Synthetic Graft Research Articles

Fucoidan and topography modification improved in situ endothelialization on acellular synthetic vascular grafts.

Thrombogenesis remains the primary failure of synthetic vascular grafts. Endothelial coverage is crucial to provide an antithrombogenic surface. However, most synthetic materials do not support cell adhesion, and transanastomotic endothelial migration is limited. Here, a surface modification strategy using fucoidan and topography was developed to enable fast in situ endothelialization of polyvinyl alcohol, which is not endothelial cell-adhesive. Among three different immobilization approaches compared, conjugation of aminated-fucoidan promoted endothelial monolayer formation while minimizing thrombogenicity in both in vitro platelet rich plasma testing and ex vivo non-human primate shunt assay. Screening of six topographical patterns showed that 2μm gratings increased endothelial cell migration without inducing inflammation responses of endothelial cells. Mechanistic studies demonstrated that fucoidan could attract fibronectin, enabling integrin binding and focal adhesion formation and activating focal adhesion kinase (FAK) signaling, and 2μm gratings further enhanced FAK-mediated cell migration. In a clinically relevant rabbit carotid artery end-to-side anastomosis model, 60% in situ endothelialization was observed throughout the entire lumen of 1.7mm inner diameter modified grafts, compared to 0% of unmodified graft, and the four-week graft patency also increased. This work presents a promising strategy to stimulate in situ endothelialization on synthetic materials for improving long-term performance.

Evaluation of the original sealant with antibacterial effect for synthetic vascular grafts

Background: Vascular graft infection is a severe cardiovascular complication with high mortality rates. Antibacterial vascular graft coatings are widely used and continue to be improved.Objective: To develop a sealant with antimicrobial effect for Dacron vascular grafts and experimentally test the coating properties.Methods: We used 2 types of vascular grafts: graft No. 1 (plain weave) with initial water permeability of 78.8 ± 2.7 mL/cm2/min and graft No. 2 (2/1 twill + 6/4 satin weave) with water permeability of 549.8 ± 20.7 mL/cm2/min. We developed an original gelatin impregnation technique, tested it using a scanning electron microscopy, and measured water permeability and kink radius. We evaluated the antibacterial activity of vancomycin and gelatin impregnation by the disk diffusion test using media with Staphylococcus aureus ATCC 29213 and Enterococcus faecalis ATCC 29212 and measured inhibition zones after 24-hour incubation. We used samples cut out of grafts with vancomycin-containing (experimental group) and no vancomycin-containing (control group) impregnation.Results: The gelatin coating of the samples is visualized as a thin even film and provides zero water permeability. On the negative side, it increased stiffness and the kink radius. Thanks to vancomycin added to the coating, bacterial growth significantly inhibits: the mean diameter of the growth inhibition zone for Staphylococcus aureus and Enterococcus faecalis was 15.60 ± 0.65 and 14.40 ± 0.66 mm, respectively. The grafts untreated with vancomycin showed no growth inhibition zones.Conclusion: Vascular graft treatment with gelatin impregnation and vancomycin solution is a simple measure to prevent the growth of gram-positive bacteria on vascular grafts. Received 14 November 2022. Revised 15 December 2022. Accepted 19 December 2022. Funding: The work was supported by Russian Science Foundation (project No. 22-15-20005). Conflict of interest: The authors declare no conflict of interest. Contribution of the authorsConception and study design: I.Yu. Zhuravleva, A.A. Shadanov, D.A. SirotaData collection and analysis: A.A. Shadanov, L.M. Samoylova, S.V. Vladimirov, T.P. Timchenko, N.E. Luchnikov, E.V. KarpovaStatistical analysis: A.A. ShadanovDrafting the article: A.A. Shadanov, L.M. Samoylova, T.P. Timchenko, A.G. EdemskiyCritical revision of the article: D.A. Sirota, I.Yu. Zhuravleva, A.V. Bogachev-Prokofiev, A.M. ChernyavskiyFinal approval of the version to be published: A.A. Shadanov, I.Yu. Zhuravleva, L.M. Samoylova, T.P. Timchenko, S.V. Vladimirov, E.V. Karpova, N.E. Luchnikov, D.A. Sirota, A.G. Edemskiy, A.V. Bogachev-Prokofiev, A.M. Chernyavskiy

Injectable Synthetic Beta-Tricalcium Phosphate/Calcium Sulfate (GeneX) for the Management of Contained Defects Following Curettage of Benign Bone Tumours.

