Bone Substitute Options for Spine Fusion in Patients With Spine Trauma-Part II: The Role of rhBMP.

In Part II, we focus on an important aspect of spine fusion in patients with spine trauma: the pivotal role of recombinant human bone morphogenetic protein-2 (rhBMP-2). Despite the influx of diverse techniques facilitated by technological advancements in spinal surgery, spinal fusion surgery remains widely used globally. The persistent challenge of spinal pseudarthrosis has driven extensive efforts to achieve clinically favorable fusion outcomes, with particular emphasis on the evolution of bone graft substitutes. Part II of this review aims to build upon the foundation laid out in Part I by providing a comprehensive summary of commonly utilized bone graft substitutes for spinal fusion in patients with spinal trauma. Additionally, it will delve into the latest advancements and insights regarding the application of rhBMP-2, offering an updated perspective on its role in enhancing the success of spinal fusion procedures.

Sinus floor augmentation using mineralized freeze-dried bone allograft combined with recombinant human bone morphogenetic protein-2 (rhBMP-2): A long-term retrospective study.

Background/purpose: The combination of recombinant human bone morphogenetic protein-2 (rhBMP-2) with a carrier material has not been extensively studied. This study aimed to evaluate the clinical, radiological, and histomorphometric outcomes of sinus floor augmentation using a 3:7 mixture of cancellous and cortical freeze-dried bone allografts (mixed AG) combined with rhBMP-2. Materials and methods: Mixed AG was used for sinus floor augmentation in a total of 21 patients with a residual alveolar bone height <5 mm. Among the total 47 sites, augmentation with and without rhBMP-2 was performed in 26 and 21 sites, respectively. Radiographic parameters were assessed using cone-beam computed tomography. After a six-month healing period, core biopsies were harvested for histomorphometric analysis. Results: The bone gain after healing was 13.36 ± 3.9 mm and 12.07 ± 3.8 mm in the mixed AG alone and mixed AG with rhBMP-2 groups, respectively. The survival rate of implants in both groups was 100% during the follow-up period. The proportion of newly formed bone was 24.6 ± 10.2% and 39.7 ± 18.3% in the mixed AG alone and mixed AG with rhBMP-2 groups, respectively (P < 0.05). Moreover, the percentage of residual graft material was 21.0 ± 12.2% and 9.6 ± 10.0% in the mixed AG alone and mixed AG with rhBMP-2 groups, respectively (P < 0.05). Conclusion: Mixed AG combined with rhBMP-2 could be a suitable material for sinus floor augmentation. This combination may reduce the treatment time and improve the predictability of implant placement.

Acute Rejection Rates in Vascularized Composite Allografts: A Systematic Review of Case Reports.

INTRODUCTION: Vascularized Composite Allografts (VCA) are usually performed in a full major histocompatibility complex mismatch setting, with a risk of acute rejection depending on factors such as the type of immunosuppression therapy and the quality of graft preservation. In this systematic review, we present the different immunosuppression protocols used in VCA and point out relationships between acute rejection rates and possible factors that might influence it. METHODS: This systematic review was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. We systematically searched Medline (PubMed), Embase, and The Cochrane Library between November 2022 and February 2023, using following Mesh Terms: Transplant, Transplantation, Hand, Face, Uterus, Penis, Abdominal Wall, Larynx, and Composite Tissue Allografts. All VCA case reports and reviews describing multiple case reports were included. RESULTS: We discovered 211 VCA cases reported. The preferred treatment was a combination of antithymocyte globulins, mycophenolate mofetil (MMF), tacrolimus, and steroids; and a combination of MMF, tacrolimus, and steroids for induction and maintenance treatment, respectively. Burn patients showed a higher acute rejection rate (P = 0.073) and were administered higher MMF doses (P = 0.020). CONCLUSIONS: In contrast to previous statements, the field of VCA is not rapidly evolving, as it has encountered challenges in addressing immune-related concerns. This is highlighted by the absence of a standardized immunosuppression regimen. Consequently, more substantial data are required to draw more conclusive results regarding the immunogenicity of VCAs and the potential superiority of one immunosuppressive treatment over another. Future efforts should be made to report the VCA surgeries comprehensively, and muti-institutional long-term prospective follow-up studies should be performed to compare the number of acute rejections with influencing factors.

