GB2163074A - Drill guide - Google Patents

Abstract

A drill guide comprises a base 1, and a guide bush 2 seated in the base for universal adjustment relative thereto. A screw 13 passing through the base locks the bush in an adjusted position to guide a drill at a selected inclination to the plane of the base as indicated by a quadrant structure 4 of graduated arms 18, 19, 20 (21) which depends from a collar 3. In a described surgical use, an arm 14 integral with the base is fixed to a bone and this guide is set by X-ray photography taken in mutually perpendicular directions as defined by the quadrant. <IMAGE>

Description

SPECIFICATION Drill guide This invention relates to a drill guide device which is particularly although not exclusively suitable for surgical use.

It is frequently necessary to pass pins longitudinally through bones, for example through the neck of the femur of the hip joint for the internal fixture of slipped upper femoral epiphysis in children and the fractured neck of the femur in adults.

The usual technique is to drive a guide wire through the neck to create a lead hold for the subsequent insertion of a pin. The guide wire is inserted on a 'line of sight' basis and even under Xray conditions the pin may drift off centre and break through the side wall of the bone.

According to the present invention, there is provided a drill guide comprising a member formed with a guide for receiving a drill the member formed with a guide for receiving a drill the member being carried by a base and being capable of limited universal movement relative to a plane passing through the base and means carried by the base to permit a drill received in the guide to be disposed at any angle, within-a limited range of angles, to a line passing through the aperture normal to the plane.

The above and other aspects of the present invention will now be described with reference to the accompanying drawing in which: Figure 1 is a side view, partly in section, of a drill guide.

Figure 2 is a bottom view of the guide of Figure 1.

Figure 3 is a top view of the guide of Figure 1 and Figure 4 is a side view, partly in section, of part of a modified drill guide.

Referring to Figures 1 to 3 a drill guide according to the present invention is made wholly of stainless steel and comprises a base 1, a ball 2 rotatably mounted within the base and a collar 3 carrying a quadrant structure indicated generally at 4.

The base 1 is a ring with a central circular aperture 5 the upper end 6 of which is of increased diameter. A lower part of the aperture constitutes a part spherical seating 7 and below this seating the aperture outwardly flared at 8. The ball 2 is formed with a dimetral hole 9 and is located in the seating 7. A ring 10 having an outwardly flared part 11 is disposed in the upper end 6 of the aperture 5 and may be retained therein by a suitable adhesive. A part 12 of the ring may also be of part spherical form and the ring presses the ball against the seating 7 so that it is freely rotatable but with some frictional restraint. A set screw 13 passes through a threaded hole in the base 1 and may be tightened to lock the ball in a desired positon.An arm 14 formed integrally with the base extends radially outwardly therefrom at such an angle to the medial plane 15 of the base as to suit a particular surgical application. The arm 14 is formed with apertures such as 16.

The collar 3 is engageable over the base 1 and can be secured thereon by tightening a set screw 17. The quadrant structure 4 is carried by the collar 3 and comprises first and second pairs of diametrally opposed, co-planar arms 18, 19 and 20,21 extending outwardly therefrom. The arms 20, 21 are disposed in a plane at right angles to the plane of the arms 18, 19. Each of the arms carries a part circular, co-planar segment 18a, 19a, 20a and 21a, each segment having its centre at the centre of the ball 2 and the inner ends 22 of each segment ter minating short of each other. The inner edges of each segment are formed with equi--spaced notches 23.

It will be assumed that the drill guide is to be used to assist in aligning a pin to be driven through the neck of the femur of a hip joint (not shown). The arm 14 is secured to the outer cortex of the femoral shaft by screws passing through the aperture 16 or a clamp (not shown) carried by an extended arm 14 so that the base 1 is spaced from and generally in register with the neck of the femur. The collar 3 is then rotated on the base 1 and fixed by its screw 17 in a position such that X-ray pictures can conveniently be made in directions mutually at right angles and respectively parallel with the planes of the arms 18, 19 and 20,21.

