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The use of mechanoregulatory schemes based on finite element (FE) analysis for the evaluation of bone ingrowth around porous surfaces is a viable approach but requires significant computational time and effort. The aim of this study is to develop a combined macro–micro FE and artificial neural network (ANN) framework for rapid and accurate prediction of the site-specific bone ingrowth around the porous beaded-coated tibial implant for total ankle replacement (TAR). A macroscale FE model of the implanted tibia was developed based on CT data. Subsequently, a microscale FE model of the implant-bone interface was created for performing bone ingrowth simulations using mechanoregulatory algorithms. An ANN was trained for rapid and accurate prediction of bone ingrowth. The results predicted by ANN are well comparable to FE-predicted results. Predicted site-specific bone ingrowth using ANN around the implant ranges from 43.04 to 98.24%, with a mean bone ingrowth of around 74.24%. Results suggested that the central region exhibited the highest bone ingrowth, which is also well corroborated with the recent explanted study on BOX®. The proposed methodology has the potential to simulate bone ingrowth rapidly and effectively at any given site over any implant surface. Graphical Abstract

Background: Artificial ligaments have been developed and used in the treatment of ligamentous injuries since the 1970s. The early generation of artificial ligaments showed promising short-term results but resulted in high rates of rupture and inflammatory reaction in the surrounding tissues. Purpose: To determine whether the use of Ligament Augmentation and Reconstruction System (LARS) ligaments is associated with the development of intra-articular foreign body reaction. Study Design: Case series; Level of evidence, 4. Methods: LARS ligaments were explanted from 15 patients under 6 consultant orthopaedic surgeons at 8 surgical centers. Of these, 14 explanted samples were sent for macroscopic and histological analysis, with the 1 remaining sample sent for scanning electron microscopy, to assess for inflammatory change as well as the degree of fibrous tissue ingrowth. Results: We observed a foreign body reaction in 10 of 14 explanted LARS ligaments. Seven samples demonstrated fibrous tissue ingrowth, with 5 producing only focal or incomplete ingrowth. The 2 samples with extensive fibrous coverage were completely free of any foreign body reaction, while all 5 remaining samples with only focal or partial fibrous ingrowth were associated with at least some degree of harmful immune response. Conclusion: The LARS ligament is still associated with a clinically significant degree of foreign body reaction despite the LARS Company’s efforts to reduce complications through improved design. The development and completion of fibrous tissue ingrowth may work to reduce the occurrence of a foreign body reaction.

While in vivo studies clearly demonstrate that supra-annular Valve-in-Valve (ViV) implantation provides the highest probability for optimal post-ViV pressure gradients (PG), there is still no physical insight into explaining anomalies where some supra-annular ViV implantations yield high pressure gradients while some sub-annular implantations yield low pressure gradients. The aim of this study is to explain how severe tissue ingrowth and calcification (TIC) in a surgical aortic valve (SAV) can be one physical mechanism leading to anomalous ViV performance characteristic. The ViV hemodynamic performance was evaluated as a function of axial positioning −9.8, −6.2, 0, and +6 mm in SAVs with and without TIC. Effective orifice area (EOA) and PG were compared. Leaflet high-speed imaging and particle image velocimetry were performed to elucidate flutter and forward jet characteristics. ViV without TIC showed significantly lower PG and greater EOA (p < 0.01). EOA and PG improve with supra-annular deployment (p < 0.01) while for ViV with TIC, EOA and PG worsen as the deployment varies from −9.8 mm to 0 mm (p < 0.01) only to recover at + 6 mm (p < 0.01). Separated jet flow at the TIC site, and consequently induced stronger TAV leaflet fluttering highlight the dynamic compromising nature of TIC on jet width and performance reduction. We conclude that the inflow TIC greatly influence ViV performance due to dynamic effects that results in a real anomalous performance characteristic different than that seen in most ViV in vivo. Further in vivo studies are needed to evaluate ViV outcomes in the presence of severe TIC in SAVs.

Tendons and ligaments injuries have become more and more common due to the increase of the general populations interest in sports and physical activities. Beginning with the 1970s many researchers have tried to reconstruct the torn ligaments and tendons, at first using products such as Polyflex and Proplast ligaments, with poor results. In recent years the use LARS ligament has been researched. The Ligament Augmentation and Reconstruction System, now at its 3rd generation, is an artificial ligament made out of polyethylene terephthalate (PET) that over time allows tissue ingrowth, recreating the natural orientation of anatomical ligament and tendon fibers.

