The invention relates tc a compression pin for the sa-fe surgic al fixation c+ minor bone fractures ot the hand or leg, an -fis: tion o-; bone fragments - bro en out o-r major bones - i their original position e.g. in case o-f avulsion fractures.

It is well-tnown that screws and bone plates are widely use for the fixation of bone fractures. These are available i various sires and shapes, thus suitable for the fixation o such small bones too.

However, this plate-screw systems, developed for rigid internal fixation o-i- bone fractures, are not applied very frequently i cases of smell fractures of the hand and foot. The reasons are:

- The wide exposure of the bone fragments required by the plat screw osteosynthesi effects scarring, which destroys the fi gliding mechanism essential to hand movements and causes limited joint motion.

- In case ot severe open fractures or the hand and the foot, the wider exposure of bone fragments causes further impairme oτ the so**-t tissue circulation with all the well-. nown serio consequences. After the consolidation of the fracture, a sec similar exposure is necessary to remove the implanted metal plate and screws.

- The plate-screw osteos nthesis is a faιrl> complicated, exp si e and time consuming method.

- In case of certain fractures - when the bone fragment is too small and -'o the structure of the bone is porous -the plate- screw osteosynthesis is out of question.

After closed or open reduction, most of the phallangeal, meta™ carpal and met a s l fractures _re treated nowadays by Kirsch-

ner-wire fixation, which is a simple, at least damaging and cheap method. The Kirschner—wire (pin) is made of a tissue- friendly alloy and is sharpened at one or both ends. One end Df the pin fixed in a hand pin inserter or in a motor gimlet, is drilled through the reduced fragments of the broken bone. The projecting end of the pin is to be cut off flat well beneath the skin.

In the majority of the cases, a closed reduction and percuta¬ neous pin fixation can be performed under X-ray image intensi- fier.

Although the K-wire (or pin) fixation is simple and has many advantages, it cannot meet all the requirements of an ideal os¬ teosynthesis:

- While the plate-screw osteosynthesiε achieves mostly stable os teosynthesis, the relative - so called adaptation - stability provided by the K-wire fixation is to be supplemented by external splinting for three-to-four weeks. During this period a varying degree ot finger-joint contracture and tendon adherence des'elops and extends the time of rehabilitation.

- Sometimes, the pin starts to wander about and red-islocation comes about.

- The wandering pin causes not only unpleasent sympto ps, but it makes difficult to remove the wire.

The object of the present invention is to provide a new means for osteosynthesis, which increases the stability and elimin¬ ates the above mentioned disadvantages of the K-wire fixation.

According to the invention a compression pin is provided with two stop elements, at least σne of which is an element slidably fitted to the pin by a bore and supported by a compression

de ice fixed on the pin.

5 The compression device may be a bush provided with a bore fitt ing to the pin, a nut is on its external thread and a retentio screw is in a radial threaded bore of the bush.

The nut is provided with a surface bearing against a stσp 0 element, or connected with a distance piece of such surface.

The distance piece has a groove surrounding the retention screw.

The stop element may be a sleeve provided with a flange. z>

One of the stop elements is fixed on the pin, and it may be a metal pearl, collar or an upset made of the material of the pin.

0 The invention is based on the recognition that safe fixation, moreover compression can be achieved with the traditionally used pins, if the ends thereof are provided with stop elements and at least one of them is provided with a compression device. This way, drawbacks of the traditional pins (K-wires) can be 5 eliminated, meanwhile the advantage remains that opening of th fracture of widening of the surgical wound is unnecessary in the majority ot the cases and removal of the pin through a small pierced wound can be accomplished.

Production of the compression pin according to the invention is extremely simple, moreover the traditional pins can also be completed to compression pins. Thus, production according to the invention is simple, inexpensive and its use is practical and safe.

The invention will be described more in detail by way of examples with reference to the accompanying drawings, in which:

Figure 1 is a semi-sectional view of an embodiment of the com¬ pression pin according to the invention, 5

Figure 2 is a semi-sectional s'iew of another embodiment

Figure 3 is a another stop element ot the pin and

0 Figure 4 shows the upper part of the stop element's position after fixation.

In the embodiment shown in Figure 1, pin 1 is of traditional shape: it is provided with a blunt end 2 at the bottom and a 15 pointed end 3 on the top. The difference compared to the tra¬ ditional pin is that a collar 4 is provided as stop element, according to the invention. The collar 4 in Figure 1 is a disc fixed to the pin 1.

0 The other stop element is a sleeve 5 on the upper part of pin 1. Above this a compression device 6 is fixed to the pin 1. The compression device 6 comprises a bush 7, and the pin 1 fits into its bore 8. The lower part of the bush 7 is externally threaded to fit the nut 10.

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A threaded radial bore 11 is on the upper part of bush 7 with a retention screw 12. A recess 13 opposite the retention screw 12 is in the bore 8 of bush 7 for fixing through deformation of the material of pin 1 by the retention screw 12.

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A projection 14 is on the lower part of nut 10 screwed on the external thread 9 of bush 7. Its surface 15 perpendicular to the geometric centerline of the pin 1 bears against the flange of sleeve 5.

