Image analysis for computer-assisted orthopaedic surgery

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Image Analysis for Computer-Assisted Surgery of Hip Fractures

. This paper focuses on the task of automatic feature detection for computer-assisted fixation of hip fractures. The features of interest are the lateral cortex line, the femoral neck centre and the femoral head centre, the latter being the most challenging of all. A nonconventional "divide-and-conquer" knowledgebased approach produces more reliable and faster results than the standard global image processing routine. 1. Introduction Fractures at the neck of the femur, also referred to as hip fractures, are one of the most common orthopaedic fractures. The treatment involves a fixation by the use of a screw and plate combination (Figure 1). A variety of internal fixation devices exist but the surgical process is similar. The screw must be positioned accurately so that it passes through the neck, taps into the femoral head and terminates at a fixed distance from the hip joint surface. The margin for error is small as only a comparatively small region of cortical bone is available to a..

Development of a clinical workflow tool to enhance the detection of vertebral fractures: accuracy and precision evaluation

STUDY DESIGN: Image analysis model development. OBJECTIVE: The objective of this study was to develop a novel clinical workflow tool that uses model-based shape recognition technology to allow efficient, semiautomated detailed annotation of each vertebra between T4 and L4 on plain lateral radiographs. SUMMARY OF BACKGROUND DATA: Identification of prevalent vertebral fractures, especially when not symptomatic, has been problematic despite their importance. There is a recognized need to increase the opportunities to detect vertebral fractures so that clinically beneficial therapeutic interventions can be initiated. METHODS: Radiographs obtained from 165 subjects in the Canadian Multicenter Osteoporosis Study (CaMos) were used to construct a vertebral shape model of the vertebral column from T4 to L4 using a statistical learning technique, as well as to estimate the accuracy and precision of this automated software tool for vertebral shape analysis. Radiographs showing scoliosis greater than 15 degrees were excluded. RESULTS: Vertebral contours defined by 95 points per vertebra, represented by 79,895 points in total, were assessed on 841 individual vertebrae. The mean absolute accuracy error calculated over each vertebra in each test image was 1.06 +/- 1.2 mm. This value corresponded to an average 3.4% of vertebral height. The mean precision error, reflecting interobserver variability, per vertebra of the resulting annotations was 0.61 +/- 0.73 mm. This value corresponded to an average 2.3% of vertebral height. Accuracy and precision error estimates did not differ notably by vertebral level. CONCLUSION: The results of the current study indicate that statistical modeling can provide a robust tool for the accurate and precise semiautomated annotation of vertebral body shape from T4 to L4 in patients who do not have scoliosis greater than 15 degrees . This method may prove useful as a clinical workflow tool to aid the physician in vertebral fracture assessment and might contribute to decision-making about pharmacologic treatment of osteoporosis

Does television crowd out spectators? New evidence from the Scottish Premier League

This paper examines the impact of live television coverage on attendance at Scottish Premier League soccer matches during the 2002-2003 season. The authors exploit a rich data set which distinguishes match-day attendance into three groups: season ticket holders, pay-at-the-gate home team supporters, and pay-at-the-gate visiting team supporters. This examination of these categories is the first study of its kind. The results indicate matches broadcast live reduce pay-at-the-gate home team supporters by 30%. These results suggest that league administrators and club owners must consider the impact on clubs' traditional supporters when negotiating future broadcasting rights