Curved intramedullary nail

Abstract

The invention relates to a curved intramedullary nail (11) for connecting, successively lengthening or shortening two parts of a bone. The intramedullary nail (11) comprises a curved tube (13) for fixation to a first bone part and a curved rod (15) with a fixation section (17) placed inside the tube and extending out of the tube. Inside the tube is an adjustment mechanism (19) which can be operated by means of repeated relative rotational movements between the tube (13) and the rod (15). The adjustment mechanism (19) comprises a screw thread element (23) rotating around the axis of rotation (D) in the internal screw thread (21) of the tube, a coupling gear (25) connecting the rod to the screw thread element, and a connecting element (27) rigidly attached to the rod (15). The connecting element (27) passes through a radial gap (31) inside the threaded element (23), preventing the formation of bending moments in the curved structure and ensuring that the rod (15) is held securely in the pipe (13).

Description

[0001] The invention relates to an intramedullary nail, in particular a distraction intramedullary nail or a contraction intramedullary nail, for connecting two parts of a bone, which may in particular be intended for successive lengthening or successive shortening of a bone.

[0002] In principle, an intramedullary nail can be surgically inserted to bridge a gap between two bone fragments of a severed bone, allowing the bone fragments to reconnect through the continuous formation of new bone tissue within the gap. For example, intramedullary nails can be used to bridge defects after comminuted fractures, bone infections, or after the removal of tumors in areas of long bones.

[0003] Furthermore, intramedullary nails can be designed as distraction nails to progressively separate two bone segments connected by the nail by gradually withdrawing the rod from the tube, thus lengthening the bone through the continuous bone formation during treatment. Similarly, intramedullary nails can be designed as contraction nails, which allow for a gradual shortening of the distance between the bone segments connected by the nail.

[0004] Distraction intramedullary nails are known, for example, from German patent applications DE 19 700 225 A1, DE 3 921 972 A1, US 9 179 938 B2, and CA 2 917 676 A1. To achieve the desired bone lengthening, known distraction intramedullary nails have an adjustment mechanism located inside the nail, which can be operated by a physician or the patient. Because of this internal arrangement of the adjustment mechanism, no connection of the distraction nail through the skin to an external adjustment device is required. This gives such distraction intramedullary nails significant advantages, for example, with regard to the potential risk of infection in the area of ​​the bone being lengthened.

[0005] A distraction nail with an adjustment mechanism that has proven reliable and durable is described in US 5,074,882. The adjustment mechanism shown therein can be actuated by repeatedly rotating and re-rotating the bone segments connected to the distraction nail relative to each other through a defined angle, with the rotation being transferred to components of the adjustment mechanism. This mechanical design allows for a robust construction of the distraction nail, particularly with respect to axial forces.

[0006] However, intramedullary nails with such an adjustment mechanism can currently only be designed as straight along their entire length, without allowing for adaptation to the physiological curvature of a bone. Due to this difference from the bone's curvature, straight intramedullary nails can be surgically complex to insert, and the procedure may potentially weaken the cortex. Therefore, there is a need for intramedullary nails, particularly distraction nails, that allow adaptation to the physiological curvature of the bone being treated and can thus be designed with a curve themselves.

[0007] A first implementation of a curved distraction nail is described in WO 2020 / 152171 A1. The nail described therein has a tube and a rod located inside it, but protruding from the tube, so that a first bone segment can be attached to one end of the tube and a second bone segment to the opposite end of the rod. Repeated relative rotations between the rod and the tube actuate an adjustment mechanism of the nail, moving the rod out of the tube to successively increase the distance between the bone segments. The desired curvature of the distraction nail is achieved by eliminating the axial coupling between the rod and the adjustment mechanism located inside the tube, unlike the straight distraction nail known from US 5,074,882.This allows the rod to be deflected relative to the tube without transferring bending moments caused by curvature to the adjustment mechanism, which could lead to damage or even breakage of its components. However, the operational use of such a distraction nail presents the problem that, due to this decoupling, the rod may unintentionally detach from the tube if, for example, the nail needs to be removed again for subsequent widening of the medullary canal.

[0008] It is therefore an object of the invention to create a reliable, stable and easy-to-operate intramedullary nail which allows adaptation to a physiological curvature of a bone as well as a secure coupling between the rod and the tube.

[0009] This problem is solved by an intramedullary nail with the features of claim 1, and in particular by the fact that the intramedullary nail is curved and has a curved tube for attachment to a first bone part, as well as a curved rod arranged inside the tube, which has a fastening section projecting from the tube for attachment to a second bone part. Furthermore, an adjustment mechanism is arranged inside the tube, which can be actuated by repeated relative rotational movements between the tube and the rod, wherein the rod can be extended out of or into the tube by actuating the adjustment mechanism. The adjustment mechanism comprises a threaded element rotatable about an axis of rotation in an internal thread of the tube, with which the rod engages via a coupling toothing.Furthermore, the adjustment mechanism features a connecting element rigidly attached to the rod, which extends through the threaded element and protrudes from the threaded element on one side facing away from the rod. This connecting element extends within the threaded element with a radial clearance.

[0010] As explained in the introduction, the adjustment mechanism, which is actuated by repeated relative rotational movements between the tube and the rod, enables a stable and resilient design of the intramedullary nail. This is achieved by preventing unintentional activation of the adjustment mechanism, particularly under axial pressure loads, such as those encountered while standing. Specifically, the mechanism can be designed so that by rotating the rod back and forth relative to the tube, the distance between the rod and the tube is increased or decreased by a predetermined amount. This allows the desired lengthening or shortening to be achieved through a clearly defined and deliberately executed two-step operation of the adjustment mechanism. When the intramedullary nail is in place, the rotational movements can be transmitted to the rod and / or the tube by the relative twisting of the bone segments connected by the nail.The adjustment mechanism can be operated by the patient himself, whereby, for example, an actuation rate previously agreed upon with the doctor can be easily implemented and documented by the patient.

[0011] To enable the rod to be moved successively within the tube, the rod engages with the threaded element via a coupling toothing, allowing the threaded element to be moved axially within the tube by rotating the rod relative to the tube. For example, the threaded element can be moved along the rod in a first direction of rotation, while the rod can rotate relative to the threaded element in a second direction opposite to the first. This allows the threaded element to be moved axially within the tube by rotating the rod in the first direction, and the adjustment mechanism can then be returned to its starting position by subsequently rotating the rod in the second direction. Depending on the pitch of the tube's internal thread, the adjustment mechanism can be adjusted accordingly.By actuating the adjusting mechanism, the internal pin can be shortened or lengthened via the external thread of the threaded element. The thread pitch also influences the lengthening or shortening achieved during actuation of the adjusting mechanism. Furthermore, the angle through which the rod can rotate relative to the tube can be predetermined, so that the axial movement of the threaded element resulting from actuation of the adjusting mechanism can be clearly predetermined.

