Figure 4.

Operator effects. (a) Angular dependence of the unnormalized BMS output from the Osteoprobe. A calibration block was tested at different angles ranging from 0° to 20° off normal. At 10° and higher, the values were significantly smaller than normal. The instrument should always be held less than 10° off of normal from the test specimen for accurate results. It is important to note that the unnormalized BMS values are all normalized with respect to the calibration material being perfectly normal to the sample. The standard BMS would compensate for angles off of normal if the calibration phantom was tested at the same angle off normal. (b) Comparison of values obtained from three different operators indenting a standard sample at different loading times. If one indents the sample while compressing the instrument rapidly, the unnormalized BMS values are lower than expected and have large variance. As one increases the loading time (duration of compression), the values stabilize. This occurs when the loading time is greater than 1 s.