WO2010054493A1

WO2010054493A1 - Intramedullary apparatus for arthrodesis or osteosynthesis

Info

Publication number: WO2010054493A1
Application number: PCT/CH2009/000354
Authority: WO
Inventors: Hans Stalder
Original assignee: Axus Medical Suisse Gmbh
Priority date: 2008-11-14
Filing date: 2009-11-10
Publication date: 2010-05-20
Also published as: WO2010054493A9; CH699896A2

Abstract

The intramedullary apparatus according to the invention for arthrodesis and osteosynthesis comprises at least one intramedullary tractive element (4), which is anchored in a first bone or bone fragment (1) and which can be guided through a first bone channel into a second bone channel of a second bone or bone fragment (2). From the second bone channel, the at least one intramedullary tractive element (4) can be guided through a bore in the bone wall to a suitable position (2.3) on an outside of the second bone or bone fragment (2), where it is fixed using a tensile element (6.1 and 6.2) and subjected to adjustable tensile stress. Said tensile stress can be reversibly adjusted in some preferred embodiments, whereby the adjustment of the spatial angle between the two bones or bone fragments in preferred embodiments can also be corrected postoperatively.

Description

EXTRAMEDULLARY DEVICE FOR ARTHRODESIS OR OSTEOSYNTHESIS

The invention relates to the field of orthopedic surgery and relates to an intramedullary device for arthrodesis or osteosynthesis, as well as a kit of components of the intramedullary device, correct grafting jigs and method of implantation, and an optional postoperative adjustment method of the relative positioning correction device the bone or bone parts to be joined. The device is suitable for stiffening joints, for example, in joint instability or in severe osteoarthritis or for stabilizing bone parts or bones, for example after osteotomies or fractures, in particular in human hand and foot surgery or even in veterinary surgery.

The stabilization of arthrodesis, osteotomies and fractures by means of screws, plates, staples, pins, intramedullary nails, wires or the like is known in the art. During the operation, the joint axes are definitely set or the bone parts are definitely positioned and stabilized by extra- or intramedullary fixation devices (plates, nails, etc.). Of course, this also applies if the fixation devices are removed again at a later time after the bone has grown together. The correct function of the treated bone depends critically on whether the goal of the planned correction position or the restoration of the normal anatomical axes and angles is achieved. Achieving a planning-oriented position and holding this position to the construction of the bone or bone parts to be joined has thus a high importance. Many improvements of such devices thus relate to the adaptability of the device such that the safety of achieving the desired postoperative position or anatomically correct alignment on the one hand and the strength and durability of the fixation achieved in the operation on the other hand is increased.

From the great diversity of the state of the art, exemplary extra and intramedullary fixation devices for foot or hand surgery are cited below. First, two documents exemplifying extramedullary fixators: US 2006/0241608 shows specially curved embodiments of a plate for arthrodesis of the metatarsal phalangeal joint to conform to the bones to be joined;

US 2006/0241607 shows a plate for the osteosynthesis of repositioned metatarsal bone parts with an adaptation to the shape of the metatarsal diaphysis and epiphysis and a plurality of holes.

Intramedullary fixation devices can be found, for example, in the following documents:

US 6203545 shows an intramedullary clip for the osteosynthesis of reduced metatarsal bone parts, which is characterized by expanding arms for better anchorage; US 2005/0283159 shows an intramedullary pair of rods

Shape memory material, which is parallel at room temperature and spreads at body temperature, suitable for arthrodesis or osteosynthesis; US 2008/0132894 shows an intramedullary device for arthrodesis of two phalangeal bones, for stable anchoring in the bone to be connected by means of several non-co-planar anchoring arms; US 2008/0177262 shows an intramedullary device with deformable anchoring parts which not only stabilizes bone parts but also compresses them to the contact zone between the bones or bone parts.

Although many of these and other devices for arthrodesis and osteosynthesis at least partially remedy the deficiencies of older, known devices, however, extramedullary fixation techniques generally suffer from the disadvantage that compression on the bones or bone parts to be joined can be built up, the compressing force however asymmetric and does not act perpendicular to the bone contact surfaces. The resulting turning and bending moment thus necessarily influences the transmission of force, which reduces the maximum possible contact surface between the bones to be joined and there is the danger of a delayed or even non-growing together (pseudoarthrosis).

In particular, none of these extra- or intramedullary devices permits a change in the relative position of two or more bone or bone parts achieved by the operation. If an intra- or postoperative correction is necessary, these fixation devices must be partially or completely removed and reassembled. If the need for a correction can only be recognized after closure of the skin or the resolution of any postoperative swelling, posture correction and reassembly always require the repetition of the entire procedure. This requires, for example, loosening the existing screws and drilling new screw holes for attachment of the extramedullary plate. Due to the example present on the foot or hand small bone size and Often, however, due to poor bone quality (osteoporosis), the number of possible holes is limited. In most cases, the necessary axis corrections only move in the range of less angular degrees, so that new drill holes necessarily come to lie partially in, or close to, the old ones. The result is that the screws no longer find the required support, so that after secondary corrections often insufficient stability of the assembly in favor of a better position must be tolerated. Even in the case of a once spread intramedullary fixation their removal and repositioning can not be done without significant damage to the bone material and associated loss of stability. Moreover, with thermoactive implants, this specific property is usually lost after the initial implantation.

In the best case, the correct position of the arthrodesis during the operation and before the wound closure can be checked by means of a suitable imaging procedure (X-ray). If this option is not available or if soft-tissue traction and mobilization effects lead to changes in position which become recognizable only after the wound has been closed, the need for a correction can only occur after some days. In the case of the methods known in the prior art, a repeat of the entire osteosynthesis is required in this case. This leads to higher treatment costs and increases the risk of complications such as infection.

It is therefore the object of the present invention to provide an intramedullary device for arthrodesis and osteosynthesis and a method of implantation thereof, which overcomes the disadvantages of the prior art. In particular, it is an object of the invention to provide an intramedullary device in which an adjustable and in preferred embodiments reversibly adjustable tensile stress causes a compression force on the bone parts to be joined. These objects are achieved by the intramedullary device, kits of components of the intramedullary device and methods of implantation, and any necessary correction adjustment of the intramedullary device as defined in the independent claims. The dependent claims define advantageous embodiments of the device according to the invention.

