Customized implants for acetabular Paprosky III defects may be positioned with high accuracy in revision hip arthroplasty.

Purpose: In revision hip arthroplasty, custom-made implants are one option in patients with acetabular Paprosky III defects.

Methods: In a retrospective analysis, we identified 11 patients undergoing cup revision using a custom-made implant. The accuracy of the intended position of the implant was assessed on post-operative 3D CT and compared to the pre-operative 3D planning in terms of inclination, anteversion, and centre of rotation.

Influence of Different Three-Dimensional Open Porous Titanium Scaffold Designs on Human Osteoblasts Behavior in Static and Dynamic Cell Investigations.

In the treatment of osseous defects micro-structured three-dimensional materials for bone replacement serve as leading structure for cell migration, proliferation and bone formation. The scaffold design and culture conditions are crucial for the limited diffusion distance of nutrients and oxygen. In static culture, decreased cell activity and irregular distribution occur within the scaffold.

Influence of three different preservative techniques on the mechanical properties of the ovine cortical bone.

Purpose: Preservative treatments are necessary for disinfection and long term storage when dealing with biological tissue. Freezing is a gold standard but infectious risk can only be eliminated by using chemical fluids that may alter the mechanical properties, depending on their composition. Therefore, we experimentally evaluated the influence of freezing and of two commonly used preservative fluids (formalin and alcohol) on the intrinsic mechanical properties of ovine cortical bone samples, compared to purely fresh samples.

Biomechanical stability of novel mechanically adapted open-porous titanium scaffolds in metatarsal bone defects of sheep.

Open-porous titanium scaffolds for large segmental bone defects offer advantages like early weight-bearing and limited risk of implant failure. The objective of this experimental study was to determine the biomechanical behavior of novel open-porous titanium scaffolds with mechanical-adapted properties in vivo. Two types of the custom-made, open-porous scaffolds made of Ti6Al4V (Young's modulus: 6-8 GPa and different pore sizes) were implanted into a 20 mm segmental defect in the mid-diaphysis of the metatarsus of sheep, and were stabilized with an osteosynthesis plate.

Numerical optimization of open-porous bone scaffold structures to match the elastic properties of human cortical bone.

Treatment of large segmental bone defects, especially in load bearing areas, is a complex procedure in orthopedic surgery. The usage of additive manufacturing processes enables the creation of customized bone implants with arbitrary open-porous structure satisfying both the mechanical and the biological requirements for a sufficient bone ingrowth. Aim of the present numerical study was to optimize the geometrical parameters of open-porous titanium scaffolds to match the elastic properties of human cortical bone with respect to an adequate pore size.

Comparative Analysis of the Oxygen Supply and Viability of Human Osteoblasts in Three-Dimensional Titanium Scaffolds Produced by Laser-Beam or Electron-Beam Melting.

Synthetic materials for bone replacement must ensure a sufficient mechanical stability and an adequate cell proliferation within the structures. Hereby, titanium materials are suitable for producing patient-individual porous bone scaffolds by using generative techniques. In this study, the viability of human osteoblasts was investigated in porous 3D Ti6Al4V scaffolds, which were produced by electron-beam (EBM) or laser-beam melting (LBM).

Biomechanical behavior of bone scaffolds made of additive manufactured tricalciumphosphate and titanium alloy under different loading conditions.

Purpose: The repair of large segmental bone defects caused by fracture, tumor or infection remains challenging in orthopedic surgery. The capability of two different bone scaffold materials, sintered tricalciumphosphate and a titanium alloy (Ti6Al4V), were determined by mechanical and biomechanical testing.

Methods: All scaffolds were fabricated by means of additive manufacturing techniques with identical design and controlled pore geometry.

The influence of head diameter and wall thickness on deformations of metallic acetabular press-fit cups and UHMWPE liners: a finite element analysis.

Background: To increase the range of motion of total hip endoprostheses, prosthetic heads need to be enlarged, which implies that the cup and/or liner thickness must decrease. This may have negative effects on the wear rate, because the acetabular cups and liners could deform during press-fit implantation and hip joint loading. We compared the metal cup and polyethylene liner deformations that occurred when different wall thicknesses were used in order to evaluate the resulting changes in the clearance of the articulating region.

Finite element analysis on the biomechanical stability of open porous titanium scaffolds for large segmental bone defects under physiological load conditions.

Repairing large segmental defects in long bones caused by fracture, tumour or infection is still a challenging problem in orthopaedic surgery. Artificial materials, i.e.

Finite element analysis of osteosynthesis screw fixation in the bone stock: an appropriate method for automatic screw modelling.

The use of finite element analysis (FEA) has grown to a more and more important method in the field of biomedical engineering and biomechanics. Although increased computational performance allows new ways to generate more complex biomechanical models, in the area of orthopaedic surgery, solid modelling of screws and drill holes represent a limitation of their use for individual cases and an increase of computational costs. To cope with these requirements, different methods for numerical screw modelling have therefore been investigated to improve its application diversity.