The optimal prosthesis for laparoscopic ventral hernia repair would combine excellent parietal surface tissue ingrowth with minimal visceral surface adhesiveness. Currently, few data are available from randomized trials comparing the commercially available prostheses. In a pig model designed to incite adhesions, three 10 x 15-cm pieces of mesh (Proceed, Parietex Composite [PCO], and polypropylene [PPM]) were randomly positioned intraperitoneally in each of 10 animals using sutures and tack fixation. After a 28-day survival, the amount of shrinkage, the area and peel strength of visceral adhesions, the peak peel strength, the work required to separate mesh from the abdominal wall, and a coefficient representing the adhesiveness of tissue ingrowth were averaged for each type of mesh and then compared with the averages for the other prostheses. The histologic appearance of each prosthesis was documented. Proceed had more shrinkage (99.6 cm2) than PCO (105.8 cm2) or PPM (112 cm2), although the difference was not statistically significant. The mean area of adhesions to PCO (11%) was significantly less than for Proceed (48%; p < 0.008) or PPM (46%; p < 0.008). Adhesion peel strength was significantly less for PCO (5.9 N) than for Proceed (12.1 N; p < 0.02) or PPM (12.9 N; p < 0.02). According to a filmy-to-dense scale of 1 to 5, adhesions were more filmy with PCO (1.7) than with PPM (2.9) or Proceed (3.7) (p < 0.007). Peak peel strength from the abdominal wall was significantly higher for PCO (17.2 N) than for Proceed (10.7 N) or PPM (10 N; p < 0.002). The histology of each prosthesis showed a neoperitoneum only with PCO. With less shrinkage, fewer and less dense adhesions to the viscera, and significantly stronger abdominal wall adherence and tissue ingrowth at 28 days in this animal study, PCO was superior to both Proceed and PPM in all categories. Furthermore, PCO demonstrated all the favorable qualities needed in an optimal prosthesis for laparoscopic ventral hernia repair, including the rapid development of a neoperitoneum.

Contraction is a well‐documented phenomenon occurring within two months of mesh implantation. Its etiology is unknown, but it is suggested to occur as a result of inadequate tissue ingrowth into the mesh and has been associated with hernia recurrence. In continuation of our previous studies, we compared tissue ingrowth characteristics of large patches of polyester (PE) and heavyweight polypropylene (PP) and their effect on mesh contraction. The materials used were eight PE and eight PP meshes measuring 10 × 10 cm2. After random assignment to the implantation sites, the meshes were fixed to the abdominal wall fascia of swine using interrupted polypropylene sutures. A necropsy was performed three months after surgery for evaluation of mesh contraction/shrinkage. Using a tensiometer, tissue ingrowth was assessed by measuring the force necessary to detach the mesh from the fascia. Histologic analysis included inflammatory and fibroblastic reactions, scored on a 0–4 point scale. One swine developed a severe wound infection that involved two PP meshes and was therefore excluded from the study. The mean area covered by the PE meshes (87 ± 7 cm2) was significantly larger than the area covered by the PP meshes (67 ± 14 cm2) (p = 0.006). Tissue ingrowth force of the PE meshes (194 ± 37 N) had a trend toward being higher than that of the PP meshes (159 ± 43 N), although it did not reach statistical significance. There was no difference in histologic inflammatory and fibroblastic reactions between mesh types. There was a significant correlation between tissue ingrowth force and mesh size (p = 0.03, 95% CI: 0.05–0.84). Our results confirm those from previous studies in that mesh materials undergo significant contraction after suture fixation to the fascia. PE resulted in less contraction than polypropylene. A strong integration of the mesh into the tissue helps prevent this phenomenon, which is evidenced by a significant correlation between tissue ingrowth force and mesh size.