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Another embodiment of the invention is shown in Figure 2.

Here, the stop element at the blunt end 2 of the pin 1 is bending lέ made o the material of pin 1. The upper sto element is « sleeve 5 provided with flange 17.

Use of the embodiment in Figure 2 is practical mainly when relatively small section from the pointed end 3 of pin 1 i accessible. For this purpose, the retention screw 12 is arrang ed on the lower part of bush 7 ot compression device 6, and th nut 10 is screwed on the external thread 9 machined on th upper part of bush 7.

In this c=ιse th*__ compression is ensured b the distance elemen ιε between the nut l* ^" - and flange 17 of sleeve 5. Its uppe flange is in contact with nut 10, and its lower surface 15 wit the flange of sleeve 5. Movement in relation to the retentio screw 12 is ensured by groove 19.

H further embodiment of the stop element is shown in Figure 3 Here, the stop element is a pearl 20 ot a material similar to or identical with that of the pin 1. The pearl 20 is pulle over the blunt end of pin 1 , or screwed on the thread, then i is faxed to the pin 3 by way of deformation brought about wit pliers made for this purpose.

Use ot the compression pin provided with stop element on one ot its ends is the following.

The blunt end of pin 1 beneath stop element is clamped in drill chuc. , and resetting of the fracture is made by the I- nown method of pinning, i.e. the skin, the subcutis and the deduced fragments are perforated with the pin clamped in the drill chucl . The pointed end of pin passing through the bone is driven out on the opposite side through the subcutis.

Thereafter the drill chuct is pulled off the blunt end of the pin and it is fastened to the pointed end. Spinning the pin

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with the drill chuck, it is pulled out, and before the stop element would reach the skin surface, the skin and the subcutis are cut through to the bone a tew mm-s width along the pin. The stop element moving further with the pin through the wound reaches the bone and bears against the surface of one of the fragments.

This is followed by taking off again the drill chuck from pin 1 and pulling over the stop elements -in this case the sleeve 5 - over the pin 1 as shown in Figures 1 and 2. The skin is perforated at the point of emersion of the pin 1, and the sleeve is pushed forward to the surface of the bone. This way, one ot the stop elements bears against one fragment and the other one against the other fragment.

Next, the compression device 6 is mounted on the pointed end 3 of pin 1 as shown in Figures 1 or 2. When the nut 10 or the lower surface 15 of the distance element IB reaches the surface of sleeve 5 and flange 17, the bush 7 is fixed with retention screw 12 on the projecting pointed end 3 of pin 1.

After fixing, the fragments between the stop elements are compressed by screwing on the nut 10 to the required extent. It is advisable to perform this procedure under X-ray image intensifier.

When the appropriate position is attained, the sleeve 5 reaching beyond the skin together with the pin is gripped with breaker tongs, and the pin 1 and sleeve 5 are bent. Then the compression device 6 is removed and the projecting end of the pin is cut off. At this point, the bent sleeve 5 maintains the position secured by the compression device 6. The other end of the pin is cut short with nippers beneath the skin in the usual way.

Until the bone is helaed, the bent pin and sleeve reach beyond the skin surface, thus the co pressison is maintained. This causes no complication at all, it suits a standard accident- surgical practice. Generally four weeks later, the pin is removed: the sleeve and pin in it are cut with nippers between the bending and the skin surface, then the end of the sleeve projecting from the skin is pulled off the pin with pliers. The pin-end projecting from the skin is pushed in toward the bone with pliers, while the opposite end of the pin lifts the skin. A small cut is made here, and the end provided with stop element is gripped with pliers and pulled out.

In the course of applying this method according to the inven¬ tion, one or more pins - depending on the type of fracture - are used for fixation of phal langeal-, metacorpal- and other type of small-bone fractures. After pinning, the finger is held in functional position with the aid of elastic bandage. Fixation with plaster, or splint can be generally dispensed with.

Depending on the degree of stability attained upon pinning, the active and assisted exercise can be commenced after a few days, but at the latest after two weeks. Thus, the serious rigidity (contracture) of the small joint can be prevented at the time of removing the pin, and the patient's ability to work would be shortly restored.

The above examples illustrate only the invention, which is not restricted to these embodiments. Other versions of the stop elements can easily be produced. The sleeve, pearl, etc. used as stop element can also be fixed to the pin in several other ways. For example, deformed section of the pin where the stepped bore of the stop element gets stuck, and this contact can be combined with deformation of the pin and/or -top element, etc. Obviously, the stop element fι-orr. the dire_ ion of the compression device can be fixeJ ι ^~ . only as presented in

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F g-jre 4, but ^* . any other w<_/, e.g. as described above.

Th.-? co prt..sion pin according to the invention can also be used ir. several ways. Fixing of the stop element before insertion of t e pin is not absolutely necessary, it can be performed e-.er. on the already inserted pins. The stop element at the blunt e d of the pin can also be formed as sleeve and fixed as shwon in Figure 4. In case of neceεsit>, compression devices can be used on both ends of the pin.