Exploring Costimulatory Blockade-Based Immunologic Strategies in Transplantation: Are They a Promising Immunomodulatory Approach for Organ and Vascularized Composite Allotransplantation?

The field of transplantation, including the specialized area of vascularized composite allotransplantation (VCA), has been transformed since the first hand transplant in 1998. The major challenge in VCA comes from the need for life-long immunosuppressive therapy due to its non-vital nature and a high rate of systemic complications. Ongoing research is focused on immunosuppressive therapeutic strategies to avoid toxicity and promote donor-specific tolerance. This includes studying the balance between tolerance and effector mechanisms in immune modulation, particularly the role of costimulatory signals in T lymphocyte activation. Costimulatory signals during T cell activation can have either stimulatory or inhibitory effects. Interfering with T cell activation through costimulation blockade strategies shows potential in avoiding rejection and prolonging the survival of transplanted organs. This review paper aims to summarize current data on the immunologic role of costimulatory blockade in the field of transplantation. It focuses on strategies that can be applied in vascularized composite allotransplantation, offering insights into novel methods for enhancing the success and safety of these procedures.

Paediatric aortic valve replacement using decellularized allografts: a multicentre update following 143 implantations and five-year mean follow-up.

OBJECTIVES: Decellularized aortic homografts (DAH) were introduced in 2008 as a further option for paediatric aortic valve replacement (AVR). METHODS: Prospective, multicentre follow-up of all paediatric patients receiving DAH for AVR in 8 European centres. RESULTS: A total of 143 DAH were implanted between February 2008 and February 2023 in 137 children (106 male, 74%) with a median age of 10.8 years (interquartile range 6.6-14.6). Eighty-four (59%) had undergone previous cardiac operations and 24 (17%) had undergone previous AVR. The median implanted DAH diameter was 21 mm (interquartile range 19-23). The median operation duration was 348 min (227-439) with a median cardiopulmonary bypass time of 212 min (171-257) and a median cross-clamp time of 135 min (113-164). After a median follow-up of 5.3 years (3.3-7.2, max. 15.2 years), the primary efficacy end-points peak gradient (median 14 mmHg, 9-28) and regurgitation (median 0.5, interquartile range 0-1, grade 0-3) showed good results but an increase over time. Freedom from death/explantation/endocarditis/bleeding/thromboembolism at 5 years were 97.8 ± 1.2/88.7 ± 3.3/99.1 ± 0.9/100 and 99.2 ± 0.8%, respectively. Freedom from death/explantation/endocarditis/bleeding/thromboembolism at 10 years were 96.3 ± 1.9/67.1 ± 8.0/93.6 ± 3.9/98.6 ± 1.4 and 86.9 ± 11.6%, respectively. In total, 21 DAH were explanted. Seven were replaced by a mechanical AVR, 1 Ross operation was performed and a re-do DAH was implanted in 13 patients with no redo mortality. The calculated expected adverse events were lower for DAH compared to cryopreserved homograft patients (mean age 8.4 years), and in the same range as for Ross patients (9.2 years) and mechanical AVR (13.0 years). CONCLUSIONS: This large-scale prospective analysis demonstrates excellent mid-term survival using DAH with adverse event rates comparable to paediatric Ross procedures.

Five-year results from a prospective, single-arm European trial on decellularized allografts for aortic valve replacement-the ARISE Study and ARISE Registry Data.