The intramedullary device according to the invention for arthrodesis and osteosynthesis has at least one intramedullary tension element which is anchored in a first bone or bone fragment and can be guided through a first bone canal into a second bone canal of a second bone or bone fragment. From the second bone canal, the at least one intramedullary tensile element is passable through a bore in the bone wall to a suitable position on an outside of the second bone or bone part where it is fixed with a tensioning element and placed under an adjustable tension, this tension being in some preferred embodiments is reversibly adjustable. Some preferred embodiments additionally have one or more securing elements which come to lie between the bone parts to be connected.

This adjustable tensile stress, which acts on the tensionable tension element between the bone anchor and tensioning element, creates a compression on the

Bone interfaces of the first and second bone or

Bone fragment. The intramedullary device allows the

Compressive force acts at least approximately orthogonal to the bone interfaces, thereby minimizing torsional and bending moments and maximizes power transmission. The uniform distribution of the compressive force over the entire contact surface of the two bone interfaces causes an intimate

Contact, which ensures the timely and complete integration of the bones or promotes bone fragments. A particular advantage of the invention is the adjustability of the tensile stress, which can thus be adapted to the physiological situation. Thus, in preferred embodiments, the clamping element may for example be equipped with a fine grid, which supports a stepwise very fine adjustment of the tensile stress. Other embodiments of the tensioning element have means for continuous adjustability of the tension. The controllable adjustment of the tensile force is thus tunable to the load capacity of the first and second bone in particular at the positions of bone anchor and clamping element, which can be taken into account, for example, due to osteoporosis reduced bone strength or the expected load on the bone or bone parts to be joined.

In preferred embodiments, the adjustable tensile stress is reversibly fixable by means of the at least one tensioning element, that is, the tensile stress is releasable, for example, if the external observation or the intraoperative X-ray control of the surgical result results in an insufficient agreement with the surgical planning. For a required correction of the spatial bone position, the compression between the bone parts to be joined must be temporarily suspended. This is achieved by reducing the tension on the at least one tension element by releasing the at least one tension element. Corresponds to the correction of the bone position of the operation planning, the at least one intramedullary tension element is again put under the required desired tension by tightening the one or more clamping elements, whereby the compression is restored in the new position.

This correction option is a great advantage over the known fixation devices, which allow neither an intra nor a postoperative correction of the achieved adjustment of the bones or bone parts to each other without the osteosynthesis must be at least partially repeated. In the case of osteosynthesis - for example, of tubular bones - the angles between the bone parts to be joined generally correspond to the anatomical specifications, the surgeon must additionally orientate himself to the functional and aesthetic demands during arthrodesis. The failure of a joint can be partially or completely compensated in a meaningful position of the arthrodesis by the remaining intact adjacent joints and also the cosmetic damage is minimal. The goal of a planning-oriented attitude and thus a good global function and cosmetics can only rarely be achieved at first attempt. Corrections are almost always necessary, should not with regard to position, function and cosmetics a suboptimal result be accepted. Even if these corrections are only a few degrees, they usually influence the final result considerably. For example, in the arthrodesis of the metatarsophalangeal joint, the spatial adjustment of the two bones to be stiffened is of central importance, both in terms of undisturbed walking ability and the possibility of wearing normal shoes, which requires an inconspicuous outer foot shape.

Such positional corrections in the implants known in the prior art require their repositioning both intra- and postoperatively, possibly combined with adjustments to the contact surfaces of the bones themselves. The intramedullary device for arthrodesis or osteosynthesis with at least one intramedullary tension element makes it possible to eliminate all of these disadvantages of previous methods, in particular their lack of ability to correct the angle and thus the position between the bones or bone parts to be joined.

In this patent specification, the term "intramedullary traction element" encompasses all intramedullary arteries extending essentially in the longitudinal direction of the medullary canal Devices such as threaded and non-threaded rods, racks, flat belts, chains, rods, screws of all types, threaded and unthreaded tubes, nails, pins, wires, wire cables, etc. of any biocompatible, biodegradable or non-degradable metallic or non-metallic materials (Titanium and its alloys, steel and its alloys, inorganic or organic compounds such as lactic acid derivatives of all kinds or plastics with high tensile strength such as carbon fibers, which are suitable for the necessary absorption of tensile forces and the assumption of a stabilizing function and to a certain extent In the following, the invention will be described mainly with respect to embodiments with an intramedullary traction element, embodiments according to the invention with two or more intramedullary traction elements th which individually, for example, substantially parallel or crossed, optionally interconnected or not connected and can be set with one or more tension elements under train.

The at least one intramedullary traction element leads through the interior of bones or bone fragments in the medullary cavity or through a drilled bone canal. The tensile element, fixed under tension, fixes and connects bones or bone fragments. Of course, therefore, two different bones or two bone fragments of the same bone or more bones or bone fragments can be connected to one or more guided through the bone canal, intramedullary tension elements. The one or more tension elements are anchored in a first bone or bone fragment and fixable in a second bone fragment with the help of one or more clamping elements so that an adjustable tensile stress can be exerted on the intramedullary traction elements. Of course, the invention also includes embodiments in which the anchoring in first bone or bone part is equipped with a functioning as an additional clamping element bone anchor.

This bone anchor consisting of one or more components is optionally an integral part of an end region of the at least one intramedullary tension element or a bone anchor can be fastened in an end region of the intramedullary tension element. In some preferred embodiments, the tension element has, in at least one end region, special structures which serve for connection to a tensioning element or to an anchor element. Also, the at least one tensioning element of the intramedullary device can consist of one or more components and, for example, a thread formed on a wire pull can ensure the connection of the tension element to the tension element or can the tension element or parts of the tension element be attached to the tension element or integrated therein Components included.

In a preferred embodiment, the anchoring of the intramedullary tension element in the medullary space of the first bone or bone fragment is accomplished, for example, by a bone anchor. Optionally, one or more drill holes serve to introduce and place the bone anchor or auxiliary members to secure it. The bone anchor is designed, for example, as a ball which is able to receive the tension element and has the appropriate elements for anchoring it in the first bone. In other embodiments, the intramedullary traction element is fixed, for example, with a pin or bolt which penetrates both the first bone and the bone anchor, a suitable eye or loop of a wire-like tension element, for example, or the intramedullary tension element itself. In yet other embodiments, the intramedullary traction element will, for example, be in the nature of one or more spreading Barb, a Spreizbolzens or a rocker arm anchored from the inside in the medullary cavity of the first bone. In further embodiments, the intramedullary tension element is guided and anchored in the first bone on an outer side of the bone, with or without tensioning element.

