FI89134C - External leg mounting device - Google Patents

Description

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External bone fixation device. - Utvändig benfästanordning.

The present invention relates to medical devices and more particularly to a device for attaching bone, which device allows the movement of bones in a broken wrist joint.

To clarify the purposes of the invention, such an attachment is referred to as a "dynamic attachment". This means bone fixation by means of pins, pins and external supports, the joint of which is in geometric relation with the joint of a human or animal body, allowing the attachment of bone chips or parts of each articulated bone but also allowing the attachment parts to rotate about their joint axis.

Extranion or fixation outside the bones is an old surgical technique that was first used a hundred years ago. Its use has long been limited to complex fractures in accident cases and consequently in orthopedics, i.e. it has been a secondary treatment for fractures, infections, slow ossification, pseudarthrosis, difficult bone fixations, etc. External anchoring is used especially for long bones such as femur, tibia, humerus, spindle and ulna. However, it is also necessary to make small anchoring devices that can be used for small bones, such as plantar bones and palms, as well as in facial surgery as well as in experimental surgeries performed on small animals.

External bone anchoring elements allow two types of bone anchoring to be performed: piercing anchoring, in which the needles extend from one side of the member to the other, and non-piercing anchoring, in which the needles are inserted into the bone without passing completely through it.

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The through-anchorage used mostly on the foot is stiffer than the impermeable anchorage. Two pins or frames are fitted on each side of the bone, to which two groups of rods are anchored and placed on each side of the fracture. The two frames or pins are joined together by a support which is as stable as possible and which may have sliding arms or rods the length of which may be increased or decreased.

Thus, the basic methods of external bone attachment are already known. Extension of external bone fixation to osteosynthesis of fractured joints has also been considered. The idea here was to fasten the bone pieces of the broken parts to the adjacent bones with thin needles or nails, push the fastening nails into another part of the joint (which may or may not be broken) and join these two parts of the external fastening device together. The purpose of this articulation is as follows. Normally, a rigid bone attachment would be sufficient to treat the fractured bone.

However, when this fractured bone is part of a joint, there is a high risk that the joint will remain stiff after healing and it is considered absolutely essential that the patient perform movement exercises on his or her broken joint as soon as possible. This movement should begin with a slight bending angle that is gradually increased. All of these movements must, of course, be such that the attached external fastening device allows them to be performed, and this is by no means the case when using, for example, the rigid fastening device disclosed in U.S. Patent No. 4,356,624.

A dynamic external fastening device is disclosed in French Patent Application No. 2,551,650, published March 15, 1985. According to the above-mentioned basic idea, this fastening device comprises a first proximal leg 3 B9134 and a second separate leg, these arms being pre-fastened to receive the fastening nails and a typically ball-like joint connecting said two arms.

In order to achieve the correct operation of the fastening device, it must, of course, be precisely matched so that the point of articulation between said arms of the device rests exactly on the pivot axis of the wrist-Vele; otherwise there is unnecessary and painful tension and compression when moving the hand relative to the arm. However, in most cases, this axis of rotation of the joints cannot be detected with sufficient accuracy in the case of a fresh fracture because the entire area is swollen and the joint cannot be rotated. In addition, the position of the hinge point of this known device cannot be adjusted.

It is a first and principal object of the present invention to provide a new and useful dynamic external bone fixation device for improving fractures in a joint area which does not suffer from the disadvantages listed above.

It is a further object of the invention to provide a fastening device as described above which allows the injured joint to be practiced at gradually increasing angles and with controlled movement resistance.

It is a further object of the invention to provide a fastening device which can be positioned very precisely by a surgeon with respect to the pivot axis of an injured joint and whose pivoting distance can be adjusted even after the fastening nails or pins have been inserted.

It is a further object of the invention to provide a dynamic external bone fixation device for use on broken joints 4 89134, which device further enables compression or stretching treatment during bone healing so that the joint and its mobility are fully restored.

