102 research outputs found
Peripheral nerve regeneration inside collagen-based artificial nerve guides in humans
No full textPurpose: Nerve gap injuries may be associated with lesions in other structures, like tendons or bones; in these cases, it is common to plan a second surgery to improve functional recovery. Since macroscopic observations of nerve regeneration in humans are rare, we exploited these second surgeries for the purpose of studying nerve regeneration in humans. Methods: We assessed the clinical outcomes of 50 implants of collagen-based nerve guides in the upper limb. We performed a second look at 20, assessing macroscopically both nerve regeneration and collagen degradation. Results and Conclusions: Pain was never recorded in these patients. An adequate sensory recovery took place whenever nerve regeneration was found inside the guide. Motor recovery seemed to occur only when the gap lesion was shorter than 10 mm. The degree of degradation appeared to be variable and was not directly correlated with time; we hypothesize that it could be associated with the site of implantation. Such a large number of second looks in humans has never been previously reported in the literature
Combining back scattered and secondary emission scanning electron microscopy to study articular cartilage morphology on undecalcified unstained samples: a descriptive study
No full textBACKGROUND: The use of undecalcified and unstained samples for articular cartilage’s study (as Authors suggest) will enable
to better preserve its three-dimensional structure. Feasibility of such approach will reduce time and complexity when analyzing a
great number of specimens.
OBJECTIVE: To test the possibility of studying articular cartilage morphology on the undecalcified inclusion blocks, avoiding
cutting and staining thin sections.
METHODS: Femoral condyles were obtained from White New Zealand rabbits and from Sardinian sheep, fixed in
paraformaldehyde, dehydrated in ethyl alcohol, and embedded into poly-methylmethacrylate. Blocks were cut and ground,
sputter-coated with gold-palladium and analyzed by a Jeol JSM 6310 electron microscope, operated between 20 and 25 kV. Data
from secondary emission scanning electron microscopy were combined with data from back scattered electron microscopy
(BSEM), performed sequentially over the same area.
RESULTS AND CONCLUSION: In the rabbit, it was easy to discern the passage between uncalcified and calcified cartilage but it
was difficult to highlight the small chondrocytic lacunae in zones II and III. The sheep proved to be more suitable for easily
discerning all the zones of articular cartilage and its cellularity; BSEM excelled in defining the structure of calcified cartilage and
the “tidemark” front. Large canals could be demarcated, digged through subchondral bone and calcified cartilage, topped by
non-calcified cartilage. The results suggested that the possibility of describing articular cartilage morphology on undecalcified and
unstained embedding blocks, by avoiding the cutting of thin sections, was illustrated. This provides an obvious advantage in terms
of less time needed and less complexity required in comparison with classical histomorphology. It may be an opportunity when a
relevant number of samples must be analyzed
Combining back scattered and secondary emission scanning electron microscopy to study articular cartilage morphology on undecalcified unstained samples: a descriptive study
No full textA degradable soybean-based biomaterial used effectively as a bone filler in vivo in a rabbit
No full textThe 'gold standard' for bone filling is currently the bone autograft, but its use is limited by material availability and by the possible risks of infection or other donor site morbidity. Materials proposed so far as bone fillers do not show all the characteristics which are desirable. These are (a) osteoconductivity, (b) controlled biodegradation and (c) ease of adaptation to the implantation site. Recently, a new class of biodegradable material based on soybeans has been presented which shows good mechanical properties and an intrinsic bioactivity on inflammatory and tissue cells in vitro. The authors investigated the morphology in vivo of bone response in repairing a surgical lesion in the presence of granules of a novel soybean-based biomaterial (SB), comparing it with a sham-operated contralateral lesion of critical size (non-healing model); 26 operations were performed in New Zealand White rabbits, with back scattered electron microscopy as the analysis technique of choice. Implantation of SB granules over 8 weeks produced bone repair with features distinct from those obtained by healing in a non-treated defect. New and progressively maturing trabeculae appeared in the animal group where SB granules were implanted, while sham operation produced only a rim of pseudo-cortical bone still featuring a large defect. The trabeculae forming in the presence of SB granules had features typical of reticular bone. These findings suggest that the bone regeneration potential of SB granules and their intrinsic bioactivity, combined with their relatively easy and cost-effective preparation procedures, make them suitable candidates as a bone filler in clinical applications
