Objective of the study: a modified technique for measuring the angle between planar anatomical structures and for determining the point of remission of the true acetabulum in dysplastic coxarthrosis using a protractor. Materials and research methods. The RSSPMCT Traumatology and Orthopedics has developed and implemented a device for measuring the angle between planar anatomical structures. A device for measuring the angle between planar anatomical structures is used as follows. The angle of the degree is preliminarily determined on MSCT(Multispiral computed tomography) for remission of the true acetabulum (from 40 ° to 60 °). The device is adjusted to measure the angle between the planar anatomical structures and to determine the point of remission of the true acetabular. The required angle is displayed on the protractor with an axial measuring scale, it is fastened using a movable protractor coupling with a screw and a screwdriver; and sterilized.