The objective of this study is to determine the intraobserver and interobserver reliability of end vertebra definition and Cobb angle measurement using printed and digital radiographs of 48 patients with scoliosis. The Cobb angle and the end vertebra were assessed by six observers in 48 patients with scoliosis using printed and digital radiographs. Definition of end vertebra and measurement of the Cobb angle was repeated three times with a 3 week interval. Intraclass correlation coefficients (ICC) were used to determine the interobserver and intraobserver reliabilities. 95% prediction limits for the errors in measurements are provided. For the Cobb angle a mean ICC of 0.97 was determined for intra-and interobserver reliability measurement of the printed radiographs. For the electronic radiographs a mean ICC value of 0.93 was determined for interobserver reliability and a mean ICC value of 0.96 for intraobserver reliability. Intraobserver ICC for definition of end vertebrae was 0.8 for both methods. Interobserver ICC was 0.83 for the manual and 0.74 in the digital method. One pitfall in angle measurement implies the Cobb method itself which measures in two dimensions. Until we develop a proper tri-dimensional measuring system an error is introduced. For the Cobb angle measurement the definition of end vertebrae introduces the main source of error. Digital radiography does not improve the measurement accuracy.

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Ultrasound devices are in use for cement extraction in cemented revision total hip arthroplasties. These instruments vibrate at a high frequency. In contact with fluids they have the potential to produce an aerosol cloud. In case of infected or colonized patients this can be a source of environmental and body contamination for the surgical team. 12 standardized cuts in cement blocks were performed with an ultrasound device. Irrigation fluid was contaminated with Staphylococcus aureus ATTC 12600. Contamination was detected using standard cultures. Bacterial growth was seen in a 5 × 7 m area. Extension was comparable to aerosol contamination produced by high speed cutters in spinal surgery as well as in hip arthroplasty, yet, concentration was lower. Ultrasound devices, such as the one tested, can produce aerosol clouds that can cover the whole operating room and potentially contaminate the surgical personnel. The same protection is necessary for everybody in the operating room for ultrasound devices as for high-speed cutters.