WO2020187463A1

WO2020187463A1 - Connecting device for connecting two bone parts

Info

Publication number: WO2020187463A1
Application number: PCT/EP2020/051423
Authority: WO
Inventors: Augustin Betz
Original assignee: Augustin Betz
Priority date: 2019-03-15
Filing date: 2020-01-21
Publication date: 2020-09-24
Also published as: EP3937808A1

Abstract

The invention relates to a connecting device for connecting two bone parts, in particular for bridging a bone gap, for bone lengthening or for bone shortening, which device extends from a first end portion, which can be connected to the first bone part, to a second end portion, which can be connected to the second bone part, and comprises an adjustment mechanism. The spacing between the first end portion and the second end portion can be changed by repeated actuation of the adjustment mechanism by a specified or specifiable adjustment travel, and the actuation of the adjustment mechanism comprises at least one translational relative movement, which can be executed manually, along the extent of the connecting device between the two end portions.

Description

Connecting device for connecting two bone parts

The invention relates to a connecting device for connecting two bone parts, in particular for bridging a gap in the bone, for lengthening or shortening the bone, which extends from a first end section connectable to the first bone part to a second end section connectable to the second bone part and which has an adjustment mechanism, wherein the distance between the first end section and the second end section can be changed by repeatedly actuating the adjustment mechanism in each case by a predefined or predefinable adjustment path.

Such connecting devices can in particular be designed as intramedullary distraction nails, which are state of the art medical technology and, inter alia, from the publications DE19700225A1, DE3921972A1, US9179938B2 and

CA2917676A1 are known. Such devices are used to lengthen long bones, e.g. to be able to restore the original bone length after tumor removal or after bone inflammation.

Distraction intramedullary nails have significant advantages over external distraction devices in which the bone parts are connected to the outside through the skin with an adjustable frame, which on the one hand results in an unfavorable application of force and on the other hand there is a constant risk of infection through the penetration of germs.

The function of known intramedullary distraction nails is the step-by-step moving apart of the two parts of the severed intramedullary nail attached to the intramedullary nail Bone and the continuous formation of new bone substance in the resulting gap between the two bone parts or ends. Distraction medullary nails of this type can have an adjustment mechanism, each actuation of the adjustment mechanism distancing the two bone parts from one another by a step or a provided adjustment path. Conversely to a bone lengthening by means of a distraction marrow nail, a shortening of bones, in particular tubular bones, is indicated in certain medical or cosmetic cases, in which the use of gradually shortening implants, referred to here as contraction marrow nails, can be advantageous. To date, however, such contracting implants are neither commercially available nor known. On the other hand, a continuous shortening after a previous removal of a bone segment could enable a continuous adaptation of the surrounding tissue structures and thus the maintenance of the function and the stability of the adjacent joints.

All known intramedullary distraction nails solve the task at hand, the adjustment of the length of a bone, through various compromises with regard to size, strength, technical complexity, reliability, patient comfort and production costs. All known systems perform a straight bone lengthening that does not take into account the physiological curvature of the bones.

However, known solutions often require expensive and complex drives, for example electromechanical drives, which often cannot develop sufficient force and are prone to errors and / or can only be subjected to low loads. Insufficient loading capacity of the mechanics and in particular the adjustment mechanics can lead to their standstill or failure, so that actuation for the desired lengthening of the bone is no longer possible and, if necessary, a further operation to replace the intramedullary nail has to be performed. Alternatively, implant types that can be operated manually can in principle also be used. Known solutions, however, require rotating movements to operate the adjustment mechanism, which can be transferred to part of the lower leg and via this to the intramedullary nail, for example when a lower leg is lengthened or shortened by turning the foot or the ankle. However, this movement is often perceived by patients as uncomfortable or painful, so that the increased resilience of such mechanical solutions is opposed to the necessity of actuating the mechanism which is uncomfortable for the patient.

It is therefore an object of the invention to create a connecting device for connecting two bone parts, in particular for lengthening or shortening bones, which has a high load-bearing capacity and durability and is as comfortable and easy to use as possible.

This object is achieved by a connecting device with the features of claim 1 and in particular in that the actuation of the adjustment mechanism comprises at least one translational, manually executable relative movement between the two end sections, in particular a manual pulling on the second end section away from the first end section and / or manual pulling on the first end section away from the second end section.

With such a construction, a technically simple and robust connection device can be realized which is highly reliable due to its low complexity. The possibility of manual actuation of the adjustment mechanism can initially replace implant types that use expensive and complex electromechanical, hydraulic or memory metal drives and are often error-prone, low-drive and only have a low load capacity, so that the connection device can withstand high loads low manufacturing costs can be achieved. Such a resilient connection device can in particular enable the patient a high level of everyday comfort and ensure continuous mobilization, whereby the healing process can be significantly accelerated.

Since the actuation of the adjustment mechanism further comprises at least one translational relative movement between the two end sections and in particular manual pulling on one of the two end sections, the construction according to the invention can also replace implant types that involve a rotating actuation that is often painful for the patient an adjustment mechanism work. Furthermore, such a translational movement, in particular for lengthening or shortening bones, can be perceived by a patient as more logical or more natural and, regardless of the pain sensation, less unpleasant than a rotational movement because the movement corresponds to the desired effect. The process of learning how to operate the adjustment mechanism by the patient can thus be accelerated due to the less overcoming.

The simple manual actuation also enables the patient to comfortably and independently bring about a continuous lengthening or shortening of the distance between the connected bone parts during the lengthening or shortening process, without there being a relevant risk of incorrect actuation. By changing the distance between the two end sections by a predetermined travel each time the adjustment mechanism is actuated, the current distance or the already achieved lengthening or shortening of the bone can also be easily checked and documented. In this way, for example, the speed at which a bone is to be lengthened can also be coordinated with a treating doctor and carried out in an uncomplicated manner by using a Patient carries out an agreed number of actuations of the adjustment mechanism per day or time unit.