[0012] To achieve the desired reliable coupling between the rod and the tube, the adjustment mechanism also includes a connecting element that is rigidly attached to the rod. This connecting element links the rod to the adjustment mechanism located inside the tube, thus creating a coupling between the rod and the tube. This allows the rod to be held securely within the tube, and the assembled intramedullary nail to form a single unit, preventing the rod from unexpectedly detaching from the tube. This facilitates particularly convenient use of the intramedullary nail during surgery, as only a single component needs to be inserted into the medullary canal, eliminating the need to worry about the rod and tube separating.Furthermore, the connecting element enables a reliable transmission of forces, particularly axial forces exerted on the rod relative to the tube, to the adjusting mechanism, in order to allow reliable actuation of the adjusting mechanism by the relative rotary movements.

[0013] With such a coupling between the adjusting mechanism and the curved rod, the fundamental problem is that the connecting element protruding from the rod can be deflected during rotation of the rod relative to the axis of rotation and thus to the threaded element, which can extend in a straight line along the axis of rotation. However, in order to allow such a wobbling motion of the connecting element and to prevent the transmission of bending moments to the connecting element caused by its deflection, the connecting element of the intramedullary nail disclosed herein extends within the threaded element with a radial clearance. This allows the connecting element, which can, for example, be designed as a screw protruding from the rod, to be deflected relative to the axis of rotation of the threaded element during rotation of the rod without striking an inner surface of the threaded element.The radial clearance can therefore be selected such that the connecting element does not strike the threaded element during rotation of the rod relative to the tube to actuate the adjustment mechanism. Accordingly, the connecting element can move freely within the radial clearance, and the rotation of the rod relative to the tube does not cause a bending stress on the connecting element that could lead to breakage. This allows the intramedullary nail to be curved yet still reliable and load-bearing, while maintaining axial coupling between the tube and the rod.

[0014] Further embodiments are described in the dependent claims, the description, and the drawings. Specifications of a radial or axial direction in connection with such embodiments generally refer to the axis of rotation of the threaded element, unless otherwise specified.

[0015] In some embodiments, a portion of the connecting element projecting from the threaded element can extend with a radial clearance within the tube. In particular, the entire portion of the connecting element projecting from the threaded element can extend with a radial clearance, allowing this portion to be deflected relative to the axis of rotation of the threaded element during actuation of the adjusting mechanism. Specifically, the radial clearance within the threaded element and / or the tube can be dimensioned such that the connecting element does not abut the inside of the threaded element and / or the tube during actuation of the adjusting mechanism. The radial clearance for the connecting element can be constant or increase progressively—continuously or in steps—from the rod to accommodate the increasing deflection of the connecting element with increasing distance from the rod.

[0016] In some embodiments, the connecting element can be linear. For example, the connecting element can be screwed to the rod to create a coupling between the adjusting mechanism and the rod. The connecting element can thus be designed, in particular, as a screw with a shank and a screw head, wherein the shank is screwed into the rod and the screw head can be formed on a portion of the screw protruding from the threaded element. Alternatively, the connecting element can also be positively and / or frictionally connected to the rod and, for example, be riveted or pressed into the rod. In particular, the connecting element can extend linearly along the axis of rotation of the threaded element when actuation of the adjusting mechanism is complete and the adjusting mechanism and / or the rod are in a starting position.

[0017] In some embodiments, the threaded element can be centered at an end section of the threaded element facing the rod by means of the threaded element. In particular, the connecting element may not extend with a radial clearance in the end section of the threaded element facing the rod, but may be enclosed by the threaded element, at least partially, with reduced radial clearance.

[0018] By centering the connecting element at its end section using the threaded element of the threaded component, the rod can also be centered relative to the threaded component, ensuring a secure and complete engagement between the rod and the threaded component via the coupling teeth. This centering, in particular, prevents the rod from moving radially relative to the threaded component during actuation of the adjustment mechanism, which could prevent the coupling teeth from fully re-engaging after the adjustment mechanism has been actuated.

[0019] For example, it may be designed that the rod engages the threaded element along a first direction of rotation around the axis of rotation via the coupling teeth, whereas the coupling teeth have a freewheel in a second direction of rotation opposite to the first, allowing the rod to be rotated relative to the threaded element and the adjusting mechanism to return to its initial position. To enable such a freewheel, however, the coupling teeth must briefly disengage when the rod rotates along the second direction of rotation, so that a tooth on the rod can jump a tooth on a tooth on the threaded element. Specifically, at the moment of this jump, there is no radial coupling between the rod and the threaded element via the coupling teeth, meaning that radial movement of the rod relative to the threaded element would, in principle, be possible.However, this can be reliably prevented by centering the connecting element in the end section of the threaded element.

[0020] Furthermore, since the connecting element is centered in or on an end section of the threaded element, the connecting element can only be directly enclosed by the threaded element in a section immediately adjoining the rod. In this end section of the threaded element, the connecting element is deflected only minimally relative to the axis of rotation of the threaded element due to the small distance to the rod. Therefore, thanks to the radially reduced play guidance of the connecting element in this end section, only negligible and thus tolerable bending moments, arising solely from the centering, can be transmitted to the connecting element.The part of the connecting element that extends further out of the rod and through the threaded element, where the wobbling motion causes a larger radial deflection relative to the axis of rotation of the threaded element, can, however, be made possible by the radial clearance, so that the transmission of relevant or critical bending moments to the connecting element can be reliably avoided.

[0021] In some embodiments, the threaded element can have a centering section for the connecting element at the end section facing the rod. Such a centering section can, for example, be designed as an annular surface circumferentially on the inside of the threaded element, which reduces the inner diameter of the threaded element in the region of the end section. Alternatively to such a circumferential rib, the threaded element can, for example, also have several, in particular two, four, six, or eight, radially inwardly directed centering supports, which restrict and / or substantially prevent radial deflection of the connecting element within the end section of the threaded element relative to the threaded element.

[0022] Furthermore, in some embodiments, the threaded element can have a radially inwardly projecting centering section for centering the connecting element. The axial length of this centering section is in the range of one-tenth to one-third, and in particular one-eighth to one-quarter, of the axial length of the threaded element. In some embodiments, the axial length of the centering section of the threaded element can also be approximately one-seventh of the axial length of the threaded element. The centering section can, for example, be designed as a rib circumferentially running along an inner surface of the threaded element or have several radially inwardly projecting centering supports.

[0023] The centering section of the threaded element can thus form an axially narrow, particularly ring-shaped, section at one end of the threaded element facing the rod, in which radial deflection of the connecting element relative to the threaded element can be restricted and / or blocked. As already explained, this reliably prevents radial relative movement between the rod and the threaded element, ensuring that the coupling teeth reliably re-engage, particularly at the end of an actuation of the adjusting mechanism, without restricting the deflection of sections of the connecting element further away from the rod.

[0024] In some embodiments, the connecting element can extend completely between the end section of the threaded element facing the rod and an end face of the threaded element facing away from the rod, with a radial clearance in the threaded element.

