Hybrid Graft Research Articles

Early Outcomes of Adolescent ACL Reconstruction With Hybrid Hamstring Tendon Autograft-Allograft Versus Hamstring Tendon Autograft Alone.

Background:Small-diameter semitendinosus-gracilis tendon autografts may be encountered intraoperatively during anterior cruciate ligament reconstruction (ACLR); these have been shown to be at increased risk of graft rupture. One option that surgeons have pursued to reduce the theoretical failure rate of these smaller-diameter grafts is augmenting them with allograft material, thereby forming a larger-diameter hybrid autograft-allograft construct.Purpose/Hypothesis:The purpose of this study was to compare outcomes in adolescent athletes of primary ACLR using a hybrid autologous hamstring tendon and soft tissue allograft construct versus ACLR using small-diameter hamstring tendon autograft. The hypothesis was that the hybrid hamstring autograft-allograft construct would provide superior short-term results.Study Design:Cohort study; Level of evidence, 3.Methods:We performed a retrospective analysis of 47 patients aged between 12 and 20 years who underwent hybrid graft ACLR (mean diameter, 9.1 mm) at a single institution. Electronic medical records including clinic notes, radiographic images, operative notes, and pathology reports were reviewed for study analysis. A control group of 64 patients who underwent small-diameter hamstring reconstruction (mean diameter, 7.1 mm) without allograft supplementation was compiled. Corresponding clinical, radiographic, and surgical characteristics were collected for the control group to allow for comparative analysis.Results:Mean follow-up was 2.7 years for the hybrid cohort and 2.3 years for the control group. Despite a significantly larger mean graft diameter in the hybrid group as compared with the control group (P < .001), no significant difference in retear rate was seen between cohorts (hybrid, 9%; control, 13%; P = .554). Patients with hybrid anterior cruciate ligament constructs also underwent a comparable number of reoperations overall (P = .838). Functionally, all patients with adequate follow-up returned to sports, with no significant difference in time to return to sports between the groups (P = .213). Radiographically, hybrid graft constructs did not undergo a significantly larger degree of tunnel lysis (P = .126).Conclusion:A cohort of adolescents with hybrid anterior cruciate ligament grafts was shown to have retear rates and overall clinical results comparable with those of a control group that received small-diameter hamstring tendon autografts alone.

Injectable hydrogels self-assembled from oligopeptide-poly(2-methacryloyloxyethyl phosphorylcholine) hybrid graft copolymers for cell scaffolds and controlled release applications

An injectable hydrogel composed of biocompatible PMPC with PEG-attached self-assembling peptide grafts was newly prepared, and it could be used as 3D cell scaffolds and controlled-release applications.

Thoraflex hybrid as frozen elephant trunk in chronic, residual type A and chronic type B aortic dissection.

The frozen elephant trunk technique is an increasingly common treatment for extensive disease of the thoracic aorta. The objective of the study was to evaluate the outcomes of frozen elephant trunk specifically in chronic (residual) aortic dissections, focusing on downstream aortic remodelling. Between 2013 and 2019, a total of 28 patients were treated using the Vascutek Thoraflex hybrid graft at our institution for chronic dissections/post-dissection aneurysms. Immediate and follow-up outcomes were studied, as well as the changes in total aortic diameter, true lumen and false lumen diameter and the status of the false lumen at 3 different levels of the thoraco-abdominal aorta. No in-hospital or 30-day mortality was observed, temporary paraparesis rate was 7% and disabling stroke incidence was 14.3%. Freedom from all-cause mortality at 2 years was 91.6 ± 5.7%, while freedom from reintervention on the downstream aorta at 2 years was 59.1 ± 10.8%. Positive aortic remodelling was achieved in 50.0%, with an enlargement in the true lumen and a reduction of the false lumen not only at the level of the proximal descending aorta with 73.1% of complete thrombosis but also at the level of the distal descending thoracic aorta, with 41.7% of complete thrombosis. The frozen elephant trunk is a good solution in chronic (residual) downstream aortic dissections inducing positive aortic remodelling and preventing from II stage operations or allowing an endovascular approach.

Arch replacement with collared elephant trunks: The Siena approach.

