Abstract. Purpose. Clinical registries are an important aspect of orthopaedic research in assessing the outcomes of surgical intervention and track medical devices. This study aimed to explore the research methodology available to account for patients lost to follow-up (LTFU) specifically in studies related to arthroscopic intervention and whether the rates of patient LTFU are within the acceptable margins for survey studies. Methods. A scoping review, where a literature search for studies from nine arthroscopy registries, was performed on EMBASE, MEDLINE, and the annual reports of each registry. Inclusion criteria included studies with information on patient-reported outcome measures and being based on nine national registries identified. Exclusion criteria included review articles, conference abstracts, studies not based on registry data, and studies from regional, claims-based, or multi-centre registries. Studies were then divided into categories based on method of LTFU analysis used. Results. Thirty-six articles were identified for the final analysis. Categories for LTFU analysis included dropout analyses (n=10), referencing validation studies (n=12), contacting non-responders (n=4), and sensitivity analyses (n=1). Referencing validation studies was the most common method (n=12). Majority (n=35) of the studies exceeded the recommended maximum rates for LTFU. Conclusions. Most arthroscopy studies have rates of LTFU higher than traditionally acceptable. Therefore, any conclusions drawn from these research papers may not be sufficiently valid or free from non-response bias

Several emerging reports suggest an important involvement of the hindfoot alignment in the outcome of knee osteotomy. At present, studies lack a comprehensive overview. Therefore, we aimed to systematically review all biomechanical and clinical studies investigating the role of the hindfoot alignment in the setting of osteotomies around the knee. A systematic literature search was conducted on multiple databases combining “knee osteotomy” and “hindfoot/ankle alignment” search terms. Articles were screened and included according to the PRISMA guidelines. A quality assessment was conducted using the Quality Appraisal for Cadaveric Studies (QUACS) - and modified methodologic index for non-randomized studies (MINORS) scales. Three cadaveric, fourteen retrospective cohort and two case-control studies were eligible for review. Biomechanical hindfoot characteristics were positively affected (n=4), except in rigid subtalar joint (n=1) or talar tilt (n=1) deformity. Patient symptoms and/or radiographic alignment at the level of the hindfoot did also improve after knee osteotomy (n=13), except in case of a small pre-operative lateral distal tibia- and hip knee ankle (HKA) angulation or in case of a large HKA correction (>14.5°). Additionally, a pre-existent hindfoot deformity (>15.9°) was associated with undercorrection of lower limb alignment following knee osteotomy. The mean QUACS score was 61.3% (range: 46–69%) and mean MINORS score was 9.2 out of 16 (range 6–12) for non-comparative and 16.5 out of 24 (range 15–18) for comparative studies. Osteotomies performed to correct knee deformity have also an impact on biomechanical and clinical outcomes of the hindfoot. In general, these are reported to be beneficial, but several parameters were identified that are associated with newly onset – or deterioration of hindfoot symptoms following knee osteotomy. Further prospective studies are warranted to assess how diagnostic and therapeutic algorithms based on the identified criteria could be implemented to optimize the overall outcome of knee osteotomy. Remark: Aline Van Oevelen and Arne Burssens contributed equally to this work