Three-dimensional four variables plot for the study of the metacarpo-phalangeal joint kinematics
No full textF. Shuind, K.N. An, W.P. Cooney III, M. Garcia-Elias Editor
“Ruffled border” formation on a CaP-free substrate: A first step towards osteoclast-recruiting bone-grafts materials able to re-establish bone turn-over
No full textOsteoclasts are large multinucleated giant cells that actively resorb bone during the physiological bone turnover (BTO), which is the continuous cycle of bone resorption (by osteoclasts) followed by new bone formation (by osteoblasts). Osteoclasts secrete chemotactic signals to recruit cells for regeneration of vasculature and bone. We hypothesize that a biomaterial that attracts osteoclasts and re-establishes BTO will induce a better healing response than currently used bone graft materials. While the majority of bone regeneration efforts have focused on maximizing bone deposition, the novelty in this approach is the focus on stimulating osteoclastic resorption as the starter for BTO and its concurrent new vascularized bone formation. A biodegradable tyrosine-derived polycarbonate, E1001(1k), was chosen as the polymer base due to its ability to support bone regeneration in vivo. The polymer was functionalized with a RGD peptide or collagen I, or blended with β-tricalcium phosphate. Osteoclast attachment and early stages of active resorption were observed on all substrates. The transparency of E1001(1k) in combination with high resolution confocal imaging enabled visualization of morphological features of osteoclast activation such as the formation of the “actin ring” and the “ruffled border”, which previously required destructive forms of imaging such as transmission electron microscopy. The significance of these results is twofold: (1) E1001(1k) is suitable for osteoclast attachment and supports osteoclast maturation, making it a base polymer that can be further modified to optimize stimulation of BTO and (2) the transparency of this polymer makes it a suitable analytical tool for studying osteoclast behavior. [Figure not available: see fulltext.]
Fibrin glue as a stabilization strategy in peripheral nerve repair when using porous nerve guidance conduits
No full textAbstract: Porous conduits provide a protected pathway for nerve regeneration, while still allowing exchange of nutrients and wastes. However, pore sizes >30 μm may permit fibrous tissue infiltration into the conduit, which may impede axonal regeneration. Coating the conduit with Fibrin Glue (FG) is one option for controlling the conduit’s porosity. FG is extensively used in clinical peripheral nerve repair, as a tissue sealant, filler and drug-delivery matrix. Here, we compared the performance of FG to an alternative, hyaluronic acid (HA) as a coating for porous conduits, using uncoated porous conduits and reverse autografts as control groups. The uncoated conduit walls had pores with a diameter of 60 to 70 μm that were uniformly covered by either FG or HA coatings. In vitro, FG coatings degraded twice as fast as HA coatings. In vivo studies in a 1 cm rat sciatic nerve model showed FG coating resulted in poor axonal density (993 ± 854 #/mm2), negligible fascicular area (0.03 ± 0.04 mm2), minimal percent wet muscle mass recovery (16 ± 1 in gastrocnemius and 15 ± 5 in tibialis anterior) and G-ratio (0.73 ± 0.01). Histology of FG-coated conduits showed excessive fibrous tissue infiltration inside the lumen, and fibrin capsule formation around the conduit. Although FG has been shown to promote nerve regeneration in non-porous conduits, we found that as a coating for porous conduits in vivo, FG encourages scar tissue infiltration that impedes nerve regeneration. This is a significant finding considering the widespread use of FG in peripheral nerve repair. Graphical Abstract: [InlineMediaObject not available: see fulltext.
Distal radius fractures: treatment using the Epibloc system
No full text: The Epibloc system of percutaneous endomedullary internal fixation is best indicated for AO type A2-3 extra-articular fractures of the distal radius and AO type C1 slightly comminuted articular fractures. This system includes pins that can be inserted into the medullary canal and advanced without breaking through the second cortex. This fixation is stabilised by an external plate and rendered dynamic by the pins' elasticity which compresses the fractured surfaces. Moreover, this system results in transversal ligamentotaxis which helps prevent secondary reduction losses. The result of a preliminary series of 326 cases is evaluated
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