[0025] In particular, it can be provided that the connecting element is centered and / or radially enclosed with reduced play exclusively at the end section of the threaded element facing the rod, while the connecting element can otherwise extend over its entire axial length with a radial clearance within the threaded element. This centering of the connecting element can specifically address the fact that the extent of the radial deflections of the connecting element relative to the axis of rotation increases with increasing distance from the rod during a wobbling motion. Such relatively large deflections can be accommodated by allowing the connecting element to extend outside the end section of the threaded element with the radial clearance and, consequently, to be radially unguided in that area.At the same time, by centering the connecting element in the end section, a centering of the coupling toothing can also be achieved, whereby the connecting element does not experience any deflections during the wobbling movement due to its proximity to the rod in the end section, which could lead to large bending moments and damage to the connecting element.

[0026] In some embodiments, the connecting element may have a radial stop widening, whereby the end section of the threaded element and the stop widening of the connecting element can limit axial relative movement between the rod and the threaded element.

[0027] In particular, the radial stop extension of the connecting element and the end section of the threaded element on which the connecting element is centered can interact in such a way as to limit axial relative movement between the rod and the threaded element, which would allow the rod to move out of the tube. Such a limitation can thus also restrict axial relative movement between the rod and the tube, reliably preventing the rod from coming loose from the tube, especially during the insertion of the intramedullary nail during surgery. Furthermore, axial movement of the rod into the tube can be limited by the threaded element and, in particular, the coupling teeth, so that axial relative movements between the rod and the tube can be restricted in both axial directions by means of the stop extension of the connecting element on the one hand and the coupling teeth on the other.However, it can also be provided that a blocking section opposite the end section is formed on the threaded element, against which the stop widening of the connecting element strikes when the rod moves into the tube, in order to further limit such axial relative movement between the rod and the tube.

[0028] In particular, the radial stop extension and the threaded element can be matched in such a way that the stop extension does not abut the inside of the threaded element during rotation of the rod to actuate the adjustment mechanism and the resulting wobbling motion of the connecting element. Consequently, sufficient radial clearance for the wobbling motion of the connecting element can be provided within the threaded element, even in the area of ​​the radial stop extension, so that in such embodiments the radial stop extension does not impede deflection of the connecting element relative to the threaded element, while the rod is secured within the tube against unintentional loosening.While the arrangement of the connecting element within the threaded element, with its radial clearance, allows for a curved design of the intramedullary nail without transmitting bending moments to the connecting element during actuation of the adjustment mechanism, the widened stop ensures reliable axial coupling between the rod and the tube. This overcomes the problem of unintentional rod detachment from the tube that occurs when the rod and the adjustment mechanism are decoupled. Therefore, such designs offer a simple way to achieve reliable coupling between the rod and the tube when using a curved intramedullary nail.

[0029] Furthermore, in some embodiments, rotation of the rod about its axis of rotation along a first direction of rotation can be transmitted to the threaded element via the coupling teeth. As already explained, such transmission of the rotation to the threaded element allows the threaded element to move axially within the tube, so that the rod, due to the axial engagement of the coupling teeth after the rotation of the threaded element, can also move axially relative to the tube. Depending on the thread pitch, the rod can be moved out of or into the tube, so that the intramedullary nail can be configured as a distraction nail or a contraction nail.

[0030] In some embodiments, the rod can be rotated around the axis of rotation relative to the threaded element in a second direction of rotation opposite to the first. Consequently, when the rod is rotated around the axis of rotation in the second direction, the threaded element is not engaged in such embodiments. Therefore, the threaded element remains axially stationary within the tube, and no change in length of the incisal nail occurs when the rod is rotated in the second direction. Instead, the adjusting mechanism can be returned to its initial position by rotating the rod in the second direction, allowing for a further change in length by subsequent rotation in the first direction.

[0031] Actuating the adjusting mechanism to change the length of the intramedullary nail by a predetermined distance can thus be a two-step process. First, the rod is rotated in the first direction, and this rotation results in the change in length. The actuation of the adjusting mechanism can then be completed by rotating the rod in the second direction to return the mechanism to its initial position. In particular, the coupling teeth can have a free-running function in the second direction of rotation. During rotation of the rod in this second direction, a tooth on the rod can be axially disengaged from a tooth on the threaded element, thus rotating the rod's teeth relative to the threaded element by one tooth.In the first direction of rotation, the coupling teeth can act as a lock, allowing the rotation of the rod to be transferred to the threaded element. The freewheel and the lock can be achieved, for example, by using suitable pitches for the teeth of the rod and the threaded element that form the coupling teeth.

[0032] In some embodiments, the rotational movement of the rod about the axis of rotation relative to the tube can be limited. In particular, rotations of the rod relative to the tube can be limited in both the first and second directions of rotation, so that the adjusting mechanism can be actuated by rotating the rod through clearly defined angles. Specifically, a predetermined axial length change can be achieved by rotating the rod through the defined angle along the first direction of rotation, and the adjusting mechanism can then be returned to its initial position by rotating the rod back through the same angle along the second direction of rotation.The rod can be rotated by such an angle during the actuation of the adjustment mechanism, for example, that a toothing of the rod is rotated back by exactly one tooth relative to a toothing of the threaded element, which together form the coupling toothing, when the rod is turned back along the second direction of rotation.

[0033] In some embodiments, the rod can have a key that is guided in a groove inside the tube, the groove being able to limit the rod's rotation about its axis of rotation. The groove can act as a stop for the rod's key, so that the width of the key and the width of the groove determine the angle by which the rod can rotate relative to the tube. Alternatively, a key can be provided in an end region of the tube from which the rod protrudes, interacting with a groove formed on the rod to limit its rotation about its axis of rotation. With this arrangement of the key, it can be located in a region of the tube that does not need to be kept clear for rotation of the threaded element.

[0034] In some embodiments, the threaded element can engage with a locking element via a locking toothing on one side facing away from the rod, wherein the connecting element can pass through the locking element and protrude from the locking element with an extension section on one side facing away from the threaded element. The connecting element can further extend with a radial clearance within the locking element.

[0035] In particular, the locking element can thus connect axially to the threaded element on a side opposite the rod, and the connecting element can extend from the rod through the threaded element and the locking element. Since the connecting element can also extend within the locking element with a radial clearance, it can be deflected radially relative to the axis of rotation of the threaded element during rotation of the rod to actuate the adjustment mechanism, without bending moments being transmitted to the connecting element. Furthermore, the radial clearance at the locking element can be selected such that the connecting element does not radially abut within the locking element during actuation of the adjustment mechanism.The radial clearance in the locking element can be equal to or greater than the radial clearance in the threaded element to allow for the radial deflection of the connecting element, which increases with the distance from the rod, during actuation of the adjusting mechanism.