Abstract. Objectives. Tendon and ligament injury poses an increasingly large burden to society. With surgical repair and grafting susceptible to high failure rates, tissue engineering provides novel avenues for treatment. This systematic review explores in vivo evidence whether mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) can facilitate tendon and ligament repair in animal models. Methods. On May 26th 2021, a systematic search was performed on PubMed, Web of Science, Cochrane Library, Embase, using search terms ‘mesenchymal stem cell’ or ‘multipotent stem cell’ AND ‘extracellular vesicles’ or ‘exosomes’ AND ‘tendon’ or ‘ligament’ or ‘connective tissue’. Risk of bias was assessed using SYstematic Review Center for Laboratory animal Experimentation (SYRCLE) tool. Studies administering EVs isolated from human or animal-derived MSCs into in vivo models of tendon/ligament injury were included. In vitro, ex vivo, in silico studies were excluded, and studies without a control group were excluded. Data on isolation and characterisation of MSCs and EVs, and in vivo findings in animal models were extracted. Results. Out of 383 relevant studies, 11 case-control studies were included for data extraction, including a total of 448 animal subjects (range 10–90). Six studies utilised bone marrow-derived MSCs. All studies characterised their MSCs via flow cytometry, which expressed CD44 and CD90, and isolated EVs via ultracentrifugation (average diameter 125nm). Five studies utilised histological scoring systems, all of which reported a lower score with EV treatment, suggesting improved healing ability. Four studies reported increased anti-inflammatory cytokine expression (IL-10, TGF-β1); three studies reported decreased endogenous M1/M2 macrophage ratio with EV treatment. Eight studies reported increased maximum stiffness, breaking load, tensile strength in EV-treated tendons. Conclusion. MSC-EVs are effective therapeutic agents for tendon/ligament pathologies, attenuating the initial inflammatory response, and accelerating tendon matrix regeneration. Future randomised controlled trials are needed to definitely demonstrate MSC-EVs superiority in management of tendon/ligament injury

The purpose of this investigation was to evaluate systematically the literature concerning biopsy, MRI signal to noise quotient (SNQ) and clinical outcomes in graft-maturity assessment after autograft anterior cruciate ligament reconstruction (ACLR) and their possible relationships. Methods: The systematic review was reported and conducted according to the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) guidelines. Studies through May 2019 evaluating methods of intra-articular ACL autograft maturity assessment were considered for inclusion. Eligible methods were histologic studies of biopsy specimens and conventional MRI studies reporting serial SNQ and/ or correlation with clinical parameters. Ten biopsy studies and 13 imaging studies, with a total of 706 patients, met the inclusion criteria. Biopsy studies show that graft remodeling undergoes an early healing phase, a phase of remodeling or proliferation and a ligamentization phase as an ongoing process even 1 year after surgery. Imaging studies showed an initial increase in SNQ, peaking at approximately 6 months, followed by a gradual decrease over time. There is no evident correlation between graft SNQ and knee stability outcome scores at the short- and long-term follow-up after ACLR. The remodeling of the graft is an ongoing process even 1 year after ACLR, based on human biopsy studies. MRI SNQ peaked at approximately 6 months, followed by a gradual decrease over time. Heterogeneity of the MRI methods and technical restrictions used in the current literature limit prediction of graft maturity and clinical and functional outcome measures by means of MRI graft SNQ after ACLR

Intervertebral disc (IVD) degeneration is inadequately understood due to the lack of in vitro systems that fully mimic the mechanical and biological complexity of this organ. We have recently made an advancement by developing a bioreactor able to simulate physiological, multiaxial IVD loading and maintain the biological environment in ex vivo IVD models [1].

To validate this new bioreactor system, we simulated natural spine movement by loading 12 bovine IVDs under a combination of static compression (0.1 MPa), cyclic flexion/extension (±3˚, ±6˚ or 0-6˚) and cyclic torsion (±2˚, ±4˚ or 0-4˚) for more than 10’000 (0.2 Hz) or 100’000 (1 Hz) cycles over 14 days. A higher number of cycles increased the release of glycosaminoglycans and nitric oxide, as an inflammation marker, whereas fewer cycles maintained these two factors at physiological levels. All applied protocols upregulated the expression of MMP13 in the outermost annulus fibrosus (AF), indicating a collagen degradation response. This was supported by fissures observed in the AF after a longer loading duration. Increasing loading cycles induced high cell death in the nucleus pulposus and inner AF, while with fewer cycles, high cell viability was maintained in all IVD regions, irrespective of the magnitude of rotation.

Less frequent multiaxial loading maintains IVD homeostasis while more frequent loading initiates an IVD degenerative profile. Specifically, the morphological and molecular changes were localized in the AF, which can be associated with combined flexion/extension and torsion. More loading cycles induced region-specific cell death and a higher release of extracellular matrix molecules from the innermost IVD regions, likely associated with longer exposure to static compression. Altogether, we demonstrated the advantages of the multiaxial bioreactor to study region-specific response in the IVD, which will allow a more profound investigation of IVD degeneration under different combinations of motions.