These and other objects are achieved by a dynamic external bone fixation device according to the present invention, which is characterized by the features set forth in the characterizing part of claim 1.

For ease of understanding of the ideas and terms of the prior art, reference is made to U.S. Patent No. 4,365,624, which is incorporated herein by reference in its entirety.

Surprisingly, it has been found that the device according to the invention can be used not only for wrist fractures but also for fractures of other joints, such as the knee, ankle, finger joints, elbow, shoulder and even the pelvis and clavicle.

The dynamic external bone fixation device according to the present invention has been developed from the basic idea that the device should not be placed on the side of a broken body so that the center of articulation of the two attachments is also on the pivot axis of said joint, but generally perpendicular to the joint. This is explained in more detail below and described in the drawings.

This displacement of the articulation point of the fastening device according to the invention causes another geometric situation / the previously known simple pivoting movement of the hinge or ball joint is replaced by simultaneous pivoting and stretching (or contraction): the invention thus provides 89134 preferably cylindrically curved sliding surfaces; one of these surfaces is convex and forms part of a "positive" element connected to one of said fastening parts and the other surface is concave and forms part of a "negative" element connected to the second fastening part.

As these surfaces slide over each other, one skilled in the art will readily appreciate that the elements attached to either surface perform a combined angular and longitudinal movement.

The concave surface is part of a slider that can slide on a correspondingly convex surface inside the body. This body is a side housing which is at right angles to the axis of said curved surfaces. In the housing and preferably on the second side surface of the body, several lines can be drawn, one point of intersection of which is outside the body. This point of intersection (and therefore the direction of said lines) is chosen so as to form the axis of curvature of said sliding surfaces. This axis is also the pivot axis of the bone joint. When the surgeon attaches the fastening device according to the invention to the body, he is able to aim at the articulated shaft by looking along said lines. He can easily find said shaft even when the joint area is swollen and he has the possibility to readjust the fastening device according to the invention if necessary, as will be explained below.

The slider can be fixed with a screw passing through the gap in the body. This gap is curved and follows the curvature of said sliding surfaces. Only the second screw, which locks in said slot, acts as a stop to limit the movement of the slider in the frame. Angle pointers can be arranged in the gap area. The sliding surfaces can be coated with a friction-reducing layer, for example Teflon (PTFE) or nylon.

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The materials of the fastening device according to the invention are selected so that they can withstand repeated sterilization. This choice of material is a conventional technique for a person skilled in the art.

It is further advantageous to control the movement of the slider in the body, taking into account the force required to move the slider, in order to determine a suitable exercise or recovery program for the patient. In some embodiments, the movement of the slider is prevented by spring forces, which may be a torsion spring or an elastic force of the rubber layer; in another embodiment, said movement is subjected to a frictional force. The amount of said frictional force can advantageously be adjusted from almost zero to a complete stop.

In order to explain in more detail the dynamic external bone fixation device according to the invention, preferred embodiments thereof will now be described with reference to the accompanying drawings, in which:

Fig. 1 is a side view of the dynamic connecting part showing the neutral position of the connecting rods in solid lines and their extreme position in dotted lines.

Figure 2 is a longitudinal sectional view of the connector of Figure 1 and a first embodiment thereof including a spring for resisting patient movement.

Fig. 3 is a fragmentary view similar to Fig. 2 showing an embodiment in which said spring part is replaced by an elastic part.

Fig. 4 is a fragmentary view similar to Fig. 2 showing an embodiment in which said spring part is replaced by a friction brake roller.

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Figure 5 is a perspective view of a dynamic external wrist fastening device with two groups and two nails in each, these groups being connected to two respective pins and these pins being articulated to a dynamic connecting part.

Fig. 6 is a sectional view taken along line VI-VI of Fig. 5 showing an embodiment in which the nails are placed at an angle of 40 °.

Fig. 7 is a partial sectional view taken along line VII-VII of Fig. 1 showing the connecting portion in the locked position.

