FIELD: medical engineering. SUBSTANCE: device has rod, removable elliptic endpiece having various types and sizes with lesser axes varying from 8 mm to 18 mm and large axis of 20 mm, removable rod handle, digital handle indication, stepped rod bent, rod scale in mm with ticks spaced every 5 mm and digital mark every 10 mm. The first digital mark on the rod scale is 2 that designates the beginning value for distance from the elliptic end piece lesser axis level to the stepped rod bent positioned 250 mm apart when the removable elliptic end piece is attached to the rod. EFFECT: high accuracy in measuring medullary canal diameter at some distance from trimmed medial femoral neck edge. 19 dwg