In the last decades, significant effort has been attempted to salvage the meniscus following injury.

Basic science approaches to meniscus repair include procedures for both meniscus regeneration and meniscus healing. Regeneration of meniscal tissue focuses on filling a defect with reparative tissue, which resembles the native structure and function of the meniscus. Procedures for meniscus healing, on the other hand, aim to accomplish adhesion between the margins of a meniscal lesion, with no attempt to regenerate or replace meniscal tissue.

Regeneration studies of tissue to fill a defect in the meniscus have shown interesting results, but complete restoration of the native meniscus has not yet been accomplished.

Healing of a meniscal lesion has been investigated in different models although none has demonstrated reproducible healing. Therefore, different paths of investigation must be undertaken, and one of these may be the cell-therapy / tissue engineering approach.

In a study from our group, we showed the capacity of chondrocyte-seeded cartilaginous scaffold to repair a bucket-handle lesion of the knee meniscus orthotopically in a large animal study. Following studies were done in order to test the potential of other scaffolds and different cell sources for the repair of the meniscal tissue. We have also evaluated the role of hypoxia in meniscal development in vitro as basis for future research in this field, as hypoxia could be be considered as a promoter for meniscal cells maturation, and opens considerably opportunities in the field of meniscus tissue engineering.

Utilization of nerve conduction studies in the investigation and management of carpal tunnel syndrome varies according to their perceived usefulness and availability. The use of steroid injections and splinting also varies according to service availability and their perceived effectiveness. We present a three year follow up of 230 patients managed in an environment where nerve conduction testing was not readily available. The majority received splinting and a steroid injection in an effort to manage their symptoms conservatively in the first instance. Our results show that a clear majority of patients who were treated with initial splinting and steroid injections saw a recurrence of their symptoms (71.9% and 79.7% respectively) requiring eventual surgical decompression. These results would seem to suggest that conservative management of carpal tunnel does not produce the desired curative results and that there may be an argument for proceeding directly to surgery. We also showed that 55% of patients referred for Nerve Conduction Studies seem to progress to surgical decompression. This would seem to suggest that Nerve Conduction Studies could form a robust part of the standard investigation of carpal tunnel in order to identify those who would benefit from surgery

A novel ex vivo intervertebral disc (IVD) organ model and corresponding sample holder were developed according to the requirements for six degrees of freedom loading and sterile culture in a new generation of multiaxial bioreactors. We tested if the model can be maintained in long-term IVD organ culture and validated the mechanical resistance of the IVD holder in compression, tension, torsion, and bending.

An ex vivo bovine caudal IVD organ model was adapted by retaining 5-6 mm of vertebral bone to machine a central cross and a hole for nutrient access through the cartilaginous endplate. A counter cross was made on a customized, circular IVD holder. The new model was compared to a standard model with a minimum of bone for the cell viability and height changes after 3 weeks of cyclic compressive uniaxial loading (0.02-0.2 MPa, 0.2 Hz, 2h/ day; n= 3 for day 0, n= 2 for week 1, 2, and 3 endpoints). Mechanical tests were conducted on the assembly of IVD and holder enhanced with different combinations of side screws, top screws, and bone adhesive (n=3 for each test).

The new model retained a high level of cell viability after three weeks of in vitro culture (outer annulus fibrosus 82%, inner annulus fibrosus 69%, nucleus pulposus 75%) and maintained the typical values of IVD height reduction after loading (≤ 10%). The holder-IVD interface reached the following highest average values in the tested configurations: 320.37 N in compression, 431.86 N in tension, 1.64 Nm in torsion, and 0.79 Nm in bending.

The new IVD organ model can be maintained in long-term culture and when combined with the corresponding holder resists sufficient loads to study IVD degeneration and therapies in a new generation of multiaxial bioreactors.

