Torque transmission mechanism

Abstract

Disclosed herein is an implantable medical device having a biocompatible housing, a driver of rotational motion, a receiver of rotational motion, and a joint configured to transmit torque from the driver to the receiver, hi various embodiments, the joint comprises a magnetic element, a mechanical element, or a magnetic and mechanical element for transmitting torque.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This patent application claims priority to U.S. Provisional Patent Application No. 63 / 375,481, filed September 13, 2022. [Background technology]

[0002] The present invention relates generally to a method and joint for transmitting torque from a rotary driver to a rotary receiver, and more particularly to an implantable medical device including a rotary driver, a rotary receiver, and a joint disposed therebetween for transmitting torque from the driver to the receiver.

[0003] Various implant systems, including spinal distraction and compression systems, intramedullary and extramedullary distraction and compression systems, and the like, function in part by transmitting rotational motion from a driver to a receiver so that the implant achieves the desired distraction or compression.

[0004] Torque transmission joints for use in implantable medical devices exist in the prior art. For example, U.S. Pat. No. 9,848,914 (filed July 15, 2014) and U.S. Pat. No. 9,421,046 (filed August 4, 2014), both of which are incorporated herein by reference in their entireties for all purposes, describe torque transmission joints that include the use of a pin and aperture arrangement to facilitate the transmission of torque from a driving element to a lead screw as a receiving element within an implant. However, torque transmission components with additional capabilities and features may be desirable. For example, a torque transmission joint that allows for side-load assembly rather than axial assembly within the implant may facilitate assembly. Joints that allow axial translation of one or both of the mechanisms while maintaining torque transmission may also be desirable. Furthermore, joints that allow or are adaptable to non-concentric shaft arrangements, facilitate torque transmission without direct contact between the components, and / or provide float between the components may be desirable. A certain degree of float may allow the components to connect despite any minor imperfections in the parts themselves.

[0005] Therefore, to address these and other challenges, mechanical and magnetic torque transmission methods and components are provided herein. Summary of the Invention

[0006] A first aspect of the present disclosure provides an implant comprising a biocompatible housing, a driver, a receiver, and a joint configured to transmit torque from the driver to the receiver. The joint comprises a first magnetic member rotatably secured to the driver, the first magnetic member comprising a dipole magnet, wherein rotation of the driver is configured to cause rotation of the first magnetic member. A second magnetic member rotatably secured to the receiver, wherein rotation of the second magnetic member is configured to cause rotation of the receiver, the first magnetic member being configured to attract the second magnetic member, and the second magnetic member being configured to rotate in response to rotation of the first magnetic member.

[0007] In some embodiments, the second magnetic member is configured to rotate more slowly than the first magnetic member, e.g., the rotation of the second magnetic member may lag behind the rotation of the first magnetic member.

[0008] In some embodiments, the second magnetic member comprises a dipole magnet.

[0009] In some embodiments, the first magnetic member is magnetically coupled to the second magnetic member.

[0010] In some embodiments, the first magnetic member comprises a disk-shaped dipole magnet and the second magnetic member comprises a disk-shaped dipole magnet.

[0011] In some embodiments, the joint further comprises a component disposed between the first magnetic member and the second magnetic member, the component comprising a thrust bearing or a friction reducing component.

[0012] In some embodiments, the first magnetic member comprises a cross-sectional shape configured to provide a complementary fit with the cross-sectional shape of the second magnetic member.

[0013] In some embodiments, the second magnetic member is at least partially disposed within the first magnetic member in a male-female arrangement, and the first and second magnetic members are substantially axially aligned.

[0014] In some embodiments, the first magnetic member further comprises a barrel or shape and the second magnetic member further comprises a solid cylindrical shape, and the first magnetic member and the second magnetic member are arranged substantially concentrically.

[0015] In some embodiments, the second magnetic member comprises a magnetic material.

[0016] In some embodiments, the first magnetic member comprises a cross-sectional shape configured to provide a complementary fit with the cross-sectional shape of the second magnetic member.

[0017] In some embodiments, the second magnetic member is at least partially disposed within the first magnetic member in a male-female arrangement, and the first and second magnetic members are substantially axially aligned.

