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

[Cost]effectiveness of withdrawal of fall-risk increasing drugs versus conservative treatment in older fallers: design of a multicenter randomized controlled trial (IMPROveFALL-study)

Background: Fall incidents represent an increasing public health problem in aging societies worldwide. A major risk factor for falls is the use of fall-risk increasing drugs. The primary aim of the study is to compare the effect of a structured medication assessment including the withdrawal of fall-risk increasing drugs on the number of new falls versus 'care as usual' in older adults presenting at the Emergency Department after a fall. Methods/Design. A prospective, multi-center, randomized controlled trial will be conducted in hospitals in the Netherlands. Persons aged 65 years who visit the Emergency Department due to a fall are invited to participate in this trial. All patients receive a full geriatric assessment at the research outpatient clinic. Patients are randomized between a structured medication assessment including withdrawal of fall-risk increasing drugs and 'care as usual'. A 3-monthly falls calendar is used for assessing the number of falls, fallers and associated injuries over a one-year follow-up period. Measurements will be at three, six, nine, and twelve months and include functional outcome, healthcare consumption, socio-demographic characteristics, and clinical information. After twelve months a second visit to the research outpatient clinic will be performed, and adherence to the new medication regimen in the intervention group will be measured. The primary outcome will be the incidence of new falls. Secondary outcome measurements are possible health effects of medication withdrawal, health-related quality of life (Short Form-12 and EuroQol-5D), costs, and cost-effectiveness of the intervention. Data will be analyzed using an intention-to-treat analysis. Discussion. The successful completion of this trial will provide evidence on the effectiveness of withdrawal of fall-risk increasing drugs in older patients as a method for falls reduction. Trial Registration. The trial is registered in the Netherlands Trial Register (NTR1593)