Adipose-Derived Stem Cell Sheets Improve Early Biomechanical Graft Strength in Rabbits After Anterior Cruciate Ligament Reconstruction

2021 ◽  
pp. 036354652110415
Author(s):  
Tatsuaki Matsumoto ◽  
Yuiko Sato ◽  
Tami Kobayashi ◽  
Kunika Suzuki ◽  
Atsushi Kimura ◽  
...  
Keyword(s):  
Scanning Transmission Electron Microscopy ◽  
Cruciate Ligament ◽  
Bone Tunnel ◽  
Control Group ◽  
Micro Computed Tomography ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Anterior Cruciate ◽  
Adipose Derived Stem Cell ◽  
Biomechanical Strength

Background: Although various reconstruction techniques are available for anterior cruciate ligament (ACL) injuries, a long recovery time is required before patients return to sports activities, as the reconstructed ACL requires time to regain strength. To date, several studies have reported use of mesenchymal stem cells in orthopaedic surgery; however, no studies have used adipose-derived stem cell (ADSC) sheets in ACL reconstruction (ACLR). Hypothesis: ADSC sheet transplantation can improve biomechanical strength of the autograft used in ACLR. Study Design: Controlled laboratory study. Methods: A total of 68 healthy Japanese white rabbits underwent unilateral ACLR with a semitendinosus tendon autograft after random enrollment into a control group (no sheet; n = 34) and a sheet group (ADSC sheet; n = 34). At 2, 4, 8, 16, and 24 weeks after surgery, rabbits in each group were sacrificed to evaluate tendon-bone healing using histological staining, micro–computed tomography, and biomechanical testing. At 24 weeks, scanning transmission electron microscopy of the graft midsubstance was performed. Results: The ultimate failure load for the control and sheet groups, respectively, was as follows: 17.2 ± 5.5 versus 37.3 ± 10.3 ( P = .01) at 2 weeks, 28.6 ± 1.9 versus 47.4 ± 10.4 ( P = .003) at 4 weeks, 53.0 ± 14.3 versus 48.1 ± 9.3 ( P = .59) at 8 weeks, 66.2 ± 9.3 versus 95.2 ± 43.1 ( P = .24) at 16 weeks, and 66.7 ± 27.3 versus 85.3 ± 29.5 ( P = .39) at 24 weeks. The histological score was also significantly higher in the sheet group compared with the control group at early stages up to 8 weeks. On micro–computed tomography, relative to the control group, the bone tunnel area was significantly narrower in the sheet group at 4 weeks, and the bone volume/tissue volume of the tendon-bone interface was significantly greater at 24 weeks. Scanning transmission electron microscopy at 24 weeks indicated that the mean collagen fiber diameter in the midsubstance was significantly greater, as was the occupation ratio of collagen fibers per field of view, in the sheet group. Conclusion: ADSC sheets improved biomechanical strength, prevented bone tunnel enlargement, and promoted tendon-bone interface healing and graft midsubstance healing in an in vivo rabbit model. Clinical Relevance: ADSC sheets may be useful for early tendon-bone healing and graft maturation in ACLR.

The Effect of Remnant Preservation on Tibial Tunnel Enlargement in Anterior Cruciate Ligament Reconstruction with Polyethylene Terephthalate Artificial Ligament in a Large Animal Model

2018 ◽  
Vol 32 (11) ◽  
pp. 1094-1101
Author(s):  
Jiangyu Cai ◽  
Fang Wan ◽  
Chengchong Ai ◽  
Wenhe Jin ◽  
Dandan Sheng ◽  
...  
Keyword(s):  
Acl Reconstruction ◽  
Cruciate Ligament ◽  
Tibial Tunnel ◽  
Bone Tunnel ◽  
Control Group ◽  
Micro Ct ◽  
Tunnel Enlargement ◽  
Artificial Ligament ◽  
Remnant Preservation ◽  
Anterior Cruciate