Osteoarthritis (OA) is a degenerative disease that lacks regenerative treatment options. Current research focuses on mesenchymal stem cells (MSCs) and Platelet-Rich Plasma (PRP) as regenerative therapies, but extracellular vesicles (EVs) have shown to be more advantageous. This study compares the regenerative potential of human umbilical cord MSC-derived EVs (cEVs) and platelet-derived EVs (pEVs) in ex vivo and in vivo OA models.

In the ex vivo study, OA conditions were induced in human cartilage explants, which were then treated either with pEVs or cEVs. Results showed a higher content of DNA and collagen in the pEVs group compared to control and cEVs groups, suggesting that pEVs could be a potential alternative to cEVs.

In the in vivo study, an OA model was established in the knee joints of rats through MIA (monoiodoacetate) injection and then treated either with pEVs or cEVs. Results showed that pEVs-treated knee joints had better subchondral bone integrity and greater OA reversion, particularly in female rats, indicating that pEVs are a viable regeneration treatment for OA and outperform cEVs in terms of efficacy.

Overall, the study demonstrates the potential of EVs as a regenerative treatment for OA, with pEVs showing promising results in both ex vivo and in vivo models. The use of pEVs in clinical practice could provide a faster path to translation due to the established use of platelet concentrates in therapeutics. However, further studies are needed to fully evaluate the potential of pEVs for OA treatment and to elucidate the mechanisms behind their regenerative effects.

Acknowledgments: The authors thank Dr Fernando Hierro (UIB) for their technical contribution with TEM, Mª Trinidad García (UIB) for the access to radioactivity facilities, Aina Arbós (IUNICS) for her contribution in the histology staining, María Tortosa (IdISBa) for her assistance with the animal care and ADEMA School of Dentistry for the access to the cone beam computed tomography (CBCT).

Funding: This research was funded by Instituto de Salud Carlos III, Ministerio de Economía y Competitividad, co-funded by the ESF European Social Fund and the ERDF European Regional Development Fund (MS16/00124; CP16/00124), PROGRAMA JUNIOR del proyecto TALENT PLUS, construyendo SALUD, generando VALOR (JUNIOR01/18), financed by the sustainable tourism tax of the Balearic Islands; the Direcció General d'Investigació and Conselleria d'Investigació, Govern Balear (FPI/2046/2017); the Mecanisme de Recuperació i Resiliència, intended to execute research projects of «Noves polítiques públiques per a un mercat de treball dinàmic, resilient i inclusiu», collected in Pla de Recuperació, Transformació i Resiliència, financed by European Union-Next Generation EU and driven by SOIB and Conselleria de Fons Europeus, Universitat i Cultura i la Conselleria de Model Econòmic, Turisme i Treball (NG0421) and the grant SYN20/03 from IdISBa.

The aim of this study was to perform a systematic review of the literature on Gustilo-Anderson (GA) type IIIB open tibial shaft (AO-42) injuries to determine the consistency of reporting in the literature.

A search of PubMed, EMBASE and Cochrane Central Register of Controlled Trials was performed to identify relevant studies published from January 2000 to January 2021 using the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statement. The study was registered using the PROSPERO International prospective register of systematic reviews. Patient/injury demographics, management and outcome reporting were recorded.

There were 32 studies that met the inclusion criteria with a total of 1,947 patients (70.3% male, 29.7% female). There were 6 studies (18.8%) studies that reported on comorbidities and smoking, with mechanism of injury reported in 22 (68.8%). No studies reported on all operative criteria included, with only three studies (9.4%) reporting for time to antibiotics, 14 studies (43.8%) for time from injury to debridement and nine studies (28.1%) for time to definitive fixation. All studies reported on the rate of deep infection, with a high proportion documenting union rate (26/32, 81.3%). However, only two studies reported on mortality or on other post-operative complications (2/32, 6.3%). Only 12 studies (37.5%) provided any patient reported outcomes.

This study has demonstrated a deficiency and a lack of standardized variable and outcome reporting in the orthopaedic literature for Gustilo-Anderson type IIIB open tibial shaft fractures. We propose a future international collaborative Delphi process is needed to standardize.

