A drill setting guide for drilling holes in bones.

The subject of this present invention is a drill setting guide for drilling holes in bones in the therapy of breaks by the plate anastomosis method. There is in recent years an increasing ten­dency aimed in orthopedic surgery not only at connecting bone fragments, but also at their in­ternal strong immobilisation, enabling gypsum dressing to be dispensed with. This is a thera­peutic method defined as the stable osteosynthes­is. One of the methods of stable anastomosis in­volves connecting bone fractures with holed bone plates and bone screws.

Depending on the kind of fracture, the anastomos­is involving the use of bone plates and screws can be performed as: - neutralising, without the pressure of fract­ures and with the application of protective plates; - pressed when the fragments compress each other. During neutralising anastomosis, operative sur­gery is carried out by the method to be describ­ed below.

The holed plate to be used together with the screws is bent to the shape of the bone, is plac­ed on the bone and is temporarily immobilised. Next, holes are drilled in the bones.

Single guides in the form of a short bush with a handle are used for drilling holes in bones. The lower part of the bush terminates in a co­nical end adapted to the hole in the bone plate. The guide is set over successive holes in the plate, in such a way, that the hole to be drilled with a drill introduced in the guide should be strictly aligned with the hole of the plate and the hole axis should also be perpendicular to the bone. Subsequently, the holes made in the bones are tapped, and the bone screws are screw­ed in for securing the holed plate.

When using pressed anastomosis and the locating plate of the compression apparatus, the guide for the compression apparatus is used for fit­ting the locating plate.

The operative surgery which uses the guide for the compression apparatus is performed in the manner described below.

The locating plate is matched to the shape of the bone. Next, it is placed on the bone and locked in place. Using a guide shaped as a bush, having a handle and fitted into the holes of the plates, holes are drilled in the bone to receive the bone screws. These holes are drilled on one side of the fracture gap. Bone screws are fit­ted into the drilled and tapped holes and thus the plate is secured on that side of the fracture gap.

The pilot of the guide for the compression ap­paratus is pushed into the end hole on the side of the plate not secured to the bone. The pilot of the guide for the compression apparatus is connected by means of a plate to a simple drill bush, which rests at a definite distance from the end of the plate on the bone on the other side of the fracture gap. A drill is fitted into the drill bush, a hole is drilled and next tapped for mounting the foot of the compression appa­ratus.

The compression apparatus is used for pressing that part of the bone which has not been con­nected to the plate to the fracture being lock­ed. Next, further holes are drilled in the bone according to those made in the plate and, next, tapped, the bone screws are introduced and the compression apparatus.

Self-pressing plates are used for compression anastomosis. At one of its ends the self-pres­sing plates have round holes and taper compres­sion holes at the other. For the purpose of se­curing the plate to a bone it is necessary to model it in such a way that it should fit to the shape of the broken bone. Next the plate is plac­ed on the bone and, using a bush-shaped guide holes are drilled and tapped.

In addition to the above, an end of the locat­ing plate having round holes is secured to the bone fragment on one side of the fracture gap by means of bone screws. After the end of the locating plate has been secured, the pressure end is secured on the other side of the fracture gap. With that end in view holes are drilled us­ing a guide in the shape of a long bush termin­ating in teeth ensuring a reliable rest of the guide against the bone.

The guide is then fitted into a successive plate hole and, next, holes are drilled through them and then, tapped. Bone screws are fitted to cause the bone fragments to be pressed to each other. The drill guides used until now for drilling holes in bones for the purposes of securing the plates with bone screws are used for drilling single holes. The construction of the guides in the form of a single line does not ensure that holes with their axes perpendicular to the bone surface will be drilled. Such guides do not allow an op­timum force for pressing the bone fragments to be obtained.

The quality of the anastomosis largely depends on the optimum compression of bone fragments. Too high a compression that can be obtained with the application of the compression apparatus leads to the ends of the bone fragments to be crushed and causes their edge necrosis, thereby preventing their correct healing. In addition, too weak a compression of the bone fragments causes static and dynamic forces to be trans­mitted by the plate only, which can cause it to be broken.

