Effect of Different Body and Hand Postures on Microsurgical Tremor

INTRODUCTION Microsurgical intervention requires high precision and steady hands to minimize damage to surrounding tissues and ensure a successful outcome of the operation. However, surgeons may experience tremor, which can complicate the operation process. To reduce the tremor, surgeons usually sit or support the hands in different points—elbow, wrist, hypothenar, little finger, and so on.1–4 However, the actual effect of these measures is still to be objectively compared. The purpose of this work was to test the effect of various body and hand poses on the severity of microsurgical tremor and develop recommendations for optimizing the working pose. MATERIALS AND METHODS The study enrolled 1 group of participants—14 neurosurgical residents (13 men and 1 woman) from the Burdenko Neurosurgical Center. Average age was 27.7 years (range: 26–35 y). All residents had the same level of microsurgical practice (no more than 6 mo of microsurgical training). The institutional review board approved the study, protocol no. 31/23. During the experiment, the participants were asked to make a linear 1–cm-long cut in a medical glove, imitating arachnoid dissection, using microsurgical scissors (Aesculap FD030R, Melsungen, Germany) and a surgical microscope (Carl Zeis, Oberkocher, Germany) through a simulated bone window. (See figure, Supplemental Digital Content 1, which displays a photograph of the simulation task. The surgeon cuts the glove through a window in a fixed artificial skull, using a microscope and microscissors. The software measures the level of tremor, https://links.lww.com/PRSGO/D902.) The level of tremor was measured using an accelerometer (LIS331DLHTR; STMicroelectronics, Geneva, Switzerland) attached to the handle of the microscissors. Mathematical processing was used to separate the instrument acceleration due to the voluntary movements from that due to the tremor. From the raw data of acceleration on 3 axes, the acceleration modulus (weighted average acceleration modulus) was calculated. The tremor of each participant was measured in 5 working positions, which we regularly use in our neurosurgical practice. (See figure, Supplemental Digital Content 2, which describes a photograph of the 5 basic working poses: standing, without hand support; sitting, without hand support; sitting, with elbow support; sitting, with elbow and wrist support; and full support, https://links.lww.com/PRSGO/D903.) Standing, without hand support (“standing”) Sitting, without hand support (“sitting”) Sitting, with elbow support (“elbow”) Sitting, with elbow and wrist support (“elbow + wrist”) Sitting, with elbow, wrist, hypothenar, and little finger support (“full support”) The Wilcoxon signed-rank test was used to assess paired samples in 5 experiments. RESULTS AND DISCUSSION The results are shown in Figure 1 and Table 1. There was no difference in the severity of tremor when working standing and sitting without support (P = 0.72634). The presence of hand support significantly reduced the level of tremor; predictably, the most stable position was full support. Table 1. - Pairwise Comparison of Tremor in 5 Basic Working Poses, According to Wilcoxon Signed-rank Test Sitting Elbow Support Elbow and Wrist Support Full Support Standing 0.72634 0.00288* 0.03572* 0.00424* Sitting — 0.00188* 0.01314* 0.00188* Elbow support — — 0.72634 0.03* Elbow and wrist support — — — 0.03572* Full support — — — — The numbers indicate the resulting P values.*The statistically significant values with P < 0.05. Fig. 1.: A graph that shows comparison of tremor severity when using 5 basic working poses. The x-axis shows the tremor amplitude. The y-axis shows the cycles of accelerometry.Interestingly, there was no difference in the elbow and elbow + wrist positions (P = 0.72634). A possible explanation for this finding is that the support on the wrist causes an overstrain of the extensor carpi radialis longus, which increases the tremor. CONCLUSIONS The present study demonstrates a lower severity of tremor when using any hand supporting points, except of the wrist, if the hand is overextended (elbow and wrist pose). We recommend practicing microsurgeons to rest their hands on accessible surfaces. The body position, either sitting or standing, does not matter and can be any position. DISCLOSURES The authors have no financial interest to declare in relation to the content of this article. This work was supported by the Russian Science Foundation grant № 22-75-10117.