroma. Our second hypothesis that drilling would cause greater osteocyte death than Microfracture due to heat necrosis was not substantiated, because more empty osteocyte lacunae were associated with Microfracture than drilling, probably due to shearing and crushing of adjacent bone. Drilling deeper to 6 mm versus 2 mm penetrated the epiphyseal scar in this model and led to greater subchondral hematoma. Our study revealed distinct differences between Microfracture and drilling for acute subchondral bone structure and osteocyte necrosis. Additional ongoing studies suggest these differences significantly affect long-term cartilage repair outcome.
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chitosan glycerol phosphate blood implants improve hyaline cartilage repair in ovine Microfracture defects
Journal of Bone and Joint Surgery American Volume, 2005Co-Authors: Caroline D Hoemann, Mark B Hurtig, Evgeny Rossomacha, Anik Chevrier, Matthew S Shive, Michael D. BuschmannAbstract:Background: Microfracture is a surgical procedure that is used to treat focal articular cartilage defects. Although joint function improves following Microfracture, the procedure elicits incomplete repair. As blood clot formation in the Microfracture defect is an essential initiating event in Microfracture therapy, we hypothesized that the repair would be improved if the Microfracture defect were filled with a blood clot that was stabilized by the incorporation of a thrombogenic and adhesive polymer, specifically, chitosan. The objectives of the present study were to evaluate (1) blood clot adhesion in fresh Microfracture defects and (2) the quality of the repair, at six months postoperatively, of Microfracture defects that had been treated with or without chitosan-glycerol phosphate/blood clot implants, using a sheep model. Methods: In eighteen sheep, two 1-cm2 full-thickness chondral defects were created in the distal part of the femur and treated with Microfracture; one defect was made in the medial femoral condyle, and the other defect was made in the trochlea. In four sheep, Microfracture defects were created bilaterally; the Microfracture defects in one knee received no further treatment, and the Microfracture defects in the contralateral knee were filled with chitosan-glycerol phosphate/autologous whole blood and the implants were allowed to solidify. Fresh defects in these four sheep were collected at one hour postoperatively to compare the retention of the chitosan-glycerol phosphate/blood clot with that of the normal clot and to define the histologic characteristics of these fresh defects. In the other fourteen sheep, Microfracture defects were made in only one knee and either were left untreated (control group; six sheep) or were treated with chitosan-glycerol phosphate/blood implant (treatment group; eight sheep), and the quality of repair was assessed histologically, histomorphometrically, and biochemically at six months postoperatively. Results: In the defects that were examined one hour postoperatively, chitosan-glycerol phosphate/blood clots showed increased adhesion to the walls of the defects as compared with the blood clots in the untreated Microfracture defects. After histological processing, all blood clots in the control Microfracture defects had been lost, whereas chitosanglycerol phosphate/blood clot adhered to and was partly retained on the surfaces of the defect. At six months, defects that had been treated with chitosan-glycerol phosphate/blood were filled with significantly more hyaline repair tissue (p < 0.05) compared with control defects. Repair tissue from medial femoral condyle defects that had been treated with chitosan-glycerol phosphate/blood contained more cells and more collagen compared with control defects and showed complete restoration of glycosaminoglycan levels. Conclusions: Solidification of a chitosan-glycerol phosphate/blood implant in Microfracture defects improved cartilage repair compared with Microfracture alone by increasing the amount of tissue and improving its biochemical composition and cellular organization. Clinical Relevance: The use of chitosan-glycerol phosphate/blood implants in conjunction with Microfracture can improve the structural and compositional properties of repaired cartilage. These effects may result in better integration, improved biomechanical properties, and longer durability of the repair tissue.
D R Faulkner - One of the best experts on this subject based on the ideXlab platform.
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towards quantifying the matrix permeability of fault damage zones in low porosity rocks
Earth and Planetary Science Letters, 2012Co-Authors: T M Mitchell, D R FaulknerAbstract:Abstract In nature, permeability is enhanced in the damage zone of faults in crystalline rocks, where fracturing occurs on a wide range of scales. Understanding this permeability structure is paramount for predicting crustal fluid flow. We combine quantitative field and laboratory measurements to predict Microfracture damage zone permeability in low-porosity granitic rocks as a function of distance from the fault core and displacement. Microfracture controlled matrix permeability exerts an increasingly dominant role on fluid flow with increasing depth. In the field we analysed the scaling relationships of Microfracture densities surrounding strike-slip faults developed in granodiorite within the Atacama fault system in northern Chile. Displacements ranging over 5 orders of magnitude (∼0.012–5000 m), allow the variation of Microfracture damage with increasing distance from faults to be determined empirically as a function of displacement. We reproduce Microfracture damage in the laboratory in a suite of triaxial deformation experiments by inducing cyclic damage in initially intact samples while continuously measuring permeability. Combining field and laboratory datasets through the Microfracture density allows the permeability profile with distance from the fault to be predicted from fault displacement.