[0036] Furthermore, the extension section can also be designed to extend radially within the tube, allowing it to deflect radially during rotation of the rod. The extension section can also be used to connect the rod to the locking element, as explained in more detail below.

[0037] In some embodiments, the locking element can be guided in the tube in a rotationally secure manner. In particular, the locking element can have a keyway which is guided in a groove inside the tube.

[0038] The locking element can therefore be axially displaceable within the tube, but not rotatable about the axis of rotation. For example, the aforementioned groove, within which a key of the rod can be guided to limit rotational movements of the rod, can be provided. The locking element can have a key guided in the groove with essentially no play to prevent rotation of the locking element. In particular, the key of the locking element can be thicker than the key of the rod, so that the rod can rotate within the groove through a predetermined angle, while the locking element is guided in the groove in a rotationally secure manner.

[0039] In some embodiments, the locking toothing can have a freewheel in the first direction of rotation, allowing the threaded element to rotate relative to the locking element in the first direction. In the second direction of rotation, however, the locking toothing can form a lock, preventing the threaded element from rotating relative to the locking element in the second direction.

[0040] In particular, the freewheel in the first direction of rotation allows rotation to be transferred via the rod to the threaded element, thus moving the threaded element axially within the tube and thereby changing the length of the intramedullary nail. Furthermore, by blocking rotation of the threaded element in the second direction, it is possible to prevent rotation of the rod in the second direction from being transferred to the threaded element, allowing the rod to be rotated relative to the threaded element. This allows the adjustment mechanism to return to its initial position, enabling controlled and incremental changes in the length of the intramedullary nail.

[0041] The freewheeling and locking mechanism of the locking toothing can be achieved, in particular, by different tooth configurations on the threaded element and the locking element, which together form the locking toothing, in the two directions of rotation. For example, the teeth can be oriented in a blocking manner and / or perpendicular to the second direction of rotation, but only slightly inclined to the first direction. This allows the threaded element, for example, to slide along the teeth of the locking element during rotation in the first direction and move axially away from the locking element, so that a tooth of the threaded element can skip a tooth of a tooth of the locking element. Conversely, rotation in the second direction can be blocked by the locking toothing.Similarly, the teeth of the coupling gear can also be designed to allow the threaded element to be carried along in the first direction of rotation and the rod to be rotated relative to the threaded element in the second direction of rotation.

[0042] Furthermore, in some embodiments, the adjusting mechanism can include a centering element that blocks the locking element against radial movement relative to the threaded element. In particular, during rotation along the first direction of rotation relative to the locking element, the threaded element can axially disengage from the locking element by rotating a tooth on the threaded element relative to a tooth on the locking element by one tooth. The centering element prevents radial relative movement between the locking element and the threaded element during such rotation, allowing the locking teeth to reliably re-engage.

[0043] In some embodiments, the centering element can be designed as a centering sleeve onto or into which the locking element and the threaded element can be inserted. Such a centering sleeve allows the locking element and the threaded element to be radially connected, so that a force acting radially on the locking element, for example, can be transmitted via the centering sleeve to the threaded element and via the threaded element to the pipe. This prevents radial relative movement between the locking element and the threaded element, ensuring, in particular, a secure engagement of the locking teeth after rotation of the threaded element. Axial relative movement between the threaded element and the locking element, however, can be permitted by allowing both the threaded element and the locking element to move axially relative to the centering sleeve.

[0044] The centering sleeve can be arranged, in particular, on an inner or outer surface of the threaded element and the locking element to establish the axial connection between the threaded element and the locking element, so that the locking teeth can be formed radially inside or radially outside the centering sleeve. Particularly when the centering sleeve is arranged on an inner surface of the threaded element and the locking element, the centering sleeve can be sufficiently thin to still allow the connecting element to have radial clearance even in the area of ​​the centering sleeve.

[0045] In some embodiments, the locking element and the threaded element can each have a radial clearance on their inner or outer surface, wherein the centering element can be arranged in the radial clearances and form a radial connection between the threaded element and the locking element. In particular, such radial clearances make it possible to arrange the centering element, and especially a centering sleeve, on the inner surface of the threaded element and the locking element without restricting the radial clearance for the connecting element. Furthermore, arranging the centering element on the inner surfaces of the threaded element and the locking element allows the coupling teeth to be positioned radially outside the centering element, so that the teeth of the locking teeth can be designed to be as large and reliable as possible.

[0046] In some embodiments, the coupling gear can have a freewheel in the second direction of rotation, which allows the rod to rotate relative to the threaded element blocked by the locking gear along the second direction of rotation. As already explained, the adjusting mechanism can be returned to its initial position by such a rotation of the rod in the second direction of rotation without the incisal nail undergoing any change in length. This can be achieved by a suitable design of the teeth on the rod and the threaded element, which together form the coupling gear.

[0047] In some embodiments, the locking element can be pre-tensioned via the connecting element in the direction of the threaded element. Such pre-tensioning allows a force to be transmitted to the locking element to close the locking teeth, reliably preventing the threaded element from rotating in the second direction, for example. Furthermore, the pre-tensioning of the locking element in the direction of the threaded element can also pre-tension the rod to which the connecting element is rigidly attached in the direction of the threaded element, thus closing the coupling teeth when the adjusting mechanism is not engaged. However, the coupling teeth can also be reliably held in engagement by the force exerted by human body tissue on the two bone components to which the rod and tube are attached.

[0048] Furthermore, in some embodiments, the locking element can be disengaged from the threaded element against the restoring force of the preload. This allows the threaded element to be rotatable relative to the locking element in the first direction of rotation, in order to change the length of the intramedullary nail. For example, when a torque is applied to the threaded element along the first direction of rotation, the locking element can be axially retracted against the preload by the sliding teeth of the locking mechanism, thus allowing rotation of the threaded element. However, once the rotation of the threaded element is complete, the teeth of the locking mechanism can re-engage due to the preload of the locking element.

[0049] In some embodiments, a clamping device can be coupled to the connecting element, which preloads the locking element in the direction of the threaded element. In particular, a spring can be coupled to the connecting element, which preloads the locking element in the direction of the threaded element. This clamping device can thus ultimately also couple the rod, to which the connecting element is rigidly attached, with the locking element, so that forces acting axially on the rod, in particular, can be transmitted to the locking element.In particular, this allows an axial force to be transferred to the locking element via the connecting element and the clamping device when the rod is axially removed from the threaded element and the locking element during a reverse rotation of the rod along the second direction of rotation, in which a toothing of the rod can be reset by one tooth relative to a toothing of the threaded element, in order to reliably close the locking toothing and prevent rotation of the threaded element.

[0050] In some embodiments, the clamping device may include a spring or be designed as a spring which is supported on the locking element and on the extension section of the connecting element. For example, the connecting element may be designed as a screw with a screw head, wherein the underside of the screw head facing the locking element may form the support for the spring.