Further work on improving the method of the ther­apy of fractures with plate anastomosis has led to the development of the design of a guide com­prising some drill guiding components. That guide consisted of two arms provided with drill guid­ing holes. These arms were mounted at the ends of a telescopic connector. The ends of the tele­scopic connector were connected on one side to the guide arms and on the other side to a bolt with a scale. Bosses were provided in there arms round the drill guiding holes.

The spacing of the arms is set by means of the bolt with a scale in such a manner that the axes of the drill guiding holes coincide with those of the holes of the locating plate. The so pre­pared guide is applied to a bone, and it rests on it with its bosses. Next, holes are drilled in the hole by introducing a drill into suc­cessive holes in the guide. After holes have been drilled in the bone, they are tapped, the guide is removed, a suitably profiled connecting plate is secured by means of bone screws that are screwed into the tapped holes.

The guide of such construction also showed many disadvantages.

Due to the rigid construction of the arms the bosses do not adhere over its entire length once the guide has been applied to bone fragments due to various analomical bends of the bone. This causes the guide-drill system to be unstable when holes are being drilled, causing the guide to slide down.

In view of the low stability of the above-men­tioned system it is not possible to prevent the axis of the hole, being drilled, from deviating in the plane perpendicular to the surface of the bone. Consequently, it is not possible to maintain an accurate spacing between the axes of consecutive holes.

The holes made in the way described above cause difficulties in the correct axial introduction and tightening of the screws and in the fault­less anatomical resetting of bone fragments, and the magnitude of tightening torque applied highly varies. This leads to impaired bone ac­cretion. Besides, the application of the said guide tends to cause the arms to incline and the bolts connecting the arms to the telescop­ic connectors to lock.

The guides can be used only for one length of the plate and enable holes to be drilled at one hole spacing. During the surgical therapy they cover the field of operation and are not suitable for the anastomosis of fractures with a transversal gap which are very extended and have intermediate fractures.

In practice, three hole spacings are prinicipal­ly encountered, i.e. holes which enable the anastomosis of bone fragments without compres­sion, with moderate compression and with heavy compression. The selection of compression de­pends on the kind of fracture. The research carried out in the field of the biomechanics of bone fracture anastomosis allowed a relation­ship to be established between basic structure, fragment displacement and compression force. For the purpose of attaining correct therapy by the method of the anastomosis of bone frag­ments with the connecting plate a new design of the drill guide has been developed for drill­ing holes in bones for introducing bone screws that secure the connecting plate.

The essence of the design as per this present invention involves a guide having a body with holes into which are introduced drill guide bushes provided at their bottom with blades and bush­es used for securing clamps.

The drill guide bushes are provided with lock nuts disposed above the body. With the guide body having a round section, the holes arranged in rows are laid out so that their spacing in a successive row corresponds to a different com­pression of bone fragments.

The guide body can also consist of two parts being slideably interconnected. When the guide body consists of two parts with flat shape they are slideably interconnected with dowels and a screw. On the other hand, when the body con­sists of two parts with a round section, they are slideably connected by means of guides to a coaxially applied knurled nut with a scale engrawed thereon.

Another connection of two body parts in the shape of bones is effected by a holder with a recess whose shape corresponds to that of the connect­ing plate secured to that holder. Along a long­er side both the bones are provided with screws of a diameter corresponding to that of the hole in the connecting plate, these screws being introduced into the holes of the connecting plate. A mark is applied on the upper surface of the bone to indicate the compression force of bone fragments and compression direction. The fundamental advantages of the guide as per this present invention is the possibility of attaining an optimum compression of bone frag­ments as a function of their displacement. The drill guide bushes fitted into the holes tap­ped in the body can be set at different heights depending on the anatomical bends of the broken bone. This allows the guide to be rested on the bone along the entire body and the blades at the bottom of the drill guide bushes prevent sliding down during hole drilling.

For the guide to be reliably secured, the body has bushes for the clamps surrounding the bone and maintaining the guide at one position dur­ing the operation. The layout of the guide holes in one plane enables the drill to be perpendic­ularly applied to the bone through the drill guide bushes and holes to be drilled with one setting of the guide. Thanks to that, the spa­ cing of successive holes can be accurately kept. The holes made in this way do not pose any dif­ficulty in the correct axial introduction and tightening of the bone screws.

