## 1 Introduction  
Gesture-based computer interfaces are well-known to many researchers [1]. The widespread use of input video game consoles (such as Microsoft, Xbox Kinect, Nintendo Wii, and PlayStation Move) has taken human-computer interaction (HCI) to entirely new, unexplored levels. There has been extensive research into developing this type of human-computer interaction [2; 3; 4]. The Picture Archiving and Communication System (PACS) has become a standard in the handling and archiving of medical images displayed in digital form. Imaging is needed on a computer screen in an operating room (OR) environment. The success of the last elective surgery is based on quick access to the preoperative and intra-operative images and the provision of preoperative planning using digital templates [5; 6; 7; 8; 9]. Viewing medical images during surgical procedures and turning on teleconferencing applications in a hybrid operating room may be necessary to verify surgical indications or seek the opinion of a consultant remotely as part of telementoring. In the operating room, where the environment requires maintaining sterility, running applications on monitors should also be available to scrubbed surgeons. Viewing patients' images on a PACS workstation is usually limited to a traditional computer mouse, touchpad, and keyboard. A surgeon wishing to use the computer independently would have to be unscrubbed. Another way is to cooperate with an additional unscrubbed assistant, i.e., an additional person is needed temporarily or permanently in the operating room to operate the PACS workstation. Increasing the number of staff in the operating room may increase the risk of environmental contamination. Almost 50 years ago, the operating room staff was shown to be the primary source of bacteria [10]. Therefore, limiting traffic in the OR is highly recommended [11].  
Moreover, additional staff can distract the operating surgeon, increasing operation time. The surgeon can communicate verbally and express the needs of the screen image and the appropriate templates and resources. The procedure itself can be time-consuming, interrupting the work and distracting the surgeon, leading to an increase in the frequency of surgeries [12; 13].  
[PERSON] [14] has shown that, on average, communication with the assistant may consume up to 7 min to click on the exact location indicated by the surgeon. They improve diagnostic imaging during the surgical procedure and maintain appropriate field sterility during the surgery. There has been considerable interest in touch-free image manipulation interfaces. In the current literature, few papers address the problem of the touchless operation of PACS browsers, including Osirix [1; 15]. There are some reports concerning such devices used for medical purposes [16; 17; 18; 19; 20; 21]. There is no evidence in the literature for using a touchless interface that allows viewing and handling medical images and connecting with an associate or supervising surgeon for telementoring sessions or educational purposes directly from the operating room using hand gestures in orthopedics. As necessary from the point of view of functionality, the use of a contactless interface was considered to increase the cleanliness of the operating room environment, reduce the necessary number of medical personnel needed to ensure the proper course of the surgery while meeting the requirements, and provide at least the same performance compared to current procedures.  
The study aimed to conduct field tests with end users (orthopedic surgeons) and assess the feasibility and suitability of the developed application for contactless control of medical image visualization and switching on the surgical telementoring session.