OBJECTIVES: Decellularized aortic homografts (DAH) were introduced as a new option for aortic valve replacement for young patients. METHODS: A prospective, EU-funded, single-arm, multicentre study in 8 centres evaluating non-cryopreserved DAH for aortic valve replacement. RESULTS: A total of 144 patients (99 male) were prospectively enrolled in the ARISE Trial between October 2015 and October 2018 with a median age of 30.4 years [interquartile range (IQR) 15.9-55.1]; 45% had undergone previous cardiac operations, with 19% having 2 or more previous procedures. The mean implanted DAH diameter was 22.6 mm (standard deviation 2.4). The median operation duration was 312 min (IQR 234-417), the median cardiopulmonary bypass time was 154 min (IQR 118-212) and the median cross-clamp time 121 min (IQR 93-150). No postoperative bypass grafting or renal replacement therapy were required. Two early deaths occurred, 1 due to a LCA thrombus on day 3 and 1 due ventricular arrhythmia 5 h postoperation. There were 3 late deaths, 1 death due to endocarditis 4 months postoperatively and 2 unrelated deaths after 5 and 7 years due to cancer and Morbus Wegener resulting in a total mortality of 3.47%. After a median follow-up of 5.9 years [IQR 5.1-6.4, mean 5.5 years. (standard deviation 1.3) max. 7.6 years], the primary efficacy end-points peak gradient with median 11.0 mmHg (IQR 7.8-17.6) and regurgitation of median 0.5 (IQR 0-0.5) of grade 0-3 were excellent. At 5 years, freedom from death/reoperation/endocarditis/bleeding/thromboembolism were 97.9%/93.5%/96.4%/99.2%/99.3%, respectively. CONCLUSIONS: The 5-year results of the prospective multicentre ARISE trial continue to show DAH to be safe for aortic valve replacement with excellent haemodynamics.

Histologic wound healing in studies using different ridge preservation protocols: A review.

BACKGROUND: Alveolar ridge preservation (ARP) procedures are designed to lessen dimensional changes in the alveolar ridge after tooth extraction. Wound healing after ridge preservation involves the formation of new vital bone in the former socket, and this vital bone is important in the osseointegration of dental implants. METHODS: A series of ARP studies have been performed to help clinicians better understand the wound-healing events that occur following tooth extraction and ridge preservation. Different protocols have been examined using various materials and periods of healing time prior to implant placement. The primary aim of these studies was to ascertain the relative percentage of vital bone formation, residual graft material, and connective tissue (CT)/other at the healing site using histomorphometric examination of bone core biopsies obtained during osteotomy preparation. RESULTS: For allografts, the use of demineralized bone alone or in combination with mineralized is associated with more vital bone formation than the use of mineralized allograft alone. For mineralized allografts, the use of cortical versus cancellous bone has only minimal impact on new bone formation. Xenografts from bovine and porcine sources appear to have similar vital bone formation. Longer healing times prior to implant placement are associated with increased vital bone formation and decreased residual graft material. The most stable component in most studies is the percentage of CT/other. CONCLUSIONS: The percentage of vital bone and residual graft at ARP sites is dependent on the materials used and the length of healing time prior to obtaining core biopsies. KEY POINTS: What factors may affect the amount of new bone at the ARP site? At a time point about 4 months after ARP, the type of graft material used for ARP plays a large role in new bone formation. Studies focus on means and standard deviations, but patients often do not "follow the mean." Even if a single ARP protocol is used for all patients, there is great interindividual variability in new bone formation, and there is often variability between sites within a single patient. How long after ARP with an allograft should I wait to place an implant? Longer healing times such as 4-5 months generally provide higher amounts of vital bone formation than shorter healing times like 2-3 months. Differences in vital bone formation between ARP protocols tend to decrease with longer healing time. FDBA that contains demineralized bone, either alone or combined with mineralized FDBA, often provides higher amounts of new bone formation than 100% mineralized allograft, especially at shorter healing periods. Even a year after ARP with an allograft, residual graft material is often still present at the ARP site.

Novel Allograft in the Load-Bearing Portion of the Femoral Head.