[0018] In some embodiments, the first magnetic member and the second magnetic member are rotationally locked relative to one another and axially free relative to one another.

[0019] In some embodiments, the first magnetic member further comprises a first engagement surface and the second magnetic member comprises a second engagement surface, the second magnetic member configured to rotate in response to a force exerted by the first engagement surface on the second engagement surface.

[0020] In some embodiments, the second magnetic member comprises a cross-sectional geometry selected from a semicircular shape, an irregular shape having at least one arc and one flat side, an irregular shape having at least one arc and two flat sides, an irregular shape having at least one arc and three flat sides, an irregular shape having at least one arc and four or more flat sides, a slotted circle, a cross or Phillips head, a hexalobular shape, and a keyed shape.

[0021] A second aspect of the present disclosure provides an implant including a biocompatible housing, a driver, a receiver, and a joint configured to transmit torque from the driver to the receiver. The joint includes a receptacle disposed on an end of the driver, the receptacle configured to receive an end portion of the receiver therein. The receptacle includes a first receptacle groove and a second receptacle groove, each disposed on an annular inner wall of the receptacle, and a first receiver groove and a second receiver groove, each disposed on a radially outer surface of the end portion of the receiver. When the receiver end portion is disposed within the receptacle, the first receptacle groove and the first receiver groove mate to form a first annular space, and the second receptacle groove and the second receiver groove mate to form a second annular space. The first toroidal spring is disposed within the first annular space and is inclined in a first direction, and the second toroidal spring is disposed within the second annular space and is inclined in a second direction, the second direction being opposite to the first direction.

[0022] In some embodiments, the first toroidal spring and the second toroidal spring each include a coil spring having a first end welded to a second end.

[0023] In some embodiments, the first toroidal spring has the same diameter as the second toroidal spring.

[0024] In some embodiments, the first toroidal spring has a first diameter and the second toroidal spring has a second diameter different from the first diameter.

[0025] In some embodiments, the first end of the receiver comprises a shaft having a stepped diameter shaft, a first annular space having a first diameter disposed in the first step, and a second annular space having a second diameter disposed in the second step.

[0026] In some embodiments, the end portion of the receiver further comprises a shaft and a collar disposed on the shaft, with one of the first annular space or the second annular space being disposed on the collar and the other of the first annular space or the second annular space being disposed on the shaft itself.

[0027] These and other aspects, advantages and salient features of the present invention will become apparent from the following detailed description, which, taken in conjunction with the accompanying drawings, in which like parts are designated with like reference characters throughout, disclose embodiments of the present invention. [Brief explanation of the drawings]