AbstractAn enlarged bone tunnel may affect the graft–bone integration and pose a problem for revision anterior cruciate ligament (ACL) surgery. The purpose of this study was to evaluate the effect of remnant preservation on tibial tunnel enlargement in ACL reconstruction with polyethylene terephthalate (PET) artificial ligament. Twenty-four skeletally mature male beagles underwent ACL reconstruction with PET artificial ligament for both knees. One knee was reconstructed with remnant preservation using sleeve technique (remnant group), while the contralateral was reconstructed without remnant preservation (control group). The animals were sacrificed at 1 day, 6 weeks, and 12 weeks after surgery for further evaluation including macroscopic observation, microcomputed tomography (micro-CT), histological assessment, and biomechanical testing. The remnant group had better synovial coverage than the control group at 6 and 12 weeks after surgery. The micro-CT analysis showed the tibial tunnel area (TTA) of the remnant group was significantly smaller and the bone volume/total volume fraction (BV/TV) value was higher than those of the control group at 6 and 12 weeks. Moreover, TTA and BV/TV at each time point were divided into three groups according to the different grade of synovial coverage. Significant association was observed between the synovial coverage degree and the TTA and BV/TV values. The histological assessment revealed that the interface width between the graft and host bone in the remnant group was smaller than that in the control group in the tibial tunnels at 6 and 12 weeks. Moreover, the remnant group had better failure load and stiffness than the control group at 12 weeks. The remnant preservation using sleeve technique could effectively promote the synovial coverage of the graft, decrease the risk of tibial tunnel enlargement by sealing the bone tunnel entrance, and enhance the biological environment for graft–bone healing after ACL reconstruction using PET artificial ligament. This technique provides a potential solution for bone tunnel enlargement following artificial ligament surgery for the acute ACL rupture in the clinical practice.

The Effect of Graft Pretensioning on Bone Tunnel Diameter and Bone Formation After Anterior Cruciate Ligament Reconstruction in a Rat Model: Evaluation With Micro–Computed Tomography

2017 ◽  
Vol 45 (6) ◽  
pp. 1349-1358 ◽  
Author(s):  
Jian-Chun Zong ◽  
Richard Ma ◽  
Hongsheng Wang ◽  
Guang-Ting Cong ◽  
Amir Lebaschi ◽  
...  
Keyword(s):  
Bone Formation ◽  
Acl Reconstruction ◽  
Cruciate Ligament ◽  
Bone Tunnel ◽  
New Bone Formation ◽  
Micro Computed Tomography ◽  
Load To Failure ◽  
Tunnel Diameter ◽  
Anterior Cruciate ◽  
Bone Tunnels

