Microstructure and biomechanical characteristics of bone substitutes for trauma and orthopaedic surgery

Abstract. BACKGROUND: Many (artificial) bone substitute materials are currently available for use in orthopaedic trauma surgery. Objective data on their biological and biomechanical characteristics, which determine their clinical application, is mostly lacking. The aim of this study was to investigate structural and in vitro mechanical properties of nine bone substitute cements registered for use in orthopaedic trauma surgery in the Netherlands. METHODS: Seven calcium phosphate cements (BoneSource®, Calcibon®, ChronOS®, Eurobone®, HydroSet™, Norian SRS®, and Ostim®), one calcium sulphate cement (MIIG® X3), and one bioactive glass cement (Cortoss®) were tested. Structural characteristics were measured by micro-CT scanning. Compression strength and stiffness were determined following unconfined compression tests. RESULTS: Each bone substitute had unique characteristics. Mean total porosity ranged from 53% (Ostim®) to 0.5% (Norian SRS®). Mean pore size exceeded 100 μm only in Eurobone® and Cortoss® (162.2 ± 107.1 μm and 148.4 ± 70.6 μm, respectively). However, 230 μm pores were found in Calcibon®, Norian SRS®, HydroSet™, and MIIG® X3. Connectivity density ranged from 27/cm3 for HydroSet™ to 0.03/cm3 for Calcibon®. The ultimate compression strength was highest in Cortoss® (47.32 MPa) and lowest in Ostim® (0.24 MPa). Young's Modulus was highest in Calcibon® (790 MPa) and lowest in Ostim® (6 MPa). CONCLUSIONS: The bone substitutes tested display a wide range in structural properties and compression strength, indicating that they will be suitable for different clinical indications. The data outlined here will help surgeons to select the most suitable products currently available for specific clinical indications

Bounds on covering codes in RT spaces using ordered covering arrays

In this work, constructions of ordered covering arrays are discussed and applied to obtain new upper bounds on covering codes in Rosenbloom-Tsfasman spaces (RT spaces), improving or extending some previous results

18F-FDG PET/CT Imaging In Oncology

Accurate diagnosis and staging are essential for the optimal management of cancer patients. Positron emission tomography with 2-deoxy-2-[fluorine-18]fluoro- D-glucose integrated with computed tomography (18F-FDG PET/CT) has emerged as a powerful imaging tool for the detection of various cancers. The combined acquisition of PET and CT has synergistic advantages over PET or CT alone and minimizes their individual limitations. It is a valuable tool for staging and restaging of some tumors and has an important role in the detection of recurrence in asymptomatic patients with rising tumor marker levels and patients with negative or equivocal findings on conventional imaging techniques. It also allows for monitoring response to therapy and permitting timely modification of therapeutic regimens. In about 27% of the patients, the course of managment is changed. This review provides guidance for oncologists/ radiotherapists and clinical and surgical specialists on the use of 18F-FDG PET/CT in oncology