[0028] [Figure 1] 1 illustrates a perspective view of an implantable device, in accordance with an embodiment of the present invention. [Figure 2] 1 illustrates a cross-sectional view of an implantable device according to an embodiment of the present disclosure. [Figure 3] 1 illustrates a cross-sectional view of a portion of an implantable device, in accordance with an embodiment of the present invention. [Figure 4] 1 illustrates a perspective view of a portion of an implantable device including a gear stage according to an embodiment of the present disclosure. [Figure 5] 1 illustrates a perspective view of a portion of an implantable device including a gear stage according to an embodiment of the present disclosure. [Figure 6] 5 illustrates a perspective view of a portion of the implantable device of FIG. 4 having a ring gear disposed around the gear according to an embodiment of the present disclosure. [Figure 7] 1 shows a perspective view of a first magnetic torque transmission joint according to an embodiment of the present invention. [Figure 8] 1 shows an exploded perspective view of a second magnetic torque transmission joint according to an embodiment of the present disclosure. [Figure 9] FIG. 10 shows a perspective view of a third magnetic torque transmission joint according to an embodiment of the present invention. [Figure 10A] 1 illustrates a cross-sectional view of a toroidal spring torque transfer joint according to an embodiment of the present invention. [Figure 10B]1 illustrates a cross-sectional top view of a portion of a toroidal spring torque transfer junction according to an embodiment of the present disclosure. [Figure 10C] 1 illustrates a cross-sectional top view of a portion of a toroidal spring torque transfer junction according to an embodiment of the present disclosure. [Figure 11A] 1 shows a perspective view of a mechanical torque transmission joint according to an embodiment of the present invention. [Figure 11B] 1 illustrates a perspective view of a portion of a mechanical torque transfer joint according to an embodiment of the present disclosure. [Figure 11C] 1 illustrates a perspective view of a portion of a mechanical torque transfer joint according to an embodiment of the present disclosure. [Figure 11D] 1 illustrates a perspective view of a portion of a mechanical torque transfer joint according to an embodiment of the present disclosure. [Figure 11E] 1 illustrates a perspective view of a portion of a mechanical torque transfer joint according to an embodiment of the present disclosure. [Figure 11F] 1 illustrates a perspective view of a portion of a mechanical torque transfer joint according to an embodiment of the present disclosure. [Figure 11G] 1 illustrates a perspective view of a portion of a mechanical torque transfer joint according to an embodiment of the present disclosure. [Figure 11H] 1 illustrates a perspective view of a portion of a mechanical torque transfer joint according to an embodiment of the present disclosure. [Figure 11I] 1 illustrates a perspective view of a portion of a mechanical torque transfer joint according to an embodiment of the present disclosure. [Figure 11J] 1A-1C show side, perspective, and end views, respectively, of a portion of a mechanical torque transfer joint according to an embodiment of the present disclosure; [Figure 11K] 1A-1C show side, perspective, and end views, respectively, of a portion of a mechanical torque transfer joint according to an embodiment of the present disclosure; [Figure 11L] 1A-1C show side, perspective, and end views, respectively, of a portion of a mechanical torque transfer joint according to an embodiment of the present disclosure; [Figure 11M] 1 illustrates a perspective view of a portion of a mechanical torque transfer joint according to an embodiment of the present disclosure. [Figure 11N] 1 illustrates a perspective view of a portion of a mechanical torque transfer joint including a keyway according to an embodiment of the present disclosure. [Figure 11O] 1 illustrates a perspective view of a portion of a mechanical torque transfer joint including a pair of keyways according to an embodiment of the present disclosure. [Figure 12] 1 illustrates a perspective view of a portion of a torque transfer joint including a pin and shank sleeve joint according to an embodiment of the present disclosure. FIG. [Figure 13A] 1A-1C show cross-sectional top and side views of a portion of a mechanical torque transfer joint including a set screw according to an embodiment of the present disclosure. [Figure 13B] 1A-1C show cross-sectional top and side views of a portion of a mechanical torque transfer joint including a set screw according to an embodiment of the present disclosure. [Figure 14A] 1 illustrates a perspective view of a portion of a mechanical torque transfer joint including a T-slot according to an embodiment of the present disclosure. [Figure 14B] 1 illustrates a perspective view of a portion of a mechanical torque transfer joint including a T-slot according to an embodiment of the present disclosure. [Figure 15A] 1 illustrates a side view of a portion of a mechanical torque transfer joint including a spline and a retaining ring according to an embodiment of the present disclosure. [Figure 15B] 1 illustrates a side view of a portion of a mechanical torque transfer joint including a spline and a retaining ring according to an embodiment of the present disclosure. [Figure 16] 1 illustrates an exploded perspective view of a portion of a mechanical torque transfer joint including multiple pins according to an embodiment of the present disclosure. [Figure 17A] 1 illustrates a perspective view of a portion of a mechanical torque transfer joint according to an embodiment of the present disclosure. [Figure 17B] 1 illustrates a perspective view of a portion of a mechanical torque transfer joint according to an embodiment of the present disclosure. [Figure 18A] 1A-1C show side cross-sectional and perspective views of a portion of a mechanical torque transfer joint according to an embodiment of the present disclosure; [Figure 18B] 1A-1C show side cross-sectional and perspective views of a portion of a mechanical torque transfer joint according to an embodiment of the present disclosure;

[0029] It should be noted that the drawings of the disclosure are not necessarily to scale. The drawings are intended to depict only typical aspects of the disclosure and therefore should not be considered limiting of the scope of the disclosure. In the drawings, like numbers represent like elements between the drawings. DETAILED DESCRIPTION OF THE INVENTION

[0030] Various embodiments of the present invention provide a junction for transmitting torque from a driver to a receiver in an implantable medical device system, or "implant," as that term is used herein. Such implants are also known as bone movement devices or distraction devices and may include spinal distraction and compression systems, intramedullary distraction and compression systems, extramedullary distraction and compression systems, etc. While certain embodiments of the present invention are illustrated in connection with an implant in the form of an intramedullary distraction device, it is understood that the present teachings are equally applicable to other distraction and compression systems.