ObjectiveTo illustrate our experience and results in patients with diffuse aneurysmal disease treated with arch replacement using the Siena collared graft, a device designed in 2002 to improve the elephant trunk technique. Results of the first step surgical implant and the subsequent treatment strategies, with extensive use of endovascular techniques, are reported.MethodsAll aortic arch–replacement procedures using the Siena graft between February 2002 and January 2020 were retrospectively analyzed for early and late clinical outcomes.ResultsOf 146 patients (54 women, 36.9%) with a median age of 69.1 years (interquartile range 58.4-75.0 years), 55 (37.6%) had acute/chronic dissection with false lumen aneurysmal dilatation, 91 (62.3%) had degenerative aneurysms, 45 (30.8%) were redo operations, and 14 (9.5%) had connective tissue disease. First-stage outcomes: 10.9% 30-day mortality (n = 16); 5.4% stroke (n = 8, 6 disabling, 2 nondisabling; 3 fatal); and 0.6% paraplegia. Outcomes for 113 second-stage procedures (77.3%, n = 97 endovascular [66.4%], n = 16 surgical [10.9%]) were 5.3% and 8.8% 30-day and 180-day mortality; no stroke; 10.6% paraplegia. Median follow-up was 5.7 years (range: 0-18.02 years) median survival was 16.65 years (95% lower confidence limit, 10.06 years) with no significant difference between aneurysm and dissection patients. Freedom from further treatment was 87.0% (95% confidence interval, 79.9%-94.7%) at 5 years and 71.4% (95% confidence interval, 71.4%-84.7%) at 10 years; median time to reintervention was 2.59 years (interquartile range, 0.52-5.20 years) with no difference (P = .22) between dissection and aneurysm groups.ConclusionsSiena collared graft represents a reliable platform for the treatment of diffuse aneurysmal disease. This device offers the flexibility required in the treatment of extended aortic lesions and guarantees the choice of the most appropriate approach for treatment completion. In this context, the availability of hybrid grafts has not modified the role of this device in arch surgery.

An Autograft for Anterior Cruciate Ligament Reconstruction Results in Better Biomechanical Performance and Tendon-Bone Incorporation Than Does a Hybrid Graft in a Rat Model

Background: The biomechanical and tendon-bone incorporation properties of allograft-augmented hybrid grafts for anterior cruciate ligament (ACL) reconstruction compared with traditional autografts are unknown. Hypothesis: Using an autograft for ACL reconstruction yields better results on biomechanical testing, radiographic analysis, and histological evaluation versus using a hybrid graft. Study Design: Controlled laboratory study. Methods: A total of 66 adult male Sprague Dawley rats underwent unilateral ACL reconstruction with an autograft (AT group; n = 33) or a hybrid graft (HB group; n = 33). The grafts used in both groups were harvested from the peroneus longus tendon and were fixed by suturing to the surrounding periosteum. Samples were harvested for biomechanical testing, micro–computed tomography (CT), and histological evaluation at 4, 8, and 12 weeks postoperatively. Bone tunnels on the femoral and tibial sides were divided into 3 subregions: intra-articular (IA), midtunnel (MT), and extra-articular (EA). A cylinder-like volume of interest in the bone tunnel and a tubular-like volume of interest around the bone tunnel were used to evaluate new bone formation and bone remodeling, respectively, via micro-CT. Results: In the AT group, there were significantly higher failure loads and stiffness at 8 weeks (failure load: 3.04 ± 0.40 vs 2.09 ± 0.54 N, respectively; P = .006) (stiffness: 3.43 ± 0.56 vs 1.75 ± 0.52 N/mm, respectively; P < .001) and 12 weeks (failure load: 9.10 ± 1.13 vs 7.14 ± 0.94 N, respectively; P = .008) (stiffness: 4.45 ± 0.75 vs 3.36 ± 0.29 N/mm, respectively; P = .008) than in the HB group. With regard to new bone formation in the bone tunnel, in the AT group, the bone volume/total volume (BV/TV) was significantly higher than in the HB group on the tibial side at 8 weeks (IA: 22.21 ± 4.98 vs 5.16 ± 3.98, respectively; P < .001) (EA: 19.66 ± 7.19 vs 10.85 ± 2.16, respectively; P = .030) and 12 weeks (IA: 30.50 ± 5.04 vs 17.11 ± 7.31, respectively; P = .010) (MT: 21.15 ± 2.58 vs 15.55 ± 4.48, respectively; P = .041) (EA: 20.75 ± 3.87 vs 10.64 ± 3.94, respectively; P = .003). With regard to bone remodeling around the tunnel, the BV/TV was also significantly higher on the tibial side at 8 weeks (MT: 33.17 ± 8.05 vs 15.21 ± 7.60, respectively; P = .007) (EA: 25.19 ± 6.38 vs 13.94 ± 7.10, respectively; P = .030) and 12 weeks (IA: 69.46 ± 4.45 vs 47.80 ± 6.16, respectively; P < .001) (MT: 33.15 ± 3.88 vs 13.76 ± 4.07, respectively; P < .001) in the AT group than in the HB group. Sharpey-like fibers had formed at 8 weeks in the AT group. A large number of fibroblasts withdrew at 12 weeks. In the AT group, the width of the interface was significantly narrower at 4 weeks (85.86 ± 17.49 vs 182.97 ± 14.35 μm, respectively; P < .001), 8 weeks (58.86 ± 10.99 vs 90.15 ± 11.53 μm, respectively; P = .002), and 12 weeks (42.70 ± 7.96 vs 67.29 ± 6.55 μm, respectively; P = .001) than in the HB group. Conclusion: Using an autograft for ACL reconstruction may result in improved biomechanical properties and tendon-bone incorporation compared with a hybrid graft. Clinical Relevance: Augmenting small autografts with allograft tissue may result in decreased biomechanical performance and worse tendon-bone incorporation, increasing the risk of graft failure.