The at least one intramedullary traction element passes from the bone canal in the medullary space of the first bone through a bone interface of that first bone or bone fragment and a bone interface of the second bone or bone fragment into the bone canal in the medullary cavity of the second bone or bone fragment and leaves the bone canal of the second bone through a bore opening its side wall. Optionally, the bones are previously appropriately processed in an arthrodesis or osteotomy so as to allow intimate contact between the two bone interfaces in the desired area. This is done, for example, by plane bone sections or concave / convex machined to the respective bone ends.

Some preferred embodiments of the intramedullary device are equipped with securing elements which lie between the first and second bone interfaces. If appropriate, these can be threaded onto the intramedullary tension element and thus held by it in a desired position, for example centered. In other embodiments, the securing elements are designed as pointed cones (spikes) or similar shapes. The securing elements are configured in such a way that they are pressed into the bone boundary surfaces as they pull against the at least one tension element and dig into, for example, both bones without being completely submerged in the bone, thus preventing a relative displacement of the bone boundary surfaces relative to one another becomes. Another embodiment of a securing element can be used, for example, as an im be designed substantially planar, multi-beam star, which is substantially parallel to the bone interfaces between them and conforms to the surface. The star points are equipped, for example, with hoes, thorns or pointed cones. These elements, which protrude on both sides from the plane formed by the star points, become entrenched when compressed in the two bone interfaces. Of course, other embodiments of fuse elements according to the invention, for example, annular grid with or without spikes, braided elements (barbed wire) and so on are possible.

The design of the securing elements prevents the two bone interfaces from sliding on one another in the event of too little friction, thereby changing their relative position to each other. By a suitable design of the fuse elements, the contact between the bone ends is only minimally reduced so that the growing together is not hindered. The security elements are made of a biocompatible material (titanium and its alloys, steel and its alloys, lactic acid derivatives of all kinds, carbonaceous plastic compounds). Biodegradable materials are preferably used because, after the bone has grown together, the securing effect is no longer necessary.

The at least one intramedullary traction element leads through the second bone interface into the second bone canal and through a drill hole positioned at a suitable location from the bone canal to a bone exterior. The intramedullary tension element can be fixed by means of an adjustable tensioning element on this outside of the bone or, if appropriate, in the drilling opening. After the desired relative positioning of the bones or bone fragments has been set, the at least one intramedullary tension element with at least one tensioning element is preferred Reversible placed under an adjustable train. As a result, the set positioning of the bones or bone fragments is fixed and a compression force acts on the bone interfaces of the bones or bone fragments to be connected. The clamping element can be equipped in preferred embodiments so that with suitable tools, such as a torque wrench, the tensile stress generated is measurable and controllable and thus adjustable limited. The metered release and retightening and optionally continuous or graduated setting the desired tension on the tension element is a particular advantage of the invention.

In a further preferred embodiment, the intramedullary tension element is a flexible threaded rod and the adjustable and reversibly fixable clamping element has a clamping nut or clamping screw and optionally an abutment element. The intramedullary traction element passes through the hole in the wall of the second bone and through the optionally applied abutment plate and is fixed or put under tension with the clamping screw or nut. 1. In a preferred embodiment with a pulling element in the form of a thread-carrying rod, the thread pitch is designed so that the ratio of feed to revolution of the clamping element between lmm / 0.1 revolutions and lmm / 0.5 revolutions, preferably between lmm / 0 , 1 revolution and lmm / 0.3 revolutions, and more preferably lmm / 0.25 revolutions. To cope with a feed of 1 mm 4 full revolutions of the clamping element are thus required in the latter case. This ensures a finely dosed release and retightening setting the desired tension on the tension element. The tear-out strength of such an intramedullary device is dependent, in particular, on the choice of material of the tension element and, in suitable embodiments, is far beyond the range required in medical applications. For example, in one test system, such an intramedullary device has been provided with a cylindrical AISI 316L grade chromium-plated tension member of 1 mm diameter in a plastic toe exercise model with near-natural properties over 60O00 load cycles of a tensile load of 500-600N exposed without tearing or breaking.

In further embodiments, a tensioning element is designed, for example, for a wire-like or cable-like intramedullary tension element in the manner of a detachable cable tie. For example, the tension element is flattened in an end region and equipped with a screening (band toothing), which is guided on the outside of the bone through an opening of a head element. The head element is a latching element which engages in the screening of the band and so fixes the tension element at an adjustable position and accordingly sets the tension element under more or less strong train. In preferred embodiments, as in the case of reusable cable ties, the band toothing and the latching element in the head are designed such that reversible toothing of the band in the latching element of the head is achieved, for example, by rotation of the band or by displacement of the band into a region of larger diameter. This ensures the already described intra- and postoperative correction of the relative position of the bones or bone fragments relative to one another in this preferred embodiment. Of course, other clamping elements and mechanisms for generating a clamping force on the at least one intramedullary tension element in the context of this invention.

A further aspect of the invention relates to a kit which contains components of the intramedullary device according to the invention, such as one or more intramedullary traction elements, for example one or more flexible threaded rods with an (optionally integrated) bone anchor and optionally one or more abutment plates and clamping elements, for example containing a clamping nut. If necessary, the kit also contains, for example, securing elements and auxiliary parts for carrying out the Osteosynthesis or arthrodesis such as drilling jigs, guidewires, pierced and non-pierced confusion-proof drills with and without depth stop, socket wrench or screwdriver with or without torque limiter, instruments for cutting wires, devices for measuring angles and the like. Of course, several components of the same type may be included in the same or different dimensions or materials in a kit. For example, a kit may be specific for performing a specific operation such as an operation on the foot (eg, metatarsophalangeal arthrodesis or hallux rigidus surgery) of a hand operation (eg, carpo-metacarpal arthrodesis or saddle joint arthrodesis) or an analogous veterinary surgery be compiled.

A further aspect of the invention relates to a method for implanting the intramedullary device for arthrodesis or osteosynthesis with the aid of an intramedullary device according to the invention. The method is described for an embodiment with an intramedullary traction element, but of course the method steps can also be adapted analogously for two or more intramedullary traction elements. Such a method is suitable for osteosynthesis and arthrodesis in human and veterinary medicine.