Benign and low-grade malignant bone tumours are often treated with curettage and filling of the resultant defect using any of a number of materials, including autologous bone grafts, allografts, or synthetic materials. The objective of this study was to report our experience using a synthetic bone graft substitute in these patients. Ten consecutive cases (four males, six females; mean age, 36 years) of benign bone tumours were treated surgically at a tertiary musculoskeletal oncology centre, between 2019 and 2021. Following curettage, the contained defects were managed with injectable beta-tricalcium phosphate/calcium sulfate (GeneX; Biocomposites Ltd., Keele, UK). The desired outcomes were early restoration of function and radiographic evidence of healing. No other graft materials were used in any of the patients. The mean follow-up was 24 months (range, 20-30 months). All patients in this series (100%) demonstrated radiographic evidence of healing and resumed their daily living activities. There were no tumour recurrences and no complications were encountered with the use of GeneX. In patients with contained defects following curettage of benign bone tumours, we found GeneX to be a safe and effective filling agent. These findings contrast with some existing studies that have reported local complications with the use of injectable beta-tricalcium phosphate/calcium sulfate.

Modified transaponeurotic method of allograft fixation in plastic surgery of median ventral hernias

A new method for fixing a synthetic graft in preperitoneal plastic surgery of median ventral hernias has been developed. The suggested method was used by us in 32 patients aged 29–75 (the main group). The size of the hernial orifice did not exceed 3 cm in diameter, the size of the hernial sac — 4–5 cm. 28 patients aged 31–74 (the control group) were operated on with the imposition of transaponeurotic sutures in the standard way. According to the main clinical characteristics, both groups were comparable. Among the evaluated indicators, the most significant were the absence of recurrence of hernias in the period from 1 to 5 years in both groups; the absence of postoperative complications in the main group; 2 cases (7.1%) of the postoperative wound hematoma in the control group (the differences are statistically significant); the reduction of the average length of hospital stay after surgery in the main group to 7.0 ± 0.2 days, and in the control group — 8.0 ± 0.1 days (the differences are statistically significant).

Корпоропластика синтетическим графтом при фибропластической индурации полового члена.

Introduction. Peyronie's disease is a multifactorial disease leading to various types of penile deformities. Surgical treatment is the most effective method of correcting erectile deviation. In patients with preserved erectile function the technique of plaque incident with grafting is widely used, in the presence of erectile dysfunction phalloprosthesis with plaque incident and grafting should be performed. The question of the choice of material for defect replacement in surgical treatment of Peyronie's disease is relevant, because today none of the used grafts is a reference. Aim of the study. Evaluation of the results of corporoplasty using synthetic grafts in patients with Peyronie's disease. Materials and methods. 11 patients underwent corporoplasty using a synthetic graft made of modified polytetrafluoroethylene (ePTFE), in 4 cases this technique was combined with falloprosthetics. Results. Erectile deviation was eliminated in all patients. At the same time, no early and long-term complications were noted during the follow-up. All patients were satisfied with the outcome of the surgical intervention. Conclusion. Synthetic grafts can be used for surgical treatment of Peyronie's disease with the achievement of a positive effect. The use of this material in the treatment of Peyronie's disease requires further study.

Evaluation of vascular repair by tissue-engineered human acellular vessels or expanded polytetrafluoroethylene grafts in a porcine model of limb ischemia and reperfusion.