Fig. 8 is an enlarged detail of Fig. 4 showing an embodiment in which a friction brake is used to resist patient movement.

The dynamic external bone fixation device shown in Figures 1 and 2 comprises an articulation part 1 connecting the pins 2 and 3. As will be explained below, the pin 2 is connected to the nails attached to the patient's palm by means of the connector indicated by reference numeral 4. Similarly, the rod 3 is connected to the patient's spindle bone by the connector shown at 5.

The articulation part 1 consists mainly of a body 6 and a sliding body 7 which slides relative to the body on a sliding surface 8.

That is, the body 6 has a convex sliding surface 8 while the reading body 7 has a corresponding concave sliding surface. These sliding surfaces are, for example, cylindrical surfaces, the axes of the respective cylinders being perpendicular to the sliding plane of the articulation part 1. In the drawings, this apparent axis is indicated by reference numeral A and corresponds to the axis of movement of the broken wrist.

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The body 6 is made of either a lightweight alloy or synthetic materials that can withstand sterilization, as all parts of the device must be subjected to gas or steam autoclave treatment. The slider 7 is made of, for example, stainless steel.

The sliding surfaces 8 of the body 6 and / or the slider 7 have a slippery coating, not shown in the drawings, which is, for example, nylon or Teflon (PTFE).

It can be seen from Figures 1 or 2 that the general shape of the body 6 is slightly curved according to the sliding surface 8. The lower part of the body 6 forms a curved surface 9.

The pin 10 secures the end of the rod 2 to the reading piece 7. The non-threaded end of the second rod 3 is fitted to the threaded arm 11 and is held in place by two bead discs 12 and 13 which allow the length of the articulation part 1 and the rods 2 and 3 to be adjusted when again, lateral movement is avoided by the protruding element 14. The other end of the threaded arm 11 cooperates with the body 6 either directly threaded into it or, as shown in Fig. 2, by means of a pin 15.

In addition, the articulation part 1 comprises a side cover 16, the general shape of which follows the shape of the body 6.

The present surface of this side cover 16 has a scale 17 for reading the mutual angular movements between the slider 7 and the body 6 and its side cover 16. Some of the degrees of the circular scale 17 have been enlarged and extended to form sight lines 18 extending into the apparent axis A. Similarly, sight lines could be placed on the side of the body opposite the cover 16 (not shown in the drawings).

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On the one hand, the scale 17 and its corresponding numbers and on the other hand the sight lines 18 can either be painted or engraved on the cover and the frame.

As shown in the detailed cross-section of Fig. 7, the side of the body 6 facing the side cover 16 has an opening 19 corresponding to the reading 7. As can be seen from Fig. 2, the opening 19 is rounded to allow mutual movement between the body 6 and the reading 7. Similarly, the cover 16 has a rounded slot 20, the center of which is also point A.

In Fig. 1, the slot 20 is shown to have two screws 21 and 22. The first is a locking screw 21 which prevents mutual movement between the body 6 and the slider 7 (see Fig. 7). The second is a stop screw 22 which is adjusted along the cover 17 to limit the gap 20 and then also to limit said mutual movement when the screw 21 is not locked.

In the first embodiment shown in Fig. 2, the mutual movement of the body 6 and the slider 7 is resisted by a spring 23, the end of which is fixed to the body 6 by a pin 24 and the other end moves with the slider 7. In this embodiment, the opening 19 includes an extension 25 in which the spring 23 is placed in the position shown by solid lines.

Although not shown in the drawings, any other torsional spring (in shape or arrangement) can be used to act directly or indirectly with both the body 6 and the slider 7.

The part preventing the movement of the body 7 in the body 6 may be a rubber band or a strip 26 extending through both the body 6 and the slider 7. In the embodiment shown in Fig. 3, the other free end of the rubber band 26 is held in place by a metal ring 27 resting on a flat surface 28 formed in the reading piece 7. The other end of the rubber band 26 is directly attached to the body 6 from the outside by a conical screw 29.