Background: An osteochondral defect in the hip can be a painful and limiting pathologic process. The damaged joint may progress into premature osteoarthritis, further limiting a patient's functionality. Case Report: A 24-year-old male presented to the clinic with left hip pain. The patient had been involved in a motor vehicle accident 3 years prior to presentation to our clinic. His injury from the high-speed accident required intramedullary rod fixation for a right-sided (contralateral) subtrochanteric femur fracture. The patient complained of left groin pain when in a sitting position, with activities of daily living, and with exercise. He failed conservative management consisting of nonsteroidal anti-inflammatory drugs and physical therapy. Imaging on presentation demonstrated an osteochondral defect in the weight-bearing portion of the left femoral head consistent with an International Cartilage Repair Society grade 4b lesion, a cam lesion was noted on assessment of bone morphology, and magnetic resonance imaging revealed degenerative labral pathology. The patient was treated with surgical hip dislocation through a modified Hardinge approach, femoral head osteochondral allograft transplantation using a Missouri Osteochondral Preservation System (MOPS) graft, acetabuloplasty, femoral neck osteoplasty, and open labral repair. Conclusion: Femoral head osteochondral MOPS allograft transplantation is a viable technique for joint preservation in young patients with posttraumatic osteochondral defects of the femoral head.

Waitlist Outcomes in Candidates With Rare Causes of Heart Failure After Implementation of the 2018 French Heart Allocation Scheme.

BACKGROUND: In 2018, an algorithm-based allocation system for heart transplantation (HT) was implemented in France. Its effect on access to HT of patients with rare causes of heart failure (HF) has not been assessed. METHODS: In this national study, including adults listed for HT between 2018 and 2020, we analyzed waitlist and posttransplant outcomes of candidates with rare causes of HF (restrictive cardiomyopathy [RCM], hypertrophic cardiomyopathy, and congenital heart disease). The primary end point was death on the waitlist or delisting for clinical deterioration. Secondary end points included access to HT and posttransplant mortality. The cumulative incidence of waitlist mortality estimated with competing risk analysis and incidence of transplantation were compared between diagnosis groups. The association of HF cause with outcomes was determined by Fine-Gray or Cox models. RESULTS: Overall, 1604 candidates were listed for HT. At 1 year postlisting, 175 patients met the primary end point and 1040 underwent HT. Candidates listed for rare causes of HF significantly differed in baseline characteristics and had more frequent score exceptions compared with other cardiomyopathies (31.3%, 32.0%, 36.4%, and 16.7% for patients with hypertrophic cardiomyopathy, RCM, congenital heart disease, and other cardiomyopathies). The cumulative incidence of death on the waitlist and probability of HT were similar between diagnosis groups (P=0.17 and 0.40, respectively). The adjusted risk of death or delisting for clinical deterioration did not significantly differ between candidates with rare and common causes of HF (subdistribution hazard ratio (HR): hypertrophic cardiomyopathy, 0.51 [95% CI, 0.19-1.38]; P=0.18; RCM, 1.04 [95% CI, 0.42-2.58]; P=0.94; congenital heart disease, 1.82 [95% CI, 0.78-4.26]; P=0.17). Similarly, the access to HT did not significantly differ between causes of HF (hypertrophic cardiomyopathy: HR, 1.18 [95% CI, 0.92-1.51]; P=0.19; RCM: HR, 1.19 [95% CI, 0.90-1.58]; P=0.23; congenital heart disease: HR, 0.76 [95% CI, 0.53-1.09]; P=0.14). RCM was an independent risk factor for 1-year posttransplant mortality (HR, 2.12 [95% CI, 1.06-4.24]; P=0.03). CONCLUSIONS: Our study shows equitable waitlist outcomes among HT candidates whatever the indication for transplantation with the new French allocation scheme.

Enhancing the Prediction of Cardiac Allograft Vasculopathy Using Intravascular Ultrasound and Machine Learning: A Proof of Concept.