The preparation of the osteosynthesis, arthrodesis or osteotomy does not differ from the previous methods. In the case of arthrodeses and osteotomies, the bone ends must be prepared so that they can grow together. For this purpose, there are various possibilities, such as, for example, plane bone cuts in the healthy bone of the joint-proximal part. Due to the position of the cuts, however, the later position of the limb is determined and changes in position require analogously new cuts in another plane. One Another method is the concave-convex processing of the bone ends. As a result, a joint can be set largely freely within certain limits and fixed by the intramedullary device according to the invention. Preferred embodiments of the method and the device are designed for the convex-concave technique, but neither apparatus nor methods are limited to these.

At a suitable location in the bone interface of a first bone or bone fragment, a first opening is created, for example, by means of a bore, if necessary for receiving an auxiliary wire, such as a K-wire and for receiving a bone anchor in the medullary space. At a suitable location in the bone interface of a second bone, a second opening is drilled. Furthermore, in preparation for intramedullary fixation, the two bone channels are drilled inside the bone to be joined. In the second bone or bone fragment is at a suitable location by a bone wall for attachment of an adjustable and optionally reversible fixable

Clamping element created a third opening, for example by means of a bore. The use of a drilling jig and tangle-free, for example, color-coded pierced drills with depth stop avoids faulty bone channels or faulty holes through the bone outer walls.

In preferred embodiments of the method, one or more further drill openings in the bone wall of the first bone or bone fragment serve to introduce an attachment of the bone anchor, with which this intramedullary tension element, for example a deformable rod, a wire or a flexible introduced into the medullary canal through the bone canal Threaded rod is fixed in the bone. In other embodiments, for example, an integrated in the intramedullary threaded rod bone anchor, after the rod introduced into the bone canal, for example, spread and wedged in the channel or anchored by flipping a, activated under train, rocker mechanism.

Preferably, one or more securing elements, for example in the form of a star, are introduced by threading onto the intramedullary tension element or, for example, biconvex pointed cones (spikes) by impacting or pushing into the bone of at least one bone interface so that it lies between the first and second bone boundary surfaces.

The intramedullary traction element is guided into the bone canal of the second bone and from this through an opening through the bone wall and optionally by an abutment on the outside thereof, and initially loosely fixed with an adjustable clamping element. After the joint axes of a joint to be stiffened in an arthrodesis or the bone fragments are set at osteosynthesis according to the surgical plan and optionally the position using angle gauges or X-ray control are controlled, the desired tensile stress on the tension element with the tensioning element is preferably initially set reversible and the Compression force constructed substantially orthogonal to the bone interfaces.

If necessary, a posture correction is necessary during the operation. By loosening the tension by loosening the clamping element, the position of the bone parts to each other in all spatial axes can be arbitrarily changed and thus the position of the arthrodesis or Ostesynthese be redefined. By turning the clamping nut in a clockwise direction, the tension element, for example, a threaded rod comes back under train. In embodiments with securing elements, they thereby dig into the two again Bone ends and thus prevent in case of insufficient friction between the bone ends a secondary change in position.

The use of a torque wrench to tighten the tensioning element prevents the compression on the joint surfaces or the bone wall of the second bone or the tension on the anchorage in the first bone from becoming too great. This can prevent complications such as tears of the implants, pressure damage to the bone, breaking of the bone wall or circulatory disturbances.

If the position of the arthrodesis or osteosynthesis coincides with the surgical planning, before the soft parts are closed, the optionally protruding part of the intramedullary tension element is placed over the tensioning element so that the tensioning element can not be removed or loosened from the tension element without special effort. When using a threaded rod as a tension element with a pitch with a ratio of feed to revolution of the clamping element of lmm / 0.25, for example, 5 mm supernatant left. This means that the nut must be turned completely at least 20 times before it can leave the thread. In addition, a crimping point is set when cutting the tension element, which can be overcome by the mother only with particular effort. Overcoming the thread length and the pinch would therefore require an effort that is at least four times higher than for the possibly necessary correction of the spatial position of the first bone relative to the second bone.

Of course, it is also within the meaning of the inventive method, the order in which the intramedullary or the traction elements in the first or the second bone canal are introduced. Further, the definition of first and second bones used herein is not physiologically relevant but refers only to one or more intramedullary traction elements being anchored in the second bone or bone fragment by one or optionally one clamping element by definition, whereas the at least one intramedullary traction element in the first bone is attached by one or a respective bone anchor or optionally as in the second bone by one or a clamping element.

Another aspect of the invention relates to a method of postoperative correction of the position of the arthrodesis or osteosynthesis after closure of the soft tissues, for example 4-5 or even up to 8 days after the first operation after any swellings have receded and the position can be assessed even more accurately or if an X-ray inspection shows a malposition. The correction can be performed under visual control, but the use of an X-ray machine is advantageous.

At the beginning of the position correction, the clamping element is loosened, for example, the clamping nut solved by a few rotations counterclockwise. The construction of the clamping nut prevents it from detaching itself from the threaded rod without any special effort. By longitudinal tension on the joint distant bone the pressure is taken from the security elements, the claw is released and the position can be changed arbitrarily. By subsequently tightening the clamping element, the corrected position is again stably fixed and secured by the securing elements. The process of the position correction can be performed several times in succession. If the correction takes place with the skin already closed, a device for tightening the clamping nut can be inserted through a small, for example 10 mm, skin opening. This may take place in local pain elimination if necessary. The possibility of correction also applies without restriction to variants of the method with intramedullary devices which have securing elements. Because the security elements fulfill their fixing function only when the bone interfaces are in intimate contact. As soon as the tension is removed and the interfaces are pulled apart, the securing elements retain their position, but lose their fixing function. Scratches in the bone interfaces caused by the securing elements heal easily and have no destabilizing effect on the bone substance. On the contrary, they increase the bone surfaces and thus contribute to improved coalescence. Once that at least one

Tension element is set by the at least one tensioning element back under train, the bone interfaces are in new relative position again under compression, and the securing elements dig into the new position again in the bone interfaces and prevent a shift from the corrected relative position.

Another aspect of the method of implanting the intramedullary arthrodesis or osteosynthesis device involves applications of the method in veterinary medicine. A preferred application relates to the arthrodesis of the fetlock joint in horses. This joint corresponds in function to the metacarpo-phalangeal joint in humans. Due to the size and the forces acting thereon, unlike in humans, at least two intramedullary tension elements, which are preferably arranged in a crossed manner, are preferably to be used on this joint.

