Accuracy in positioning of handheld instruments

Microsurgery with handheld instruments requires accurate positioning. The attainable degree of accuracy depends on the amplitude of the components of error, from whatever source, in hand motion. Here, the authors quantify attainable accuracy in positioning of handheld instruments over a 1 min time span. No prefiltering of measured data is used. The average error standard deviation norm is found to be 0.34 mm with the forearm supported, and 0.19 mm with the hand supported. In both cases, a substantial amount of error is detected at frequencies lower than the range typically attributed to physiological tremor.