GB922007A - Improvements in or relating to surgical instruments - Google Patents

Abstract

922,007. Brain centres localizing and treating. T. J. CONNELLEY. Sept. 5, 1960 [June 19. 1959], No. 21181/59. Class 81 (2). An instrument for use in brain surgery comprises a hollow plug which, resting in a hole formed in the patient's skull, forms the sole support of the instrument, a guideway fixed to the plug and arranged to constrain a part of another guideway to swing about a first axis transverse to the axis of the hollow plug which other guideway constrains an instrument holder to swing about an axis at right angles to and intersecting the first axis and the axis of the hollow plug, and which instrument holder is arranged to constrain the instrument to move along an axis passing through the point of intersection of the other axes. As shown, a frame 10 having a flange 11 at each end is spanned by an arcuate inverted channel section bridge 13 which moves in arcuate slots 12 in the flanges 11 and has flanges 14 which engage the upper surface of the flanges on which a scale in degrees is marked. Slidably engaged in a slot 8 in the bridge 13 is a surgical instrument carrier 19 which comprises a T-shaped member 20 on which a guide tube 24 is screwed, Fig. 1, or through which an alternative form of guide tube 48, Fig. 4, is passed. The lower end of the tube is held in a mounting 25 allowing universal pivoting movement about a point 15 at the intersection of the axes about which the arcuate slots 12 and 8 are struck. Means for securing the frame 10 on the skull of a patient comprises an externally threaded hollow plug 27 with a flange 27b secured by set screws 29 in a boss 26 in the base of the frame. The internal surface of the plug is conical. In operation, the plug 27 is screwed into a hole drilled in the skull and a reference gauge 34, Fig. 5, is inserted in the plug a mark 37 on the gauge coinciding with the point 15. Spaced from the mark 37 is a hole 38, and spaced from the hole 38 by an equal distance is a hole 39. Lateral and antero-posterior X-rays are taken with the patient in a supine position and the target point 49 is plotted on the film, Fig. 7, from known landmarks. The gauge 34 is continued downwardly as a line 41. The point 15 is found by measuring the distance between the holes 38 and 39, and a line 42 drawn from the target point 49 through the point 15 gives the angle of correction 50. A similar angular measurement can be made from the other X-ray. These angles are set on a scale on the bridge 13 and the scales on the flanges 11 and the frame 10 are mounted on the plug 27 so that the bridge 13 lies in plane of one X-ray and the slots 12 in the plane of the other. To determine the length of instrument to be used, a depth gauge (not shown) shorter than the estimated length and having a hole at a measured distance from its tip is fitted in the carrier 19 and passed into the brain. Further X-rays are taken and the required length of instrument calculated by comparing the distance from the tip to the target point 49 with the distance from the tip to the hole.