BACKGROUND: Cardiac allograft vasculopathy (CAV) is the leading cause of late graft dysfunction in heart transplantation. Building on previous unsupervised learning models, we sought to identify CAV clusters using serial maximal intimal thickness and baseline clinical risk factors to predict the development of early CAV. METHODS: This is a single-center retrospective study including adult heart transplantation recipients. A latent class mixed-effects model was used to identify patient clusters with similar trajectories of maximal intimal thickness posttransplant and pretransplant covariates associated with each cluster. RESULTS: Among 186 heart transplantation recipients, we identified 4 patient phenotypes: very low, low, moderate, and high risk. The 5-year risk (95% CI) of the International Society for Heart and Lung Transplantation-defined CAV in the high, moderate, low, and very low risk groups was 49.1% (35.2%-68.5%), 23.4% (13.3%-41.2%), 5.0% (1.3%-19.6%), and 0%, respectively. Only patients in the moderate to high risk cluster developed the International Society for Heart and Lung Transplantation CAV 2-3 at 5 years (P=0.02). Of the 4 groups, the low risk group had significantly younger female recipients, shorter ischemic time, and younger female donors compared with the high risk group. CONCLUSIONS: We identified 4 clusters characterized by distinct maximal intimal thickness trajectories. These clusters were shown to discriminate against the development of angiographic CAV. This approach allows for the personalization of surveillance and CAV-directed treatment before the development of angiographically apparent disease.

The Macrophage Landscape Across the Lifespan of a Human Cardiac Allograft.

BACKGROUND: Much of our knowledge of organ rejection after transplantation is derived from rodent models. METHODS: We used single-nucleus RNA sequencing to investigate the inflammatory myocardial microenvironment in human pediatric cardiac allografts at different stages after transplantation. We distinguished donor- from recipient-derived cells using naturally occurring genetic variants embedded in single-nucleus RNA sequencing data. RESULTS: Donor-derived tissue resident macrophages, which accompany the allograft into the recipient, are lost over time after transplantation. In contrast, monocyte-derived macrophages from the recipient populate the heart within days after transplantation and form 2 macrophage populations: recipient MP1 and recipient MP2. Recipient MP2s have cell signatures similar to donor-derived resident macrophages; however, they lack signatures of pro-reparative phagocytic activity typical of donor-derived resident macrophages and instead express profibrotic genes. In contrast, recipient MP1s express genes consistent with hallmarks of cellular rejection. Our data suggest that recipient MP1s activate a subset of natural killer cells, turning them into a cytotoxic cell population through feed-forward signaling between recipient MP1s and natural killer. CONCLUSIONS: Our findings reveal an imbalance of donor-derived and recipient-derived macrophages in the pediatric cardiac allograft that contributes to allograft failure.

Allografts use in orthopedic surgery: trend change over the past 11 years from a regional tissue bank.

Allografts are the second most transplanted tissue in medicine after blood and are now increasingly used for both primary and revision surgery. Allografts have the advantages of lower donor site morbidity, availability of multiple grafts, and shorter operative time. The Banks represents the bridge between Donor and Recipient and guarantees the quality and safety of the distributed allografts Given the increasing interest in these tissues, a retrospective analysis of data collected from the Regional Musculoskeletal Tissue Bank registry over an 11-year period (2009-2019) was conducted. The statistical analyses used were the Shapiro-Wilk normality test and a Poisson regression model. From January 2009 to December 2019, a total of 14,199 musculoskeletal tissues stored in the Regional Musculoskeletal Tissue Bank were provided for surgical allograft procedures. In 2009, the number of allografts performed was 925; this figure has steadily increased to 1599 in 2019. Epiphyses were taken as the reference tissue with an almost constant trend over the period, while a significant increase was denoted for extensor mechanism allograft, ligaments, tendons and long bone corticals (p < 0.001), processed bone tissues had no change in trend (p = 0.841). There was also a gradual decrease in the rate of microbiological positivity, as determined by bacteriological and serological tests performed on the collected tissues. This phenomenon is due to improved sampling techniques and the training of a dedicated team. Thus, we have seen how the use of allografts in orthopedic surgery has increased over the past 11 years, uniformly in terms of tissue type, except for the noticeable increase in ligamentous tissue.

Restrictive Allograft Syndrome After COVID-19 Pneumonia: A Case Report.

