Neurosurgeons have to perform fine and accurate procedures in microneurosurgery. If supporting places for their hands and arms are prepared adequately, it is possible to stabilize their hands and arms and then to reduce their tremor. To answer to this request, freely movable armrest (FMA) which can follow operator’s arm motion has been developed. Although some FMAs have been already commercially available, the FMA has not widely been used yet. We have made an original FMA and investigated the system with basic examinations. The efficacy and the limitation of the system were discussed. Materials and methods: A FMA, consisted of an arm holder, a flexible holding arm and a stand, was made. It can be freely moved and follow the operator’s motion. With a task of stitching an incised vessel model, effect of the FMA was evaluated for three factors: 1) performance time to complete 10-stitch suturing, 2) subjective fatigue and 3) subjective maneuverability. Subjective evaluations were scored in 1-10 scale (1: the least fatigue and the worst to perform, 10: the most fatigue and the best to perform). Results: The simulated surgery was successfully performed without technical and mechanical errors. Mean performance time with the FMA (790.8 seconds) was significantly shorter than that without the FMA (P=0.038). Mean fatigue score with the FMA (4.33) was smaller than that with the FMA (6.17), and mean maneuverability score with the FMA (6.33) was larger than that without the FMA (4.00). Conclusions: Installing a freely movable armrest, which can follow the operator’s motion, into microneurosurgery has a possibility to reduce operator’s fatigue and to improve maneuverability.

Key words: Freely movable armrest, microneurosurgery operator’s fatigue