This study evaluated performance of a tissue-engineered human acellular vessel (HAV) in a porcine model of acute vascular injury and ischemia. The HAV is an engineered blood vessel consisted of human vascular extracellular matrix proteins. Limb reperfusion and vascular outcomes of the HAV were compared with those from synthetic expanded polytetrafluoroethylene (ePTFE) grafts. Thirty-six pigs were randomly assigned to four treatment groups, receiving either the HAV or a PTFE graft following a hind limb ischemia period of either 0 or 6 hours. All grafts were 3-cm-long interposition 6-mm diameter grafts implanted within the right iliac artery. Animals were not immunosuppressed and followed for up to 28 days after surgery. Assessments performed preoperatively and postoperatively included evaluation of graft patency, hind limb function, and biochemical markers of tissue ischemia or reperfusion injury. Histological analysis was performed on explants to assess host cell responses. Postoperative gait assessment and biochemical analysis confirmed that ischemia and reperfusion injury were caused by 6-hour ischemia, regardless of vascular graft type. Hind limb function and tissue damage biomarkers improved in all groups postoperatively. Final patency rates at postoperative day 28 were higher for HAV than for ePTFE graft in both the 0-hour (HAV, 85.7%; ePTFE, 66.7%) and 6-hour (HAV, 100%; ePTFE, 75%) ischemia groups, but these differences were not statistically significant. Histological analyses identified some intimal hyperplasia and host reactivity to the xenogeneic HAV and also to the synthetic ePTFE graft. Positive host integration and vascular cell infiltration were identified in HAV but not ePTFE explants. Based on the functional performance and the histologic profile of explanted HAVs, this study supports further investigation to evaluate long-term performance of the HAV when used to repair traumatic vascular injuries.

Six different surgical method options according to etiology in repair of arteriovenous fistula aneurysms

Aim: This study aims to evaluate the considerations that should be taken into account when choosing a surgical method and the early results of six methods used for repair in patients who underwent surgical repair due to arteriovenous fistula (AVF) aneurysms. Material and Methods: One hundred and five patients who underwent AVF aneurysm repair between 2012 and 2020 were reviewed retrospectively. Methods for surgical repair were used according to the etiology: Plication, Arteriotomy constrictions and plication, Aneurysm excision and creation of a new fistula, Saphenous vein or synthetic graft interposition, End-to-end anastomosis and plication after aneurysm excision, Banding method. Results: Sixty-one of the cases were male and 44 were female. The mean age was 56.6 (27-75) years. The total number of surgeries was 119, including the surgeries and reoperations performed in 2 planned sessions. As surgical method, 44 Plication, 13 Arteriotomy constrictions and plication, 10 Aneurysm excision and creation of a new fistula, 25 Saphenous vein or synthetic graft interposition, 13 End-to-end anastomosis and plication after aneurysm excision and 14 Banding methods were used. AVF flow of 38 patients was measured to be over 1700 ml/min, and 34 of these patients had an arteriotomy length of more than 7 mm. In patients who underwent repair due to high flow rate, an average of 30-65% flow reduction was achieved compared to the preoperative period. In the first postoperative 3 months, 7 (6%) patients required reoperation. Fistula loss did not occur in any of the patients who underwent repair. Conclusion: The etiology of aneurysm, flow rate, aneurysm localization, and the presence of intimal hyperplasia or chronic thrombus are important in choosing an aneurysm repair method. We think that the results will be positively affected if the surgical method is determined according to the association of one or few of these factors.