In such a connection device, particularly due to the simple design of the adjustment mechanism, highly corrosion-resistant materials can be used for all components and sealing elements can be dispensed with, which are usually intended to protect the internal corrosion-prone mechanism from the effects of aggressive body fluids. The connection device can be made permeable to body fluid by eliminating the sealing elements, so that a gas-filled space within the connection device can be avoided. In contrast to sealed connection devices, a change in air pressure prevents gas and possibly aged body fluid influenced by corrosion from escaping, which can lead to extreme pain at greater geodetic heights, such as during a flight or when staying in the mountains. Furthermore, avoiding corrosion can mean that the implant does not necessarily have to be removed immediately after the end of the treatment, so that in medically indicated cases the intramedullary nail can remain in the patient for an unlimited period of time.

Possible embodiments can be found in the dependent claims, the description and the figures.

In some embodiments, the actuation of the adjustment mechanism can result in an increase in the distance between the first end section and the second end section by the adjustment path, while in other embodiments the actuation of the adjustment mechanism results in a reduction in the distance between the first end section and the second end portion can result around the travel. In principle, such a connecting device can thus be provided to the distance between the respective connected bone parts can be increased or decreased continuously by repeatedly operating the adjustment mechanism. In particular, such a connecting device can thus be used, for example, as a distraction intramedullary nail in order to be able, for example, to enlarge a thigh bone. Equally, it is also possible to design it as a contraction medullary nail in order to continuously bring the respective bone parts closer together by reducing the distance between the two end sections.

The actuation of the adjustment mechanism can exclusively comprise translational relative movements between the second end section and the first end section. In particular, all of these relative movements can be carried out manually and can be generated by pulling on a respective end section or by pressing on a respective end section. However, minimal, in particular production-related, rotational components during such translational relative movements, for example during a pulling of an end section, can in principle also occur and be tolerated in such embodiments.

In some embodiments, the actuation of the adjustment mechanism can comprise at least two oppositely directed, directly successive manual actuation steps, in particular manual pulling followed by manual pushing. In particular, the setting mechanism can be returned to an initial state by the second, opposite movement and the actuation of the setting mechanism can be completed, so that the distance between the two end sections has changed by the setting path after this movement has been completed. The adjustment mechanism can then, starting from the initial state, be actuated again in order to again change the distance between the first end section and the second end section around the adjustment path and to adjust this distance step by step. The actuation of the adjustment mechanism can be started by manually pulling the second end section away from the first end section and / or by manually pulling the first end section away from the second end section. Such a manual pulling can consequently initiate or initiate the actuation of the adjustment mechanism, wherein in particular a first part of the adjustment path can already be covered during or as a result of the pulling. Alternatively, an unlocking process in the adjustment mechanism can be triggered by pulling, for example, in order to enable the adjustment path to be covered in a further step of actuating the adjustment mechanism.

The adjustment mechanism can be operated by manually pressing the second end section in the direction of the first end section following the manual pulling on the second end section or by pressing the first end section towards the second end section following the manual pulling on the first end section be. In particular, the travel or part of the travel can be covered during or as a result of the manual pressing. Furthermore, by completing the actuation, the setting mechanism can be reset to an initial state from which actuation can take place again.

In some embodiments, the second end section can be arranged on a rod and the first end section can be arranged on a tube, the rod being partially arranged inside the tube and a length of a section of the rod being changeable by actuating the adjustment mechanism protrudes from the pipe. The end sections can in particular be formed by the rod or the tube, so that the rod or the tube can be connected to the associated bone parts at their respective end sections. For this connection with the bone parts, one or more bores can be provided on the end sections through which the respective end section or the rod or the tube can be connected to the associated bone parts by means of screws.

The rod and the tube can have a circular cross section, and the tube can in particular be designed as a hollow cylinder. In principle, however, other cross-sectional shapes are also possible, for example rectangular or polygonal or polygonal designs are possible. The cross-sections of the rod and the tube can correspond or be of the same type, or different cross-sections can be provided for the two parts. In this case, for example, an insert element can be arranged within the tube which matches an inner wall of the tube to the cross section of the rod guided inside the tube.

The tube and / or the rod can be curved. Alternatively, the tube and the rod can be straight. A straight design can enable simple manufacture and assembly with high load capacity of the connecting device and can be used in particular to lengthen or shorten straight bones, to bridge only short distances or, for example, as a spinal distraction or contraction system for the surgical treatment of curvatures of the spine .

Conversely, a curved design of the tube and / or the rod can be provided, in particular in the case of a connecting device used as an intramedullary nail, wherein the curvature can correspond in particular to the physiological curvature of the bone to be lengthened or shortened. This can initially make it easier for a surgeon to insert the intramedullary nail into a curved medullary canal of a long bone, with the two parts of the bone growing together naturally in a curved manner in the subsequent healing process. In some embodiments, the rod can be guided inside the tube in a manner secure against rotation, wherein the rod can in particular have a feather key which is guided along the extension of the connecting device in a groove formed inside the tube. In this case, the groove can run in a straight line or curved, in particular on an inner surface of the pipe and accordingly, depending on the design of the pipe. As an alternative to this, the rod can also have the groove and the tube the feather key in order to achieve a torsion-proof guidance of the rod. By means of such a guide, relative rotational movements between the rod and the tube can be excluded or at least limited, taking into account possible manufacturing tolerances. Such movements of the two connected bone parts relative to one another, which may be painful for the patient, can accordingly be avoided.

The adjustment mechanism can be arranged between the first end section and the second end section.

Furthermore, the adjustment mechanism can be arranged inside the tube. In particular, the adjustment mechanism can interact with an end of the rod opposite the second end section and, when the adjustment mechanism is actuated, push the rod out of the tube or enable it to be moved into the tube. Furthermore, the connection device can be protected against impacts, for example, by arranging the adjustment mechanism inside the pipe, while conversely no components arranged outside the pipe which could possibly impair the healing process need to be provided.

In some embodiments, the tube can have an internal thread and the adjustment mechanism can have a threaded element with an external thread, which is rotatably guided in the internal thread. Due to the thread pitch, a rotation of the thread element can result in a translational movement Component comprise, wherein the threaded element can move away from the first end section or towards the first end section depending on the thread pitch or the direction of rotation. As a result of the interaction of the thread element with the rod, this translational movement component can consequently also be transmitted to the rod in order to reduce the distance between the first end section arranged on the tube or formed by the tube and the end section arranged on the rod or from the To change rod formed second end portion.