HuBiogel incorporated fibro-porous hybrid nanomatrix graft for vascular tissue interfaces

Native extracellular matrix (ECM) possesses the biochemical cues to promote cell survival. However, decellularized, the ECM loses its cell supporting mechanical integrity. We report, here, a new biohybrid vascular graft fabricated from a blend of polycaprolactone (PCL), poliglecaprone (PGC), and incorporated with human biomatrix as functional materials for vascular tissue interfacing applications, thus harnessing the biochemical cues from the ECM and the mechanical integrity of the polymer blends. The fabricated fibro-porous tubular small diameter graft (i.d. = 4 mm) from electrospun polymer blend was coated with HuBiogeltm, a cocktail of collagenous matrix derived from human placenta called . The compositional, morphological, and mechanical properties of graft were measured, analyzed, and compared with a non-coated tubular PCL/PGC graft using Fourier Transform infrared spectroscopy (FTIR), x-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). BCA assay was used to calculate the protein content and coating-uniformity throughout the hybrid graft. Mechanical properties such as tensile strength (1.6 MPa), Young's modulus (2.4 MPa), burst pressure (>1900 mmHg), and suture retention strength (2.3 N) of hybrid graft were found to be comparable to native blood vessels. Protein coating has improved the hydrophilicity and the biocompatibility (cell viability and cell-attachment) enhanced with human umbilical vein endothelial cells (HUVECs) seeded in vitro onto the lumen layer of the graft over two weeks. The overall results promise this new biohybrid graft to be a potential candidate for vascular tissue interface and regeneration.

Ceramic Biologics for Bony Fusion-a Journey from First to Third Generations.

To provide information on characteristics and use of various ceramics in spine fusion and future directions. In most recent years, focus has been shifted to the use of ceramics in minimally invasive surgeries or implementation of nanostructured surface modification features to promote osteoinductive properties. In addition, effort has been placed on the development of bioactive synthetics. Core characteristic of bioactive synthetics is that they undergo change to simulate a beneficial response within the bone. This change is based on chemical reaction and various chemical elements present in the bioactive ceramics. Recently, a synthetic 15-amino acid polypeptide bound to an anorganic bone material which mimics the cell-binding domain of type-I collagen opened a possibility for osteogenic and osteoinductive roles of this hybrid graft material. Ceramics have been present in the spine fusion arena for several decades; however, their use has been limited. The major obstacle in published literature is small sample size resulting in low evidence and a potential for bias. In addition, different physical and chemical properties of various ceramics further contribute to the limited evidence. Although ceramics have several disadvantages, they still hold a great promise as a value-based graft material with being easily available, relatively inexpensive, and non-immunogenic.

New 3-zone hybrid graft: First-in-man experience in acute type I dissection

ObjectiveAcute type I aortic dissection (AAD) represents a surgical emergency with time-dependent evolving complications. Frozen elephant trunk (FET) enables false lumen exclusion downstream but is still debated in AAD due to its greater dimension of surgery. To combine the benefits of fast proximal repair with the FET benefits, a 3-zone hybrid graft was developed consisting of an ascending polyester portion, an arch noncovered stent, and a descending stent graft. Mid-term results of this new technique are presented. MethodsA total of 6 patients (age mean 69 years) with type I AAD in critical status (Penn classification B n = 5, BC n = 1) were operated between July 2016 and April 2018 using the 3-zone hybrid graft. The device was implanted on the basis of strict compassionate use. Operations were performed under distal hypothermic circulatory arrest and selective antegrade cerebral perfusion (SACP). ResultsOperative mortality was 17% (n = 1). Mean crossclamp and SACP time were 92 and 34 minutes, respectively, but came down in the last 2 cases to 75/65 crossclamp and 23/24 SACP minutes each. During follow up, mean 19 ± 12 months, one endovascular extension downstream was performed. Imaging control demonstrated no anastomotic-related proximal entry and no true lumen collapse downstream. ConclusionsThe goal to achieve fast and reliable repair of complicated type I AAD down to midthoracic level seems to be achievable. Noncovered stenting of the head vessel's origin does not cause stenosis or obstruction. A multicenter studying of this concept is next.

Frozen elephant trunk with straight vascular prosthesis.