Arthroscopic Superior Capsule Reconstruction With Combined Fascia Lata Autograft and Synthetic Scaffold Patch Graft for the Treatment of Irreparable Rotator Cuff Tears Yields Favorable Clinical and Radiographic Outcomes at Minimum 2-Year Follow-Up

To report the results of the arthroscopic superior capsule reconstruction (ASCR) technique with a combined fascia lata autograft and synthetic scaffold patch graft for irreparable massive rotator cuff tears (RCTs). The period for this retrospective study was between December 2016 and December 2020. The criteria for inclusion were patients treated arthroscopically for an incompletely repaired massive RCT (dimension >5 cm and 2 tendons fully torn, intact or reparable subscapularis tendons and teres minor tendon with or without irreparable infraspinatus, a radiological Hamada classification between grade 0 and 4, and a minimum 24-month postoperative follow-up). Clinical outcomes were evaluated preoperatively and at a final follow-up by a visual analog scale (VAS) for pain and range of motion along with the American Shoulder and Elbow Surgeons score (ASES), the University of California Los Angeles score (UCLA), and the Constant-Murley score (CMS). Radiological outcomes were assessed, according to the rotator cuff arthropathy (RCA) and the acromiohumeral distance (AHD) stages. Graft integrity and muscle fatty infiltration were evaluated by magnetic resonance imaging (MRI). A total of 43 patients were enrolled in the study with a mean follow-up duration of 45.6 months (range: 24 to 64). All clinical scores also improved at the 2-year follow-up (mean: VAS 0.7 [SD 0.7] vs 5.4 [SD 1.1]; P < .001; mean: ASES 92.6 [SD 8.0] vs 34.8 [SD 13.4]; P < .001; mean UCLA 31.5 [SD 3.9] vs 11.0 [SD 3.2]; P < .001; and mean CMS 86.6 [SD 7.2] vs 40.0 [SD 11.6]; P < .001), and 39 of 43 fascia lata grafts were fully intact on MRI (91%). ASCR with a combined fascia lata autograft and synthetic scaffold patch graft resulted in good functional outcomes, with a high rate of graft healing at the 2-year follow-up. All patients achieved clinically relevant improvement (met minimal clinically important differences [MCID]) on ASES, UCLA, and VAS with improved abduction strength restoration. Level IV, retrospective case series.

The influence of pregelatinized starch on the rheology of a gellan gum-collagen IPN hydrogel for 3D bioprinting

Hydrogel scaffolds infused with stem cells are valuable alternatives to skin grafts in replacement of lost host tissues. In a prior study, we developed an adipose-derived stem cells (ADSC)-laden gellan gum-collagen interpenetrating network (IPN) hydrogel with enhanced wound healing properties upon application on murine full thickness burn wounds. With the perspective of enabling the clinical translation and healthcare adaptation of the hydrogel wound-dressing, we report a novel ADCS-laden collagen-gellan gum full IPN hydrogel formula compatible with 3D bioprinting technology. The stable new bio-ink showed improved printability for extrusion-based 3D biofabrication and preserved scaffold quality for stem cell proliferation. Pregelatinized starch (PGF, PREGEFLO®PI10) and glycerol were successfully incorporated to the bio-ink as molecular lubricant and hydrophilic plasticizer. When subjected to rheological measurements, the new glycerol-PGF-gellan gum composite hydrogel demonstrated good shear recovery ability, improved resistance to step-strain deformations and adequate stiffness as cell-conducive environment. Subsequently, a dual-head two-step temperature-guided 3D bioprinting methodology was developed to extrude ADSC-laden collagen into the composite hydrogel thick film to achieve in-situ polymer interpenetration. After their fabrication, the printed cell-laden hydrogel constructs were able to maintain high shape fidelity and stability after 21 days of incubation in cell culture media. Results from cell proliferation assay (MTS) and confocal laser scanning microscopy (CLSM) suggested that ADSC retained their normal cellular functions of adhesion, proliferation, and migration within the 3D bioprinted hydrogel scaffold. Taken together, our study brings forward the use of PREGEFLO®PI10 in upgrading the ADSC-laden IPN hydrogel formula towards potential clinical translation of synthetic skin grafts.