[0031] FIG. 1 illustrates an exemplary implant 100 having an adjustable portion 104 and a distraction rod 106. The implant 100 is configured to be attached at its first end 108 to a first section of bone and at its second end 110 to a second section of bone. A variety of different rod configurations can be used, each having a specific angle and length depending on the condition to be treated. Multiple configurations are contemplated, such as for the tibia, femur, both anterior and posterior positions, and spinal distraction and compression. In FIG. 1 , the adjustable portion 104 is angled, while the distraction rod 106 is straight. However, in other embodiments, the adjustable portion 104 may be straight through the first end 108. The holes 116, 118, 120, 122, and 124 are configured with specific diameters and orientations to accommodate bone screws within each respective hole for securing the implant 100 to the bone sections. The implant 100 may be used to perform distraction and compression procedures as understood in the art and as described, for example, in U.S. Pat. Nos. 9,848,914 and 9,421,046, previously incorporated by reference herein.

[0032] 2 and 3 provide cross-sectional views illustrating the interaction between the distraction rod 106 and the adjustable portion 104. As best seen in FIG. 2, the end 110 of the distraction rod 106 includes an elongated recess 112 disposed therein and opens to an end disposed within the adjustable portion 104. The recess 112 is sized to receive a lead screw 160. The lead screw 160 may be made from a high-strength material, such as titanium. As shown in more detail in FIG. 3, at least a portion of the lead screw 160 includes external threads 162 configured to engage a nut 156 mounted within the recess 112. The nut 156 provides a threaded portion on the interior surface of the recess 112 of the distraction rod 106. The lead screw 160 may have, for example, 80 threads per inch, although more or less than this number may be used. The nut 156 may include threads or a chamfer on its outer diameter to facilitate secure attachment to the inner diameter of the recess 112 of the distraction rod 106. For example, the nut 156 may be bonded to the distraction rod 106 using an adhesive. This allows the distraction rod 106 to be manufactured from a single piece of stronger material. This also provides clearance between the lead screw 160 and the inner diameter of the distraction rod 106. Alternatively, the threaded portion may be formed directly into the recess 112 without the aid of a separate nut 156.

[0033] The nut 156 includes internal threads 158 that mate with external threads 162 of the lead screw 160. In one particular embodiment, the nut 156 may be made from aluminum bronze #630. Using dissimilar metals with different hardness values, for example, titanium for the lead screw 160 and aluminum bronze for the nut 156, may reduce galling / binding between the lead screw 160 and the nut 156. This further allows the lead screw 160 and the nut 156 to operate with reduced friction. Optionally, various wet or dry lubricants may be used to reduce friction between the lead screw 160 and the nut 156.

[0034] The end of the distraction rod 106 opposite the end 110 containing the fixation apertures or holes 120, 122, 124 is disposed within the interior surface of a tubular housing 126 of the adjustable portion 104. The distraction rod 106 is configured to telescope relative to the tubular housing 126. Despite the telescopic movement of the distraction rod 106 in and out of the tubular housing 126, the ingress of foreign matter into the housing 126 can be prevented using one or more O-rings and other features, such as those described in U.S. Pat. No. 9,848,914.

[0035] The distraction rod 106 may be coupled to the magnetic assembly 136 via the lead screw 160 in combination with any of several torque transmission joints 300 as described herein. The magnetic assembly 136, described in more detail below, functions as a driver to drive the rotation. This rotation may be transmitted through the torque transmission joint 300 to a torque receiving component or receiver used herein. In the embodiments described herein, the receiver may typically be the lead screw 160.