Preferred embodiments of the intramedullary device and methods for their implantation and postoperative posture correction of the intramedullary device will be described with reference to the following figures. However, the invention is not limited to the embodiments illustrated below. Of course, different embodiments of the components of the intramedullary device can also be used in other than the combinations shown. The figures show:

Figure 1: Schematic drawings of an arthrodesis of a joint by means of an intramedullary device with a flexible threaded rod, a

Bone anchor, securing elements and a clamping element consisting of a clamping nut and abutment plate: Fig. Ia as

Exploded view before the clamping of the clamping element and Fig.

Ib as a view of the stiffened joint after the tensioning of the clamping element.

FIG. 2: Drawing of a ready-to-assemble arrangement of an exemplary selection of elements of the intramedullary device prior to implantation into the bone.

Figure 3: Schematic views and a cross section of various embodiments of the bone anchor:

Fig. 3a: View of a cylinder anchor with bolt 3.1

Fig. 3b: View of an eye anchor

Fig. 3c: view of an expansion anchor

Fig. 3d: View of a tilting anchor Fig. 3e: View of a ball anchor

Fig. 3f: Cross section of a ball anchor in the two rotational positions A and B.

Figure 4: Schematic views of various embodiments of a? Fuse element: Fig. 4a: Fuse rosette and Fig. 4b:

backup Spike FIG. 5 Schematic views of various embodiments of a tensioning element:

Fig. 5a: View of the clamping element with a clamping screw and a free abutment plate Fig. 5b: View of a clamping element with an integrated

Abutment plate

Figure 6: Schematic view of a drilling jig

FIG. 7: a step-by-step illustration of an embodiment of the method according to the invention

LIST OF REFERENCE NUMBERS

1 first bone with bone interface 1.1 with recess in the first bone channel 1.2 and 1.3 bore preferably perpendicular to the

Bone longitudinal axis of the first bone.

2 second bone with bone interface 2.1 with hole in the second bone canal 2.2 and 2.3 hole in the bone wall of the second bone 3 bone anchor with fasteners 3.1 such as bolts or

Pin, and if necessary with flange 3.2 and conical bore 3.3

4 intramedullary traction element, for example, a threaded rod with protruding end 4.1 and direction of tension 4.2

5 Retaining element, if necessary, rosette or star with arms or star points 5.1, hole for threading on tension element 5.2, thorns, hoes, etc. substantially perpendicular to the plane of the star points or arms 5.3 or optionally as a double cone with smooth shorter pointed cone 5.4, opposite longer pointed cone 5.5, equipped with elements for retention in the bone 5.6 and height stop 5.7

6 clamping element 6 with clamping screw of the clamping element 6.1 and abutment element of the clamping element 6.2

7 Drilling jig 7 with drill guide 7.1, angle arm 7.2, target cylinder or target cone 7.3 and drill 7.4

1 1 target wire 1 1.1 for the first bone and 1 1.2 for the second bone

12 convex cutters 13 cutters with depth stop 14 concave cutters 14

Same or analog parts in the different figures are labeled with the same numbers.

FIG. 1a: shows, in a schematic exploded view, an embodiment of an intramedullary device suitable, for example, for arthrodesis of a metatarsophalangeal joint (stiffening of a metatarsophalangeal joint). Such surgery is often performed in severe hallux rigidus joint deformity. An intramedullary tension element 4, here a threaded rod, is fastened in a first bone 1 with a bone anchor 3. Various

Variants of bone anchors are described in FIG. The intramedullary tension element 4 runs in a bone canal 1.2 and leaves the first bone at a bone interface 1.1. Securing elements such as spikes 5, which are used at least in the bone interface 1.1 or in a bone interface 2.1 of a second bone. Of course, could be between the two bone interfaces and another fuse element such as a threaded on the threaded rod 4 backup rosette, etc. as described above. The threaded rod 4 leads through the Bone boundary surface 2.1 in a bone canal 2.2 of a second bone 2. Through a hole 2.3 in a bone wall of the second bone 2, the threaded rod 4 leaves the second bone canal 2.2. An abutment plate 6.2 of a clamping element 6 is threaded onto the threaded rod 4 and is positioned over the hole 2.3. A clamping nut or clamping screw 6.1 of the clamping element 6 is screwed onto the threaded rod 4. Of course, instead of a clamping nut or clamping screw and other clamping elements, for example equipped with a bayonet lock or in the manner of a ribbon cable tie suitable to a tension element such as a suitably equipped in the end threaded rod or wire rope, etc. usable. The possibly protruding end of the tension element 4.1 is settable after the setting of the desired tension on the tension element 4. The clamping element is arranged so that after discontinuation of the optionally protruding end of the clamping element can not be removed without special effort from the tension element and that preferably the tension of the clamping element initially remains reversible, in the event that a position correction is necessary.

FIG. 1 b shows a view of a stiffened joint after the arthrodesis illustrated in FIG. 1 a has been completed, and the tension element 4 is anchored to the bone anchor 3 and a bolt 3.1 in the first bone 1 and tensioned with the tensioning element 4 in the second bone 2 ,

FIG. 2 shows a ready-to-install arrangement of an exemplary selection of components of the intramedullary device prior to implantation into the bone, wherein identical or analogous parts in the figures are labeled with the same numbers.