The rubber band 26 may also be attached in some other manner without departing from the scope of the present invention.

Figure 4 shows an embodiment using a friction brake whose force can be adjusted. This friction brake consists in principle of the following parts: - a fixed part 30 threaded into the body 6, - a sealing sleeve screw 31 adapted to be threaded into said fixed part 30, and - a piston rod 32 sliding in the sealing sleeve screw 31, the end extending through the fixed part 30 and cooperating by means of a pin 33 projecting into the corresponding opening in the

As shown in the detailed figure 8, the fixed part 30 and the sealing sleeve screw 31 each have extensions 34 and 35, respectively, for co-operation: with O-rings 36 and compression rings 37 arranged around the piston rod 32. The section of the compression rings 37 is V-shaped and their function is explained below.

The piston rod 32 is made of polished stainless steel or some other ground material. The other parts of this embodiment are made of materials that can withstand sterilization.

The fixed part 30 and the sealing sleeve 31 each have scales 38 and 39 for reading the amount of frictional force. The markings on scales 38 and 39 are either painted or engraved.

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Having now described several embodiments of the present invention, the placement of a dynamic external bone fixation device will now be explained.

In Fig. 5, the articulation part is indicated by reference numeral 1. Using the same reference numerals as in the above description, it can be seen that the pins 2 and 3 are attached to ball joints 4 and 5 attached to two presses 40 and 41.

The base plates 42 and 43 of the presses 40 and 41 are coated with a fiber-reinforced phenolic material to hold the sets of nails 44 and 45 placed in the palm 46 and the Spinal bone 47 in place. It can be seen that the base plates 42 and 43 have holes arranged to position the nails 44 and 45 exactly.

It can be further seen from Figure 6 that the fastening device is even closer to the fractured member than the known devices because the nails 44 are fastened to the second palm 46 at an angle of up to 45 ° for clinical reasons to be explained below.

Referring to Figure 5, the installation of the device will now be explained in detail.

According to known methods, at least two nails 44 are inserted into the second palm bone 46. The nails 44 can be provided with continuous threads, the other end having a self-drilling tip. The opposite end of the nails 44 is shaped to be securely attached to a seat not shown in the drawings. The self-rotating thread gives the maximum possible gripping force.

Alternatively, non-drilled nails V can be used which are inserted into the guide holes through both shells. Naturally, a guide can be used to position the nails 44 in the correct position.

Both nails 44 in the palm 46 are attached to the base plate 42 of the press 40.

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After the fracture has been placed approximately in place, at least two nails 45 are similarly inserted into the spindle bone 47 and fixed to the base plate 43 of the press 41.

Both presses 40 and 41 have ball joints 4 and 5 to which the ends of the pins 2 and 3 can be fastened with wing nuts 48 and 49.

To reduce fracture, the physician positions the device by first centering the sights 18 on the pivot axis of the joint and then securing the device with wing nuts 48 and 49.

An X-ray may then be taken to determine the correct reduction of the fracture. If necessary, the wing nuts can be loosened and further adjustment can be made.

Further adjustment can be made by means of wheel discs 12 and 13, which are first centered on the threaded arm 11 and then moved to ensure the required distance. In the initial stage of healing, the device is fixed in place by means of a locking screw 21 (Figures 1 and 7).

As already mentioned in the introduction, it is advantageous to give the joint a progressive movement after the first step, whereby the device holds the fractured member firmly in place.

Without showing a complete program, the bending control can be shown according to the following table: 1. week after fracture no movement 2. "" "no movement 3." "" bending to 10 ° 13 891 34 4. week after fracture bending to 20 ° 5. "" "Bend to 30 ° 6." "" bend to 40 °

The amount of bending allowed is determined by a physician who locks the stop screw 22 in the corresponding position.

For example, in Fig. 1, the bending is limited by the screw 22 to a bend of 20 °, and therefore the mutual movement of the pins 2 and 3 takes place between the neutral position shown by intact lines and the maximum turning position shown by dotted lines.