We present a recapitulation of 15 years of experience starting with conception, inception, development, and clinical implementation and application of the E-vita open hybrid graft. Concomitantly, we delve into surgical techniques that shaped our clinical results. Introduced in February 2005, the novel "Essen I Prosthesis", was first-in-human surgically implanted. Follow on to this success, and within six months, eight further applications were performed. Once, the CE mark was attained, the prosthesis was branded as E-vita Open Prosthesis. In 2008, the blood-tight modification was introduced, and with time and clinical practice and application, the device's indications were expanded. Hence, the focus remained on managing complex thoracic aneurysmal disease and in particular acute and chronic type I aortic dissections. With the surge of our surgical experience and the integration of various surgical modifications, 30-days mortality was reduced to 12%, while morbidities such as stroke and spinal cord injury were reduced to 7% and 3%, respectively. The rate of re-intervention on distal aorta was significantly reduced; an attestation to the prosthesis's effectuated performance which contrasted proximal aortic repairs. With new additional device variations on the horizon, a wider range of patient-specific treatment options can now be offered.

Open total arch replacement with trifurcated graft and frozen elephant trunk.

The frozen elephant trunk (FET) technique was introduced in Hannover Medical School in 2001 to treat patients with complex aortic arch pathologies. Since 2012, we primarily use the trifurcated Thoraflex Hybrid FET graft. In this article, we report our experience with the trifurcated FET graft. Between November 2012 and September 2018, 211 patients underwent FET implantation with the trifurcated Vascutek Thoraflex Hybrid graft. The indications for surgery were: degenerative aneurysms in 68 patients, acute aortic dissections (AD) in 96 patients, and chronic ADs in 47 patients. And, 18% of cases were sternal re-operations. Mean cardiopulmonary bypass time, aortic cross-clamp time, and myocardial ischemia time were 262±84, 115±71, 50±26 minutes, respectively. Incidence of re-thoracotomy for bleeding, stroke, permanent paraplegia/paraparesis, prolonged ventilatory support (>96 h), and long-term dialysis were 13%, 18%, 2%, 21%, and 5%, respectively. In-hospital mortality was 12%. Follow-up was complete for 100% of patients and comprised a total of 513 patient years. The mean follow-up time was 2.2 [0-6] years. During follow-up, there were 32 aortic re-interventions distal to the FET. The survival rate at 1 and 5 years was 84% and 81%, respectively. Total aortic arch replacements with trifurcated FET can be performed with positive results. The trifurcated graft allows selective anastomosis of the supra-aortic vessels, which might result in improved hemostasis.

Results of frozen elephant trunk from the international E-vita Open registry.

Over the years, frozen elephant trunk (FET) has become the treatment of choice for multisegmental thoracic aortic disease. This multicenter study presents the evolution of FET results using the E-vita Open hybrid graft with respect to institutional experience and time. The data of International E-vita Open registry were studied according to the institutional experience of the participating centers (high- versus low-volume centers) and according to the evolution of FET treatment during time (1st period, 2005-2011 versus 2nd period, 2012-2018). Overall, 1,165 patients were enrolled in the study with a wide variety of multisegmental thoracic aortic pathologies and aortic emergencies. Participating centers determined their own surgical protocol. The overall 30-day mortality was 12%. Short- and long-term survival were higher in high- versus low-volume centers (P=0.048 and P=0.013, respectively). In the 2nd time period, cerebral complications were reduced significantly (P=0.015). Incidence of permanent spinal cord-related symptoms was reduced to 3% in the 2nd time period, but did not reach statistical significance. Hypothermic circulatory arrest time (P<0.001) and incidence of postoperative temporary renal replacement therapy (P=0.008) were significantly reduced in the 2nd time period. Ten-year survival and freedom from aortic-related death rates were 46.6% and 85.7%, respectively, for the entire group. The freedom from distal aortic re-interventions for a new or progressive residual aortic disease was 76.0%. Evolution of FET arch repair techniques with the E-vita Open graft and increasing institutional experience were associated with improved results. Progression of residual aortic disease makes close follow-up with aortic imaging mandatory in such patients.

Revision Risk of Soft Tissue Allograft Versus Hybrid Graft After Anterior Cruciate Ligament Reconstruction