Orthopedic device-related infection (ODRI) preclinical models are widely used in translational research. Most models require induction of general anesthesia, which frequently results in hypothermia in rodents. This study aimed to evaluate the impact of peri anesthetic hypothermia in rodents on outcomes in preclinical orthopedic device-related infection studies.

A retrospective analysis of all rodents that underwent surgery under general anesthesia to induce an ODRI model with inoculation of Staphylococcus epidermidis between 2016 and 2020 was conducted. A one-way multivariate analysis of covariance was used to determine the fixed effect of peri anesthetic hypothermia (hypothermic defined as rectal temperature <35°C) on the combined harvested tissue and implant colonies forming unit counts, and having controlled for the study groups including treatments received duration of surgery and anesthesia and study period. All animal experiments were approved by relevant ethical committee.

A total of 127 rodents (102 rats and 25 mice) were enrolled in an ODRI and met the inclusion criteria. The mean lowest peri-anesthetic temperature was 35.3 ± 1.5 °C. The overall incidence of peri-anesthetic hypothermia was 41% and was less frequently reported in rats (34% in rats versus 68% in mice). Statistical analysis showed a significant effect of peri anesthetic hypothermia on the post-mortem combined colonies forming unit counts from the harvested tissue and implant(s) (p=0.01) when comparing normo- versus hypothermic rodents. Using Wilks’ Λ as a criterion to determine the contribution of independent variables to the model, peri-anesthetic hypothermia was the most significant, though still a weak predictor, of increased harvested colonies forming unit counts.

Altogether, the data corroborate the concept that bacterial colonization is affected by abnormal body temperature during general anesthesia at the time of bacterial inoculation in rodents, which needs to be taken into consideration to decrease infection data variability and improve experimental reproducibility.

Summary Statement. Flow chambers have been implemented in stem cell research to apply controlled dilational (volume changing) and deviatoric (shape changing) mechanical cues to living cells. Studies implementing such chambers demonstrate that controlled delivery of mechanical cues correlates strongly to changes in stem cell shape, structure, and fate. Introduction. A custom designed flow chamber, capable of delivering highly controlled stresses at the cellular scale, enables the study of flow-induced normal and shear stresses on cell behavior. Specifically, computational fluid dynamics (CFD) and multiphysics modeling (coupling of CFD with finite element models) allow for controlled delivery of mechanical cues via fluid flow and cell seeding protocols, concomitant to optical mapping of cell displacements due to mechanical load, and calculation of flow velocities, imbued stresses, and cellular strains within a given volume of interest. Akin to conducting a mechanical loading test on single cells and groups of cells, paired experimental and computational experiments using the custom-designed chamber enabled calculation of the flow field's effect on the cell(s) as well as the cells’ effect on the flow field, a critical step in predicting the local stress and strain fields at the cell-fluid interface within the chamber, during exposure to fluid flow. These stresses-strains experienced by stem cells demonstrate significant correlation to cell gene expression, and strongly suggest that stresses at the cell-fluid interface influence cell fate. The current study uses a parametric approach to define next steps to prospectively guide mechanically-modulated lineage commitment. Methods. An experimentally validated, coupled computational fluid dynamics (CFD) finite element (FEM) model has elucidated the local mechanical environment at live cell surfaces during exposure to normal and shear stresses imparted by flow. The current study tests this model parametrically, assessing sensitivity of predicted stress-strain-fate relationships to estimates of cells’ mechanical properties, and prioritizing experiments for prospective mapping of the mechanome. Results. Results indicate that an accurate estimation of the cell's elastic modulus is critical for exact measurements of cell surface stresses and strains. However, an accurate estimation of the cell's Poisson's ratio is less critical for measurement validity. Furthermore, the application of a low pressure gradient to cells at high density maximises precise delivery of a range of mechanical cues. While next stage experiments can begin to map the stem cell mechanome, modifications to the current experimental setup will increase the range of deliverable stresses as well as the precision of these stresses. Discussion/Conclusion. Overall, the results of this study demonstrate the regions of the mechanome that can be experimentally assessed with current approaches, as well as the precision of these assessments, through the control of cell seeding density, pressure gradient, and fluid viscosity

To analyse the efficacy and safety of cellular therapy utilizing Mesenchymal Stromal Cells (MSCs) in the management of rotator cuff(RC) tears from clinical studies available in the literature.