FIG. 3 schematically shows various embodiments of a bone anchor. FIG. 3 a shows a first embodiment in which the bone anchor 3 is designed as an intramedullary cylinder, which is externally connected with a bolt 3.1 is fixed, wherein the bolt pierces at least one bone wall of the first bone. In Fig. 3b, a Ösenanker is shown, which is particularly suitable as an integral part of embodiments of the tension element 4 made of wire or wire rope or plastic rope. As shown in FIG. 3b, the eyelet 3 can lie intramedullary and be fastened with a bolt or pin analogously to the cylindrical bone anchor shown in FIG. 3a from the outside of the bone. In another not shown variant of a Ösenankers the eyelet is at least partially guided through a hole in the first bone on the outside and fixed there, for example, with a parallel to the bone shaft running pin. Figures 3b and 3c show variants of intramedullary bone anchors which are inserted in a slender configuration into the bone canal and widen to tension, such as a spreading anchor or a tipping anchor. A particularly preferred form of a bone anchor is shown in FIGS. 3d and 3e, which is particularly suitable for fastening an intramedullary traction element with limited

Elasticity or bendability such as threaded rods made of metallic materials such as chrome steel or titanium. The tensile stress on the intramedullary traction element in most applications does not act in exactly the same direction as the longitudinal axis of the intramedullary canal in the first bone. However, the longitudinal axis of a cylinder anchor described for example in Fig. 3a is aligned in the longitudinal direction of the intramedullary canal and is substantially limited to this orientation. Once the cylinder anchor is fixed in the first bone with a bolt 3.1, a later alignment in the pulling direction of the tensile stress acting on the tension element is made impossible. A deviation of the pulling direction of the cylinder axis therefore causes a slight kinking of the intramedullary tension element at the attachment point of the tension element on the cylinder anchor. An embodiment of the bone anchor as a ball anchor, which allows a rotation of the anchor for orientation in the pulling direction is therefore much less prone to breakage. 3e shows an exemplary embodiment of such a ball anchor 3. The ball anchor 3 points to the spherical surface optionally a flange 3.2, which has a structure for fixing the tension element, such as an internal thread, which receives the equipped with a complementary thread intramedullary tension element. Next, the ball anchor on conical holes 3.3, which lead from the ball wall to the ball center for receiving a bolt 3.1. Such a bolt 3.1 is guided from the outer bone side of the first bone through a first conical bore 3.3 to and through the ball center of the ball anchor and through a second conical bore to the opposite bone wall on the outside of the first bone. Particularly preferred embodiments of the ball anchor have more than two, for example, four orthogonal conical bores to allow a situational selection of one or the other pair of conical holes for the implementation of the bolt 3.1. Since the holes are conical, a limited rotation of the ball anchor already fixed in the first bone is thus possible, wherein the turning or tilting angle depending on the size of the outer diameter of the conical bore (in relation to the ball diameter), for example in the context of a lower limit of 5 ° to 10 ° to an upper limit of 15 ° to 20 ° degrees and preferably 10 ° to 15 ° degrees. FIG. 3f shows a section A and a section B through the two positions of maximum rotation of the ball anchor. Such a ball anchor is also independent of this concrete

Use as an embodiment of a bone anchor of this intramedullary device in orthopedic surgery.

Figure 4 shows various embodiments of securing elements: Fig. 4a shows an exemplary securing element in the manner of a rosette or a star formed with arms or teeth 5.1 on soft perpendicular to its longitudinal axis holding elements 5.3, such as pointed cone are applied, and wherein the securing rosette so by the hole 5.2 can be threaded onto the tension member 4, that it comes to lie substantially centered between the two bone boundary surfaces 1.1 and 2.1 and in the absence of tension through the Traction element is held in position. 4b shows an exemplary backup spike. Preferred embodiments of the securing spikes are formed as two opposite pointed cones 5.4 and 5.5 and have, for example, on one side a short smooth pointed cone 5.4 and on the opposite side a longer part 5.5. The longer part is with

Elements 5.6 provided for the retention of the cone in the bone. The backup spikes can be plugged into the bone at suitable actuators of the first or the second interface so that the short part projects out of the bone and is anchored in the bone for a long time. A height stop 5.7 prevents the safety spikes from being completely buried in the bone. The protruding smooth shorter pointed cone burrows under tension on the pulling element in the opposing bone interface and two or more such securing spikes prevent relative displacement of the bone interfaces as soon as the traction element is put under tension. The intra- and postoperative position correction is ensured even with the use of securing elements, since the relative fixation in the absence of tension on the tension element and slight pull on the distal bone or bone part, the claw or burial of the fuse element in the bone interfaces is solvable and the relative Bone position is correctable.

FIG. 5 shows schematic views of two different embodiments of a tensioning element. In Fig. 5a, the clamping element is designed as a clamping nut, which is screwed onto a traction element 4 equipped with a corresponding thread. The tension element is shown here only hinted at as a straight line. This clamping nut has distally a convex here hemispherical surface 6.3, which fits into a concave recess 6.4 of an abutment 6.2. As a result, an at least partial alignment of the clamping nut in the pulling direction is possible, which counteracts a bending of the connected to the clamping nut 6.1 tension element 4. This possibility of alignment with the direction of pull is further enhanced in the embodiment shown in FIG. 5a with a convex surface 6.5 of the abutment, which fits with play in a corresponding hole in the second bone. In an alternative embodiment, not shown, the clamping nut 6.1 with the convex surface 6.3 is screwed directly without an abutment in a concave bore hole of the second bone on the tension element 4. Another embodiment, not shown, combines the clamping screw and the abutment in a spherical or, for example, hemispherical clamping screw with an internal thread and a hexagon socket for attachment and tension of the tension element. For fastening a special tool is used in the manner of a Allen key, which has a channel for the passage of the protruding end of the tension element. A further embodiment is shown in Fig. 5b in which only the clamping screw 6.1 has a convex surface the abutment 6.2 but substantially planar design and is suitable for a sufficiently flexible tension element that is less vulnerable to kink at the junction between the clamping screw and tension element. Of course, combinations of the versions described are possible.

Figure 6: shows schematic drawings of a drilling jig. In Fig. 6a an exemplary drilling jig 7 is shown in section. This has an angle arm 7.2, wherein on a leg 7.2.1 of the angle arm a sleeve-shaped bore guide 7.1 is attached and on the other leg 7.2.2 of the angle arm a target cylinder 7.3 is attached. A drill 7.4 is guided through the sleeve-shaped drilling guide 7.1 and into the bone 1. Fig. 6b shows a view of an application of the drilling jig for drilling a hole through a bone wall in the first bone 1 for insertion of a fastening bolt into a bone anchor. By the predefined by the drilling jig position of the guide cylinder 7.3 and the drill sleeve 7.1 an accurate hole of the hole is possible, so that after removal of the drill guide from the bone canal as shown in Fig. Ia a bone anchor 3 in the bone canal with a mounting bolt 3.3, which is insertable through the correctly positioned, can be fixed. Fig. 7.1 - 7.21 describe stepwise one embodiment of the inventive method using the example of an arthrodesis of a metatarsophalangeal joint (metatarsophalangeal joint). Of course, the embodiments of components described here in this example can be replaced by other embodiments of these components according to the invention. The various embodiments of the various components of the intramedullary device can be combined as desired with one another, as the person skilled in the art accordingly tunes the interfaces to the components used in a meaningful and known manner.