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scaling of fault damage zones with displacement and the implications for fault growth processes
Journal of Geophysical Research, 2011Co-Authors: D R Faulkner, T M Mitchell, Erik Jensen, Jose CembranoAbstract:[1] Knowledge of the spatial extent of damage surrounding fault zones is important for understanding crustal fluid flow and also for understanding the physical processes and mechanics by which fault zones develop with slip. There are few data available on the scaling of the fault damage zone with fault displacement, and of those that exist, deriving scaling relationships is hampered by comparing faults that run through different lithologies, have formed at different crustal depths or tectonic regimes (e.g., normal versus strike‐slip movement). We describe new data on the Microfracture damage zone width from small displacement fault zones within the Atacama fault zone in northern Chile that formed at ∼6 km depth within a dioritic protolith. The Microfracture damage zone is shown by an alteration halo surrounding the faults in which the density of the Microfractures is much greater than background levels in the undeformed protolith. The data show that damage zone width increases with fault displacement and there appears to be a zero intercept to this relationship, meaning that at zero displacement, there is no Microfracture damage zone. This is supported by field observations at fault tips that show a tapering out of fault damage zones. These data, combined with data from the literature, indicate that this same relationship might hold for much larger displacement faults. There is also a distinct asymmetry to the fracture damage. Several processes for the development of the observed scaling are discussed. The widely accepted theory of a process zone predicts that fault damage zone width increases with fault length and thus should always be largest at a propagating fault tip where displacement is lowest. This prediction is opposite to that seen in the current data set, leading to suggestion that other processes, such as damage zone growth with increasing displacement due to geometric irregularities or coseismic damage formation might better explain the spatial extent of damage surrounding even low‐displacement faults.
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the nature and origin of off fault damage surrounding strike slip fault zones with a wide range of displacements a field study from the atacama fault system northern chile
Journal of Structural Geology, 2009Co-Authors: T M Mitchell, D R FaulknerAbstract:Abstract Damage surrounding the core of faults is represented by deformation on a range of scales from microfracturing of the rock matrix to macroscopic fracture networks. The spatial distribution and geometric characterization of damage at various scales can help to predict fault growth processes, subsequent mechanics, bulk hydraulic and seismological properties of a fault zone. Within the excellently exposed Atacama fault system, northern Chile, micro- and macroscale fracture densities and orientation surrounding strike-slip faults with well-constrained displacements ranging over nearly 5 orders of magnitude (∼0.12 m–5000 m) have been analyzed. Faults have been studied that cut granodiorite and have been passively exhumed from 6 to 10 km depth. This allows direct comparison of the damage surrounding faults of different displacements. The faults consist of a fault core and associated damage zone. Macrofractures in the damage zone are predominantly shear fractures orientated at high angles to the faults studied. They have a reasonably well-defined exponential decrease with distance from the fault core. Microfractures are a combination of open, healed, partially healed and fluid inclusion planes (FIPs). FIPs are the earliest set of fractures and show an exponential decrease in fracture density with perpendicular distance from the fault core. Later Microfractures do not show a clear relationship of Microfracture density with perpendicular distance from the fault core. Damage zone widths defined by the density of FIPs scale with fault displacement but appear to reach a maximum at a few km displacement. One fault, where damage was characterized on both sides of the fault core shows no damage asymmetry. All faults appear to have a critical Microfracture density at the fault core/damage zone boundary that is independent of displacement. An empirical relationship for Microfracture density distribution with displacement is presented. Preferred FIP orientations have a high angle to the fault close to the fault core and become more diffuse with distance. Models that predict off-fault damage such as a migrating process zone during fault formation, wear from geometrical irregularities and dynamic rupture are all consistent with our data. We conclude it is very difficult to distinguish between them on the basis of field data alone, at least within the limits of this study.
Shuxia Cui - One of the best experts on this subject based on the ideXlab platform.
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influence of hydrolyzed polyacrylamide hpam molecular weight on the cross linking reaction of the hpam cr3 system and transportation of the hpam cr3 system in Microfractures
Energy & Fuels, 2016Co-Authors: Lei Zhang, Liming Zheng, Shuxia CuiAbstract:The influence of the molecular weight (Mw) of hydrolyzed polyacrylamide (HPAM) on the cross-linking reaction of HPAM/Cr3+ and the transportation of HPAM/Cr3+ in Microfractures is systematically studied using viscometry, ultraviolet–visible absorption spectrophotometry, and displacement experiment with a visual Microfractured model. The results show that a high-Mw HPAM is advantageous to the intramolecular cross-linking reaction of the HPAM/Cr3+ system but disadvantageous to the transportation of the HPAM/Cr3+ system in Microfractures. At the intramolecular cross-linking stage, the injection pressure of the HPAM/Cr3+ system in Microfractures is almost equal to that of the HPAM solution, which undergoes no change with the degree of the cross-linking reaction. The higher the HPAM Mw, the earlier the intramolecular cross-linking ends (thus, the intermolecular cross-linking reaction of HPAM/Cr3+ occurs earlier, which leads to an earlier increase in the injection pressure of the HPAM/Cr3+ system). Moreover, the...