The threaded element can have a locking toothing on the rod side and the rod can have a locking toothing opposite the second end section, which in a locked position of the rod engages with the locking toothing of the threaded element on the rod side, the engagement being able to block a rotation of the threaded element . The blocking position of the rod relates in particular to a position along the extension of the connecting device, so that the rod can be guided out of the blocking position by translational movements.

The blocking position can in particular represent a starting point from which, in principle, the adjustment mechanism can be actuated in order to adjust the distance between the two end sections. Likewise, the blocking position can represent an end point of the actuation of the adjustment mechanism, at which the rod is positioned at the end of the actuation in order to enable a renewed actuation.

Since a rotation of the threaded element is blocked in this blocking position, an undesired change in the distance between the actuations of the adjustment mechanism can be avoided. In this way, in particular, the load-bearing capacity of the connection device can be guaranteed between deliberately executed distance adjustments, so that a patient can, for example, use the Connection device connected leg bones can be easily mobilized and walk or stand.

The rod-side locking toothing of the threaded element and the rod locking toothing can be designed symmetrically. Correspondingly, the respective blocking teeth can be designed with tooth flanks that correspond to one another and in such a way that they can be brought into exact engagement with one another. Such an exact engagement can achieve a reliable blocking effect of the threaded element when the rod is in the blocking position.

It can be provided that the rod can be transferred by manual pulling from the blocking position into a release position in which the rod blocking toothing releases the rod-side blocking toothing of the threaded element. In this release position, the rod blocking toothing can consequently be out of engagement with the rod-side blocking toothing and release the threaded element for rotation. This pulling, which can take place in particular on the bone part connected to the second end section, for example a lower leg, can correspondingly represent a start of the actuation of the adjustment mechanism in order to rotate the threaded element and the associated translational displacement of the same enable or initiate. By fixing the first end section to the first bone part, a relative pulling movement between the two end sections can be achieved by pulling the second bone part in this way, in order to be able to move the rod relative to the tube and thereby to be able to operate the adjustment mechanism.

In some embodiments, the adjustment mechanism can have a drive element which has a drive toothing on the thread element side, via which the drive element with a drive toothing facing away from the rod tion of the threaded element can be connected, wherein the drive toothing of the threaded element facing away from the rod can be offset by a deflection distance with respect to the threaded element-side drive toothing of the drive element with respect to a direction of rotation of the threaded element. This offset between the drive toothing of the threaded element facing away from the rod and the threaded element-side drive toothing of the drive element can in particular be provided in a starting position from which the adjustment mechanism can be actuated. The rod can in particular be in the blocking position mentioned. In principle, in the direction of the drive element, a further element which is coupled to the threaded element in a rotationally fixed manner can also be provided, which has a toothing that faces the drive element and is offset with respect to the drive toothing on the threaded element side.

Due to the offset of the aforementioned drive toothings with respect to one another, a torque can be transmitted to the threaded element by a translational movement of the drive element in the direction of the threaded element or the second end section. This can be done, for example, by manually pulling the rod, which can be coupled or connected to the drive element in order to be able to transmit the translational movement. In particular, the rod can be brought into a release position which enables the threaded element to rotate. Due to the offset of the respective drive toothings with respect to one another, rotation can be transmitted to the threaded element during or as a result of pulling on the rod and at least part of the travel can be covered.

The drive element can be guided within the tube in a manner secure against rotation, wherein the drive element can in particular have a feather key, which is guided along the extension of the connecting device in a groove running inside the tube. In particular, this can be the drive element-guiding groove correspond to the groove already mentioned for guiding the rod inside the tube. Conversely, the drive element can also have the groove, while the feather key is formed on an inside of the tube. In particular, by guiding the drive element in such a way that it is secured against rotation, a translational movement of the drive element due to the offset of the mentioned drive gears can reliably transmit a rotation to the threaded element without the drive element, for example, evasive rotational movements. gen executes. Furthermore, the non-rotating guidance of the drive element can clearly define and specify the deflection distance by which the drive gears are offset from one another, especially in an initial state for actuating the setting mechanism, and it can be ensured that the drive gears are always activated after the setting mechanism are again just offset from one another by the specified deflection distance.

In some embodiments, the drive teeth of the drive element and the threaded element can be biased into engagement with one another by biasing the drive element in the direction of the threaded element. Due to the drive toothing of the drive element on the thread element side, a pretensioning-related axial force can thus be exerted on the threaded element, which results in a torque acting on the threaded element as a result of the offset of the drive toothings with respect to one another. While the rod is in the blocking position, this torque can be absorbed by the interlocking blocking teeth of the rod and the threaded element and the non-rotating guidance of the rod and undesired rotation of the threaded element can be prevented. By moving the rod into the release position in which the blocking teeth are out of engagement with one another, the threaded element can, on the other hand, execute a rotational movement, the drive teeth being able to come into complete engagement with one another by overcoming the mutual offset. In some embodiments, the rod can be connected to the drive element by a connecting element, in particular a screw screwed into the rod, with manual pulling on the first end section or on the second end section exerting a force in the direction of the second end section Drive element is transferable. In turn, a torque can be transmitted to the threaded element through this force and the offset of the drive gears with respect to one another. In this case, by manually pulling on the rod or on the tube, in addition to a preload, a further force can be transmitted to the drive element in order to increase the torque on the threaded element. As an alternative to this, the force necessary to generate a torque can be applied exclusively by manual pulling, without pretensioning by a spring element.

The connecting element can extend inside the tube from a side of the drive element facing away from the rod, through the drive element and the threaded element, and can be anchored to the rod. Such an anchoring allows, in particular, a translational movement of the rod relative to the tube, for example by manual pulling or pushing, to be transmitted directly to the connecting element and from this to the drive element.