Outflow Reconstruction in Right Lobe Living Donor Liver Transplant: Middle Hepatic Vein Reconstruction Versus Separate Tributaries to Inferior Vena Cava Anastomosis

In right lobe living donor liver transplant, proper reconstruction of the segment 5 vein and segment 8 vein is essential. Herein, we compared 2 different techniques for segment 5 vein reconstruction. This prospective nonrandomized study included all recipients of modified right lobe living donor liver transplant who had reconstruction of the segment 5 vein, with or without segment 8 veins, from October 2018 to October 2021. Patients were grouped into group A (classical technique) and group B (modified technique). For group A, the segment 5 (and segment 8, if present) vein was anastomosed in an end-to-side fashion to a polytetrafluoroethylene synthetic graft positioned parallel to the cut surface of the liver graft; then, during implant, its proximal end was anastomosed to recipient's middle hepatic or middle-left hepatic veins unified orifice. In group B (modified technique), the stumps of segment 5 (and segment 8 if present) were anastomosed in an end-to-end fashion to 2 different polytetrafluoroethylene grafts; then during implant, the other ends of the segment 5 grafts were anastomosed directly to the inferior vena cava. Postoperative segment 5 vein patency and graft recovery were compared. Forty patients were included: 22 in group A and 18 group B. There were no significant differences in the demographic data or characteristics of donors, grafts, and recipients between the groups. There was better patency in segment 5 synthetic grafts in group A at all time points compared with group B, but this difference was statistically significant only at 1 month (18 [81.8%] vs 9 [50%, respectively; P = .046).There was no statistically significant difference in the markers of graft recovery in both groups. Reconstruction of the segment 5 vein by polytetrafluoroethylene synthetic graft in a fashion to resemble the native middle hepatic vein in modified right lobe living donor liver transplant has better patency than anastomosis of the segment 5 vein in an end-to-end fashion to the synthetic graft and then to the inferior vena cava. Both techniques did not affect graft recovery.

A Systematic Review on Electrospun Polymer Nanocomposites Used for Bone Tissue Engineering

Trauma, disease and various pathological conditions of bone may lead to the need of bone grafts and their substitutes to the affected patients. Bone grafting is a surgical process that repairs, rebuilds or replaces the lost bone. The main function of bone grafts is to induce osteoconduction, osteoinduction and osteogenesis along with providing the structural support for adherence and proliferation of bone cells at the implanted site. Bone grafts are available in a variety of substances broadly categorized into natural and synthetic grafts. The gold standard is autografts, where the bone from a person’s own body is used for implant. Other than autogenous grafts, allografts, xenografts and various isolated or polymer composites of calcium phosphate, tricalcium phosphate, calcium sulfate and hydroxyapatite are available. Zeroing in on an ideal bone graft for a specific clinical situation is a surmounting task as all grafts do not have the same properties. Hence, this review presents a deep study on the history of bone developments in the field of tissue engineering. It presents a thorough account on the natural and synthetic biodegradable electrospun polymers used for scaffolding purpose to engineer the bone.

Effect of moisture on the reactivity of alpha-tricalcium phosphate

The ability of the high-temperature polymorph of tricalcium phosphate, α-TCP, to hydrolyse to calcium-deficient hydroxyapatite underlies many developments in the field of synthetic bone grafts, including calcium phosphate cements, foams, and self-setting inks. The objective of the present work was to investigate the effect of humidity on α-TCP powder reactivity. The results showed that a 3-week incubation at high relative humidity (80%) had no impact on reactivity, but, as the incubation was prolonged, the powder started to hydrolyse. This reactivity was associated to the presence of defects and to an amorphous phase induced during powder milling. Moisture studies performed under static/dynamic conditions gave comparable water adsorption percentages. The dynamic studies further proved irreversible water sorption, indicating that some water molecules reacted with the powder after short incubation times. Taken together, these results demonstrate that, although α-TCP powder adsorbs water from moisture immediately, the impact on reactivity appears only after several weeks of storage.

