Dynamic titanium prosthesis based on 3D-printed replica for chest wall resection and reconstruction

3D-printing technologies can assist the surgical planning and prosthesis engineering for the management of extended chest wall resection. Different types of prosthesis have been utilized over time, but some concerns remain about their impact on the respiratory function. Here we present a new kind of 3D-printed titanium prosthesis designed to be either strong and flexible. The prosthesis was created on a 1:1 3D-printed anatomic replica of the chest, used to delineate surgical margins and to define the reconstructive requirements

Desarrollo de implantes protesicos personalizados mediante impresión 3D de metales para el tratamiento quirúrgico de defectos maxilares

La osteonecrosis mandibular es una patología que suele presentarse como efecto secundario de la radioterapia con que se tratan los procesos oncológicos de cabeza y cuello, o después de tratamientos prolongados con bifosfonatos. Su única solución posible consiste en la resección quirúrgica del hueso dañado seguida de una reconstrucción anatómico-funcional con placas metálicas e implantes de diversos materiales. Debido a la dificultad técnica de la cirugía y la mala calidad que suele presentar el hueso del paciente, dicha reconstrucción rara vez es satisfactoria, ni desde el punto de vista funcional, ni desde el estético. El desarrollo de tecnologías de impresión 3D de metales ha abierto la posibilidad de fabricar prótesis personalizadas, hechas a partir de datos de TAC del paciente, para darles la forma exacta del segmento a sustituir. El proyecto que presentamos partió de dos premisas: i) las prótesis personalizadas, fabricadas por sinterizado metálico suponen una alternativa viable, y que mejora la situación actual; y ii) la adición de elementos de ingeniería tisular podría implementar estas prótesis personalizadas, promoviendo su osteointegración. Las dos hipótesis se pusieron a prueba mediante la creación de un modelo de resección maxilar en un animal de tamaño medio (conejo), y el diseño de prótesis personalizadas a dicho defecto, que se fabricaron en aleación Ti6Al4V mediante fabricación aditiva. En un desarrollo posterior, estas prótesis se combinaron con biomateriales, biomoléculas y células mesenquimales. Los resultados obtenidos prueban la utilidad de la impresión 3D de prótesis maxilares personalizadas, y la mejora de su osteointegración mediante adición de elementos de ingeniería tisular.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Extending the k-nearest-neighbor classification algorithm to symbolic objects

L’analisi di dati simbolici generalizza alcuni metodi statistici standard al caso di oggetti simbolici (SO). Questi oggetti, informalmente definiti “dati aggregati”, poiché sintetizzano le informazioni relative ad un gruppo di individui, possono essere confrontati al fine di individuare dei cluster, di classificarli o ordinarli in base al loro grado di generalizzazione. L’articolo propone un’estensione dell’algoritmo classico di classificazione K-Nearest Neighbor a tali oggetti. Il risultato di questo algoritmo è ancora un insieme di oggetti simbolici che possono essere studiati mediante altre tecniche di analisi di dati simbolici

Trading-off Local versus Global Effects of Regression

Model trees are an extension of regression trees that associate leaves with multiple regression models. In this paper a method for the top-down induction of model trees is presented, namely the Stepwise Model Tree Induction (SMOTI) method. Its main characteristic is the induction of trees with two types of nodes: regression nodes, which perform only straight-line regression, and split nodes, which partition the sample space. The multiple linear model associated to each leaf is then obtained by combining straight-line regressions reported along the path from the root to the leaf. In this way, internal regression nodes contribute to the definition of multiple models and have a "global" effect, while straight-line regressions at leaves have only "local" effects. This peculiarity of SMOTI has been evaluated in an empirical study involving both real and artificial data

Extending the K-Nearest Neighbour Classification

This paper presents the extension of the distance weighted K-Nearest Neighbour (KNN) classification algorithm to SOs. The main novelties of the proposed extension are the use of a dissimilarity measure between SOs, the automated selection of K on the basis of cross-validation, and the output of a symbolic modal variable instead of a single classvalue. 2. KNN for Symbolic Objects The problem to be solved is the following: given a training set of SOs described by p modal or Boolean symbolic variables V 1 , V 2 , ..., V p and by a single-valued variable C, named target or class variable, with domain C, we want to determine the value of a modal variable C' with domain C for a new SO (test case) described by the same set of symbolic variables used for the training set, namely V 1 , V 2 , ..., V p . The modality of the C' is probabilistic, meaning that we associate the new SO with a class probability vector whose dimension corresponds to the number of distinct values or classes in C. According to the KNN algorithm, the assignment of a value to C' can be based on the values taken by C for the K-nearest neighbors of the test case. However, the standard KNN algorithm assumes all training cases correspond to points in the p-dimensional space # , and the nearest neighbours of a new case are defined in terms of the standard Euclidean distance. Therefore, the extension of KNN to SOs requires the use of a dissimilarity measure d for SOs, which cannot be represented as points in # . Many proposals of dissimilarity measures for BSOs have been reported in literature; an extensive review of their definitions is reported in (Esposito et al., 2000), while a preliminary comparative study on their suitability to real-world problems is reported in (Malerba et al., 2001)..

