Achieving precise open reduction and fixation of acetabular fractures by using a plate osteosynthesis is a complex procedure. Increasing availability of affordable 3D printing devices and services now allow to actually print physical models of the patient's anatomy by segmenting the patient's CT image. The data processing and printing of the model however still take too much time and usually the resulting model is rigid and doesn't allow fracture reduction on the model itself.

Our proposed solution automatically detects relevant structures such as the fracture gaps and cortical bone while eliminating irrelevant structures such as debris and cancellous bone. This is done by approximating a sphere to the exterior surface of a classic segmented STL model. Stepwise, these approximated vertices are projected deeper into any structure such as the acetabular socket or fractures, following a specific set of rules. The resulting surface model finally is adapted precisely to the primary segmented model.

Creating an enhanced surface reconstruction model from the primary model took a median time of 42 sec. The whole workflow from DICOM to enhanced printable 3D file took a median time of 13:25 min. The median time and material needed for the prints without the process was 32:25:36 h and 241,04 g, with the process 09:41:33 h and 65,89 g, which is 70% faster. The price of material was very low with a median of 2,18€ per case. Moreover, fracture reduction becomes possible, allowing a dry-run of the procedure and allowing more precise plate placement.

Pre-contouring of osteosynthesis plates by using these 3D printouts was done for eleven patients prior to surgery. These printouts were validated to be accurate by three experiences surgeons and compared to classic segmented models regarding printing time, material cost and reduction ability. The pre-contouring of the plates was safely achievable. Our results show that improving the operative treatment with the help of enhanced 3D printed fracture models seems feasible and needs comparably little time and cost, thus making it a technique that can easily integrated into the clinical workflow.

Introduction: Randomised Controlled Trials (RCTs) of interventions to reduce the incidence of falls have used a variety of methods to define and measure outcomes. A standardised approach to defining and measuring outcomes, and a shared taxonomy of interventions is a prerequisite to interpret and disseminate the findings of studies.

Method: We agreed to focus on five areas: falls, injuries, psychological consequences, physical activity and quality of life. A systematic literature review has been performed to identify outcome definitions currently used in RCTs and is focusing on the quality of outcome measures in terms of reliability, validity and acceptability. A consensus building process is being performed using a modified nominal group technique to define a core set of outcome definitions and measures, which can then be piloted in a number of sites across Europe. Where consensus cannot be achieved, suggestions are made for future research to develop and/or appraise new methods of measurement and these will feed into future revisions of the recommendations. The taxonomy of interventions is being developed in parallel with this process.

Results: The presentation will demonstrate how varying methods of defining falls can lead to a different interpretation of trial results and suggest a range of definitions than might be included in future trials. We consider the number of falls, number of fallers, time to first fall, and fractures per fall ratios as examples.

Conclusions: An agreed and standardised set of outcome definitions and measures is important to improve the robustness of data from intervention studies, will enable comparison across studies, good quality measurement in multi-centre trials, and facilitate meta-analysis of trial results. A taxonomy of interventions facilitates comparisons between studies, helps to determine the most effective components or sub-components of interventions, and aids the decision making process of policy makers and health insurance plans.

Aims: The pathomechanism of avascular necrosis of the femoral head (AVN) is still debated. Hip joint synovitis and effusion may impair blood ßow to the femoral head. The critical ischemia time is around 6 hours, but repeated ischemic episodes may impair reperfusion and elicit AVN. The aims of this study were to investigate the value of dynamic MRI in femoral head after ischemia and during reperfusion. Methods: In 15 domestic pigs, 3–4 months old, femoral head ischemia was achieved by raising the joint pressure to 250 mmHg by dextran infusion through a hole in the acetabular wall. MRI was performed (Philips gyroscan S15, 1.5 T, Gd-DTPA enhancement, dynamic imaging interval 39 sec.) before ischemia, after 6 hours of ischemia, and again after 4 hours of reperfusion. Results: Signal intensity versus time (SI/t) plots were constructed from 347 MR studies. By regression analysis of SI/t curves an index (enhancement/decrease) was developed as criterion for arterial or venous circulatory disturbance. Index values < 1.1 signiþed arterial impairment, > 100 venous disturbance. Values between 1.1 and 100 were considered normal. The positive predictive value for disturbed osseous blood ßow was 96%. Conclusions: Early detection of intraosseous circulatory disturbance was possible with a mathematical model for dynamic MRI results. The method is reproducible and may be employed in the early diagnosis of AVN and during treatment for monitoration of revascularisation.

Treatment with corticosteroids is a risk factor for non-traumatic avascular necrosis of the femoral head, but the pathological mechanism is poorly understood. Short-term treatment with high doses of methylprednisolone is used in severe neurotrauma and after kidney and heart transplantation. We investigated the effect of such treatment on the pattern of perfusion of the femoral head and of bone in general in the pig.

We allocated 15 immature pigs to treatment with high-dose methylprednisolone (20 mg/kg per day intramuscularly for three days, followed by 10 mg/kg intramuscularly for a further 11 days) and 15 to a control group. Perfusion of the systematically subdivided femoral head, proximal femur, acetabulum, humerus, and soft tissues was determined by the microsphere technique. Blood flow in bone was severely reduced in the steroid-treated group. The reduction of flow affected all the segments and the entire epiphysis of the femoral head. No changes in flow were found in non-osseous tissue. Short-term treatment with high-dose methylprednisolone causes reduction of osseous blood flow which may be the pathogenetic factor in the early stage of steroid-induced osteonecrosis.