The connecting element can have a stop which limits a movement of the connecting element in the direction of the second end section relative to the drive element, wherein the connecting element can in particular be designed as a screw with a stepped shaft which forms the stop. With such a stop it is consequently possible to predetermine the distance by which the connecting element can move before it comes into contact with the drive element. For example, this distance can be the distance between a blocking position of the rod in which the respective blocking Locking teeth of the rod and the threaded element are in engagement and block rotation of the threaded element, corresponding to a release position in which the blocking teeth are out of engagement and the threaded element is released for a rotary movement. As a result, when the release position is reached, a force can be applied to the drive element in the direction of the second end section by slightly further manual pulling on the rod or the bone part connected to it, whereby a torque can be transmitted to the threaded element. Due to the thread pitch, the subsequent rotation of the thread element can achieve a translational movement component of the thread element in the direction of the second end section or away from it, in order to cover a first part of the adjustment path.

The connecting element can comprise a spring element which, as a result of manual pulling on the first end section or on the second end section, exerts a force on the drive element in the direction of the second end section.

The spring element can be effective between the connecting element, in particular a head of a screw forming the connecting element, and the drive element. Such a spring element can be compressed or compressed, for example, by pulling on the rod in order to transmit a force to the drive element in the direction of the second end section arranged on the rod. In particular, the spring can be pre-tensioned, so that the force already exerted on the drive element by the pre-tension can be further increased by the manual pulling. Alternatively to this, the spring element can be in a basic state before the adjustment mechanism is actuated, so that the spring element is only deflected or compressed by the manual pulling and exerts a force on the drive element. In particular, the connecting element can have a have written stop to prevent overloading of the spring as a result of pulling on the rod.

Furthermore, in some embodiments, the drive element can be connected to the threaded element by a connecting element, in particular by a screw screwed into the threaded element, wherein the connecting element can have a pretensioned spring element which exerts a force on the drive element in the direction of the second end portion exercises. In such embodiments, only the threaded element and drive element are consequently connected to one another, while the rod or the rod blocking toothing can be kept in engagement with the rod-side blocking toothing of the threaded element by the soft tissue tension when the connecting device is inserted. The spring element can permanently exert a force on the drive element, so that a torque acts on the threaded element due to the offset of the drive teeth with respect to one another. While the mutually engaged blocking teeth counteract this torque in a blocking position of the rod, a rotation of the threaded element can take place immediately due to this torque as soon as the rod is moved into a release position and the blocking teeth are out of engagement. In particular with a curved design of the connecting device, such a decoupling can be provided between the rod and the connecting element, which is generally designed as a straight screw.

In some embodiments, the drive element can be moved in the direction of the second end section as a result of the rod being moved into the release position and the force transmitted to the drive element by the connecting element, the threaded element being moved by the movement of the drive element due to the offset of the drive teeth a first circumferential section is rotatable. As a result of this turning of the threaded element, in particular a first part of the translational adjustment path can be covered which, depending on the direction of rotation of the threaded element and the thread pitch of the internal thread of the pipe, can run towards or away from the first end section arranged on the pipe. By moving towards the first end section, the distance between the first end section and the second end section can consequently be reduced in order to achieve a contraction or shortening of the bone, while the opposite direction enables a distraction or bone lengthening. In particular, the first circumferential distance can correspond to the deflection distance by which the drive gears are offset from one another.

The drive toothing of the drive element on the thread element side can be brought into full engagement with the drive toothing of the threaded element facing away from the rod by rotating the threaded element around the first circumferential distance while eliminating the deflection path. As the threaded element rotates around the first circumferential path, the deflection path or the offset of the drive toothings with respect to one another can be overcome and the drive toothings can be brought into full engagement with one another.

The first circumferential section can accordingly correspond precisely to the deflection section. The drive toothing facing away from the rod and the rod-side drive toothing can in particular be designed symmetrically in order to be able to achieve complete engagement.

Covering the first circumferential distance and / or reaching full engagement of the drive gears can be audible to the human ear. For example, the force required to rotate the threaded element can be transmitted to the drive element via a connecting element and a spring, with the snapback of the spring being audible as a result of the twisting of the threaded element and the achievement of complete engagement of the drive teeth. A patient can thus twist the threaded element and cover the first circumferential distance perceive immediately, so that the success of this operating step can be registered and, for example, documented. As a result, the change in the distance between the first end section and the second end section that occurred up to a respective point in time of the treatment or the healing process can always be traced and checked.

The rod-side blocking toothing of the threaded element can be displaced by the rotation of the threaded element by the first circumferential distance with respect to the rod blocking toothing of the rod by the first circumferential distance. Since the blocking teeth are disengaged from one another in the release position of the rod, the threaded element can rotate around the first circumferential distance. If the distance between two teeth of at least one of the blocking teeth does not correspond to the circumferential path, the blocking teeth can subsequently be offset from one another, while the drive teeth come into mutual engagement.

The threaded element can be rotated by a second circumferential distance by returning the rod from the release position to the blocking position, in particular by manually pressing the rod, due to the rod-side blocking toothing of the threaded element being offset with respect to the rod blocking toothing. The sum of the translational movements of the threaded element during the rotation around the first circumferential distance and the second circumferential distance can correspond to the adjustment path by which the distance between the first end section and the second end section can be changed by actuating the adjustment mechanism. The actuation of the adjustment mechanism can thus in particular comprise two steps or consist of two steps, with manual pulling on the rod followed by manual pressing on the rod. A first part of the travel range can be covered during or as a result of the manual pulling and a second part of the travel range can be covered during or as a result of the manual pushing. The travel is correspondingly predetermined by the thread pitch and the sum of the two circumferential distances or, in particular, predetermined during the construction of the connecting device.

Reaching the blocking position can be audible to the human ear. In particular, a force can also be transmitted to a spring element, which is coupled to a connecting element, while pressing the rod and transferring the rod from the release position to the blocking position, the spring element snapping back when the blocking position is reached and an audible one Can generate noise. The skipping of a tooth of the drive toothing can thus be audible, through which the rod can return to the blocking position. In particular, the completion of an actuation of the adjustment mechanism can thus be acoustically perceptible, so that the success of the change in distance around the adjustment path can be determined and documented.