We conducted independent and duplicate electronic database searches including PubMed, Embase, Web of Science, and Cochrane Library on August 2021 for studies analyzing the efficacy and safety of cellular therapy (CT) utilizing MSCs in the management of RC tears. VAS for pain, ASES Score, DASH Score, Constant Score, radiological assessment of healing and complications and adverse events were the outcomes analyzed. Analysis was performed in R-platform using OpenMeta [Analyst] software.

Summary. Biomechanical studies comparing fixation constructs are predictable and do not relate to the significant clinical problems. We believe there is a need for more careful use of resources in the lab and better collaboration with surgeons to enhance clinical relevance. Introduction. It is our impression that many biomechanical studies invest substantial resources studying the obvious: that open reduction and internal fixation with more and larger metal is stronger. Studies that investigate “which construct is the strongest?” are distracted from the more clinically important question of “how strong is strong enough?”. The aim of this study is to show that specific biomechanical questions do not require formal testing. This study tested our hypothesis that the outcome of a subset of peer reviewed biomechanical studies comparing fracture fixation constructs can be predicted based on common sense with great accuracy and good interobserver reliability. Patients & Methods. Between 2000 and 2012, we found 254 peer reviewed biomechanical studies in prestigious orthopaedic journals comparing construct ‘A’ versus construct ‘B’ to evaluate load to failure in order to determine ‘which construct is the strongest?’. Eleven studies comparing fracture fixation constructs were randomly selected from different journals based on our sense that the answer was obvious prior to performing the study. Three-hundred independent observers; including orthopaedic- and general- surgeons affiliated with the Science of Variation Group (. www.scienceofvariation.org. ), predicted the outcome of these biomechanical studies. Observers were presented the original published illustrations of different treatment modalities and were asked to answer one question: “which construct is the strongest?” Sensitivity, specificity and accuracy were calculated according to standardised formulas. The agreement among the observers was calculated by using a multirater kappa, described by Siegel and Castellan. The kappa values were interpreted as proposed by Landis and Koch. Results. Accuracy was the same or greater than 80% for all studies except for study 1. The level of experience had no influence on the accuracy of predicting outcomes. Sensitivity averaged 84%, ranging from 60% (for study 1) to 99% (for study 7), specificity 86%, ranging from 60% (for study 1) to 99% (for study 7), and accuracy averaged 86% from 60% (for study 1) to 99% (for study 7). The overall categorical rating of inter-observer reliability according to Landis and Koch was moderate (κ = 0,53; SE = 0.01), ranging from κ = 0,03 (SE = 0.01) to κ = 0,95 (SE = 0.01). Analyses of SOVG subgroups identified excellent agreement among Canadian surgeons. Moderate and substantial agreement were found in most of other subgroups: ranging from first year medical students to specialists 20 years or more in practice; and specialists who practice in Australia, Europe and United States. Study 5 was easiest to predict based on common sense (Accuracy 97%, inter-observer reliability 0,88). Study 1 was predicted with least accuracy 61% and the lowest kappa value 0,04. Conclusions. The outcomes of biomechanical studies comparing fracture reduction and fixation constructs are highly predictable with good inter-observer reliability