[0036] The joint 300 between the lead screw 160 and the magnetic assembly 136 has several functions. The joint must withstand large compressive loads. It may also need to withstand large tensile loads. Additionally, the joint must transmit torque from the rotating magnetic assembly 136 to the lead screw 160. The joint 300 must also maintain concentric alignment between the lead screw 160 and the nut 156. Compressive loads are transmitted down the lead screw 160 into the magnetic assembly 136, which rests on the thrust ball bearing 150. Tensile loads are transmitted from the magnetic assembly 136 across the joint 300 to the lead screw 160. Torque forces are transmitted from the magnetic assembly 136 through the joint 300 to the lead screw 160. Because the magnetic assembly 136 cannot transmit unlimited torque, it is desirable to avoid even small mechanical losses due to component coupling.

[0037] An embodiment of the magnetic assembly 136 is best seen in FIG. 3 . The magnetic assembly 136 includes an upper cup 140 and a lower cup 142. A permanent magnet 154 is located within a recess formed between the inner portions of the upper cup 140 and the lower cup 142. The permanent magnet 154 may be cylindrical and may be a radially polarized magnet. The permanent magnet 154 may have, for example, a diameter of approximately 0.28 inches and a length of approximately 0.73 inches, although other dimensions may be used. The permanent magnet 154 may include a rare earth magnet formed, for example, from neodymium-iron-boron. The magnet may be made from an N35 grade or higher, such as an N50 grade. The permanent magnet 154 is glued or otherwise attached to the upper cup 140 and the lower cup 142. This allows torque applied to the permanent magnet 154 to be transmitted to the upper cup 140 and, therefore, to the lead screw 160. The length of the permanent magnet 154 is shorter than the combined length of the interior cavities of the upper and lower cups 140, 142. This ensures that when the magnetic assembly 136 is under compression, the stress is applied to the upper and lower cups 140, 142, rather than the permanent magnet 154.

[0038] The permanent magnet 154 may be rotated or "driven" through application of a magnetic field by an external adjustment device, such as the external adjustment device described in U.S. Patent No. 9,848,914. The external adjustment device may be placed against the subject's skin in the manner described herein to remotely rotate the internal permanent magnet 154. As described herein, rotation of the internal permanent magnet 154 causes rotational movement of the magnetic assembly 136. This rotational movement is then transmitted to the lead screw 160 via the joint 300. Depending on the direction of rotation of the lead screw 160, the distraction rod 106 telescopes out or in from the adjustable portion 104 in response to movement of the lead screw within the cavity 112. In this regard, by controlling the rotational movement of the magnetic assembly 136 using the external adjustment device, the operator can controllably adjust the linear movement of the distraction rod 106.

[0039] Returning to the magnetic assembly 136, the permanent magnet 154 may be contained within a magnet housing 164 having an end cap 166. The magnet housing 164 may further be welded to the end cap 166 to create an airtight seal. The end cap 166 includes a cylindrical extension or axle 168 that fits within the inner diameter of a radial bearing 170, allowing for low-friction rotation. The outer diameter of the radial bearing 170 fits within a cavity 172. The magnetic assembly 136 may terminate at an opposite end in a first sun gear 178, which may be integral with the magnet housing 164. Alternatively, the first sun gear 178 may also be fabricated as a separate component and secured to the magnet housing 164, for example, by welding. In either case, the first sun gear 178 orbits in a 1:1 manner with the rotation of the magnetic assembly 136 upon application of a moving magnetic field applied to the patient from an external location, as discussed herein. As best shown in FIG. 4, the first sun gear 178 is configured to be inserted into an opening 190 in a first gear stage 180 having three planetary gears 186 rotatably held in a frame 188 by axles 192. A second sun gear 194 (see FIG. 3), which is the output of the first gear stage 180, orbits with the frame 188. Identical components, including the opening 190, frame 188, and three planetary gears 186 held by respective axles 192, exist in the second gear stage 182, which outputs to a third sun gear 196 (see FIG. 3), and in the third gear stage 184, which, like the first and second gear stages 180, 182, also includes the opening 190, frame 188, and three planetary gears 186 held by respective axles 192. The third gear stage 184 outputs to an output shaft 198, as best seen in FIG. 5. As shown in Figure 6, ring gear 176 is disposed around and extends axially along the length of first through third gear stages 180, 182, and 184. Ring gear 176 includes internal teeth 202 along its inner wall 200. The internal teeth 202 of ring gear 176 are configured to engage outwardly extending teeth 204 of planet gears 186 as they orbit.Each illustrated gear stage has a 4:1 gear ratio, so that the output shaft 198 rotates once for every 64 revolutions of the magnetic assembly 136. The 64:1 gear ratio enables the implant 100 to axially displace bone segments against strong resistance forces, such as those created by soft tissue. To protect the gear stages 180, 182, 184 and the magnetic assembly 136 from compressive forces transmitted from the lead screw 160, a thrust bearing 262 (see FIG. 3) may be disposed between the lead screw 160 and the gear stages 180, 182, 184.