Figures 7.1 to 7.5 show the preparation of the first bone for receiving a bone anchor

Fig. 7.1 shows the setting of an example, color-coded target wire 1 1 in the middle of the joint surface 1.1 of the first bone 1, here the proximal phalanx of the metatarsophalangeal joint to be stiffened. Fig. 7.2 shows the over-milling of the joint surface 1.1 with a pierced, for example color-coded convex cutter 12, whereby a first spherical-concave contact surface is created on the first bone.

Fig. 7.3 shows the milling of an example conical recess 1.2 for the bone anchor with a pierced example color-coded cutter 13 with depth stop. Then the target wire 1 1 can be removed.

Fig. 7.4 shows the milled in the previous step conical recess 1.2 in the first bone, in which now a first, for example, color-coded drilling jig 7 is used to present a preferably perpendicular to the bone longitudinal axis Bohrkanals for the introduction of a securing bolt to prepare the attachment of the bone anchor. After the desired positioning of the drilling jig 7, the drilling channel is drilled with the color-coded drill, with the drill penetrating the drilling jig. Fig. 7.5 View of the first bone lying in the longitudinal direction of the bone, for example, conical recess 1.2 and perpendicular to the longitudinal axis bone drill channel 1.3 for a self-anchoring safety bolt, for example. Of course, the recess 1.2 instead of a conical, for example, a cylindrical or other shape, which serves to receive a bone anchor in the first bone canal.

Figs. 7.6 to 7.10 show the preparation of the second bone for receiving a tension member and its attachment

Fig. 7. 6 Setting a small depression - preferably with a trocar at the desired location 2.3 of the second bone 2, where the tension element out on the bone outside, or where the tension element preferably comes to rest. Inserting a second, for example, color-coded drilling jig with a fixed leg 7.2.2, which carries at one end, for example, a pierced cone 7.2.3 and at the other end 7.2.4, for example, with a half-round rod 7.2.5 is firmly connected, and a movable leg, 7.2.6, which is displaceable, for example, on the half-round rod 7.2.5 only in one plane, and carries at its opposite end a directed to the pierced cone tip 7.2.7, so that the tip of the conical part 7.2.3 on the fixed leg 7.2.2 and the tip 7.2.7 of the movable leg 7.2.6 lie on an axis 7.2.8. Setting the tip of the moving part of the target device 7.2.7 in the groove in area 2.3 and setting the cone 7.2.3 of the fixed part 7.2.2 in the center of the joint surface of the second bone. Build up a compressive stress on the target device by pushing together the two legs 7.2.2 and 7.2.6 against each other so that they dig into the respective bone sections. Reading the estimated length of the intramedullary drilling channel on the basis of preferably three or more length marks on the top of the example, half-round rod 7.2.5. Fig. 7.7 Introduction of an example, color-coded target wire 1 1.2 through the pierced cone 7.2.3 so that it meets the top of 7.2.7 of the movable leg 7.2.6.

FIG. 7.8 Milling the joint surface 2.1 of the second bone 2 with a pierced, for example, color-coded concave milling cutter 14 to create a spherical-convex contact surface.

Fig.7.9, 7.10 Milling or drilling a channel in the medullary canal for the passage of the tension element from the center 2.2 of the bone interface 2.1 to the bone outer side in the area 2.3 of the bone 2 and removing the target wire 1 1.2.

Fig. 7.11 to Fig. 7.13 show the positioning of securing elements.

Fig. 7.11 insertion of a biconvex security element (spike) with, for example, a stop at a suitable location of the convex bone surface so that a smooth part (5.4 in Fig. 4b) of the spike looks out of the bone and processed for retention in the bone part 5.5 im Bone is broken. Preferably repeat the process until at least two securing elements can be anchored at different locations.

Fig. 7.12 insertion of a self-centering securing element with, for example, in the manner of a securing rosette with a central hole 5.2 and two or more beams 5.1 on soft perpendicular to its longitudinal axis holding elements 5.3, for example, pointed cone are applied.

FIG. 7.13 shows a view of the bone interface 2.1 with, for example, three inserted securing elements.

Figures 7.14 to 7.21 show the implantation and posture correction procedure of the intramedullary device.

FIG. 7.14 Introduction of the intramedullary tension element 4 (length according to step described in FIG. 7.6) with preassembled bone anchor 3, for example a ball anchor for the time being, into the bone canal 2.2 of the second bone 2 so that the free end 4.1 of the tension element 4 protrudes through the opening 2.3 in the outer bone wall of the second bone from the bone canal.

Fig. 7.15 introducing the example spherical anchor 3 in the bone canal of the example, the first bone 1 to the bottom of the example, conical recess 1.2.

Fig. 7.16, 7.17 inserting the preferably self-retaining locking bolt 3.1 by at least two of the converging anchoring holes 1.3 in the bone anchor and at least as long that it preferably penetrates the bone wall on the opposite side of the bone. Fig. 7.18 Threading the example hemispherical abutment 6.2 and the clamping element such as a clamping nut 6.1 on the thread-free protruding part of the tension element 4.1 on the thread and grasping the thread with preferably at least five turns clockwise.

Fig. 7.19 Adjusting the position of the two bones to each other according to surgical planning. Joining the two joint surfaces so that the free portions of the securing elements 5.4 dig into the opposite bone interface.

FIG. 7.20 Tightening of the tensioning element 6 with the preferably torque-controlled tightening aid so that the two bone boundary surfaces 1.1 and 2.1 are pressed against one another.

Fig. 7.21 Comparison of the achieved position of the bones in the room to each other with the operation planning or by means of X-ray control. If necessary, release the tensioning element 6 and repeat from step 20.

Fig. 7.21 Settling of the protruding part 4.1 of the intramedullary tension element with the cutting aid, preferably a side cutter.

Claims

1. Intramedullary device for arthrodesis or osteosynthesis, with at least one intramedullary tension element (4) anchored in a first bone or bone part (1), can be guided through a first bone canal into a second bone canal of a second bone or bone part (2), characterized in that the at least one intramedullary

Pulling element (4) from the bone canal (2.2) of the second bone (2) through the bone wall on the outside of the second bone or bone part is feasible and by a clamping element (6) can be fixed and adjustable by an adjustable tension.