When the guide body has a round-sectioned shape with the holes spaced in a row relative to a given magnitude of the compression of bone fragments, it is possible using one guide to select an appropriate bone fragment compression value and to introduce the drill guide bushes into the correct row. On the other hand, when the body consists of two parts capable of be­ing moved to and away from each other, the com­pression of bone fragments can be continuously regulated.

A sliding connection of the two parts of the body of the guide allows the inclination of the arms to be avoided as was otherwise the case with the guides employed until now. The sliding connection having the shape either of dowels and a screw or of guides with a coaxially ap­plied knurled nut with an engraved scale allows the required compression of bone fragments to be planned.

The locks located at the ends of the body allow the guide to be extended by adding a component and a number of drill guide bushes correspond­ing to the length of the connecting plate.

The guide whose body consists of two bones se­cured to the connecting plate placed in a hold­ er allows anastomosis to be performed on a trans­versal gap of a fracture and very extensive with an intermediate fracture. The bones are mount­ed in the holes of the connecting plate on bolts and are locked with typical nuts.

The individual bones can differ from one anoth­er by the axis spacing of bolts and holes for the drill bushes. Depending on the mutual shift of these axes, the fragments of the broken bone can be compressed with different forces. When the axes coincide one another, no compression occurs.

For the purpose of correctly matching the bone to the required compression, a number is engrav­ed on the bone and it corresponds to the mag­nitude of compression in millimetres and an ar­row which indicates the direction of the re­quired compression.

The subject of this present invention is em­bodied in a drawing where <ul id="ul0001" list-style="none"><li>Fig. 1 shows a side half section of the guide whose body has the shape of a plate,</li><li>Fig. 2 shows a top view of the same guide,</li><li>Fig. 3 shows a front view of the guide whose body is round-sectioned,</li><li>Fig. 4 shows a side view of the same guide,</li><li>Fig. 5 shows a front half section of the guide whose body consists of two parts of the shape of plates,</li><li>Fig. 6 shows the top view of the same guide,</li><li>Fig. 7 shows a front half section of the guide whose body consists of two round-sectioned parts,</li><li>Fig. 8 shows a side view of the same guide,</li><li>Fig. 9 shows a front view of the guide whose body consists of two parts shaped like bones,</li><li>Fig. 10 shows a side view of the same guide, and</li><li>Fig. 11 shows a top view of the bone. The essence of this present invention will be disclosed in the following examples.</li></ul>

Example 1

Body 1 shaped like a plate of the guide shown in Figs. 1 and 2 has two tapped holes into which drill guide bushes 2 and clamp mounting bushes 3 have been screwed in. Drill guide bushes 2 and clamp mounting bushes 3 are symmetrically laid out on either side of body 1 relative to its transversial axis in such a way that clamp mounting bush 3 is between drill guide bushes 2.

Close to the transversal axis of symmetry of body 1 there are two recesses 4 used for fitt­ing additional clamps that lock the guide in place. Drill guide bushes 2 have blades 5 in their bottom parts.

Prior to drilling holes in a bone,drill guide bushes 2 are appropriately screwed in with al­ lowance for the anatomical bends of the bone so that each of them rests with blade 5 on the bone. Next, the clamps are fitted around the bones to lock them in clamp mounting bushes 3 and recesses. With the guide being so mount­ed,its body 1 is lifted about the fracture gap, thanks to which an orthopaedist can continuous­ly control the drilling operation.

A drill is introduced through drill guide bush­es 2 and successive holes are drilled in the bone. After having drilled the holes in the bone, the clamps and the guide are removed. At the same time bone fragments are prepared for receiving bone screws and for fitting the con­necting plate.

Example 2

Body 1 of the tubular section of the guide shown in Figs. 3 and 4 has three rows of tapped holes appropriately spaced for anastomosis without compression, with medium compression and high compression. Drill guide bushes 2 having blad­es 5 in their bottom parts are screwed into the tapped holes. Drill guide bushes 2 are provid­ed with lock nut 6 placed above body 1. Holder 7 is mounted in the middle part of body 1. Drill guide bushes 2 are screwed into the tap­ped holes drilled in body 7 in such a manner that each drill guide bush 2 rests with its blade 5 on the bone. Screwed-in drill guide bushes 2 are locked with lock nuts 6 so that the drill should not cause drill guide bush 2 to shift when a hole is being drilled in a broken bone. For the anastomosis of bone fragments without compression, drill guide bushes 2 are screwed into a row of the holes whose axes coincide with those of the holes of the pressure plate. Holder 7 is used for keeping the guide in the requir­ed position.