Chronic lung allograft dysfunction (CLAD) continues to be the leading cause of death in the long term after lung transplantation (LTx). CLAD has the following two main subtypes: bronchiolitis obliterans syndrome (BOS) and restrictive allograft syndrome (RAS). BOS features obstructive lung dysfunction, while RAS features restrictive lung dysfunction. Overall, RAS has a worse prognosis. The pathophysiology of CLAD is not fully understood; however, pulmonary infections can trigger CLAD, including coronavirus disease 2019 (COVID-19) pneumonia. Here, we describe a case of a 55-year-old female who received LTx about seven years ago and developed RAS after COVID-19 pneumonia. RAS was ultimately diagnosed based on the clinical course and imaging findings. Steroid pulse therapy and empirical antimicrobial therapy were initiated, but respiratory failure progressed, and the patient died 139 days after COVID-19 diagnosis, and 83 days after dyspnea progression. Clinicians should be aware of unusual stair-step clinical courses and imaging features in a given setting of pulmonary infection including COVID-19 to suspect CLAD in lung transplant patients.

A Comparison between Structural Allografts and Polyetheretherketone Interbody Spacers Used in Anterior Cervical Discectomy and Fusion: A Systematic Review and Meta-analysis.

Among interbody implants used during anterior cervical discectomy and fusion (ACDF), structural allografts and polyetheretherketone (PEEK) are the most used spacers. Currently, no consensus has been established regarding the superiority of either implant, with US surgeons preferring structural allografts, whereas UK surgeons preferring PEEK. The purpose of this systematic review (level of evidence, 4) was to compare postoperative and patient-reported outcomes between the use of structural allografts PEEK interbody spacers during ACDF. Five electronic databases (PubMed, Embase, Scopus, Web of Science, and Cochrane) were searched for articles comparing the usage of structural allograft and PEEK interbody spacers during ACDF procedures from inception to April 10, 2023. The searches were conducted using the keywords "Spine," "Allograft," and "PEEK" and were performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines. Subsequent quality and sensitivity analyses were performed on the included studies. Nine studies involving 1,074 patients were included. Compared with the PEEK group, the structural allograft group had comparable rates of postoperative pseudoarthrosis (p=0.58). However, when stratified according to the number of levels treated, the 3-level ACDF PEEK group was 3.45 times more likely to have postoperative pseudoarthrosis than the structural allograft group (p=0.01). Subsequent postoperative outcomes (rate of subsidence and change in the preoperative and postoperative segmental disc heights) were comparable between the PEEK and structural allograft groups. Patient-reported outcomes (Visual Analog Scale [VAS] of neck pain and Neck Disability Index [NDI]) were comparable. This study showed that for 3-level ACDFs, the use of structural allografts may confer higher fusion rates. However, VAS neck pain, NDI, and subsidence rates were comparable between structural allografts and PEEK cages. In addition, no significant difference in pseudoarthrosis rates was found between PEEK cages and structural allografts in patients undergoing 1- and 2-level ACDFs.

Contemporary outcomes for arterial reconstruction with non-saphenous vein cryo-preserved conduits.