Background: Moderate graft pretensioning in anterior cruciate ligament (ACL) reconstruction is paramount to restore knee stability and normalize knee kinematics. However, little is known about the effect of graft pretensioning on graft-to-bone healing after ACL reconstruction. Hypothesis: Moderate graft pretensioning will improve bone formation within the bone tunnel after ACL reconstruction, resulting in superior load to failure. Study Design: Controlled laboratory study. Methods: 67 male Sprague-Dawley rats underwent unilateral ACL reconstruction with a flexor digitorum longus tendon autograft. The graft was subjected to pretensioning forces of 0 N, 5 N, or 10 N. Custom-made external fixators were used for knee immobilization postoperatively. Rats were euthanized for biomechanical load-to-failure testing (n = 45) and micro–computed tomography (μCT) examination (n = 22) at 3 and 6 weeks after surgery. Three regions of each femoral and tibial bone tunnel (aperture, middle, and tunnel exit) were chosen for measurement of tunnel diameter and new bone formation. Results: Biomechanical tests revealed significantly higher load-to-failure in the 5-N graft pretensioned group compared with the 0- and 10-N groups at 3 weeks (8.58 ± 2.67 N vs 3.96 ± 1.83 N and 4.46 ± 2.62 N, respectively) and 6 weeks (16.56 ± 3.50 N vs 10.82 ± 1.97 N and 7.35 ± 2.85 N, respectively) after surgery ( P < .05). The mean bone tunnel diameters at each of the 3 regions were significantly smaller in the 5-N group, at both the femoral and tibial tunnel sites, than in the 0- and 10-N groups ( P < .05). At 3 and 6 weeks postoperatively, the bone mineral density, bone volume fraction, and connectivity density around the aperture and middle regions of the tibial bone tunnels were all significantly higher in the 5-N group compared with the 0- and 10-N groups ( P < .05). In the aperture and middle regions of the femoral bone tunnels, pretensioning at either 5 or 10 N resulted in increased bone formation compared with the nonpretensioned group at 3 weeks postoperatively. No differences were found in bone formation between any of the 3 femoral tunnel regions at 6 weeks. Conclusion: Graft pretensioning can stimulate new bone formation and improve tendon-to-bone tunnel healing after ACL reconstruction. Clinical Relevance: Optimal graft pretensioning force in ACL reconstruction can improve bone tunnel healing. Further study is necessary to understand the mechanisms underlying the effect of graft pretensioning on healing at the bone-tunnel interface.

Advantages of an Attached Semitendinosus Tendon Graft in Anterior Cruciate Ligament Reconstruction in a Rabbit Model

2018 ◽  
Vol 46 (13) ◽  
pp. 3227-3236 ◽  
Author(s):  
Shaohua Liu ◽  
Yaying Sun ◽  
Fang Wan ◽  
Zheci Ding ◽  
Shiyi Chen ◽  
...  
Keyword(s):  
Bone Healing ◽  
Cruciate Ligament ◽  
Tendon Graft ◽  
Semitendinosus Tendon ◽  
Control Group ◽  
Study Group ◽  
Micro Ct ◽  
Tibial Insertion ◽  
Anterior Cruciate ◽  
Biomechanical Strength

Background: The semitendinosus tendon graft with an intact tibial insertion has a sustainable blood supply and might be beneficial for graft maturation after anterior cruciate ligament reconstruction (ACLR); however, its potential advantages for graft tendon-bone healing is still unclear. Hypothesis: Intact tibial insertion of the hamstring tendon can preserve enough blood supply to keep the harvested tendon alive, which can improve tendon-bone healing and the biomechanical strength of the graft. Study Design: Controlled laboratory study. Methods: Sixty-four healthy New Zealand White rabbits underwent unilateral ACLR with a semitendinosus tendon autograft after random enrollment into 2 groups (study group, n = 32 rabbits with semitendinosus tendon–preserved tibial insertions; control group, n = 32 rabbits with free semitendinosus tendons). At weeks 3, 6, 12, and 24, 8 rabbits in each group were sacrificed to evaluate tendon-bone healing by histologic staining, micro–computed tomography (micro-CT) examination, and biomechanical test. Results: The grafts in the study group maintained a similar cell count with no signs of necrosis or hypocellularity across all time points, but the grafts in the control group underwent a characteristic stage of necrosis at weeks 3 and 6. Sharpey-like fibers were observed from postoperative 3 weeks at the tendon-bone interface in the study group, and a normal insertion-like structure was formed at week 12, which became more mature at week 24. In the control group, however, Sharpey-like fibers could not be observed until week 12, and a normal transition through cartilage from bone to tendon was not observed at any time point. Histologic scores of the tendon-bone interface in the study group were significantly higher than those in the control group at week 6 ( P = .04), week 12 ( P < .001), and week 24 ( P = .04). As compared with the control group via micro-CT, the study group had a significantly smaller bone tunnel area at week 6 ( P = .01) and larger bone volume/total volume at week 3 ( P = .0026) and week 6 ( P = .01). Also, the study group had a significantly higher failure load at weeks 12 and 24 (both P = .03) and a significantly higher stiffness at week 24 ( P < .001) versus the control group. Conclusion: The semitendinosus tendon graft with an intact tibial insertion in ACLR would bypass the graft avascular necrosis stage, which improves tendon-bone healing and biomechanical strength. Clinical Relevance: An alive graft in ACLR could improve tendon-bone healing and the biomechanical strength of the graft, which might be beneficial to early and intensive rehabilitation after ACLR.