Background: When a harvested hamstring autograft is deemed by the surgeon to be of inadequate diameter, the options include using the small graft, using another autograft from a different site, augmenting with an allograft (hybrid graft), using a different configuration of the graft (eg, 5- or 6-stranded), or abandoning the autograft and using allograft alone. A small graft diameter is associated with a higher revision risk, and using another autograft site includes added harvest-site morbidity; therefore, use of a hybrid graft or an allograft alone may be appealing alternative options. Revision risk for hybrid graft compared with soft tissue allograft is not known. Purpose: To evaluate the risk for aseptic revision surgery after primary anterior cruciate ligament reconstruction (ACLR) using a soft tissue allograft compared with ACLR using a hybrid graft in patients 25 years and younger. Study Design: Cohort study; Level of evidence, 3. Methods: Data from a health care system’s ACLR registry were used to identify primary isolated unilateral ACLRs between 2009 and 2016 using either a hybrid graft (hamstring autograft with soft tissue allograft) or a soft tissue allograft alone. Multivariable Cox proportional hazards regression was used to evaluate risk for aseptic revision after ACLR according to graft used after adjustment for age, allograft processing, tunnel drilling technique, and region where the primary ACLR was performed. Results: The cohort included 2080 ACLR procedures; a hybrid graft was used for 479 (23.0%) ACLRs. Median follow-up time was 3.4 years (interquartile range, 1.8-5.1 years). The crude 2-year aseptic revision probability was 5.4% (95% CI, 4.3%-6.7%) for soft tissue allograft ACLR and 3.8% (95% CI, 2.3%-6.4%) for hybrid graft ACLR. After adjustment for covariates, soft tissue allograft ACLR had a higher risk of aseptic revision during follow-up compared with hybrid graft ACLR (hazard ratio, 2.00; 95% CI, 1.21-3.31; P = .007). Conclusion: Soft tissue allografts had a 2-fold higher risk of aseptic revision compared with hybrid graft after ACLR. Future studies evaluating the indications for using hybrid grafts and the optimal hybrid graft diameter is needed.

Revision Risk Of Soft Tissue Allograft Versus Hybrid Graft Following Anterior Cruciate Ligament Reconstruction

Objectives: Prior studies have found smaller hamstring autograft diameter to be associated with a higher revision risk following anterior cruciate ligament reconstruction (ACLR). Therefore, when a harvested hamstring autograft is deemed by the surgeon to be of inadequate diameter, the options include: using the small graft, using another autograft from a different site, augmenting with an allograft (hybrid graft), or abandoning the autograft and using allograft alone. Using another autograft site includes added harvest-site morbidity, therefore utilization of an allograft to augment the autograft (hybrid) or allograft alone may be an appealing alternative option. Revision risk for hybrid graft compared to soft tissue allograft in is not known. The purpose of our study was to determine the risk for aseptic revision following soft tissue allograft ACLR compared to hybrid graft ACLR in patients 25 years and younger. Methods: Data from a healthcare system’s ACLR registry was used to conduct a cohort study. Primary isolated unilateral ACLR from 2009-2016 using either a hybrid graft (hamstring autograft + soft tissue allograft) or soft tissue allograft alone were identified. Time-to-aseptic revision surgery following primary ACLR was the primary endpoint. Multivariable Cox proportional hazard regression was used to evaluate risk for aseptic revision according to graft utilization after adjustment for age, allograft processing, tunnel drilling technique, and region where the primary ACLR was performed. Analysis censored patients at the time lost to follow-up (healthcare plan termination or death) or the end of study follow-up. A sandwich covariance matrix estimator was used to account for clustering of ACLR at the surgeon level. Results: The cohort included 2080 ACLR performed by 161 surgeons at 42 healthcare centers. Soft tissue allograft was used for 1601 (77.0%) ACLR and hybrid graft for 478 (23.0%). For the soft tissue allograft ACLR group, mean age was 19.2 (standard deviation [SD]=3.5) years, 79.1% of allografts were irradiated or chemically processed, and 50.4% of femoral tunnels were through the trans-tibial technique. For the hybrid graft ACLR group, mean age was 18.4 (SD=3.3) years, 81.5% were irradiated or chemically processed, and 72.3% of femoral tunnels were through the trans-tibial technique. Median follow-up time was 3.4 years (interquartile range=1.8-5.1 years). The crude 2-year aseptic revision probability was 5.4% (95% confidence interval [CI]=4.3-6.7) for soft tissue allograft ACLR and 3.8% (95% CI=2.3-6.4) for hybrid ACLR. After adjustment for covariates, soft tissue allograft ACLR had a higher risk of aseptic revision during follow-up compared to hybrid graft ACLR (hazard ratio=2.00, 95% CI=1.21-3.31, p=0.007). Conclusion: Soft tissue allograft had twice the risk of aseptic revision compared to hybrid graft following ACLR. Based on our findings, when faced with a hamstring autograft that is deemed to have an inadequate diameter, augmenting it with allograft tendon may be preferred over abandoning it for an allograft alone. Future study evaluating the indications and the optimal hybrid graft diameter is needed.

Comparison between Arch Zones in Modified Frozen Elephant Trunk Procedure for Complex Thoracic Aortic Diseases.