An optical coherence tomography and endothelial shear stress study of a novel bioresorbable bypass graft

Endothelial shear stress (ESS) plays a key role in the clinical outcomes in native and stented segments; however, their implications in bypass grafts and especially in a synthetic biorestorative coronary artery bypass graft are yet unclear. This report aims to examine the interplay between ESS and the morphological alterations of a biorestorative coronary bypass graft in an animal model. Computational fluid dynamics (CFD) simulation derived from the fusion of angiography and optical coherence tomography (OCT) imaging was used to reconstruct data on the luminal anatomy of a bioresorbable coronary bypass graft with an endoluminal “flap” identified during OCT acquisition. The “flap” compromised the smooth lumen surface and considerably disturbed the local flow, leading to abnormally low ESS and high oscillatory shear stress (OSI) in the vicinity of the “flap”. In the presence of the catheter, the flow is more stable (median OSI 0.02384 versus 0.02635, p < 0.0001; maximum OSI 0.4612 versus 0.4837). Conversely, OSI increased as the catheter was withdrawn which can potentially cause back-and-forth motions of the “flap”, triggering tissue fatigue failure. CFD analysis in this report provided sophisticated physiological information that complements the anatomic assessment from imaging enabling a complete understanding of biorestorative graft pathophysiology.

A Knitted PET Patch Enhances the Maturation of Regenerated Tendons in Bridging Reconstruction of Massive Rotator Cuff Tears in a Rabbit Model

Background: Although nondegradable synthetic grafts for bridging reconstruction of massive rotator cuff tears (MRCTs) have shown satisfactory clinical outcomes, their function and details on graft-tendon healing and enthesis regeneration have not been fully studied. Hypothesis: The knitted polyethylene terephthalate (PET) patch as a nondegradable synthetic graft could provide sustained mechanical support, facilitating enthesis and tendon regeneration in the treatment of MRCTs. Study Design: Controlled laboratory study. Methods: A knitted PET patch was fabricated for bridging reconstruction (PET group) in a New Zealand White rabbit model of MRCTs (negative control group), and an autologous Achilles tendon was used as a control (autograft group). The animals were sacrificed, and tissue samples were harvested for gross observation as well as histological and biomechanical analyses at 4, 8, and 12 weeks postoperatively. Results: Histological analysis showed no significant difference in the graft-bone interface score between the PET and autograft groups at 4, 8, and 12 weeks postoperatively. Interestingly, in the PET group, Sharpey-like fibers were observed at 8 weeks, while fibrocartilage formation and the ingrowth of chondrocytes were recognized at 12 weeks. Meanwhile, the tendon maturing score was significantly higher in the PET group than in the autograft group (19.7 ± 1.5 vs 15.3 ± 1.2, respectively; P = .008) at 12 weeks, with parallel-oriented collagen fibers around the knitted PET patch. Moreover, the ultimate failure load of the PET group was similar to that of a healthy rabbit tendon at 8 weeks (125.6 ± 13.6 vs 130.8 ± 28.6 N, respectively; P > .05) and no different from that of the autograft group at 4, 8, and 12 weeks. Conclusion: The knitted PET patch could not only immediately reconstruct the mechanical support for the torn tendon postoperatively in the rabbit model of MRCTs but also enhanced maturation of the regenerated tendon by fibrocartilage formation and improved the organization of collagen fibers. Herein, the knitted PET patch could be a promising candidate graft adopted in bridging reconstruction of MRCTs. Clinical Relevance: A nondegradable knitted PET patch can safely bridge MRCTs with satisfactory mechanical strength and the promotion of tissue regeneration.