[0051] In some embodiments, the spring can be supported on an end face of the locking element facing away from the threaded element. In particular, the spring can be arranged between a screw head of a connecting element designed as a screw, facing the locking element, and an end face of the locking element, so that the spring can extend axially between the locking element and an underside of the screw head.

[0052] Alternatively, in some embodiments, the locking element can have a spring receptacle in which the spring is at least partially received, and the spring can be supported against a base of the spring receptacle in the direction of the threaded element. For example, such a spring receptacle can be configured as a bore, a slot, or a circumferential recess in the locking element. In such embodiments, the axial length of the extension section of the connecting element projecting from the locking element can be shortened, in particular, by arranging part of the spring axially within the locking element. This also reduces the maximum radial deflection of the connecting element relative to the axis of rotation of the threaded element during rotation of the rod.

[0053] In some embodiments, the adjusting mechanism may also have a stop which limits axial movement of the connecting element against the force of the clamping device.

[0054] In particular, the stop of the adjusting mechanism can be formed by a stop element formed on the connecting element and a stop element formed on another component of the adjusting mechanism, which interact to limit axial movement of the connecting element against the force of the clamping device, especially a spring. Accordingly, due to the rigid attachment of the connecting element to the rod, the stop can also limit axial relative movements between the rod and the tube to prevent overloading of the clamping device as a result of such relative movements. For example, during an operation, the tube or rod can be pulled to, for instance, remove the intramedullary nail from a long bone, whereby the tube and the rod can be moved relative to each other and the clamping device can be tensioned.However, the stop allows such relative movements to be limited in such a way that the clamping device is not overloaded.

[0055] In some embodiments, the stop may include a radial widening of the connecting element. In particular, such a radial widening of the connecting element may, during axial movement of the connecting element, abut against another element of the adjusting mechanism and thereby limit the movement of the connecting element.

[0056] For example, in some embodiments, the radial widening of the connecting element can be formed by a stop widening located on a section of the connecting element that extends within the threaded element. The stop widening and a radially inwardly directed centering section of the threaded element can form the stop for the adjustment mechanism. This centering section of the threaded element can be, in particular, the aforementioned centering section, which can be formed on an end section of the threaded element facing the rod in order to limit radial relative movement between the threaded element and the rod.This centering section can thus fulfill a dual function: on the one hand, it centers the coupling teeth, and on the other hand, together with the stop extension, it prevents axial movement of the connecting element against the force of the clamping device, thereby preventing overloading of the clamping device. Furthermore, as already explained, the interaction of the centering section and the stop extension also ensures reliable axial coupling between the rod and the tube, even with a curved design of the intramedullary nail.

[0057] Alternatively, in some embodiments, the radial widening of the connecting element can be formed on the extension section of the connecting element, with the radial widening and an end face of the locking element facing away from the threaded element forming the stop of the adjusting mechanism. In particular, in such embodiments, a spring receptacle can be formed on the locking element, in which a spring forming the clamping device is partially received. Furthermore, in such embodiments, the radial widening of the connecting element can be formed, in particular, by a screw head, which can abut the locking element as a result of axial movement of the screw-type connecting element. This can also, in principle, prevent both overloading of the clamping device and loosening of the rod from the tube.

[0058] In some embodiments, the connecting element can be designed as a screw with a shank and a screw head, wherein the radial widening is formed by the screw head or wherein the radial widening is formed between the screw head and the locking element on the shank of the screw. In such embodiments, the stop can thus also comprise an end face of the locking element, which can interact either with the screw head or with a radial widening provided specifically for this purpose on the shank of the screw.

[0059] The invention is explained below by way of example with reference to the drawings.

[0060] They show: Fig. 1 is a schematic longitudinal sectional view of a curved intramedullary nail, comprising a curved tube and a curved rod arranged inside the tube. Figs. 2A and 2B are schematic longitudinal sectional views and a schematic perspective longitudinal sectional view of the intramedullary nail to illustrate an adjustment mechanism actuated by repeated relative rotational movements between the rod and the tube, by means of which the rod is axially movable relative to the tube. Fig. 3 is a schematic longitudinal sectional view to further illustrate the adjustment mechanism. Fig. 4 is a schematic longitudinal sectional view to illustrate the adjustment mechanism of a further embodiment of the intramedullary nail.

[0061] Fig. 1 Figure 1 shows an intramedullary nail 11, which has a curved tube 13 within which a curved rod 15 is arranged. The intramedullary nail 11 is designed to be connected to two bone fragments (not shown) of a severed bone and to bridge a bone gap between the bone fragments, so that the bone fragments can grow together through the continuous regeneration of bone tissue in the bone gap. For this purpose, several fastening openings 85 are provided on the tube 13, so that the tube 13 can be attached, for example, to a first bone fragment and, in particular, screwed into place. The rod 15 projects from the tube 13 at an end opposite the fastening openings 85 of the tube 13 with a fastening section 17, which also has several fastening openings 85, in order to attach the rod 15 to a second bone fragment (not shown).

[0062] Due to the curvature of tube 13 and rod 15, the intramedullary nail 11 is not straight but curved. The curvature of the intramedullary nail 11 can, in particular, correspond to the physiological curvature of a long bone being treated, so that the drilling required to insert the intramedullary nail 11 into a medullary canal of the long bone can follow the physiological curvature of the bone. In contrast, when inserting conventional straight intramedullary nails, correspondingly straight drilling is required, meaning that the curvature of the bone is not taken into account and the drilling can result in a weakening of the cortex. The curved design of the intramedullary nail 11, however, prevents such weakening.

[0063] In particular, the intramedullary nail 11 can be configured as a distraction nail, and the rod 15 can be moved stepwise out of the tube 13 in order to successively increase the distance between the bone fragments connected to the intramedullary nail 11 and ultimately lengthen the bone through the continuous formation of bone tissue in the bone gap. It is also possible to configure such an intramedullary nail 11 as a contraction nail, in which the rod 15 can be moved stepwise into the tube 13.

[0064] To allow for a gradual change in the length of the intramedullary nail 11, an adjustment mechanism 19 is arranged inside the tube 13, which can be actuated by repeated relative rotational movements between the tube 13 and the rod 15. As the Fig. 2A bis 4 As shown, the adjusting mechanism 19 has a threaded element 23 rotatable about an axis of rotation D in an internal thread 21 of the tube 13, with which the rod 15 engages via a coupling toothing 25 (see in particular Fig. 3 Furthermore, the adjusting mechanism 19 includes a locking element 49, which engages with the threaded element 23 on its side 29 facing away from the rod 15 via a locking toothing 47 and is guided within the tube 13 in a rotationally secure manner. A connecting element 27 of the adjusting mechanism 19 is also rigidly connected to the rod 15. This connecting element is designed as a screw 79 with a shank 81 and a screw head 83, which is screwed into the rod 15. The connecting element 27 extends through the threaded element 23 and into the locking element 49 with a portion 33 projecting from the threaded element 23. The connecting element 27 also projects from the locking element 49 with an extension section 51, so that the screw head 83 is surrounded by the tube 13.A clamping device 67 designed as a spring 69 is supported on an underside of the screw head 83 and on an end face 71 of the locking element 49 facing away from the threaded element 23, by which the locking element 49 is pre-tensioned in the direction of the threaded element 23.