Role of Tibial Tuberosity Fracture/Fissure through the Maquet Hole in Stifle Osteoarthritis after Porous Tibial Tuberosity Advancement in Dogs at Mid-Term Follow-Up

Tibial tuberosity advancement (TTA) is used to treat cranial cruciate ligament rupture of the stifle joint in dogs. Tibial tuberosity fracture/fissure is a complication of TTA that may have a favorable prognosis. The aim of this study was to detect how tibial tuberosity fracture/fissure through the Maquet hole worsens the progression of osteoarthritis (OA) in the stifle joint of dogs treated with porous TTA. Seventeen cases were included in the study, divided into two groups. The first group (n = 10) included subjects that had tibial tuberosity fracture/fissure through the Maquet, and the second group included subjects that had no complications (n = 7). Both groups showed significant progression compared to OA at 3 months after surgery. We observed that at T0, the control group showed a higher level of OA. For this reason, we normalized the OA scores, evaluating the percentage difference from T0 and T1. We verified that there were no statistically significant differences between the two groups. The results confirm that OA progression in subjects undergoing TTA was not significantly influenced by fracture/fissure of the tibial tuberosity through the Maquet hole. Therefore, fracture fissure through the Maquet hole should be considered as a common minor complication during TTA

Dendritic Scaffold onto Titanium Implants. A Versatile Strategy Increasing Biocompatibility

Osseointegration of metal prosthetic implants is a yet unresolved clinical need that depends on the interplay between the implant surface and bone cells. The lack of a relationship between bone cells and metal has traditionally been solved by coating the former with "organic" ceramics, such as hydroxyapatite. A novel approach is hereby presented, immobilizing covalently dendrimeric structures onto titanium implants. Amide-based amino terminal dendrons were synthetized and coupled to titanium surfaces in a versatile and controlled way. The dendritic moieties provide an excellent scaffold for the covalent immobilization of bioactive molecules, such as extracellular matrix (ECM) protein components or antibiotics. Herein, tripeptide arginine-glycine-aspartic acid (RGD) motifs were used to decorate the dendritic scaffolds and their influence on cell adhesion and proliferation processes was evaluated.This work was supported by the Spanish Ministerio de Economía, Industria y Competitividad (CTQ2016-75870-P and BIO2015-66266-R), Junta de Andalucía (Consejería de Salud, PI0250-2016 and PI-0555-2013) and (UMA18-FEDERJA-007), Consejería de Innovación, Ciencia y Empresa, Junta de Andalucía-PAIDI-FQM-017 and PAIDI-BIO-217, and FEDER funds. N.M. holds a FPU grant of MECD (FPU15/00641). Centro de Investigación Biomédica en Red – Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN) and Red de Terapia Celular are initiatives funded by Instituto de Salud Carlos III in collaboration with FEDER (CB06/01/1015 and RD16/0011/0022).Ye

41 Cases of Treatment of Cranial Cruciate Ligament Rupture with Porous TTA: Three Years of Follow Up

Tibial Tuberosity Advancement (TTA) is a surgical technique based on a linear osteotomy that determines a cranial advancement of the tibial tuberosity in patients suffering from cranial cruciate ligament rupture (CCL). The aim is to neutralize the cranial tibial thrust (CTT) and to reach a 90° angle between the patellar tendon and the tibial plateau with a physiological knee extension of 135°. In our study, a Ti6AI4V ELI (Titanium Aluminium Vanadium) titanium scaffold for the Porous TTA, with excellent properties of osteointegration and osteoconduction when subjected to cyclic loading has been adopted. Based on the previous scientific work on an ovine model, the use of this type of porous scaffolds has subverted the previous models. Scaffold production technology is based on direct mechanical manufacturing called Electron Beam Melting (EBM). For this study, 41 dogs, different breeds, medium-large size, weighing between 10 and 80 kg, aged between 1 and 13 years, were enrolled. The inclusion criteria were based on clinical evaluations (different gaits), drawer test and tibial compression, LOAD score (Liverpool Osteoarthritis in Dogs questionnaire), radiographic diagnosis in sedation with a 135° positioning of the joint and baropodometric investigations (Stance Analyzer). The results show that Porous TTA is an excellent method for functional recovery of the knee joint following the partial and total rupture of the CCL

3D Biomimetic Porous Titanium (Ti6Al4V ELI) Scaffolds for Large Bone Critical Defect Reconstruction: An Experimental Study in Sheep

The main goal in the treatment of large bone defects is to guarantee a rapid loading of the affected limb. In this paper, the authors proposed a new reconstructive technique that proved to be suitable to reach this purpose through the use of a custom-made biomimetic porous titanium scaffold. An in vivo study was undertaken where a complete critical defect was experimentally created in the diaphysis of the right tibia of twelve sheep and replaced with a five-centimeter porous scaffold of electron beam melting (EBM)-sintered titanium alloy (EBM group n = 6) or a porous hydroxyapatite scaffold (CONTROL group, n = 6). After surgery, the sheep were allowed to move freely in the barns. The outcome was monitored for up to 12 months by periodical X-ray and clinical examination. All animals in the CONTROL group were euthanized for humane reasons within the first month after surgery due to the onset of plate bending due to mechanical overload. Nine months after surgery, X-ray imaging showed the complete integration of the titanium implant in the tibia diaphysis and remodeling of the periosteal callus, with a well-defined cortical bone. At 12 months, sheep were euthanized, and the tibia were harvested and subjected to histological analysis. This showed bone tissue formations with bone trabeculae bridging titanium trabeculae, evidencing an optimal tissue-metal interaction. Our results show that EBM-sintered titanium devices, if used to repair critical bone defects in a large animal model, can guarantee immediate body weight-bearing, a rapid functional recovery, and a good osseointegration. The porous hydroxyapatite scaffolds proved to be not suitable in this model of large bone defect due to their known poor mechanical properties.This study was co-supported by the Spanish Network on Cell Therapy (Red TerCel), MINECO-Spain (BIO2015-66266-R), and Junta de Andalucía-Spain (PI-0555-2013). CIBER-BBN is an initiative funded by the VI National R&D&I Plan 2008–2011, Iniciativa Ingenio 2010, Consolider Program and CIBER Actions and is financed by the Instituto de Salud Carlos III, Spain, with assistance from the European Regional Development Fund.Ye