Migration Capacity and Viability of Human Primary Osteoblasts in Synthetic Three-dimensional Bone Scaffolds Made of Tricalciumphosphate.

In current therapeutic strategies, bone defects are filled up by bone auto- or allografts. Since they are limited by insufficient availability and donor site morbidity, it is necessary to find an appropriate alternative of synthetic porous bone materials. Because of their osteoconductive characteristics, ceramic materials like tricalciumphosphate (TCP) are suitable to fill up bone defects.

Retention test Homburg to monitor the adhesive properties of von Willebrand factor after substitution or desmopressin therapy.

To diagnose von Willebrand disease (vWD) and to monitor drug efficacy, several tests have been established that are not, however, focused on the platelet adhesion properties of von Willebrand factor (vWF). The new platelet retention test Homburg (RTH) is characterized by a nonthrombogenic filter that retains platelets from blood when it is pressed through this filter. It was the aim of this study to examine the capability of this test to monitor the adhesive properties of vWF after its substitution in vWD or its release by desmopressin infusion.

[Platelet retention test Homburg (RTH) and drug monitoring of platelet adhesive properties of von Willebrand factor].

Platelet plug formation is initiated by the process of platelet adhesion, mainly mediated by the von Wille-brand factor (VWF). Therefore, apart from established criteria the platelet adhesion property is a further criterion to determine VWF e. g.

Prestorage inline filtration of whole blood for obtaining white cell-reduced blood components.

Background: Preliminary studies have indicated that the inline filtration of whole blood is a feasible method of obtaining white cell (WBC)-reduced packaged red cells (RBCs) and WBC-reduced fresh-frozen plasma (FFP) while using only one filter.

Study Design And Methods: An inline WBC-reduction filter, specially designed for this purpose and integrated in a "top-top" system, was used in the preparation of 24 units of WBC-reduced RBCs (RBC-F) and FFP (FFP-F) in each of two transfusion centers (Vienna and Göttingen). Twelve conventionally prepared units of RBCs (RBC-C) and FFP (FFP-C) served as controls.

Fibronectin in the plasma during pregnancy and parturition.

Fibronectin can be detected in the plasma and the extracellular matrix of the uterus of pregnant women. Studies so far have compared individual observations, whilst serial investigations during pregnancy, and during and after parturition have not been carried out. Plasma fibronectin levels were measured in 153 women with healthy pregnancies in relation to the gestational age.

[Virus inactivated plasma].

Two different virus inactivated plasma preparations are available in Germany. Methylene blue ephotoxidized (MB) plasma is plasma from a single donation, which is photoxidized using 1 microM methylene blue and visible light (1 hour 60,000 Lux). Photochemical inactivation reduces HIV by at least 5 log10, but also fibrinogen is altered.

[Platelet membrane glycoproteins in thrombocytapheresis and platelet concentrates].

Membrane glycoprotein (GP) expression on platelets changes during preparation of concentrates and storage. Recent studies proved that the increased expression of the GMP-140 (CD 62), a GP appearing on platelets after activation, correlates with the in vivo recovery of transfused platelets. We therefore investigated the expression of this and three other GP (GP IIb/IIIa, GP, Ib, GP 53), detected by flow cytometry, in normal controls and in platelet concentrates prepared by four different methods (apheresis, preparation from buffy coat, from pooled buffy coat and platelet-rich plasma) after preparation and during storage.

[Leukocyte filtration of stored whole blood for preparation of components].

Prophylaxis of infection and alloimmunisation is the main reason for leucocyte depletion by filtration of blood components. The question is whether all red cell concentrates (RCC) should be filtered and whether plasma has to be filtered, too. For leucocyte-poor units whole blood was filtered before preparation using the 'top and bottom' system.

Inactivation of viruses in fresh-frozen plasma.

Methylene blue (MB) or solvent/detergent (SD) treatment is used for the inactivation of lipid-enveloped viruses in plasma. One important characteristic of the SD treatment is the necessity to pool plasma from different donors, thus inducing the risk of spreading infectious particles. MB treatment can be applied to single-donor plasma, causing no greater infectious risk than conventional fresh-frozen plasma (FFP).

[Methylene blue/light treatment of virus inactivated human plasma: production and clinical experience].

A photodynamic procedure to inactivate viruses in fresh plasma for therapeutical use is carried out by illuminating single units of plasma with visible light in the presence of the phenothiazine dye methylene blue. The blood bag systems of all common suppliers can be used for this purpose. Photodynamic treatment only moderately influences the activities of plasma proteins.

[Comparative analysis of various plasmapheresis methods--modern procedures of mechanical plasma collection compared with each other and with manual bag centrifugation procedures].

Four plasmapheresis procedures (manual blood bag centrifugation plasmapheresis, and the three plasmapheresis machines P.C.S.

[Initial experiences with methylene blue virus inactivated fresh frozen plasma: results of a clinical and in vitro study].

Methylene blue (MB) has recently been introduced to inactivate viruses in single donor fresh frozen plasma (FFP) units. In the first clinical study 519 units of MB-treated FFP were given to 103 patients. No specific clinical side effects with adverse reactions were recorded.