A pin 24 (Figure 2) is then passed through the hole 9 in the ball 2 and, by line of sight, hammered into the femur. Two X-ray pictures are then taken in the directions mentioned above so that on each plate (not shown) the shadow of the pin 24 is visible in relation to the shadow of the notches 23 on those segments 18 to 21 at right angles to the direction of taking the picture. Any errors in pin location can then be ascertained in two directions at right angles. These errors can be calculated as "so many notches 23" from-the location of the outer end of the pin 24; the latter can be withdrawn and a new pin accurately located through the femur by placing its outer end at the necessary location relative to the quadrant 4. The new pin may for example be as shown at 25.

It will be understood that once the desired alignment of the pin has been ascertained more than one pin can be accurately driven into the femur at varying angles.

Figure 4 shows a modification of the quadrant structure 4 in which opposed segments 18a, 19a and 20a, 21a are integrally formed. The arms 18, 19 are pivoted at 26 to the collar 3 and are cranked at 27 so that in their median position the segments 18a, 19a are spaced from but parallel with a line 28 passing through the hole 9 in the ball 2 normal to the plane 15. The notches 23 on the segments 18a, 19a are on the outer edges thereof. The arms 20, 21 are pivoted at 26a at right angles to the pivots 26 and are shorter than the arms 18, 19. A block 29 formed with slots 30 slides on the outer edge of the segments 20a, 21a (not shown) and the inner edge of the segments 18a, 19a. The block 29 is formed with a hole 31 which is aligned with the hole 9 in the ball 2 when the arms 18, 19 and 20, 21 are in their medial positions.

This arrangement enables a pin to be passed through the ho [ es 31 and 9 tilted to pivot both the arms 18, 19 and 20, 21 while the block 29 slides along the edges of the segments until it is in "line of sight" position. The block 29 can then be locked to-the segments by a set screw (not shown) and two X-ray photographs taken as described above but before the pin is driven into the femur. As before an accurate location of the pin can be deduced as "so many notches" from the photographed position and the block 29 moved to a new position so that the first pin can be accurately located.

if desired only one pair of arms 18,19 or 20,21 are pivoted; the other pair being fixed. With such an arrangement the block 29 would #be slidable only on the segments of the pivoted arms. Alternatively the block 29 could be-omitted. In either case reasonably accurate pre-alignment of the pin is possible.

Claims (8)

1 A drill guide comprising a member formed with a guide for receiving a drill, the member being carried by a base and being capable of limited universal movement relative to a plane passing through the base and means carried by the base to permit a drill received in the guide to be disposed at any angle, within a limited range of angles, to a line passing through the aperture and normal to the plane.

2. A drill guide according to claim f in which the member comprises a part spherical ball formed with a hole for receiving a drill the ball being frictionally movable in a seating and means being provided to lock it in any predetermined position.

3. A drill guide according to claim 1 or claim 2 comprising a pair of calibrated quadrant structures mutually at right angles and symmetrically disposed on the same side of the base.

4. A drill guide according to claim 3 in which the quadrant structures lie in planes passing through the hole in the ball and are each formed with a gap at the position of their intersection to enable a member to pass freely between each part of each structure and through the hole in the ball.

5. A drill guide according to claim 3 in which the quadrant structures are pivoted to the base about axes in the same plane and mutually at right angles and are each offset from planes passing through the hole in the ball and are interconnected by a member slidable on-each structure and formed with an aperture which is in line with the hole in the ball when the structures are mutually at right angles.

6. A drill guide according to any one of the preceding claims comprising an arm extending away from the base to enable the guide to be secured to a rigid support.

7. A drill guide according to any one of claims 3 to 6 in which the quadrant structures are together rotatable relative to the base and means are provided to lock the structures relative to the base.

8. A drill guide substantially as herein described with reference to Figures 1 to 3 or Figure 4 of the accompanying drawing.