[0065] As especially from Fig. 3 As can be seen, the coupling gear 25 comprises a toothing 87 formed on the rod 15 and a toothing 89 formed on the threaded element 23, which are in engagement with each other in a starting position of the adjusting mechanism 19. The toothings 87 and 89 are designed such that a rotation of the rod 15 relative to the tube 13 about the axis of rotation D of the threaded element 23 along a first direction of rotation D1 can be transmitted to the threaded element 23, so that the threaded element 23 can be rotated and moved axially in the tube 13 by the rotation of the rod 15 along the first direction of rotation D1. By coupling the rod 15 with the threaded element 23, the rod 15 can also be moved by rotation along the first direction of rotation D1 relative to the tube 13 and in particular out of the tube 13, whereby the change in length caused by the rotation is achieved by a thread pitch of the internal thread 21 of the tube 13.the thread pitch of the threaded element 23 and the angle by which the rod 15 is rotated can be specified.

[0066] To enable the threaded element 23 to be carried along when the rod 15 rotates in the first direction of rotation D1, the locking toothing 47 of the locking element 49, which is guided in the tube 13 in a rotationally secure manner, has a free play in the first direction of rotation D1, so that the threaded element 23 can be rotated relative to the locking element 49 in the first direction of rotation D1. For this purpose, the locking toothing 47 comprises a toothing 91 formed on the threaded element 23 and a toothing 93 formed on the locking element 49, wherein the pitch of the toothings 91 and 93 in the first direction of rotation D1 is selected such that the locking element 49 can be axially repulsed against the force of the spring 69 by the sliding toothings 91 and 93 during a rotation of the threaded element 23 in the first direction of rotation D1 (see Figure 1). Fig. 3 In particular, as a result of such a rotation, the toothing 91 can be displaced by one tooth relative to the toothing 93.

[0067] To ensure controlled actuation of the adjusting mechanism 19, and in particular to precisely control the change in length of the nail 11 achieved during actuation, the rotational movement of the rod 15 relative to the tube 13 about the axis of rotation D of the threaded element 23 is limited. For this purpose, a key 43 is formed on the rod 15, which is guided in a groove 45 inside the tube 13. After the rod 15 is rotated through a predetermined angle, the key abuts the groove 43 in the groove 45, so that when the rod 15 is rotated along the first direction of rotation D1, the threaded element 23 is also rotated by a precisely predetermined angle, resulting in a defined change in length of the nail 11. Furthermore, the groove 45 serves to guide the locking element 49 in the tube 13 in a rotationally secure manner. The locking element 49 also has a key 53 guided in the groove 45 for this purpose.The key 53 is thicker than the key 43, so that the locking element 49 is rotationally secure, while the threaded element 23 can be rotated by the specified angle.

[0068] After the threaded element 23 has been rotated by the rod 15 along the first direction of rotation D1 by the angle defined by the key 43 and the groove 45, the rod 15 can be rotated back along a direction of rotation D2 opposite to the first direction of rotation D1 in order to return the adjusting mechanism 19 to its initial position and to allow the adjusting mechanism 19 to be actuated again to change the length of the incisal nail 11. For this purpose, the coupling toothing 25 has a free-running direction along the second direction of rotation D2, while the locking element 49 forms a lock for the threaded element 23 with respect to rotations along the second direction of rotation D2.Due to the locking toothing 47 blocking the threaded element 23 with respect to rotations along the second direction of rotation D2, the rod 15 can thus be rotated along the second direction of rotation D2 relative to the threaded element 23 without the threaded element 23 itself rotating or moving axially within the tube 13. During such rotation of the rod 15 along the second direction of rotation D2, the toothing 87 of the rod 15 slides on the toothing 89 of the threaded element 23, so that the rod 15 and the connecting element 27 move axially relative to the threaded element 23 and the locking element 49, and the spring 69 is compressed again. In particular, this ensures that the locking toothing 47 closes securely during this rotation of the rod 15, thus preventing the threaded element 23 from rotating.The locking of the blocking toothing 47 is also achieved by a perpendicular alignment of the teeth 91 and 93 to the second direction of rotation D2, whereby a corresponding alignment of the teeth 87 and 89 of the coupling toothing 25 to the direction of rotation D1 enables the threaded element 23 to be carried along when the rod 15 is rotated along the first direction of rotation D1.

[0069] In addition to transferring a preload to the locking element 49, the connecting element 27 of the adjusting mechanism 19 is specifically designed to couple the rod 15 to the adjusting mechanism 19 and thereby prevent the rod 15 from unintentionally detaching from the tube 13. As shown in particular by the Fig. 2 and 2BTo illustrate, the connecting element 27 is designed in a straight line and, in the initial position of the adjusting mechanism 19 shown, in which the coupling toothing 25 is engaged, extends along the axis of rotation D of the threaded element 23. However, due to the curvature of the rod 15, the straight connecting element 27 is deflected radially relative to the axis of rotation D when the rod 15 is rotated about the axis of rotation D and performs a wobbling motion, which could fundamentally result in bending moments being applied to the connecting element 27, potentially even leading to breakage of the connecting element 27, and which has so far prevented the use of curved intramedullary nails.

[0070] However, in order to allow this wobbling motion and to prevent the connecting element 27 from being subjected to bending moments, the connecting element 27 of the intramedullary nail 11 disclosed herein extends within the threaded element 23 with a radial clearance 31. This radial clearance 31 is specifically chosen such that the connecting element 27 does not abut an inner surface of the threaded element 23 during rotation of the rod 15 relative to the tube 13 about the axis of rotation D of the threaded element 23. The portion 33 of the connecting element 27 projecting from the threaded element 23 also extends within the locking element 49 with a radial clearance 31a, in order to likewise allow deflection of the connecting element 27 relative to the axis of rotation D within the locking element 49 during rotation of the rod 15.

[0071] Likewise, the extension section 51 of the connecting element 27, projecting from the locking element 49 and surrounded only by the tube 13, extends with a radial clearance 31b within the tube 13, so that this extension section 51 of the connecting element 27, which is axially furthest from the rod 15, can also be deflected during rotation of the rod 15 relative to the axis of rotation D, without the extension section 51 contacting an inner surface or the internal thread 21 of the tube 13 and without the connecting element 27 experiencing a bending load. In particular, the radial clearance 31b and the screw head 83 of the connecting element 27 can be designed such that the screw head 83, which experiences the greatest radial deflection with respect to the axis of rotation D during rotation of the rod 15 about the axis of rotation D, does not come into contact with the internal thread 21 of the tube 13 during rotation of the rod 15.Furthermore, the radial clearance 31b can be larger than the radial clearance 31 and / or the radial clearance 31a to allow the radial deflection of the connecting element 27 to increase with the distance from the rod 15.