OBJECTIVE: Cryopreserved (CP) products are utilized during challenging cases when autogenous or prosthetic conduit use is not feasible. Despite decades of experience with cadaveric greater saphenous vein (GSV), there is limited available data regarding the outcomes and patency of other CP products, specifically arterial and deep venous grafts. This study was designed to evaluate outcomes of non-GSV CP conduits in patients undergoing urgent, emergent, and elective arterial reconstruction at our institution. We hypothesized that non-GSV CP allografts have adequate patency and outcomes and are therefore a feasible alternative to GSV in settings where autologous graft is unavailable or prosthetic grafts are contraindicated. METHODS: This study was approved by the Institutional Review Board at our institution. We retrospectively reviewed charts of patients undergoing arterial reconstructions using CP conduits from 2010 to 2022. Data collected included demographics, comorbidities, smoking status, indications for surgery, indication for CP conduit use, anatomic reconstruction, urgency of procedure, and blood loss. Time-to-event outcomes included primary and secondary graft patency rates, follow-up amputations, and mortality; other complications included follow-up infection/reinfection and 30-day complications, including return to the operating room and perioperative mortality. Time-to-event analyses were evaluated using product-limit survival estimates. RESULTS: Of 96 identified patients receiving CP conduits, 56 patients received non-GSV conduits for 66 arterial reconstructions. The most common type of non-GSV CP product used was femoral artery (31 patients), followed by aorto-iliac artery (22 patients), and femoral vein (19 patients), with some patients receiving more than one reconstruction or CP product. Patients were mostly male (75%), with a mean age of 63.1 years and a mean body mass index of 26.7 kg/m2. Indications for CP conduit use included infection in 53 patients, hostile environment in 36 patients, contaminated field in 30 patients, tissue coverage concerns in 30 patients, inadequate conduit in nine patients, and patient preference in one patient. Notably, multiple patients had more than one indication. Most surgeries (95%) were performed in urgent or emergent settings. Supra-inguinal reconstructions were most common (53%), followed by extra-anatomic bypasses (47%). Thirty-day mortality occurred in 10 patients (19%). Fifteen patients (27%) required return to the operating room for indications related to the vascular reconstructions, with 10 (18%) cases being unplanned and five (9%) cases planned/staged. Overall survival at 6, 12, and 24 months was 80%, 68%, and 59%, respectively. Primary patency at 6, 12, and 24 months was 86%, 70%, and 62%, respectively. Amputation freedom at 6 months, 12 months, and 24 months was 98%, 95%, and 86%, respectively for non-traumatic indications. CONCLUSIONS: Non-GSV CP products may be used in complex arterial reconstructions when autogenous or prosthetic options are not feasible or available.

Functional Assessment of Human Articular Cartilage Using Second Harmonic Generation (SHG) Imaging: A Feasibility Study.

Many arthroscopic tools developed for knee joint assessment are contact-based, which is challenging for in vivo application in narrow joint spaces. Second harmonic generation (SHG) laser imaging is a non-invasive and non-contact method, thus presenting an attractive alternative. However, the association between SHG-based measures and cartilage quality has not been established systematically. Here, we investigated the feasibility of using image-based measures derived from SHG microscopy for objective evaluation of cartilage quality as assessed by mechanical testing. Human tibial plateaus harvested from nine patients were used. Cartilage mechanical properties were determined using indentation stiffness (Einst) and streaming potential-based quantitative parameters (QP). The correspondence of the cartilage electromechanical properties (Einst and QP) and the image-based measures derived from SHG imaging, tissue thickness and cell viability were evaluated using correlation and logistic regression analyses. The SHG-related parameters included the newly developed volumetric fraction of organised collagenous network (Φcol) and the coefficient of variation of the SHG intensity (CVSHG). We found that Φcol correlated strongly with Einst and QP (ρ = 0.97 and - 0.89, respectively). CVSHG also correlated, albeit weakly, with QP and Einst, (|ρ| = 0.52-0.58). Einst and Φcol were the most sensitive predictors of cartilage quality whereas CVSHG only showed moderate sensitivity. Cell viability and tissue thickness, often used as measures of cartilage health, predicted the cartilage quality poorly. We present a simple, objective, yet effective image-based approach for assessment of cartilage quality. Φcol correlated strongly with electromechanical properties of cartilage and could fuel the continuous development of SHG-based arthroscopy.

High-Speed Centrifugation Efficiently Removes Immunogenic Elements in Osteochondral Allografts.