[0040] Torque is transmitted from the driver to the receiver at junction 300, as previously described. The magnetic assembly 136, the first, second, and third gear stages 180, 182, 184, and the output shaft 198, and the components that couple these features together as described herein, may collectively be considered a driver 302, while the lead screw 160 and the features coupled thereto whose movement is fixed relative to the lead screw 160 may collectively be considered a receiver 304 (see FIG. 2 ). Torque is therefore generated by the magnetic assembly 136, amplified by the gear stages 180, 182, 184, output from the output shaft 198, and transmitted by junction 300 to the lead screw 160 and downstream driven or receiving components.

[0041] 7-19 illustrate various joints 300 according to embodiments of the present disclosure. In certain embodiments, the joint 300 may be configured to transmit torque from the driver 302 to the receiver 304 while allowing axial translation of one or more components without compromising torque transmission. In certain embodiments, the joint 300 may further provide the advantage of facilitating side loading of components during assembly of the implant 100, rather than axial insertion. In still further embodiments, the joint 300 may be configured to provide a margin of float between the driver 302 and the receiver 304, allowing torque coupling and transmission despite any imperfections that may exist in one component or another. Still further, in certain embodiments, the joint 300 may limit or avoid direct contact between the driver 302 and the receiver 304 and / or may adaptably accommodate non-concentric shafts. These features provide the advantage of reducing friction and wear and improving the efficiency of the torque-transmitting joint.

[0042] 7-9 illustrate an embodiment in which the joint 300 may be a magnetic joint and may include a primary or first magnetic member 306 rotationally fixed to the driver 302 such that rotation of the driver 302 is configured to cause rotation of the first magnetic member 306. The first magnetic member 306 may be, in particular, a dipole magnet having a north pole 312 and a south pole 314. A secondary or second magnetic member is rotationally fixed to the receiver 304 such that rotation of the second magnetic member 308 is configured to cause rotation of the receiver 304. The first magnetic member 306 is configured to attract the second magnetic member 308, which is configured to rotate in response to rotation of the first magnetic member 306.

[0043] 7, the second magnetic member 308 may also comprise a dipole magnet having a north pole 316 and a south pole 318. The first magnetic member 306 and the second magnetic member 308 may be magnetically coupled to one another, for example, such that the north pole 316 of the second magnetic member 306 attracts the south pole 314 of the first magnetic member 308 and the north pole 312 of the first magnetic member 306 attracts the south pole 318 of the second magnetic member 308.

[0044] 7 , in certain embodiments, the second magnetic member 308 can be configured to rotate more slowly than the first magnetic member 306. For example, the rotation of the second magnetic member 308 can lag behind the rotation of the first magnetic member 306, either in the speed or time of initiation of the rotational movement. In this manner, the relationship between the first magnetic member 306 and the second magnetic member 308 can cushion the movement of the second magnetic member 308, such that even if the first magnetic member 306 rotates immediately upon rotation of the driver 302, the second magnetic member 308 can tend to seek ideal alignment for a short period of time after the driver 302 has rotated. In this manner, the magnetic relationship between the first magnetic member 306 and the second magnetic member 308 can act as a shock absorber to limit the application of sudden changes in force to patient tissue, for example, during a distraction procedure.