[0072] While the connecting element 27 is thus guided in the threaded element 23, in the locking element 49 and in the tube 13 within the radial clearances 31, 31a and 31b to allow the required wobbling movement of the connecting element 27, the connecting element 27 is nevertheless centered by means of the threaded element 23 on an end section 35 of the threaded element 23 facing the rod 15 (cf. Fig. 2A , 2B and 4 ). For this purpose, a radially inwardly projecting centering section 37 is formed on the end section 35 of the threaded element 23, which can, for example, extend in a ring-like manner around the connecting element 27 and surround the connecting element 27 essentially radially without play.

[0073] In particular, the centering of the connecting element 27 by means of the centering section 37 also enables the rod, to which the connecting element 27 is rigidly attached, to be centered and radially aligned with the threaded element 23. This prevents, for example, the rod 15 from moving radially relative to the threaded element 23 during actuation of the adjusting mechanism 19, thus ensuring that the coupling teeth 25 do not re-engage precisely. This is especially important when the rod 15 is rotated back along the second direction of rotation D2, during which the rod 15 moves axially relative to the threaded element 23 and the toothing 87 is offset by one tooth relative to the toothing 89 (see Figure 1). Fig. 3 ), the rod 15 is not radially aligned relative to the threaded element 23 by the coupling teeth 25 at the moment the toothing 87 engages, so that a radial relative movement of the rod 15 to the threaded element 23 would be possible in principle. However, this can be prevented by centering the connecting element 27 by means of the centering section 37.

[0074] However, since the centering section 37 is designed merely as an axially narrow section at the end region 35 of the threaded element 23, the connecting element 27 is centered in an area where it is deflected only slightly relative to the axis of rotation D of the threaded element 23 when the rod 15 is rotated around the axis of rotation D. Accordingly, only small and tolerable bending moments can be transferred to the connecting element 27 by means of this centering, and these moments cannot lead to high stress or even breakage of the connecting element 27.Between the centering section 37, whose axial length corresponds in particular to about 1 / 7 of the axial length of the threaded element 23, and an end face 39 of the threaded element 23 facing away from the rod 15, the connecting element 27 extends completely with the radial clearance 31 in the threaded element 23, so that the deflections of the connecting element 27, which increase with increasing distance from the rod 15, are made possible during a rotation of the rod about the axis of rotation D.

[0075] Furthermore, a radial widening 77 is formed on the shaft 81 of the connecting element 27, which, based on the Fig. 2A and 2BIn the illustrated embodiment, the radial stop extension 41 is arranged within the threaded element 23. In particular, this radial stop extension 41 limits axial relative movement between the rod 15 and the tube 13, during which the rod 15 is moved out of the tube 13, by abutting the centering section 37. This allows the rod 15 to be reliably secured axially within the tube 13, preventing, for example, unintentional loosening of the rod 15 from the tube 13 during an operation. In this respect, the centering section 37 fulfills a dual function: it serves both to center the connecting element 27 and the rod 15 and to secure the rod 15 within the tube 13.

[0076] Furthermore, the centering section 37 and the radial stop extension 41 together form a stop 75, which also limits axial movement of the rod 15 and the rigidly attached connecting element 27 against the force of the spring 69. Thus, the radial stop extension 41 and the centering section 37 also serve to prevent any overloading of the spring 69 during the insertion or withdrawal of the intramedullary nail 11 during an operation.

[0077] In order to ensure a secure engagement of the locking toothing 47 after a rotation of the threaded element 23, the locking element 49 is also centered relative to the threaded element 23 (see figure). Fig. 2A , 2B and 4A centering element 57 is provided for this purpose, which blocks the locking element 47 against radial movement relative to the threaded element 23. This centering element 57 is specifically designed as a centering sleeve 59, which is inserted into a radial recess 61 on the inside of the threaded element 61. The locking element 49 also has a radial recess 63 on its inside, so that the locking element 49 can be placed onto the centering sleeve 59, and the centering sleeve 59, arranged in the recesses 61 and 63, radially connects the threaded element 23 to the locking element 49. Due to the recesses 61 and 63, the centering sleeve 59 can be arranged such that the radial clearance 31 in the threaded element 23 or the radial clearance 31a in the locking element 49 for the connecting element 27 is not restricted.Here too, the centering sleeve 59 can prevent, in particular, a radial deflection of the blocking element 49 relative to the threaded element 23 at the moment when the teeth 91 and 93 disengage from each other during a rotation of the threaded element 23 along the first direction of rotation D1 (see also . Fig. 3 ).

[0078] Fig. 4 Figure 1 schematically illustrates another embodiment of the intramedullary nail 11, which is basically designed as described above. However, in this embodiment, the spring 69, by which the locking element 49 is biased towards the threaded element 23, is not supported on the end face 71 of the locking element 49, but rather the locking element 49 has a spring receptacle 73, at the base 74 of which the spring 69 is supported. For example, the spring receptacle 63 can be designed as a bore in the locking element 49.

[0079] The design of the locking element 49 with the spring receptacle 73 makes it possible, in particular, to minimize the distance between the screw head 83 and the locking element 49 in the axial direction, so that the deflection of the connecting element 27 relative to the axis of rotation D of the threaded element 23 can also be limited. Furthermore, the connecting element 27 can, as Fig. 4 The figure shows that, without the radial stop widening 41, the stop 75 for limiting the load on the spring 69 can be formed by the end face 71 of the locking element 49 facing away from the threaded element and the screw head 83, which in this respect represents a radial widening 77 of the connecting element 27. Likewise, the interaction of the end face 71 of the locking element 49 with the screw head 83 can reliably prevent the rod 15 from loosening from the tube 13. Bezugszeichenliste

[0080] 11 Marking nail 13 Tube 15 Rod 17 Fastening section 19 Adjusting mechanism 21 Internal thread 23 Threaded element 25 Coupling toothing 27 Connecting element 29 Side of the threaded element 31 Radial clearance 31 Radial clearance 31 Radial clearance 33 Part of the connecting element protruding from the threaded element 35 End section of the threaded element 37 Centering section 39 End face of the threaded element facing away from the rod 41 Radial stop widening 43 Key of the rod 45 Groove 47 Locking toothing 49 Locking element 51 Extension section of the connecting element 53 Key of the locking element 57 Centering element 59 Centering sleeve 61 Radial clearance 63 Radial clearance 67 Clamping device 69 Spring 71 End face of the locking element 73 Spring receptacle 74 Base 75 Stop 77 Radial widening of the connecting element 79 Screw 81 Shank 83 Screw head 85 Mounting opening 87 Toothing 89 Toothing 91 Toothing 93 Toothing D Axis of rotation D1 First direction of rotation D2 Second direction of rotation

