RU2066129C1 - Semiautomatic device for cranial trepanation - Google Patents

Abstract

FIELD: medicine, at cutting of bone tissue. SUBSTANCE: device comprises casing 1 with holder 4, drive and master cam-safety device 8 positioned in the holder, cutting instrument in the form of an end milling cutter; holder 4, drive and master cam-safety device 8 combined in the common casing of holder 4 can move along the axis of rotation of holder 4 relative to device casing 1 accomplishing automatic adjustment of instrument entry in tissues, depending on the thickness of the cut bone. In the process of operation the casing of holder 4 is squeezed out upwards by the force arising in the drive, made in the form of a gear set of a helical gearing. For removal of cuttings from the zone of cutting, cooling of the cut bone and instrument the casing is provided with duct 10 for feeding of liquid. EFFECT: enhanced efficiency. 3 cl, 1 dwg

Description

 The invention relates to medical equipment, in particular, to cutting bone tissue.

 A device for trepanation of the skull, comprising a housing with a chuck and a drive, a cutting tool in the form of an end mill, a copier-guard, which can rotate around the axis of rotation of the chuck / 1 /, is located in the chuck.

 The rotation of the safety guard around the axis of rotation of the cartridge allows you to make cuts of complex configuration with minimal radii, but due to the lack of regulation of the deepening of the working part in the tissue, the possibility of injury to the dura mater and brain substance remains. In addition, during operation of the device, the tissue is heated and the accumulation of decay products in the cutting zone.

 A device is known, in the outer casing of which a channel is made for supplying a washing liquid to the cutting zone, which facilitates the work with the device / 2 /.

 The closest technical solution to the proposed one is a device for craniotomy, containing an inner casing with an axial protrusion, a chuck, a drive and a cutting tool located in the chuck, while the device has an additional (outer) casing connected to the inner casing by means of a movable axial joint made in in the form of guides and provided with stops, the housings being mutually spring-loaded / 3 /.

 However, this device does not completely exclude the possibility of injury to the patient.

 EFFECT: invention allows to completely avoid trauma to the dura mater and brain substance, heating the bone during operation of the device, and ensures the removal of cut products from the cutting zone.

 This is achieved by the fact that in the device for craniotomy, containing a body with a cartridge, a drive and a safety copy, a cutting tool in the form of an end mill located in the cartridge, a cartridge, a drive and a safety copy combined in a common cartridge case, can move along axis of rotation of the cartridge relative to the housing of the device.

 The cartridge case has a constant upward pressure by a spring placed in the device case and interacting at one end with it and the other with the cartridge case.

 To ensure ease of change of the cutting tool and the separation of the moving parts of the device from the electric motor, a helical gear transmission has been introduced into the drive structure.

 In gears of known designs, where helical gears are used, of the two components of the engagement force, only one tangential is used as the working one, the axial one is parasitic. To prevent the displacement of the shaft and the wheel under the action of this component, they are forced to use one of the shaft supports of a special design that accepts both radial and axial loads.

 In the developed gear, both components of the engagement force are used as useful.

 To do this, in a gear transmission containing a housing, a helical gear pair of gears and wheel shafts with bearings, the driven wheel is made wider than the leading one and together with the shaft and shaft supports is placed in its own case, which, in turn, is fixed in the guides of the transmission case. During operation, the driven wheel receives rotational motion and, together with its housing, is displaced in the direction and under the action of the axial component of the engagement force.

The angle of inclination of the tooth gears choose 15 ^o (3).

, (4)
где F осевая составляющая усилия зацепления;
М крутящий момент;
β угол наклона зуба;
d диаметр колеса.The axial force developed by the drive is calculated by the formula:

, (4)
where F is the axial component of the engagement force;
M torque;
β angle of inclination of the tooth;
d wheel diameter.

 In this particular case, with a DPR-72 engine torque of 0.039 N / m and a wheel diameter of 0.02 m, we have an axial force of 1.0 N.

 The movement of the cartridge case during operation is limited by the thickness of the cut bone, with a copier fuse interacting with the inside.

 The principle of operation of the device is illustrated by the drawing. Figure 1 shows a general view of the device. And the move of the moving parts relative to the housing of the device.

 A device for craniotomy contains a housing 1 with a drive wheel 2 located in it and a cartridge case 3 with a cartridge 4 located in it, with a cutting tool 5 (end mill). The cartridge 4 is made integral with the driven wheel 6 of the drive, and the width of the driven wheel exceeds the width of the drive wheel 2 by the stroke of the cartridge case.

 A bearing 7 is mounted on the cartridge case 3 with a fuse-copier 8 made on it. The cartridge case is preloaded by a spring 9. A channel 10 is made in the device case 1 for supplying liquid to the cutting zone.

 For trepanation of the skull in the bone, a hole 11 is obtained with its known tool. Then, by squeezing the spring 9, a milling cutter 5 and a safety copy 7 are inserted into the hole 11. A safety copy 7 is brought under the inner side of the bone 12, squeezing the dura mater 13. Spring 9 raising the cartridge case 3, fixes the tool on the bone 12, clamping it between the device body 1 and the safety copier 8.

 The cutter receives rotation from the drive. The force arising in the helical wheels 2 and 6, provides an additional preload of the cartridge case.

 The surgeon performs only the feed movement and the direction of the tool along the cut line.

 When moving the tool along the cut line, the copier-guard 7, tracking the change in the thickness of the bone 12, adjusts the depth of the tool in the tissue, exfoliates the dura mater 13, and the cutter 5 cuts the bone 12.

 Through the channel 10 in the housing 1 of the device, a fluid is supplied, washing the bone chips from the cutting zone, which facilitates its subsequent collection, and reduces the temperature of the cut bone.

 Using the proposed device for craniotomy provides an automatic change in the depth of the instrument in the tissue, depending on changes in the thickness of the cut bone, cutting without heating the bone and tool, timely removal of bone chips from the cutting area and facilitates its subsequent collection, reduces the injury rate and facilitates the work of the surgeon.

Claims (2)

 1. A semi-automatic device for trepanation of the skull, comprising a main body with stops, axial guides and a spring-loaded additional body placed in the guides with an end protrusion, a chuck, a drive and a cutting tool installed in the chuck, characterized in that the end protrusion is made in the form of a safety copy, the cutting tool is made in the form of an end mill, while in the main body there is a channel for flushing liquid, the drive is made with a helical pinion gear located on the shafts th pair, where one of the gears is greater than the width of the other, and the shafts are arranged in the bearings.  2. The device according to claim 1, characterized in that the driven gear exceeds the width of the drive gear.