The direction of rotation around the second circumferential path can be the same as the direction of rotation around the first circumferential path. In both steps of actuating the adjustment mechanism, for example pulling on the rod and pressing on the rod, the threaded element can consequently rotate in the same direction. The distance between the two end sections increases or decreases accordingly, depending on the thread pitch and the direction of rotation as a result of both rotations.

A rotation of the thread element in the direction of rotation can result in an increase in the distance between the thread element and the first end section due to the thread pitch of the internal thread of the pipe, or a rotation of the thread element in the direction of rotation can result in a reduction in the size of the thread due to the pitch of the internal thread of the pipe Distance between the threaded element and the first end portion result. Connecting Generation devices for enlarging bones and for reducing bones can thus basically have similar adjustment mechanisms, the desired effect for example by setting the thread pitch or by changing the direction of rotation, in particular by changing the offset of the drive teeth with respect to one another or the Direction of the deflection can be achieved.

In some embodiments, the second circumferential distance can be greater than the first circumferential distance. Consequently, when the rod is transferred from the release position to the blocking position, a greater part of the travel can be covered than when the rod was previously transferred from the blocking position to the release position.

In some embodiments, the drive toothing of the threaded element facing away from the rod can skip at least one tooth compared to the threaded element-side drive toothing of the drive element due to the twisting of the threaded element about the second circumferential distance. The direction of rotation of the threaded element can consequently correspond to a freewheeling direction of the drive toothing, so that it is possible to rotate the threaded element about the second circumferential distance despite the engagement of the drive toothing.

The drive element can be movable relative to the threaded element in the direction of the first end section in order to jump over a tooth while the threaded element is being rotated by the second circumferential distance. In particular, the drive element can be connected to the threaded element via a spring-loaded connecting element, in particular a screw with a spring acting between the head of the screw and the drive element, so that the spring is compressed as a result of the relative movement between the drive element and the threaded element. As soon as the tooth is skipped or the threaded element is twisted by the second circumferential distance, the to move the drive element back onto the threaded element due to the spring force, the snapback of the spring or the impact of the drive teeth on one another can be audible to the human ear. As a result, the success of the actuation of the adjustment mechanism can be immediately perceptible to a patient.

Provision can be made for the drive toothing of the drive element on the thread element side to be offset by the deflection distance by the deflection distance as a result of the rotation of the threaded element by the second circumferential distance compared to the drive toothing of the threaded element facing away from the rod. After the rod has been transferred from the release position to the blocking position and the second circumferential section has been covered by the threaded element, the adjustment mechanism can consequently be in an initial state again in order to enable it to be actuated again. This can also ensure that the same travel is covered each time the adjustment mechanism is actuated.

The return of the rod to the blocking position and the turning of the threaded element around the second circumferential distance can complete the actuation of the adjustment mechanism. After the rod has been returned to the blocking position, the adjustment path can consequently have been covered by the threaded element and thereby transferred to the rod, so that the distance between the first end section and the second end section has changed by this adjustment path. With every further actuation, in particular every two-step actuation by manually pulling and pressing on or on the rod, a further change in the distance can be made by the adjustment path, so that two bone parts connected to one another via the connecting device can be moved incrementally towards or away from one another.

In some embodiments, the connecting device can act as a distraction marrow nail for lengthening bones, in particular long bones. be educated. The thread pitch or the direction of rotation of the thread element can be selected in such a way that actuating the adjustment mechanism and covering the adjustment path results in an increase in the distance between the first end section and the second end section.

The connecting device can also be designed as a contraction medullary nail for shortening bones, in particular long bones. This can be achieved, for example, by a thread pitch that is reversed compared to a distraction intramedullary nail or a reversed direction of rotation of the thread element with the same thread pitch.

The intramedullary nails can in particular be designed with a curvature corresponding to the physiological curvature of a bone to be changed, whereby the introduction into the bone is made considerably easier for the surgeon, the medullary canal can be optimally used and the bone substance can be spared.

The invention also relates to the use of a connecting device as disclosed herein for a spinal distraction system or a spinal contraction system, in particular for treating spinal curvatures by gradually stretching and straightening the spine. Such a system can be used to surgically treat curvatures of the spine, for example scolioses, whereby after the insertion of the connecting device, a step-by-step stretching and straightening of the spine is made possible without further surgical interventions during the correction. Complex and, in particular, non-MRT-compatible systems can thus be replaced. In particular, such connecting devices can be suitable for use in scoliosis in children, which require stick technology that grows with them. The invention also relates to the use of a connecting device as disclosed herein as a component or supplement for a prosthesis that grows with the patient, in particular for use after a tumor resection, in particular on a child's skeleton. In such treatments, the bony defect is usually bridged by a prosthesis after the tumor resection, but this can lead to considerable length deficits in the course of growth in the growing skeleton. By using a connecting device of the type disclosed herein, a continuous length adjustment can be implemented in a simple manner.

The invention also relates to a spinal distraction system or spinal contraction system, in particular for the treatment of curvatures of the spine by gradually stretching and straightening the spine, with at least one connecting device as disclosed herein.

The invention also relates to a prosthesis, in particular a prosthesis that grows with the patient, in particular for use after a tumor resection, in particular on a child's skeleton, with at least one connecting device as disclosed herein, in particular as a component or as a supplement to the prosthesis.

The invention is explained below purely by way of example using an embodiment with reference to the drawings.

Show it:

1 shows a schematic representation of a connecting device designed as an intramedullary nail, and FIG

2A to 2D respective schematic enlarged representations of the adjustment mechanism to explain their mode of operation. 1 shows a connecting device 31 which is designed as a distraction intramedullary nail. The connecting device 31 has a rod 1 with bores 2 in a second end section 35 formed by the rod 1, so that the rod 1 can be fastened to a first part of the bone by screws (not shown). This second end section 35 is formed on a section 39 of the rod 1 which protrudes from a tube 5 within which the rod 1 is arranged. The rod 1 is guided with a feather key 7 in a groove 6 within the tube 5 so as to be axially movable and free of rotation (see also section AA). A nut 3 screwed into the tube 5 guides the rod 1 radially at the front end of the tube 5. Furthermore, the tube 5 has a plurality of bores 13 through which a first end section 33 formed by the tube 5 can be fastened to a second part of the long bone.