Claims

1. A curved intramedullary nail (11), in particular a distraction intramedullary nail or a contraction intramedullary nail, for connecting two parts of a bone, in particular for successively extending or for successively shortening a bone, said curved intramedullary nail (11) comprising a curved tube (13) for fastening to a first bone part; and a curved rod (15) which is arranged within the tube (13) and which has a fastening section (17) projecting from the tube (13) for fastening to a second bone part, wherein a setting mechanism (19) is arranged within the tube (18) and can be actuated by repeated relative rotational movements between the tube (13) and the rod (15), wherein the rod (15) can be moved out of the tube (13) or can be moved into the tube (13) by actuating the setting mechanism (19), wherein the setting mechanism (19) comprises a threaded element (23) which is rotatable about an axis of rotation (D) in an internal thread (21) of the tube (13) and with which the rod (15) is in engagement via a coupling toothed arrangement (25), and wherein the setting mechanism (19) has a connection element (27) rigidly fastened to the rod (15), wherein the connection element (27) extends through the threaded element (23) and projects from the threaded element (23) at a side (29) facing away from the rod (15), and wherein the connection element (27) extends within the threaded element (23) with a radial free space (31).

2. A curved intramedullary nail (11) according to claim 1, wherein a part (33) of the connection element (27) that projects from the threaded element (23) extends with a radial free space (31a, 31b) in the tube (13); and / or wherein the connection element (27) is formed in a straight line.

3. A curved intramedullary nail (11) according to claim 1 or 2, wherein the connection element (27) is centered at an end section (35) of the threaded element (23), said end section facing the rod (15), by means of the threaded element (23), in particular wherein the threaded element (23) has a radially inwardly projecting centering section (37) for centering the connection element (27), the axial length of said centering section (37) being in a range from 1 / 10 to 1 / 3, in particular 1 / 8 to 1 / 4, of the axial length of the threaded element (23) or amounting to 1 / 7 of the axial length of the threaded element (23).

4. A curved intramedullary nail (11) according to claim 3, wherein the connection element (27) extends completely with a radial free space (31) in the threaded element (23) between the end section (35) of the threaded element (23) that faces the rod (15) and an end face (39) of the threaded element (23) that faces away from the rod (15); and / or wherein the connection element (27) has a radial abutment widening (41), wherein the end section (35) of the threaded element (23) and the abutment widening (41) of the connection element (27) limit an axial relative movement between the rod (15) and the threaded element (23).

5. A curved intramedullary nail (11) according to any one of the preceding claims, wherein a rotational movement of the rod (15) about the axis of rotation (D) relative to the tube (13) is limited, wherein the rod (15) in particular has a key (43) which is guided within the tube (13) in a groove (45), wherein the groove (45) limits a rotational movement of the rod (15) about the axis of rotation.

6. A curved intramedullary nail (11) according to any one of the preceding claims, wherein a rotation of the rod (15) about the axis of rotation (D) along a first direction of rotation (D1) can be transmitted to the threaded element (23) via the coupling toothed arrangement (25).

7. A curved intramedullary nail (11) according to claim 6, wherein the rod (15) is rotatable relative to the threaded element (23) about the axis of rotation (D) in a second direction of rotation (D2) opposite the first direction of rotation (D1).

8. A curved intramedullary nail (11) according to claim 7, wherein the threaded element (23) is in engagement with a blocking element (49) at a side facing away from the rod (15) via a blocking toothed arrangement (47), wherein the connection element (27) is guided through the blocking element (49) and projects out of the blocking element (49) with an extension section (51) at a side facing away from the threaded element (23), and wherein the connection element (27) extends with a radial free space (31a) in the blocking element (49).

9. A curved intramedullary nail (11) according to claim 8, wherein the blocking element (49) is guided in a manner secure against rotation in the tube (13), in particular wherein the blocking element (49) has a key (53) which is guided within the tube (13) in a groove (45); and / or wherein the blocking toothed arrangement (47) has a freewheel in the first direction of rotation (D1), by which freewheel the threaded element (23) is released for a rotation along the first direction of rotation (D1) relative to the blocking element (49), and wherein the blocking toothed arrangement (47) forms a detent in the second direction of rotation (D2) that blocks a rotation of the threaded element (23) relative to the blocking element (49) along the second direction of rotation (D2), wherein the coupling toothed arrangement (25) in particular has a freewheel in the second direction of rotation (D2) that enables a rotation of the rod (15) relative to the threaded element (23), which is blocked by the blocking toothed arrangement (47), along the second direction of rotation (D2).

10. A curved intramedullary nail (11) according to claim 8 or 9, wherein the setting mechanism (19) comprises a centering element (57) which blocks the blocking element (49) against movements in a radial direction relative to the threaded element (23), in particular wherein the centering element (57) is configured as a centering sleeve (59) onto or into which the blocking element (49) and the threaded element (23) can be plugged; and / or in particular wherein the blocking element (49) and the threaded element (23) have a respective radial opening (61, 63) at their inner side or their outer side, wherein the centering element (57) is arranged in the radial openings (61, 63) and forms an axial connection between the threaded element (23) and the blocking element (49).

11. A curved intramedullary nail (11) according to any one of the claims 8 to 10, wherein the blocking element (49) is preloaded towards the threaded element (G) via the connection element (27), in particular wherein the blocking element (49) can be brought out of engagement with the threaded element (23) against the return force of the preload.

12. A curved intramedullary nail (11) according to claim 11, wherein a tensioning device (67), in particular a spring (69), is coupled to the connection element (27) and preloads the blocking element (49) towards the threaded element (23).

13. A curved intramedullary nail (11) according to claim 12, wherein the tensioning device (67) comprises a spring (69) or is configured as a spring (69) which is supported at the blocking element (49) and at the extension section (51) of the connection element (27), in particular wherein the spring (69) is supported at an end face (71) of the blocking element (49) that faces away from the threaded element (23); or in particular wherein the blocking element (49) has a spring receiver (73), in particular a bore or a slot, in which the spring (69) is at least partly received, wherein the spring (69) is supported in the direction of the threaded element (23) at a base (74) of the spring receiver (73).

14. A curved intramedullary nail (11) according to claim 12 or 13, wherein the setting mechanism (19) has an abutment (75) which limits an axial movement of the connection element (27) against the force of the tensioning device (67).

15. A curved intramedullary nail (11) according to claim 14, wherein the abutment (75) comprises a radial widening (77) of the connection element (27), in particular wherein the radial widening (77) of the connection element (27) is formed by an abutment widening (41) at a section of the connection element (27) that extends within the threaded element (23), wherein the abutment widening (41) and a radially inwardly directed centering section (37) of the threaded element (23) form the abutment (75) of the setting mechanism (19); or in particular wherein the radial widening (77) of the connection element (27) is formed at the extension section (51) of the connection element (27), wherein the radial widening (77) and an end face (71) of the blocking element (49) that faces away from the threaded element (23) form the abutment (75) of the setting mechanism (19).