Poor tendon repair is an unsolved issue in clinical practice, due to complex tendon structure. Tendon stem/progenitor cells (TSPCs) play key roles in homeostasis, regeneration, and inflammation regulation in acute tendon injuries, and rely on TGF-β signaling for recruitment into degenerative tendons. In this study, we aimed to develop an in vitro model for tenogenesis adopting a dynamic culture of a fibrin 3D scaffold, bioengineered with human TSPCs collected from both healthy and tendinopathic surgery explants (Review Board prot./SCCE n.151, 29 October 2020). 3D culture was maintained for 21 days under perfusion provided by a custom-made bioreactor, in a medium supplemented with hTGF-β1 at 20 ng/mL. The data collected suggested that the 3D in vitro model well supported survival of both pathological and healthy cells, and that hTGF-β signaling, coupled to a dynamic environment, promoted differentiation events. However, pathological hTSPCs showed a different expression pattern of tendon-related genes throughout the culture and an impaired balance of pro-inflammatory and anti-inflammatory cytokines, compared to healthy hTSPCs, as indicated by qRT-PCT and immunofluorescence analyses. Additionally, the expression of both tenogenic and cytokine genes in hTSPCs was influenced by hTGF-β1, indicating that the environment assembled was suitable for studying tendon stem cells differentiation. The study offers insights into the use of 3D cultures of hTSPCs as an in vitro model for investigating their behavior during tenogenic events and opens perspectives for following the potential impact on resident stem cells during regeneration and healing events.

Total joint replacement is a successful clinical intervention. However, aseptic loosening due to wear related particulate debris is still one of the most frequent reasons for late revision of total joint replacement. This lecture gives an overview about the application of methods to study wear and friction in total joint replacements (e.g. hip, knee, shoulder). This involves complex joint simulation conditions as well as analytical assessments. Regarding joint simulation the focus will be on ligament stabilized joints. New approaches will be shown and discussed. Furthermore, analytical methods to study the release of wear products in term of solid particles and soluble complexes like metal ions will be presented.

Abstract

For unrepairable nerve defects, to date autogenous nerves are considered the golden standard, but donor site morbidity, limited availability and operation time prolongation are relevant problem. Acellular nerves from cadaveric donor, introduced since more than one decade ago, represent a novel promising alternative to bridge unrepairable nerve gaps.

Aim of this study is to provide a new tool to ameliorate the assistance of the numerous patients suffering from traumatic, oncological and jatrogenic nerve lesions. For this purpose, our project is promoting a progress beyond the state of the art of nerve gaps bridging surgery by developing a new technique to obtain acellular nerve allografts (ANAs).

Several methods to examine the effect of detergents on nerve tissue morphology and protein composition have been previously reported. Most of them are too expensive and time consuming. The presented novel decellularization technique is a modification of the Michigan detergent-based organic material removal, to speed up myelin and cellular debris detachment. The previously published Hudson's method¹has been chosen as control of the decellularization process). To validate the new nerve decellularization method, in terms of histological characteristics, outcomes were estimated through morphological and immunohistochemical studies in vitro and in vivo. The in vivo study consisted of a 1 cm defect in the tibial nerve of 3 new Zealand rabbits. This nerve defect was microsurgically replaced with a “Rizzoli” acellular nerve allograft. Rabbits were sacrificed 12 weeks after surgery. Endpoints were nerve conduction studies and histology.

Histological analysis of processed acellular nerve have been performed to evaluate the preservation of the structure and almost complete clearance of donor cells and cellular debris. Immunostaining analysis confirmed absence of Schwann cells and the maintenance of basal lamina. In vivo studies showed an effective and abundant nerve regeneration through the microsurgically reconstructed nerve defects. This was histologically proven. However no electophysiological return of function was showed.

The novel method will allow the storing of acellular nerve allografts. First results obtained by morphological analysis and immunofluorescence experiments and in vivo studies indicate that the internal structure of native nerve is maintained. It is then possible to decellularize nerves with the novel technique reducing both manufacturing times and costs. The relatively inexpensive method of decellularization will facilitate the number of patients that will benefit from reconstruction of nerve defects with ANAs.

Summary Statement

Umbilical cord derived stem cell secretion could enhance the osteogenic differentiation of human bone marrow stem cells. It may promote bone, cartilage and tendon regeneration in rat models, but the effect was not significant up to now.

Summary

Human amniotic membrane has interesting properties for regenerative medicine. To use it as an Advanced Therapeutic Medicinal Product in bone surgery, we are evaluating: the necessity of its osteodifferentiation and the impact on immunogenicity; its optimal condition for storage.