In order to be able to adapt the length L of the section 39 of the rod 1 which protrudes from the tube 5 and to be able to change or, in this case, lengthen the distance between the first end section 33 and the second end section 35, the connecting device 31 has an adjustment mechanism 37 on. By actuating the adjustment mechanism 37, the mentioned distance or length L can be changed by an adjustment path S (cf. also FIGS. 2A to 2D).

The adjustment mechanism 37 initially comprises a threaded element 8 which is screwed into an internal thread 4 of the tube 5 and in which the rod 1 engages with a blocking toothing 17 (see also section BB). The rod 1 has a rod blocking toothing 17a which engages in a rod-side blocking toothing 17b of the threaded element 8 and together with this forms the blocking toothing 17. In order to achieve the most exact possible engagement of the blocking teeth 17a and 17b, they are designed symmetrically and with mutually corresponding tooth flanks 18. The threaded element 8 is also in contact with a drive element 9 on a side facing away from the rod 1 via a drive toothing 16. The drive toothing 16 is formed by a drive toothing 16a of the threaded element 8 facing away from the rod and a threaded element-side drive toothing 16b of the drive element 9. In order to prevent any rotational movements of the drive element 9, the drive element 9 can also be moved axially by a feather key 10 in the tube 5, but is non-rotatably guided (see also section CC).

The rod 1, the threaded element 8 and the drive element 9 are braced in the direction of the extension E of the connecting device 31 by means of a connecting element 12 anchored in the rod 1, which is designed as a screw 12, and a spring element 11. The spring element 11 can exert a pretension on the toothings 16 and 17, although this does not necessarily have to be provided. The shoulder 41 resulting from the two different diameters 14 and 15 of the shaft 43 of the screw 12 serves as an axial stop 41 or a stop 41 acting in the direction of the second end section 35 and running against the drive element 9. This stop 41 can overload the Prevent the spring element 11 by a relative movement between the screw 12 or its head 45, to which the spring element 11 is connected, and the drive element 9 is limited by the stop 41.

In the initial state shown in FIG. 2A for actuating the adjustment mechanism 37, the rod 1 is in a blocking position Q in which the blocking teeth 17 are completely closed and the drive teeth 16 are offset by the deflection distance b. As a result of this offset of the drive toothing 16, the axial spring force or spring force acting in the direction of the second end section 35 exerts a torque on the threaded element 8 via the drive toothing 16, which in turn is prevented from rotating by the interlocking locking teeth 17a and 17b By pulling on the rod 1 in direction a, the rod 1 can be brought into a release position F, in which the blocking toothing 17 is out of engagement (cf. FIG. 2B). The threaded element 8 can then rotate by the torque acting via the tooth flanks of the drive toothing 16 along a direction of rotation R by a first circumferential distance U, the drive toothing 16 being completely closed and the blocking toothing 17 being offset by the first circumferential distance U, see Figure 2B. Pulling on the rod 1 or on the second end section 35 away from the first end section 33 can thus represent a first step in the actuation of the adjustment mechanism 37. As a result of this rotation of the threaded element 8 by the first circumferential distance U, the drive toothing 16a facing away from the rod and the threaded element-side drive toothing 16b also come into complete engagement c with one another, so that the drive toothing 16 just overcomes the deflection distance b and the deflection distance b of the first circumferential distance U corresponds.

When the rod 1 is pushed back or pressed in the direction d, the threaded element 8 is rotated further in the direction of rotation R by the tooth flanks 18 of the blocking teeth 17 by a second circumferential distance e (see FIGS. 2C and 2D). The drive toothing 16 skips over a tooth, the position of a tooth 47 being marked in FIGS. 2C and 2D before and after the pressing to illustrate this skipping. In order to enable this skipping or turning of the threaded element 8 by the second circumferential distance e, the drive toothing 16 has an axial degree of freedom f, so that the drive element 9 moves relative to the threaded element 8 in the direction of the first end section 33 during the rotation can. Since the spring element 11 is tensioned during this relative movement, the spring element 11 snaps back when the locking position Q of the rod 11 is reached, as a result of which a noise audible to the human ear is generated. As a result, the success of the actuation of the adjustment mechanism 37 can be immediately traced and for example can be easily documented by the patient. In the same way, such a noise can also be achieved during the previous pulling on the rod when the drive toothings 16a and 16b come into engagement with one another.

As FIG. 2D shows, the initial state of the adjustment mechanism 37 is restored after pressing and the threaded element 8 and the rod 1 are advanced by an increment resulting from the thread pitch and the tooth pitch, the adjustment path S. Correspondingly, pressing the rod 1 or transferring the rod 1 from the release position F into the blocking position Q can complete the actuation of the adjustment mechanism 37. After the rod 1 has been returned to the blocking position Q, the drive toothing 16 is again offset by the deflection distance b so that the intramedullary distraction nail can be gradually extended to the desired length by repeating the process or actuating the adjustment mechanism 37. With each actuation, the distance between the first end section 33 and the second end section 35 or the length L of the section 39 of the rod 1 protruding from the tube 5 can be increased by the travel S.

The function of the adjustment mechanism 37 can also be given without the spring element 11, but without the intended acoustically clearly perceptible click when the adjustment mechanism 37 is actuated, which is considered to be a helpful control of every successful extension step. If such an acoustic control is not required, the spring element 11 can be omitted. In this case, the force required to rotate the threaded element 8 on the drive element 9 is achieved at the end of the pulling movement of the rod 1 by the shaft section 14 abutting the drive element 9 or the stop 41 of the screw 12. While the figures illustrate a design of the connecting device 31 as a distraction medullary nail, each actuation of the setting mechanism 37 results in an increase in the distance between the first end section 33 and the second end section 35 by the travel S, the same can A connecting device 31 for shortening bones, in particular a contraction medullary nail, may be provided. For this purpose, for example, the thread pitch of the internal thread 4 can be reversed, so that a rotation of the thread element 8 in the direction of rotation R results in a translational movement component towards the first end section 33. Alternatively, with the same thread pitch of the internal thread 4, the direction of rotation R of the threaded element 8 can be reversed, for which purpose, in particular, the offset of the drive toothing 16 or the direction of the deflection path b can be adapted. Furthermore, such a connecting device 31 can in particular be used as a spinal

Contraction or distraction system or as part of a prosthesis that grows with the patient.