Purpose The objective of this study was to determine the mesh contracture, adhesion, tissue ingrowth, and histologic characteristics of a novel absorbable barrier mesh (Ventrio ™ ST Hernia Patch) compared to existing permanent (Ventrio ™ Hernia Patch) and absorbable barrier meshes (Sepramesh ™ IP Composite and PROCEED ™ Surgical Mesh). Methods Standard laparoscopic technique was utilized to bilaterally implant meshes in 20 female Yorkshire pigs ( n  = 5 pigs/group). Meshes were fixated to the intact peritoneum with SorbaFix ™ absorbable fixation devices. Mesh contracture, adhesion coverage, and adhesion tenacity were evaluated after 4 weeks. T-Peel testing and hematoxylin and eosin (H&E) staining were utilized to assess tissue ingrowth and host response. Results A significantly greater percent area contracture was demonstrated for PROCEED ™ (26.9%) compared to Ventrio ™ ST (8.8%), Ventrio ™ (14.5%) and Sepramesh ™ (9.2%). Ventrio ™ ST demonstrated similar adhesion area, tenacity, and tissue ingrowth compared to all other meshes. Histological scoring revealed a comparable host inflammatory response for all meshes, with a few exceptions. A greater number of giant cells were observed in Ventrio ™ ST and Sepramesh ™ near the multifilament polyglycolic acid (PGA) fibers; a greater number of macrophages were observed in PROCEED ™ compared to Ventrio ™ ; and a greater number of neutrophils were observed in PROCEED ™ , compared to Sepramesh ™ ( P  < 0.05). Focal areas of hemorrhage were also observed on the visceral surface of PROCEED ™. Conclusions Ventrio ™ ST Hernia Patch demonstrated comparable contracture, adhesion, tissue ingrowth, and histologic characteristics compared to existing permanent and absorbable barrier meshes. Host inflammatory and fibrotic responses for all four meshes were minimal and representative of a biocompatible response.

Penile implant malfunction is usually treated by removal of the original malfunctioning implant followed by replacement with a new device. During replacement, the original implant can be explanted without any difficulty, as it is not adherent to the surrounding tissue. Herein, we describe two cases of tissue ingrowth into the implant that produced difficulty during explantation and suggest ways in which this condition can be managed.

Scaffold-based bone tissue engineering has been extensively developed as a potential means to treatment of large bone defects. To enhance the biomechanical performance of porous tissue scaffolds, computational design techniques have gained growing popularity attributable to their compelling efficiency and strong predictive features compared with time-consuming trial-and-error experiments. Nevertheless, the mechanical stimulus necessary for bone regeneration, which characterizes dynamic nature due to continuous variation in the bone-scaffold construct system as a result of bone-ingrowth and scaffold biodegradation, is often neglected. Thus, this study proposes a time-dependent mechanobiology-based topology optimization framework for design of tissue scaffolds, thereby developing an ongoing favorable microenvironment and ensuring a long-term outcome for bone regeneration. For the first time, a level-set based topology optimization algorithm and a time-dependent shape derivative are developed to optimize the scaffold architecture. In this study, a large bone defect in a simulated 2D femur model and a partial defect in a 3D femur model are considered to demonstrate the effectiveness of the proposed design method. The results are compared with those obtained from stiffness-based topology optimization, time-independent design and typical scaffold constructs, showing significant advantages in continuing bone ingrowth outcomes.

Graphene oxide (GO) consisting of a carbon monolayer has been widely investigated for tissue engineering platforms because of its unique properties. For this study, we fabricated a GO-applied scaffold and assessed the cellular and tissue behaviors in the scaffold. A preclinical test was conducted to ascertain whether the GO scaffold promoted bone induction in dog tooth extraction sockets. For this study, GO scaffolds were prepared by coating the surface of a collagen sponge scaffold with 0.1 and 1 µg/mL GO dispersion. Scaffolds were characterized using scanning electron microscopy (SEM), physical testing, cell seeding, and rat subcutaneous implant testing. Then a GO scaffold was implanted into a dog tooth extraction socket. Histological observations were made at 2 weeks postsurgery. SEM observations show that GO attached to the surface of collagen scaffold struts. The GO scaffold exhibited an interconnected structure resembling that of control subjects. GO application improved the physical strength, enzyme resistance, and adsorption of calcium and proteins. Cytocompatibility tests showed that GO application significantly increased osteoblastic MC3T3-E1 cell proliferation. In addition, an assessment of rat subcutaneous tissue response revealed that implantation of 1 µg/mL GO scaffold stimulated cellular ingrowth behavior, suggesting that the GO scaffold exhibited good biocompatibility. The tissue ingrowth area and DNA contents of 1 µg/mL GO scaffold were, respectively, approximately 2.5-fold and 1.4-fold greater than those of the control. Particularly, the infiltration of ED2-positive (M2) macrophages and blood vessels were prominent in the GO scaffold. Dog bone-formation tests showed that 1 µg/mL GO scaffold implantation enhanced bone formation. New bone formation following GO scaffold implantation was enhanced fivefold compared to that in control subjects. These results suggest that GO was biocompatible and had high bone-formation capability for the scaffold. The GO scaffold is expected to be beneficial for bone tissue engineering therapy.