IntroductionThe aim of this study is to compare postoperative outcomes and follow-up of two different modifications facilitating surgical technique of frozen elephant trunk (FET) procedure for complex thoracic aortic diseases - zone 0 (fixation with total arch debranching) and zone 3 (fixation with islet-shape arch repair).MethodsFrom May 2012 to December 2018, data were collected from 139 patients who had been treated with FET procedure for complex thoracic aortic diseases. According to Ishimaru arch map, patients with proximal anastomotic site of hybrid graft at zone 0 and zone 3 were grouped as Group A (n=58, 41.7%) and Group B (n=81, 58.3%), respectively. Mean age of study population was 54.7±11.4 years, and 111 patients were male (79.9%).ResultsIn-hospital mortality was observed in 20 (14.4%) patients (n=12, acute type A aortic dissection, and n=4, previous aortic dissection surgery). There was no significant difference between both groups in terms of in-hospital mortality. Four patients from Group A and three patients from Group B had permanent neurological deficit (P=0.32). Three patients from both groups had transient spinal cord ischemia (P=0.334). Although mean total perfusion time was longer in Group A, duration of visceral ischemia, when compared with Group B, was shorter (P<0.001). Five-year survival rate was 82.8% in Group A and 81.5% in Group B (P=0.876).ConclusionFET procedure is a feasible repair technique in the treatment of complex aortic diseases, providing satisfactory early results. Because of its advantageous aspects, zone 0 fixation with debranching is the preferred technique in our clinic.

Hemodynamic and Metabolic Determinants of End-Organ Perfusion and Microcirculation in an Animal Model of Thoracoabdominal Aortic Repair

Introduction - Open repair of thoracoabdominal aorta (TAA) requires prolonged aortic crossclamping and extracorporeal circulation. Hybrid repair with proximal endovascular graft fixation can reduce ischemic time and eliminate the need for the pump. We measured the effects of hybrid approach on intraoperative and recovery hemodynamics in an experimental pig model. Methods - Four approaches were compared; group 1: open surgical TAA repair, group 2: 1st generation SPIDER graft, group 3: 2nd generation SPIDER with loop graft for implantation of lumbar arteries, and group 4: 3rd generation SPIDER graft with volume-based resuscitation. Hemodynamic variables, tissue perfusion, branch vessel flow, and clinical laboratory values were measured at baseline, at end-operation and at six hours (6H) postoperatively. Organ microperfusion was measured by gold-standard fluorescent microsphere (MS) technique. Data were analyzed by hierarchical linear mixed models to account for multilevel repeated measurements. Results - 27 pigs (75-85 kg) were studied. Total ischemic times were significantly longer for open grafts than SPIDER grafts for all branch vessels (p<0.0001). Branch vessel flows were not present in the OSR group during crossclamping, but recovered at clamp release and 6H postoperatively. Perfusion of the visceral organs measured by fluorescent microsphere varied significantly between baseline, post-implant and 6H postoperatively in all groups (p<0.0001). Between graft types, highly significant time-by-group interactions were observed for liver and bowel (all p<0.015). Hierarchical modeling demonstrated significant multilevel correlational influence of macro-hemodynamic changes (celiac or SMA flow and ischemic time) on microcirculation (end-organ perfusion) of hepatic and mesenteric beds (multilevel R2 0.61). Lactate levels were strongly correlated with bowel but not liver perfusion. Conclusion - Hybrid grafts significantly reduce intraoperative ischemia, end-organ perfusion abnormalities and metabolic derangements during thoracoabdominal aortic repair.

Clinical outcomes and second-look arthroscopic findings of anterior cruciate ligament reconstruction with autograft, hybrid graft, and allograft

BackgroundThere is no consensus as to the choice of grafts for primary anterior cruciate ligament (ACL) reconstruction. The purpose of this study was to compare the clinical and second-look arthroscopic outcomes after ACL reconstruction by use of autograft, hybrid graft, and γ-irradiated allograft.MethodsNinety-seven patients who underwent second-look arthroscopy after ACL reconstruction with autografts (28 patients, hamstring autograft), hybrid grafts (32 patients, hamstring autograft augmented with γ-irradiated tibialis anterior tendon allograft), or γ-irradiated allografts (37 patients, tibialis anterior tendons) were included in this study. The clinical outcomes were compared by using Lysholm score, International Knee Documentation Committee (IKDC) score, and Tegner activity score, and the side-to-side differences of KT-1000 measurement. Second-look arthroscopic findings were compared in terms of synovial coverage and graft tension.ResultsThere were no statistical significances among the three groups in Lysholm score, IKDC score, or Tegner activity score (P > 0.05). The KT-1000 examination showed more anterior laxity in the γ-irradiated allograft group than in the autograft or hybrid graft groups (P = 0.006, and P = 0.013, respectively). Two patients in the autograft group, 2 patients in the hybrid graft group and 4 patients in the allograft group were evaluated as graft failure on second-look arthroscopy. The synovial coverage was superior in the autograft group than that in the hybrid graft group or the allograft group (P = 0.013 and P = 0.010, respectively), and was comparable between the hybrid graft group and allograft group (P = 0.876). With regard to graft tension, the autograft group and hybrid group were comparable (P = 0.883) but showed better results than the allograft group (P = 0.011 and P = 0.007, respectively).ConclusionThe hamstring autografts and hybrid grafts used for ACL reconstruction produced equal efficacy but provided better knee stability than allografts. In addition, the hamstring autografts showed better synovial coverage than the other two graft types.