Looking at Figure 2, it can be further seen that in the neutral position shown by the intact lines, the pins 2 and 3 are not aligned but form an angle of about 10 °. This is due to the normal position of the wrist at rest. The bending angle / 3 shown in this figure is thus formed between 0 and 40 °.

As already mentioned, it is important that the training movement during healing is performed against the opposing force.

In the embodiment shown in Figures 2 and 3, this force is generally non-linear because its spring '23 than the Kimmo-Osaka 26 does not generate a corresponding force depending on its position.

. To further improve the device, an embodiment according to Figure 4 is shown (detail in Figure 8). In this embodiment, the movement is resisted equally strongly in both directions because the reaction force is caused by the friction of the pin 32 against the O-rings 36.

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In addition, either the patient or the physician can adjust this force by turning the sealing sleeve screw 31. As the extensions 34 and 35 then get closer to each other, the O-rings 36 press against the piston rod 32 as they press between the rings 37 with a cutting shape V pointing toward the center. On the other hand, the force decreases as the extensions move away from each other, because then the pressure or compression of the O-rings decreases.

The degrees on the scales 38 and 39 allow the value of friction to be read. The scales 38 and 39 can be divided to form a noon.

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Claims (11)

A dynamic external bone fixation device for osteosynthesis of fractured wrist joints, the device comprising: (1) a first part having a fixation pin (3) adapted to be connected to bone nails (45) inserted into the bone (47) on one side of said joint, (2) a second a part, the fixing pin (2) of which is adapted to be connected to bone nails (44) inserted into the bone from one side of said joint, and (3) said two-part articulation part (1) adapted to be placed outside the bending axis of the broken joint, said articulation part comprising means for restricting the movement of said articulation part, characterized in that said articulation part (1) comprises: a) a body (6) fixed to the first fixing pin (3) and a slider (7) arranged in said body (6); ) and attached to a second mounting pin (2), the body having a convex surface and the inner The reader has a concave cylindrical surface, each surface sliding on a second cylindrical surface, b) means for aiming the axis of curvature (A) of the cylindrical surfaces to align it with the bending axis of the fractured joint, and c) means for limiting said slider to an angular slide A dynamic fastening device according to claim 1, characterized in that said articulation part further comprises a side cover (16) with a curved slot (20), the center of curvature of which is aligned with said shaft (A). A dynamic fastening device according to claim 2, characterized in that said means for aiming the axis of said cylindrical sliding surface, i.e. 89134, are sight lines (18) engraved or painted on said side cover. A dynamic fastening device according to claim 2, characterized in that said side cover is provided with markings (17) indicating the angular displacement of said slider. The dynamic fastening device of claim 1, further comprising means for pushing said slider toward its rest position in said body, wherein said two fastening pins form a straight line or a small angle of at most about ± 10 ° with respect to the straight line. A dynamic fastening device according to claim 5, characterized in that said pressing members comprise an elastomeric strip (26), one end of which is fastened to the body and the other end to said slider. A dynamic fastening device according to claim 5, characterized in that said pressing means comprise a spring (23) mounted between said slider and said body. A dynamic fastening device according to claim 1, characterized in that it further comprises friction means for stressing or loading the sliding movement of the slider with an adjustable frictional force. A dynamic fastening device according to claim 8, characterized in that said friction means comprise: a piston rod (32), one end of which is fastened to a slider; a sleeve (30) screwed to said body; li; 17,891 34 O-rings (36) disposed in said sleeve and surrounding said piston rod; compression rings (37) arranged between two adjacent O-rings; and a sealing sleeve screw (31) adapted to be screwed by hand into said sleeve, thereby thereby compressing said O-rings more or less and thereby adjusting said frictional force. A dynamic fastening device according to claim 9, characterized in that said sleeve and the sealing sleeve screw are provided with a cone. A dynamic fastening device according to claim 1, characterized in that at least one of the sliding surfaces of said body and said slider is provided with a friction-reducing layer. 89134 BC