Open reduction intramedullary rod with synthetic bone graft for the treatment of radius ulna pseudoarthrosis with neurofibromatosis type 1: a case report

Background: Pseudoarthrosis is a false joint that occurs in cases of non-union and is commonly associated with neurofibromatosis. Treatment of refracture and non-union remains a challenge, and many methods have been attempted with varying results. Case Presentation: A 7-year-old, left-handed male sought consult at the Philippine Orthopedic Center (POC) last February 2016 with a complaint of left forearm deformity. This patient was diagnosed with neurofibromatosis type 1 with pseudoarthrosis of the radius and ulna. The pseudoarthrosis was treated with an application of an intramedullary rod and synthetic bone graft. Union and a full range of motion of the forearm were achieved at 1.5 years post-op. Conclusion: Pseudoarthrosis is a rare case of non-union that occurs spontaneously or after a minor trauma, most commonly associated with Neurofibromatosis Type 1. Since the condition is so rare, many methods have been attempted with varying results. Successful treatment of most atrophic non-union is achieved by optimizing the mechanical and biological environment of the pseudoarthrosis site.

Ultrasonographic Appearance of the Lower Extremity Arteries After Femoropopliteal Bypass Surgery

Objective: The aim of this study was to assess the ultrasonographic appearance of the lower extremity arteries, after a femoropopliteal bypass surgery. Materials and Methods: Ninety patients, with atherosclerotic peripheral artery disease, underwent either autologous vein (30 subjects) or synthetic femoropopliteal bypass grafting, using an end-to-side (30 subjects) or end-to-end anastomotic technique. The outcomes were compared to 30 volunteers, who were recruited to serve as healthy controls. A lower extremity duplex ultrasonogram (DUS) was performed 1 year after treatment. The healthy volunteers underwent DUS at the point of being included in the study. Results: In healthy volunteers, the angle between the profunda femoris artery (deep femoral artery, PFA) and common femoral artery (CFA) did not exceed 30° of angulation. The diameter of the CFA, in the bifurcation area, was 9.8 ± 1.5 mm. The bypass patency rates, CFA diameter, PFA angle, and neointimal hyperplasia rates differed between the groups as presented. Conclusion: The results that were obtained may indicate the importance of bypass graft surveillance, using DUS, with precise analysis of the topography and geometry of the lower extremity arteries and vascular conduits, during the perioperative period. In addition, in this cohort, femoropopliteal bypass procedures were associated with an increase in the angle of the PFA from 30° to 80° of angulation. An increase in the diameter of the CFA in the area of the proximal anastomosis from 9.8 to 15.1 mm was also noted. In these patients, the saphenous vein bypasses were associated with minimal changes of the vascular geometry and better patency rates.

Polydioxanone Membrane Compared with Collagen Membrane for Bone Regeneration

Guided bone regeneration (GBR) is an approach that induces osteopromotion through the regenerative membranes. These barriers exhibit bioactive behavior and mechanical function. Polydioxanone is a synthetic option, already used in medicine and dentistry, with good results in bone regeneration. This study aimed to evaluate bone repair in critical defects in rat calvaria using a polydioxanone membrane (Plenum® Guide) compared with a commercially available collagen-based membrane (Bio-Gide®). The bone defects were filled with Plenum® Osshp, a synthetic bone graft, hydroxyapatite:β-tricalcium phosphate, 70:30%, Group PG (Plenum® Guide + Plenum® Osshp), and Group BG (Geistlich Bio-Gide® + Plenum® Osshp). The specimens were submitted to immunohistochemical (RUNX2 and OPN), gene expression (RUNX2, IBSP, and VEGF), histometric, and microtomography analyses after 07, 15, 30, and 60 days postoperative. PG group showed greater immunolabeling area for RUNX2 and OPN, higher gene expression of VEGF (3.15 ± 0.85), and IBSP (24.9 ± 0.59). However, there was no statistical difference between groups in the histometric analysis regarding the percentage of connective tissue PG (0.83 ± 0.45), BG (0.70 ± 0.34), neoformed bone PG (0.60 ± 0.4), BG (0.65 ± 0.51), and remaining biomaterial PG (0.84 ± 0.31), BG (0.91 ± 0.33). In addition, there was no statistical difference between groups by micro-CT analysis. The absorbable-synthetic membrane, Plenum® Guide, is an effective membrane for guided bone regeneration.