OBJECTIVES: The current clinical pulse lavage technique for flushing fresh osteochondral allografts (OCAs) to remove immunogenic elements from the subchondral bone is ineffective. This study aimed to identify the optimal method for removing immunogenic elements from OCAs. METHODS: We examined five methods for the physical removal of immunogenic elements from OCAs from the femoral condyle of porcine knees. We distributed the OCAs randomly into the following seven groups: (1) control, (2) saline, (3) ultrasound, (4) vortex vibration (VV), (5) low-pulse lavage (LPL), (6) high-pulse lavage (HPL), and (7) high-speed centrifugation (HSC). OCAs were evaluated using weight measurement, micro-computed tomography (micro-CT), macroscopic and histological evaluation, DNA quantification, and chondrocyte activity testing. Additionally, the subchondral bone was zoned to assess the bone marrow and nucleated cell contents. One-way ANOVA and paired two-tailed Student's t-test are used for statistical analysis. RESULTS: Histological evaluation and DNA quantification showed no significant reduction in marrow elements compared to the control group after the OCAs were treated with saline, ultrasound, or VV treatments; however, there was a significant reduction in marrow elements after LPL, HPL, and HSC treatments. Furthermore, HSC more effectively reduced the marrow elements of OCAs in the middle and deep zones compared with LPL (p < 0.0001) and HPL (p < 0.0001). Macroscopic evaluation revealed a significant reduction in blood, lipid, and marrow elements in the subchondral bone after HSC. Micro-CT, histological analyses, and chondrocyte viability results showed that HSC did not damage the subchondral bone and cartilage; however, LPL and HPL may damage the subchondral bone. CONCLUSION: HSC may play an important role in decreasing immunogenicity and therefore potentially increasing the success of OCA transplantation.

How to counteract the lack of donor tissue in cardiac surgery? Initial experiences with a newly established homograft procurement program.

Homograft heart valves may have significant advantages and are preferred for the repair of congenital valve malformations, especially in young women of childbearing age, athletes and in patients with active endocarditis. A growing problem, however, is the mismatch between tissue donation and the increasing demand. The aim of this paper is to describe the initiation process of a homograft procurement program to attenuate the shortage of organs. A comprehensive description of the infrastructure and procedural steps required to initiate a cardiac and vascular tissue donation program combined with a prospective follow-up of all homografts explanted at our institution. Between January 2020 and May 2022, 28 hearts and 12 pulmonary bifurcations were harvested at our institution and delivered to the European homograft bank. Twenty-seven valves (19 pulmonary valves, 8 aortic valves) were processed and allocated for implantation. The reasons for discarding a graft were either contamination (n = 14), or morphology (n = 13) or leaflet damage (n = 2). Five homografts (3 PV, 2 AV) have been cryopreserved and stored while awaiting allocation. One pulmonary homograft with a leaflet cut was retrieved by bicuspidization technique and awaits allocation, as a highly requested small diameter graft. The implementation of a tissue donation program in cooperation with a homograft bank can be achieved with reasonable additional efforts at a transplant center with an in-house cardiac surgery department. Challenging situations with a potential risk of tissue injury during procurement include re-operation, harvesting by a non-specialist surgeon and prior central cannulation for mechanical circulatory support.

Matched comparison of decellularized homografts and bovine jugular vein conduits for pulmonary valve replacement in congenital heart disease.

For decades, bovine jugular vein conduits (BJV) and classic cryopreserved homografts have been the two most widely used options for pulmonary valve replacement (PVR) in congenital heart disease. More recently, decellularized pulmonary homografts (DPH) have provided an alternative avenue for PVR. Matched comparison of patients who received DPH for PVR with patients who received bovine jugular vein conduits (BJV) considering patient age group, type of heart defect, and previous procedures. 319 DPH patients were matched to 319 BJV patients; the mean age of BJV patients was 15.3 (SD 9.5) years versus 19.1 (12.4) years in DPH patients (p = 0.001). The mean conduit diameter was 24.5 (3.5) mm for DPH and 20.3 (2.5) mm for BJV (p < 0.001). There was no difference in survival rates between the two groups after 10 years (97.0 vs. 98.1%, p = 0.45). The rate of freedom from endocarditis was significantly lower for BJV patients (87.1 vs. 96.5%, p = 0.006). Freedom from explantation was significantly lower for BJV at 10 years (81.7 vs. 95.5%, p = 0.001) as well as freedom from any significant degeneration at 10 years (39.6 vs. 65.4%, p < 0.001). 140 Patients, matched for age, heart defect type, prior procedures, and conduit sizes of 20-22 mm (± 2 mm), were compared separately; mean age BJV 8.7 (4.9) and DPH 9.5 (7.3) years (p = n.s.). DPH showed 20% higher freedom from explantation and degeneration in this subgroup (p = 0.232). Decellularized pulmonary homografts exhibit superior 10-year results to bovine jugular vein conduits in PVR.