scholarly journals Effect of Demineralized Bone Matrix, Bone Marrow Mesenchymal Stromal Cells, and Platelet-Rich Plasma on Bone Tunnel Healing After Anterior Cruciate Ligament Reconstruction: A Comparative Micro-Computed Tomography Study in a Tendon Allograft Sheep Model

2021 ◽  
Vol 9 (9) ◽  
pp. 232596712110341
Author(s):  
Adam T. Hexter ◽  
Aikaterina Karali ◽  
Alex Kao ◽  
Gianluca Tozzi ◽  
Nima Heidari ◽  
...  
Keyword(s):  
Femoral Tunnel ◽  
Demineralized Bone Matrix ◽  
Platelet Rich Plasma ◽  
Cruciate Ligament ◽  
Bone Matrix ◽  
Bone Tunnel ◽  
Bone Volume ◽  
Tunnel Widening ◽  
Micro Computed Tomography ◽  
Anterior Cruciate

Background: The effect of demineralized bone matrix (DBM), bone marrow–derived mesenchymal stromal cells (BMSCs), and platelet-rich plasma (PRP) on bone tunnel healing in anterior cruciate ligament reconstruction (ACLR) has not been comparatively assessed. Hypothesis: These orthobiologics would reduce tunnel widening, and the effects on tunnel diameter would be correlated with tunnel wall sclerosis. Study Design: Controlled laboratory study. Methods: A total of 20 sheep underwent unilateral ACLR using tendon allograft and outside-in interference screw fixation. The animals were randomized into 4 groups (n = 5 per group): Group 1 received 4mL of DBM paste, group 2 received 10 million BMSCs in fibrin sealant, group 3 received 12 mL of activated leukocyte-poor platelet-rich plasma, and group 4 (control) received no treatment. The sheep were euthanized after 12 weeks, and micro-computed tomography scans were performed. The femoral and tibial tunnels were divided into thirds (aperture, midportion, and exit), and the trabecular bone structure, bone mineral density (BMD), and tunnel diameter were measured. Tunnel sclerosis was defined by a higher bone volume in a 250-µm volume of interest compared with a 4-mm volume of interest surrounding the tunnel. Results: Compared with the controls, the DBM group had a significantly higher bone volume fraction (bone volume/total volume [BV/TV]) (52.7% vs 31.8%; P = .020) and BMD (0.55 vs 0.47 g/cm3; P = .008) at the femoral aperture and significantly higher BV/TV at femoral midportion (44.2% vs 32.9%; P = .038). There were no significant differences between the PRP and BMSC groups versus controls in terms of trabecular bone analysis or BMD. In the controls, widening at the femoral tunnel aperture was significantly greater than at the midportion (46.7 vs 41.7 mm2; P = .034). Sclerosis of the tunnel was common and most often seen at the femoral aperture. In the midportion of the femoral tunnel, BV/TV ( r = 0.52; P = .019) and trabecular number ( r S = 0.50; P = .024) were positively correlated with tunnel widening. Conclusion: Only DBM led to a significant increase in bone volume, which was seen in the femoral tunnel aperture and midportion. No treatment significantly reduced bone tunnel widening. Tunnel sclerosis in the femoral tunnel midportion was correlated significantly with tunnel widening. Clinical Relevance: DBM might have potential clinical use to enhance healing in the femoral tunnel after ACLR.

scholarly journals Bioresorbable Stent in Anterior Cruciate Ligament Reconstruction