Reference list

1 rod

2 hole on the rod

3 mother

4 internal threads

5 pipe

6 keyway of the rod

7 key

8 threaded element

9 drive element

10 Key of the drive element

1 1 spring element

12 connecting element, screw

13 Hole on the pipe

14 first screw diameter

15 second screw diameter

16 drive teeth

16a drive toothing facing away from the rod

16b drive toothing on the thread element side

17 blocking teeth

17a rod locking teeth

17b locking teeth on the rod side

18 tooth flanks of the blocking toothing

31 Connection device

33 first end section

35 second end section

37 Adjustment mechanism

39 Section of the rod protruding from the tube

41 stop

43 stepped shaft

45 head of the screw

47 skipped tooth

a pull

b Deflection section, first circumferential section

c Complete engagement of the blocking teeth

d Press

e second circumferential section

f Free running

D distance

E Extension of the connecting device

Q blocking position

F Release position

L Length of the section of the rod protruding from the tube. R Direction of rotation

S travel

Claims

Expectations

1. Connecting device (31) for connecting two bone parts, in particular for bridging a gap in the bone, for lengthening or shortening the bone, which extends from a first end section (33) connectable to the first bone part to a second end section connectable to the second bone part (35) and which has an adjustment mechanism (37),

wherein the distance between the first end section (33) and the second end section (35) can be changed by repeatedly actuating the setting mechanism (37) in each case by a predefined or predefinable adjustment path (S),

wherein the actuation of the adjustment mechanism (37) comprises at least one translatory, manually executable relative movement between the two end sections (33, 35) running along the extension (E) of the connecting device (31), in particular manual pulling ( a) on the second end portion (35) away from the first end portion (33) and / or a manual pull (a) on the first end portion (33) away from the second end portion (35).

2. Connecting device (31) according to claim 1,

wherein the actuation of the adjustment mechanism (37) results in an increase in the distance between the first end section (33) and the second end section (35) by the adjustment path (S); or

the actuation of the adjustment mechanism (37) results in a reduction in the distance between the first end section (33) and the second end section (35) by the adjustment path (S).

3. Connecting device (31) according to claim 1 or 2,

wherein the actuation of the adjustment mechanism (37) exclusively comprises translational relative movements between the second end section (35) and the first end section (33).

4. Connecting device (31) according to one of the preceding claims, wherein the actuation of the adjustment mechanism (37) comprises at least two oppositely directed, immediately successive manual actuation steps (a, d), in particular manual pulling (a), followed from a manual push (d).

5. Connecting device (31) according to one of the preceding claims, wherein the actuation of the adjustment mechanism (37) by manual pulling (a) on the second end portion (35) away from the first end portion (33) and / or by manual pulling (a) can be started at the first end section (33) away from the second end section (35).

6. connecting device (31) according to claim 5,

wherein the actuation of the adjustment mechanism (37) by a manual pulling (a) on the second end section (35) following manual pushing (d) of the second end section (35) in the direction of the first end section (33) or by a manual push Pulling (a) on the first end section (33), subsequent manual pressing (d) of the first end section (33) in the direction of the second end section (35) can be locked.

7. Connecting device (31) according to one of the preceding claims, wherein the second end portion (35) is arranged on a rod (1) and the first end portion (33) on a tube (5), the rod (1) part - Is arranged within the tube (5), and wherein by pressing of the adjusting mechanism (37), a length (L) of a section (39) of the rod (1) which protrudes from the tube (5) can be changed.

8. connecting device (31) according to claim 7,

wherein the tube (5) and / or the rod (1) are curved; or wherein the tube (5) and the rod (1) are straight.

9. connecting device (31) according to claim 7 or 8,

wherein the rod (1) is arranged so that it cannot rotate inside the tube (5), in particular wherein the rod (1) has a feather key (7) which is in a groove (6) formed inside the tube (5) along the extension ( E) the connecting device (31) is displaceably guided.

10. Connecting device (31) according to one of the preceding claims, wherein the adjusting mechanism (37) is arranged between the first end portion (33) and the second end portion (35).

11. Connecting device (31) according to one of claims 7 to 10,

wherein the adjustment mechanism (37) is arranged inside the tube (5).

12. Connecting device (31) according to one of claims 7 to 11,

wherein the tube (5) has an internal thread (4) and the adjustment mechanism (37) has a threaded element (8) with an external thread which is rotatably guided in the internal thread (4).

13. Connecting device (31) according to claim 12,

wherein the threaded element (8) has a rod-side blocking toothing (17b) and the rod (1) has a rod blocking toothing (17a) opposite the second end section (35), which in a blocking position (Q) of the rod (1) in engagement with the rod-side blocking Toothing (17b) of the threaded element (8) stands, the engagement blocking a rotation of the threaded element (8).

14. Connecting device (31) according to claim 13,

the rod-side blocking toothing (17b) of the threaded element (8) and the rod blocking toothing (17a) being symmetrical (18).

15. Connecting device (31) according to claim 13 or 14,

whereby the rod (1) can be transferred by manual pulling (a) from the blocking position (Q) to a release position (F), in which the rod blocking toothing (17a) releases the rod-side blocking toothing (17b) of the threaded element (8).

16. Connecting device (31) according to one of claims 12 to 15,

wherein the adjustment mechanism (37) has a drive element (9) which has a drive toothing (16b) on the thread element side, via which the drive element (9) is connected to a drive toothing (16a) of the threaded element (8) facing away from the rod, the The drive toothing (16a) of the threaded element (8) facing away from the rod is offset by a deflection distance (b) with respect to a direction of rotation (R) of the threaded element (8) in relation to the driving toothing (16b) of the drive element (9) on the screwing element side.

17. Connecting device (31) according to claim 16,

wherein the drive element (9) is guided so that it cannot rotate inside the tube (5), in particular wherein the drive element (9) has a feather key (10) which is inserted in a groove (6) running inside the tube (5) along the extension ( E) the connecting device (31) is displaceably guided.

