Can the material properties of regenerate bone be predicted with non-invasive methods of assessment? Exploring the correlation between dual X-ray absorptiometry and compression testing to failure in an animal model of distraction osteogenesis

Evaluation of the material properties of regenerate bone is of fundamental importance to a successful outcome following distraction osteogenesis using an external fixator. Plain radiographs are in widespread use for assessment of alignment and the distraction gap but are unable to detect bone formation in the early stages of distraction osteogenesis and do not quantify accurately the structural properties of the regenerate. Dual X-ray absorptiometry (DXA) is a widely available non-invasive imaging modality that, unlike X-ray, can be used to measure bone mineral content (BMC) and density quantitatively. In order to be useful as a clinical investigation; however, the structural two-dimensional geometry and density distributions assessed by DXA should reflect material properties such as modulus and also predict the structural mechanical properties of the regenerate bone formed. We explored the hypothesis that there is a relationship between DXA assessment of regenerate bone and structural mechanical properties in an animal model of distraction osteogenesis. Distraction osteogenesis was carried out on the tibial diaphysis of 41 male, 12 week old, New Zealand white rabbits as part of a larger study. Distraction started after a latent period of 24 h at a rate of 0.375 mm every 12 h and continued for 10-days, achieving average lengthening of 7.1 mm. Following an 18-day period of consolidation, the regenerate bone was subject to bone density measurements using a total body dual-energy X-ray densitometer. This produced measurement of BMC, bone mineral density (BMD) and volumetric bone mineral density (vBMD). The tibiae were then disarticulated and cleaned of soft tissue before loading in compression to failure using an Instron mechanical testing machine (Instron Corporation, Massachusetts USA). Using Spearman rank correlation and linear regression, there was a significant correlation between vBMD and the Modulus of Elasticity, Yield Stress and Failure Stress of the bone. No correlation was seen between BMC, BMD, vBMR and any mechanical parameter. DXA is a promising tool for the assessment of regenerate bone formed by DO during limb lengthening and requires further investigation. © 2014 The Author(s)

Defining the trials nurses’ role in operationalising a medicinal cannabis clinical trial

Background: With increasing use of medicinal cannabis for symptom management, clinical trials nurses need to consider the various legal, social, ethical, and interdisciplinary care issues of implementing these clinical trials, especially in a palliative care population. Aim: To define the trials nurses’ role in operationalising a medicinal cannabis pharmacokinetic inpatient trial in an advanced cancer population. Methods: A qualitative, descriptive design incorporating case study methodology was used. Data were collected from minuted meetings, field notes, telephone, and email discussions involving trials nurses at two palliative care sites. Data were integrated and synthesised to identify the key considerations required to operationalise the trial and define the trials nurses’ role. Findings: Three key considerations were identified: (i) Normalising the trial, (ii) Creating the environment to undertake the trial, and (iii) Managing the complexity. The trials nurses’ role was explored through subthemes of these considerations including: their understanding of the purpose of the research and training in the protocol; organising inpatient resources, pharmacy requirements and managing the external scrutiny; participant recruitment, staffing requirements, safety, and supporting caregivers. Discussion: This study emphasises the multifactorial role of the trials nurses in managing a complex palliative care trial, and the importance of their early involvement and recognition as the vital link between all parties. Conclusion: Defining the trials nurses’ role, within the confines of the protocol, the context of efficient nursing processes and ensuring a patient-centred approach enabled the operationalisation of a Phase I/II medicinal cannabis trial which will have global impact