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1961
Author(s):  
Krzysztof Ficek ◽  
Jolanta Rajca ◽  
Mateusz Stolarz ◽  
Ewa Stodolak-Zych ◽  
Jarosław Wieczorek ◽  
...  
Keyword(s):  
Anterior Cruciate Ligament ◽  
Acl Reconstruction ◽  
Cruciate Ligament ◽  
Healing Process ◽  
Tendon Graft ◽  
Bone Tunnel ◽  
Control Group ◽  
Microstructural Parameters ◽  
Beneficial Effects ◽  
Anterior Cruciate

The exact causes of failure of anterior cruciate ligament (ACL) reconstruction are still unknown. A key to successful ACL reconstruction is the prevention of bone tunnel enlargement (BTE). In this study, a new strategy to improve the outcome of ACL reconstruction was analyzed using a bioresorbable polylactide (PLA) stent as a catalyst for the healing process. The study included 24 sheep with 12 months of age. The animals were randomized to the PLA group (n = 16) and control group (n = 8), subjected to the ACL reconstruction with and without the implantation of the PLA tube, respectively. The sheep were sacrificed 6 or 12 weeks post-procedure, and their knee joints were evaluated by X-ray microcomputed tomography with a 50 μm resolution. While the analysis of tibial and femoral tunnel diameters and volumes demonstrated the presence of BTE in both groups, the enlargement was less evident in the PLA group. Also, the microstructural parameters of the bone adjacent to the tunnels tended to be better in the PLA group. This suggested that the implantation of a bioresorbable PLA tube might facilitate osteointegration of the tendon graft after the ACL reconstruction. The beneficial effects of the stent were likely associated with osteogenic and osteoconductive properties of polylactide.

scholarly journals BIOMECHANIC STUDY OF GRAFT BONE TUNNEL MODEL IN ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION USING INTRATUNNEL ALLOGENIC BONE MARROW MESENCHYMAL STEM CELLS (BM-MSCs) AND VASCULAR ENDOTHELIAL GROWTH FACTOR (VEGF)

2018 ◽  
Vol 2 (1) ◽  
Author(s):  
Brian Vicky Faridyan
Keyword(s):  
Vascular Endothelial Growth Factor ◽  
Anterior Cruciate Ligament ◽  
Cruciate Ligament ◽  
Bone Tunnel ◽  
Control Group ◽  
Vascular Endothelial ◽  
Allogenic Bone ◽  
Allogenic Bone Marrow ◽  
Anterior Cruciate ◽  
Tension Strength

Successful anterior cruciate ligament (ACL) reconstruction using tendon graft requires good and rapid integration between the tendon graft and the bone tunnel. The strength of the tendon-bone tunnel graft in the initial phase is very important to facilitate aggressive rehabilitation and as early as possible to support rapid recovery to normal activities. The objective of this study was to determine ultimate tension strength (UTS) on the femoral tendon-bone tunnel graft model after reconstruction of anterior cruciate ligament (ACL) by administering allogenic bone marrow mesenchymal stemcells (BM-MSCs) and vascular endothelial growth factor (VEGF) intratunnel in experimental animals. The design of this research was Post-Test Only Control Group Design using 24 rabbits divided into treatment and control group. Biomechanical evaluation was done at week 3 and 6. Evaluation at week 3 found ultimate tension strength of treatment group significantly higher than control (p <0,05). In the 6th week evaluation, Ultimate tension strength was found that the treatment group significantly higher than the control group (p <0.05). Ultimate tension strength at week 3 did not differ significantly with week 6 (p> 0.05). Intravenous administration of BM-MSCs and VEGF on ACL reconstruction increased ultimate tension strength in graft-bone tunnel significantly since week 3. The study of Ferdiansis et al using BM-MSCs and VEGF intraarticular, only showed a significant increase in ultimate tension strength in graft-bone tunnel since week 6. Comparison of this method indicates acceleration in incorporation of tendon graft with bone tunnel on intratunnel method better thaninvitro intraarticular method.Keywords : Anterior cruciate ligament, allogenic bone marrow mesenchymal stem cells, vascular endothelial growth factor and biomechanic study.