The Experience of ACL Reconstruction with Synthetics Ligament: Where are we now?

The dispute on artificial ligaments used for anterior cruciate ligament (ACL) reconstruction has been a long time issue. Admittedly, due to designing defects, materials deficient without creeping, viscoelasticity and biocompatibility, and incorrect surgical technique, early application of synthetic ligament in ACL reconstruction did not yield good outcomes. For a long time, a poor outcome occupied our consensus. Whilst the poignant lessons didn’t drive people to thoroughly figure out underlying reasons but amplified the fear of synthetics ligament in the ACL reconstruction. Recent 15 years, a new generation synthetic ligament, Ligament Advanced Reinforcement System (LARS) developed for ACL/PCL reconstruction has been widely used in China. There are at least 147 papers on LARS published in Chinese and over 47 SCI papers published in English. Consistently, a positive outcome has been concluded in most reports with an early return to sports and lower complication or failure rate. Cumulative failure rate from short- and mid-term follow-ups was only 2.6% according to Batty et al., which has been commended as “surprisingly impressive” by James H. Lubowitz of journal Arthroscopy. In China, LARS ligaments have been approved by CFDA since 2004 and been used for ACL reconstruction over 30,000 cases. Recently a national multi-centers clinical investigation has been done in long-term failure analysis of the ACLR with LARS, which has involved 20 Chinese clinical centers and 1146 cases with mean follow-up time of 87 months（7 years）, organized by the Chinese Artificial Ligament Study Group (CALSG), with an acceptable outcome in failure rate of 4.5% and complication rate of 4.1%. The following factors were concluded as main failure reasons, 1）incorrect surgical technique in a non-isometric ACL reconstruction, 2）lack of the graft biocompatibility and rigid screw interface fixation, 3) non-suitable indicated patients’ selection and rehabilitation program. Compared with reported long-term failure rate in auto（10%）or in allografts（24%）, the outcome of Synthetic ligament was more superior and acceptable results. Moreover, the functional evaluation and return to sports of the patients were also high satisfying, despite some complication, such as screw loose, remnant stimulation but very rear synovitis. Non-isometric tunnel position was the main failure reason which caused by surgeons tech. An ISOMETRIC surgical technique should be stressed especially in ACL reconstruction using synthetic, focused on surgeon education, instead of simply blaming the artificial graft. Based on the systemic review and our study, a modification of synthetic graft has been developed successfully in experiment, graft fixation, synthetics materials modified with Polyethylene Terephthalate (PET) which has facilitated the biocompatibility. Our clinical investigation has also focused on a near-isometric ACL reconstruction, which would decrease the graft tunnel motion and facilitate artificial graft successful. Non-isometric input will predispose the grafts easy failure because of over tension on the graft while joint moving. Carefully selected patients, proper surgical technique, and standard rehabilitation program will ensure artificial ligament successfully. We will keep devoting to innovate artificial ligaments, including tissue engineering, bio-mimics design, advanced fixation, hybrid graft designing and more precise Isometric surgical technique. Never forgetting our beginning mind, the artificial ligaments will open a new epoch in the future of ACL reconstruction.

Delivery of targeted gene therapies using a hybrid cryogel-coated prosthetic vascular graft.