18. Connecting device (31) according to claim 16 or 17,

wherein the drive toothings (16) of the drive element (9) and of the threaded element (8) are pretensioned in engagement with one another by pretensioning the drive element (9) in the direction of the threaded element (8).

19. Connecting device (31) according to one of claims 16 to 18,

the rod (1) being connected to the drive element (9) by a connecting element (12), in particular a screw screwed into the rod (1), with manual pulling (a) on the first end section (33 ) or at the second end section (35) a force can be transmitted in the direction of the second end section (35) to the drive element (9).

20. Connecting device (31) according to claim 19,

wherein the connecting element (12) extends within the tube (5) from a side of the drive element (9) facing away from the rod, through the drive element (9) and the threaded element (8) and is anchored to the rod (1).

21. Connecting device (31) according to claim 19 or 20,

wherein the connecting element (12) has a stop (41) which limits a movement of the connecting element (12) in the direction of the second end section (35) relative to the drive element (9), in particular the connecting element (12) as a screw a stepped shaft (43) is formed which forms the stop (41).

22. Connecting device (31) according to one of claims 19 to 21,

wherein the connecting element (12) comprises a spring element (11) which as a result of a manual pull (a) on the first end section (33) or exerts a force on the second end section (35) in the direction of the second end section (35) on the drive element (9).

23. Connecting device (31) according to claim 22,

wherein the spring element (11) is effective between the connection element (12), in particular a head (45) of a screw forming the connection element (12), and the drive element (9).

24. Connecting device (31) according to one of claims 16 to 18,

wherein the drive element (9) is connected to the threaded element (8) by a connecting element (12), in particular by a screw screwed into the threaded element (8), the connecting element (12) having a pretensioned spring element (11), which exerts a force on the drive element (9) in the direction of the second end section (35).

25. Connecting device (31) according to one of claims 19 to 24,

wherein the drive element (9) can be moved in the direction of the second end section (35) as a result of the rod (1) being moved into the release position (F) and the force transmitted to the drive element (9) by the connecting element (12), the threaded element (8) being rotatable by a first circumferential distance (b) due to the offset of the drive teeth (16) by the movement of the drive element (9).

26. Connecting device (31) according to claim 25,

The drive toothing (16b) of the drive element (9) on the threaded element side is fully engaged (c) with the drive toothing facing away from the rod by rotating the threaded element (8) around the first circumferential distance (U) while eliminating the deflection distance (b) (16a) of the threaded element (8) can be brought.

27. Connecting device (31) according to claim 25 or 26, wherein the covering of the first circumferential distance (U) and / or the reaching of the complete engagement (c) of the drive teeth (16) can be heard by the human ear.

28. Connecting device (31) according to claim 25 to 27,

The rod-side blocking toothing (17b) of the threaded element (8) can be displaced by the first circumferential distance (U) with respect to the rod blocking toothing (17a) of the rod (1) by rotating the threaded element (8) around the first circumferential distance (U) is.

29. Connecting device (31) according to claim 28,

wherein the threaded element (8) by returning the rod (1) from the release position (F) to the blocking position (Q), in particular by manually pressing (d) on the rod (1), due to the blocking toothing opposite the rod ( 17a) offset locking toothing (17b) of the threaded element (8) on the rod side can be rotated by a second circumferential distance (e).

30. Connecting device (31) according to claim 29,

the reaching of the blocking position (Q) can be heard by the human ear.

31. Connecting device (31) according to claim 29 or 30,

wherein the direction of rotation (R) about the second circumferential distance (e) is the same as the direction of rotation (R) about the first circumferential distance (U).

32. Connecting device (31) according to one of claims 29 to 31,

wherein the second circumferential distance (e) is greater than the first circumferential distance (U).

33. connecting device (31) according to claim 31 or 32,

a rotation of the threaded element (8) in the direction of rotation (R) results in an increase in the distance between the threaded element (8) and the first end section (33) due to the thread pitch of the internal thread (4) of the tube (5); or

a rotation of the threaded element (8) in the direction of rotation (R) results in a reduction in the distance between the threaded element (8) and the first end section (33) due to the thread pitch of the internal thread (4) of the pipe (5).

34. Connecting device (31) according to one of claims 29 to 33,

the drive toothing (16a) of the threaded element (8) facing away from the rod opposite the threaded-element-side drive toothing (16b) of the drive element (9) as a result of the twisting of the threaded element (8) by the second circumferential distance (e) at least one tooth (47) skips.

35. Connecting device (31) according to one of claims 29 to 34,

the drive toothing (16b) of the drive element (9) on the threaded element side opposite the drive toothing (16a) of the threaded element (8) facing away from the rod as a result of the twisting of the threaded element (8) by the second circumferential distance (e) by the deflection distance (b) is offset.

36. Connecting device (31) according to one of claims 29 to 35,

the return of the rod (1) to the blocking position (Q) and the turning of the threaded element (8) by the second circumferential distance (e) concluding the actuation of the adjustment mechanism (37).

37. Connecting device (31) according to one of the preceding claims, wherein the connecting device (31) is designed as a distraction intramedullary nail for lengthening bones, in particular tubular bones.

38. Connecting device (31) according to one of claims 1 to 36,

wherein the connecting device (31) is designed as a contraction marrow nail for shortening bones, in particular long bones.

39. Use of a connecting device (31) according to one of claims 1 to 36 for a spinal distraction system or a spinal contraction system, in particular for the treatment of curvatures of the spine by gradually stretching and straightening the spine.

40. Use of a connecting device (31) according to one of claims 1 to 36 as a component or supplement for a prosthesis that grows with the patient, in particular for use after a tumor resection, in particular on a child's skeleton.

41. Spinal distraction system or spinal contraction system, in particular for the treatment of curvatures of the spine by gradually stretching and straightening the spine, with at least one connecting device according to one of claims 1 to 38.

42. Prosthesis, in particular a prosthesis that grows with the child, in particular for use after a tumor resection, in particular on a child's skeleton, with at least one connecting device according to one of claims 1 to 38.