High-Voltage Scanning Electron Microscopy

1970 ◽  
Vol 28 ◽  
pp. 6-7
Author(s):  
J. M. Cowley
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Scanning Transmission Electron Microscopy ◽  
Wave Optics ◽  
Contrast Effects ◽  
Transmission Electron ◽  
Mode Of Operation ◽  
Scanning Transmission ◽  
Types Of Information ◽  
Voltage Scanning

The comparison of scanning transmission electron microscopy (STEM) with conventional transmission electron microscopy (CTEM) can best be made by means of the Reciprocity Theorem of wave optics. In Fig. 1 the intensity measured at a point A’ in the CTEM image due to emission from a point B’ in the electron source is equated to the intensity at a point of the detector, B, due to emission from a point A In the source In the STEM. On this basis it can be demonstrated that contrast effects In the two types of instrument will be similar. The reciprocity relationship can be carried further to include the Instrument design and experimental procedures required to obtain particular types of information. For any. mode of operation providing particular information with one type of microscope, the analagous type of operation giving the same information can be postulated for the other type of microscope. Then the choice between the two types of instrument depends on the practical convenience for obtaining the required Information.

Imaging and diffraction modes in Scanning Transmission Electron Microscopy

1986 ◽  
Vol 44 ◽  
pp. 684-687
Author(s):  
J. M. Cowley ◽  
R. Glaisher ◽  
J. A. Lin ◽  
H.-J. Ou
Keyword(s):  
Scanning Transmission Electron Microscopy ◽  
High Efficiency ◽  
Fiber Optic ◽  
Image Intensifier ◽  
Detector System ◽  
Detector Plane ◽  
Secondary Electrons ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Special Detector

Some of the most important applications of STEM depend on the variety of imaging and diffraction made possible by the versatility of the detector system and the serial nature, of the image acquisition. A special detector system, previously described, has been added to our STEM instrument to allow us to take full advantage of this versatility. In this, the diffraction pattern in the detector plane may be formed on either of two phosphor screens, one with P47 (very fast) phosphor and the other with P20 (high efficiency) phosphor. The light from the phosphor is conveyed through a fiber-optic rod to an image intensifier and TV system and may be photographed, recorded on videotape, or stored digitally on a frame store. The P47 screen has a hole through it to allow electrons to enter a Gatan EELS spectrometer. Recently a modified SEM detector has been added so that high resolution (10Å) imaging with secondary electrons may be used in conjunction with other modes.

Scanning Transmission Electron Microscopy of Polyethylene Crystals

1980 ◽  
Vol 38 ◽  
pp. 242-245
Author(s):  
F. Khoury ◽  
L. H. Bolz
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Crystallization Temperature ◽  
Scanning Transmission Electron Microscopy ◽  
Growth Habit ◽  
Lateral Growth ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Growth Habits

The lateral growth habits and non-planar conformations of polyethylene crystals grown from dilute solutions (<0.1% wt./vol.) are known to vary depending on the crystallization temperature.1-3 With the notable exception of a study by Keith2, most previous studies have been limited to crystals grown at <95°C. The trend in the change of the lateral growth habit of the crystals with increasing crystallization temperature (other factors remaining equal, i.e. polymer mol. wt. and concentration, solvent) is illustrated in Fig.l. The lateral growth faces in the lozenge shaped type of crystal (Fig.la) which is formed at lower temperatures are {110}. Crystals formed at higher temperatures exhibit 'truncated' profiles (Figs. lb,c) and are bound laterally by (110) and (200} growth faces. In addition, the shape of the latter crystals is all the more truncated (Fig.lc), and hence all the more elongated parallel to the b-axis, the higher the crystallization temperature.

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