ObjectivesThe success of prosthetic vascular grafts in the management of peripheral arterial disease is frequently limited by the development of anastomotic neointimal hyperplasia (ANIH), with the host response to prosthetic grafts beginning soon after implantation. To address this, we combine a platform of polyethylene terephthalate (PET) fabric with an applied cryogel layer containing biologic agents to create a bioactive prosthetic graft system, with the ability to deliver therapeutics targeting modulators of the ANIH-associated transcriptome response, along with antithrombotic agents.MethodsHybrid graft materials were synthesized by cryopolymerization of methacrylated alginate and heparin onto electrospun (ePET), knitted PET (kPET), or woven PET (wPET). Arg-Gly-Asp (RGD) peptides were added to increase cell adhesion. Scanning electron microscopy (SEM) was used to study the microstructure at 1 day, and 2, 4, and 8 weeks. Physical properties such as swelling ratio, pore connectivity, shape recovery, and stiffness were evaluated. Human aortic endothelial cell (HAoEC) adherence was visualized using confocal microscopy after 24 hours and proliferation was evaluated with a resazurin-based assay for 7 days. Confocal microscopy was used to assess delivery of adeno-associated virus (AAV-GFP) after incubation of hybrid grafts with HAoECs. Heparin activity of the materials was measured using an anti-Xa assay.ResultsSEM demonstrated large interconnected pores throughout the entire structure for all graft types, with minimal degradation of the cryogel after 8 weeks. Hybrid materials showed a trend towards increased shape recovery, increased stiffness, decreased swelling ratio, and no difference in pore connectivity. HAoECs incorporated, adhered, and proliferated over 7 days on all materials. HAoECs were successfully transduced with AAV-GFP from the hybrid graft materials. Anti-Xa assay confirmed continued activity of heparin from all materials for over 7 days.ConclusionsWe have developed a bioactive prosthetic graft system with a cryogel coating capable of delivering biologic agents with antithrombotic activity. By applying the cryogel and selected agents onto PET prior to graft implantation, this study sets the stage for the system to be individualized and tailored to the patient, with bioengineering and targeted gene therapy strategies dovetailing to create an improved prosthetic graft adaptable to emerging knowledge and technologies.

De-epithelialization of porcine tracheal allografts as an approach for tracheal tissue engineering

Replacement of large tracheal defects remains an unmet clinical need. While recellularization of acellular tracheal grafts appeared to be a viable pathway, evidence from the clinic suggests otherwise. In hindsight, complete removal of chondrocytes and repopulation of the tracheal chondroid matrix to achieve functional tracheal cartilage may have been unrealistic. In contrast, the concept of a hybrid graft whereby the epithelium is removed and the immune-privileged cartilage is preserved is a radically different path with initial reports indicating potential clinical success. Here, we present a novel approach using a double-chamber bioreactor to de-epithelialize tracheal grafts and subsequently repopulate the grafts with exogenous cells. A 3 h treatment with sodium dodecyl sulfate perfused through the inner chamber efficiently removes the majority of the tracheal epithelium while the outer chamber, perfused with growth media, keeps most (68.6 ± 7.3%) of the chondrocyte population viable. De-epithelialized grafts support human bronchial epithelial cell (BEAS-2B) attachment, viability and growth over 7 days. While not without limitations, our approach suggests value in the ultimate use of a chimeric allograft with intact donor cartilage re-epithelialized with recipient-derived epithelium. By adopting a brief and partial decellularization approach, specifically removing the epithelium, we avoid the need for cartilage regeneration.

Root coverage using a connective tissue graft with epithelial striation in combination with enamel matrix derivatives - a long-term retrospective clinical interventional study

BackgroundThe application of a connective tissue graft with epithelial striation (CTG-ES) has been shown to improve the outcome of root coverage (RC) using the coronally advanced flap (CAF) and adjunctive administration of enamel matrix derivatives (EMD). Aim of the present study was to evaluate the long-term (mean: 16.19 ± 1.80 years, range: 13 to 18 years) stability of this treatment method with special focus on the location of the gingival margin and the width of keratinized tissue (WKT).Methods16 patients (10 female, 6 male, aged 35.36 ± 14.70 years at surgery) with 25 Miller class I or II gingival recession (GR) defects were treated using the CAF combined with the CTG-ES and EMD. The clinical measurements recorded at baseline (t0), 6 months (t1), and 13 to 18 years (t2) after surgery included recession depth (RED), probing pocket depth (PPD), clinical attachment level (CAL), and WKT. In addition, the number of sites with complete RC (CRC) and the mean RC (MRC) were documented at t1 and t2. The statistical analysis was performed using a linear mixed model.ResultsThe RED (t0: 4.52 ± 1.56 mm; t1: 0.36 ± 0.76 mm; t2: 0.30 ± 0.60 mm) and CAL (t0: 6.16 ± 1.62 mm; t1: 1.86 ± 0.87 mm; t2: 1.54 ± 0.92 mm) were significantly reduced at t1 and t2 compared to t0 (p < 0.001). The PPD was significantly reduced at t2 compared to t0 (p = 0.016). The WKT (t0: 1.18 ± 1.28 mm; t1: 3.26 ± 0.98 mm; t2: 4.26 ± 1.83 mm) significantly increased from t0 to t1, from t0 to t2 (p < 0.001) and from t1 to t2 (p = 0.007). A CRC was recorded at 19 sites (76.0%) at t1 and t2. The MRC was 93.6 ± 12.8% at t1 and 93.3 ± 13.3% at t2.ConclusionsThe use of the CAF combined with CTG-ES and EMD leads to stable long-term outcomes on teeth with Miller Class I or II GR defects. The CTG-ES represents a hybrid graft with increased position stability and advantageous properties for the healing process. We assume that the ES is responsible for the increase of the WKT.