Example 3

Body 1 of the guide presented in Figs. 5 and 6 consists of two parts shaped like plates inter­connected with guiding dowels 8 and adjustment screw 9. Drill guide bushes 2 and clamp mount­ing bushes 3 are introduced into the holes dril­led in body 1. The ends of drill guide bushes 2 are provided with blades 5.

Body 1 together with drill guide bushes 2 and clamp mounting bushes 3 is applied to a broken bone. Drill guide bushes 2 are screwed in in such a way that each of them rests with blade 5 on the bone. The spacing of both the parts of body 1 is adjusted with adjustment screw 9. Thanks to an appropriate shift of the axes of the holes of drill guide bushes 2, relative to those of the connecting plate, medium compression of bone fragments is attained after the screws and con­necting plate has been fitted.

The guide is secured to the bone by means of the clamps snapped in clamp mounting bushes 3. Next, the drill is introduced into successive drill guide bushes 2 and a hole is drilled in the bone. After the operation has been completed both the clamp and the guide are removed.

Example 4

Body 1 of the guide presented in Figs. 7 and 8 consists of two round-sectioned parts intercon­nected by means or guides 19. The guide is co­axially adjusted with knurled nut 11 with the hole axis displacement value engraved thereon. Drill guide bushes 2 with lock nut 6 placed above body are introduced into the holes tapped in body 1. At an end of body 1 there is lock 12 connecting component 13 extending body 1 by a length corresponding to that of the connecting plate being applied.

When applying the guide, drill guide bushes 2 are matched to the anatomical bends of the bone, and next, they are locked in place with nuts 6. Us­ing knurled nut 11 the guide is previously pre­set for attaining the anastomosis of bone frag­ments without compression. Due to the fracture requiring the application of a longer connect­ing plate, body 1 is extended with component 13 connected to body 1 via lock 12.

The guide prepared in the way described above may be used for drilling holes in a bone by in­troducing a drill into successive drill guide bushes 2.

Example 5

Connecting plate 15 additionally secured with pressure plate 16 is placed in the recess of holder 14 of the guide presented in Figs. 9, 10 and 11. Pressure plate 16 is connected to hold­er 14 with dowel 17 and bolt 18. Body 1 in the form of two blocks is secured to connecting plate on either sides of holder 14. The blocks of body 1 are secured to the connecting plate in such a man­ner that bolts 19 placed at a side of the block of body 1 enter the holes of connecting plate 15 and typical nuts are screwed thereon. Drill guide bushes 2, complete with lock nuts 6 are introduced into the tapped holes made in the blocks of body 1.

In Figure 11, an arrow two marked on the top surface of the block of body 1 indicates the direction of compression and that the compression force of bone fragments is high. Holder 14 is connected to handle 20.

Connecting plate 15 should be placed in the re­cess of holder 1 and pressed by means of pres­sure plate 16 and bolt 18. The blocks of body 1 should be screwed to connecting plate 15 so mounted by tightening the nuts on bolts 19 fit­ted into the holes of connecting plate 15. Using the block on one side of body 1, marked zero (not illustrated), the axes of bolts 19 and of the holes to receive drill guide bushes 2 are coincident with one another, thanks to which the holes drilled in the bone and those of connecting plate 15 will also coincide with one another.

In the above-described situation, bone fragments will not be compressed. When the block of body 1 marked two is tightened in a similar way on the other side of body 1, the axes of bolts 19 will be shifted relative to the holes for drill guide bushes 2 by 2 mm, thereby shifting the holes drilled in the bone relative to the holes of connecting plate 15 also by 2 mm.

The direction of the compression of bone frag­ments is indicated by an arrow as shown on the top surface of the block of body 1 in Figure 11. When connect­ing plate 15 is screwed onto the screws mounted in the drilled holes, bone fragments will tend to shift by 2 mm and a high compression force will be developed between those bone fragments during the anastomosis.