2. Intramedullary device according to claim 1, characterized in that the adjustable tension is intra- and postoperatively releasably and re-adjustable, the intramedullary device repeatedly ensures this reversible adjustability of the tension.

3. Intramedullary device according to claim 1 or 2, characterized in that the device additionally comprises one or more securing elements (5) which are arranged between the two bone boundary surfaces 1.1 and 2.1.

4. Intramedullary device according to claim 3, characterized in that a securing element (5) has a rosette or star-like shape with a central hole 5.2 and two or more jets 5.1, which lie in a substantially planar surface and wherein the jets 5.1 can be equipped with protruding on both sides of this plane structures such as spikes 5.3.

5. Intramedullary device according to claim 3, characterized in that the securing element (5) is formed by one or more biconical securing spikes, such a biconical securing spike having a longer conical point (5.5) for anchoring in one of the two bone interfaces and a shorter smooth conical point (5.4 ) for clipping in the other bone interface and a height stop (5.7) positioned at a suitable height.

6. Intramedullary device according to one of claims 1-5, characterized in that the at least one intramedullary tension element (4) contains metal, for example titanium and its alloys or steel and its alloys or other biocompatible metal compounds.

7. Intramedullary device according to one of claims 1-5, characterized in that the at least one intramedullary tension element (4) contains a non-metallic substance such as in particular degradable lactic acid derivatives and other organic compounds.

8. Intramedullary device according to one of claims 1-7, characterized in that the at least one intramedullary tension element (4) has an integrated bone anchor (3).

9. intramedullary device according to one of claims 1-7, characterized in that the at least one intramedullary tension element (4) has a bone anchor fastened to it (3).

10. Intramedullary device according to claim 8 or 9, characterized in that the bone anchor is a spherical and at least one conical

Has bore from the ball wall to the ball center.

1 1. Intramedullary device according to one of claims 1-10, characterized in that the at least one intramedullary tension element (4) has one or more threads or a threaded rod.

12. Intramedullary device according to claim 1 1, characterized in that the clamping element (6) has a clamping nut or clamping screw (1) and an abutment element (6.2)

13. Intramedullary device according to one of claims 1-12, characterized in that the clamping element is continuously or stepwise adjustable.

14. Intramedullary device according to claim 13, characterized in that the at least one tension element is equipped with at least one threaded portion for fastening the tensioning element in the form of a clamping screw or clamping nut, wherein the thread pitch of the threaded portion designed so that the ratio of feed to Rotation of the clamping element in the range lmm / 0.1 revolutions to

1 mm / 0.5 turns.

15. Intramedullary device according to one of claims 1-14 for use in hand and foot surgery in human medicine and analogously in veterinary medicine.

16. Kit comprising components of the intramedullary device according to one of claims 1-15.

17. Kit according to claim 16, characterized in that it additionally contains one or more drilling jigs, which are suitable for the implantation of the intramedullary device in the hand and foot surgery of humans.

18. Kit according to one of claims 16 or 17, characterized in that the components are provided for a hallux operation (metatarsophalangeal arthrodesis).

19. Kit according to one of claims 16 or 17, characterized in that the components are provided for a carpo-metacarpal arthrodesis (saddle joint stiffening).

20. Kit according to any one of claims 16, 18 or 19, characterized in that the components are provided for operations on the musculoskeletal system of animals.

A method of implanting an intramedullary device into a human or animal body according to any one of the preceding claims 1-15 or using a kit according to any one of claims 16-20 for implantation of an intramedullary device in a human or animal body, comprising the following steps:

A. creating a first opening in the bone interface (1.1) of the first bone or bone fragment (1) for receiving a bone anchor (3) in the medullary cavity;

B. creating a second opening in the bone interface (2.1) of the second bone or bone fragment in the medullary canal of the second bone;

C. creating a third opening through a bone wall in the second bone or bone fragment (2) for fixing an adjustable and optionally reversibly adjustable clamping element (6);

D. inserting the at least one intramedullary tension element (4) with the bone anchor (3) integrated in the tension element or attachable to the tension element through the first opening into the medullary bone canal of the first bone (1); E. anchoring the intramedullary tension element (3) in the first bone (1) by means of the bone anchor (3);

F. inserting the at least one intramedullary pulling element (4) into the bone canal of the second bone (2) through the second opening and passing it through the third opening in the bone wall to an outside of the bone wall of the second bone (2);

G. Attaching, with play, the at least one intramedullary tension element (4) with a tensioning element (6);

H. setting a desired spatial angle of the bones or bone parts to be joined (1 and 2); I. Tensioning of the tensioning element (6) to the at least one intramedullary

To put tension element (4) under tension, and to cause a compression on the bone interfaces (1.1 and 2.1) of the bones to be joined; J. Checking the relative position of the bones (1 and 2) to each other and optionally correcting the position by loosening the tension element (6) and repeating steps H and I.

22. The method of claim 21, wherein in addition at least a fourth opening is made through the bone wall of the first bone or bone fragment (1) for receiving a fastener for the bone anchor.

23. The method of claim 21 or 22, wherein in addition between the first bone interface (1.1) and the second bone interface (2.1) at least one securing element (5) is used.

24. The method according to any one of claims 21-23, wherein the contact interfaces

(1.1 and 2.1) of the first and second bone or bone fragment and optionally further bone to be connected with a planar or convex / concave machining be prepared.

25. The method according to any one of claims 21-24, wherein postoperatively after wound closure, the relative position of the bone or bone fragments (1 and 2) is changed by the clamping element (6) loosened by Längszug on the first cooking (1) optionally the claw of the Retained security elements (5) in the bone interfaces (1.1 and 2.1), corrects the position and the intramedullary tension element (4) is put back under train.

26. The method according to any one of claims 20-24, characterized in that it is used for arthrodesis or osteosynthesis, in particular of hand and foot surgery in human medicine.

27. The method according to any one of claims 20-24, characterized in that it is used for arthrodesis and osteosynthesis of the foot and toe joints, in particular for a metatarso-phalangeal arthrodesis.

28. The method according to claim 20 - 24, characterized in that it is for

Arthrodesis and osteosynthesis of the hand and finger joints in particular the thumb joints is applied.

29. The method of claim 20-24 or 26 or 27, characterized in that it is used for arthrodesis of metatarso-phalangeal or other joints or for osteosynthesis of long bones in small and large animals.