The combined use of carbon nanotubes with synthetic ceramics enhances posterolateral fusion: an experimental study in a rat spinal fusion model.

The aim of the present study was to evaluate the effectiveness of carbon nanotubes (CNTs)/ HA-tricalcium phosphate (TCP) composite in a posterolateral spinal fusion model. At first, CNTs and CNTs/HA-TCP composites were prepared. Twenty adult male Sprague Dawley rats were randomized into four groups with five rats in each group. Decortication was carried out in standard manner in all animals. Group 1 (only decortication), group 2 (CNTs), group 3 (HA-TCP) and group 4 (CNTs/HA-TCP) were formed. Eight weeks later, all animals were killed and obtained fusion segments were evaluated by manual palpation, histomorphometry and micro-computed tomography (mCT). In all evaluations, highest fusion values were obtained in Group 4. In mCT investigations, bone volume/ tissue volume (BV/TV) ratio was found to be significantly higher in composite group (group 4) only compared to ceramic group (group 3) (p < 0.001). Although in Group 2, in which only CNTs were used, the ratio was found to be statistically significantly higher than group 1(p < 0.001), the difference was not considered as significant in terms of fusion and in addition in group 2, CNTs were completely surrounded by fibrous tissue, i.e., no bone formation was observed. The CNTs/HA-TCP composite is a promising synthetic bone graft substitute for spinal fusion. Although CNTs are inadequate in producing spinal fusion when they are used alone, due to their high biocompatibility due to their high biocompatibility, and multiple effect on bone regeneration, they seem to increase fusion rates significantly when they are used in combination with ceramic-based synthetic grafts.

Osteonecrosis of the Femoral Head

Avascular necrosis when occurring as osteonecrosis of the femoral head poses a challenge for hip surgeons due to the risk of collapse of the articular cartilage. The pathological process and its various stages have been classified using a number of systems to aid with diagnostic decision making and employing a variety of methods of operative intervention for appropriate indications. When there is such a plethora of manage-ment options, it highlights that there is no one “excellent” option for management of the condition. Having undertaken a scoping review, the authors conclude that surgical decision-making, based on the options available, should be tailored to patient factors (aetiology, age, collapse, etc.) and surgical skills set (microvascular surgery, pedicle grafting versus non-vascularised versus synthetic grafting). There are different hip preservation techniques in the literature with different success rates, however, from the current data available, it can be observed that vascularised techniques result in a lesser rate of conversion to arthroplasty but require greater time and technical abilities in microsurgery than non-vascularised techniques.

Injured nerves respond favorably to an integrated tension- and conduit-based regenerative strategy

Introduction: Numerous synthetic, hybrid, and biological grafts and conduits have been deployed to facilitate axonal regeneration across peripheral nerve gaps. Though some strategies have showed promise, larger gaps continue to be an unsolved clinical challenge. Recent evidence suggests that tension-based strategies offer a promising alternative approach to nerve repair. However, whether and to what degree severed peripheral nerves tolerate and accommodate tension, especially in the critical early stages of intervention, is less clear.Methods: In this study, we evaluated a number of immuno-histochemical outcomes to test the hypothesis that injured rat sciatic nerves accommodate strains of up to 20%, a deformation magnitude that exceeds oft-quoted thresholds for nerve damage. We also assessed the possibility of integrating tension with conduit-based approaches for nerve repair.Results and Discussion: There were no deficits in axonal, basal laminar, or extracellular matrix morphology with tension, though proximal and distal stumps of nerves in all experimental groups displayed abnormal morphology in proximity to the site of injury. Axons of stretched nerves successfully grew through guidance conduits into the distal stump within 6 weeks of repair, thus demonstrating the feasibility of combining tension- and conduit-based regenerative strategies.