[0045] For example, for bone movement processes such as distraction, the optimal motion for bone growth is continuous, smooth, and slow. Thus, a torque transfer joint employing magnetic coupling between driver 302 and receiver 304 as described herein may provide an improved ability to achieve torque transfer with gradual motion as the magnets transition from out-of-phase to in-phase.

[0046] The first magnetic member 306 may have a cross-sectional shape configured to provide a complementary fit with the cross-sectional shape of the second magnetic member 308. In such embodiments, the second magnetic member 308 may be at least partially disposed within the first magnetic member 306 in a male-female arrangement, although the opposite arrangement may also be used. In either orientation, in certain embodiments, the first and second magnetic members 306, 308 may be substantially axially aligned with one another.

[0047] As illustrated in FIG. 7 , in certain embodiments, the second magnetic member 308 may be substantially or completely disposed within an opening or hollow space 310 in the first magnetic member 306. A certain amount of axial movement of the second magnetic member 308 relative to the first magnetic member 306 may be permitted, for example, a fraction of a millimeter. The first magnetic member 306 may be substantially annular, may have a hollow cylindrical or barrel shape, and may have a circular cross-sectional geometry, while the second magnetic member 308 may have a solid cylindrical shape and a circular cross-sectional geometry. The first magnetic member 306 and the second magnetic member 308 may also be substantially concentrically disposed around the rotation axis 320. Due to the magnetic coupling between the first magnetic member 306 and the second magnetic member 308, the driver 302 and the receiver 304 are rotationally locked relative to each other. However, due to the opening of hollow space 310 to the end of first magnetic member 306 facing receiver 304, the coupling between first magnetic member 306 and second magnetic member 308 allows axial movement of first magnetic member 306 relative to second magnetic member 308 at joint 300. As illustrated in FIG. 7 , in some embodiments, a space or gap may exist within hollow space 310 between inner wall 307 of first magnetic member 306 and outer wall 309 of second magnetic member 308. In other embodiments, this space may be substantially eliminated, and second magnetic member 308 may fit closely within first magnetic member 306.

[0048] Turning now to FIG. 8 , according to another embodiment, the first or primary magnetic member 306 is a dipole magnet having a north pole 312 and a south pole 314 and a hollow space or opening 310, as discussed above with respect to FIG. 7 . Similar to the first magnetic member 306 of FIG. 7 , the first magnetic member 306 of FIG. 8 may be substantially annular or may have a hollow cylindrical configuration with a radially outward surface 305 and a hollow space or opening 310 therein. The hollow space 310 is open at least at the end of the first magnetic member 306 facing the second magnetic member 308 and is configured to receive the second magnetic member 308 therein. The second magnetic member 308 may be at least partially disposed within the hollow space 310 within the first magnetic member 306 in a male-female arrangement. As illustrated in FIG. 8 , the second magnetic member 308 may be inserted into the hollow space 310 within the first magnetic member 306 in the direction of the arrow. In certain embodiments, the first and second magnetic members 306, 308 may be partially, substantially, or completely axially aligned with one another such that the second magnetic member 308 may be partially, substantially, or completely disposed within a hollow space 310 disposed within the first magnetic member 306. Some axial movement of the second magnetic member 308 relative to the first magnetic member 306 may be permitted. In some embodiments, the hollow space 310 may be open at the end of the first magnetic member 306 facing the driver 302 in addition to being open at the end of the first magnetic member facing the receiver 304. Such embodiments may permit a greater amount of axial movement of the second magnetic member 308 relative to the first magnetic member 306.

[0049] In the embodiment of FIG. 8 , the second magnetic member 308 is made of a magnetic material. In certain embodiments, the second magnetic member 308 may not be a magnet itself, but may be, for example, a ferrous metal bar. As discussed above, the joint of FIG. 8 may allow axial movement of the first and second magnetic members 306, 308 relative to one another, although this axial movement may tend to be limited by magnetic attraction between the first and second magnetic members 306, 308. This magnetic attraction may tend to contribute to achieving and maintaining axial alignment of the first and second magnetic members 306, 308 relative to one another.

[0050] The first magnetic member 306, and particularly the internal hollow space 310, may have a cross-sectional shape 325 configured to provide a complementary fit with a cross-sectional shape 326 of the second magnetic member 308. As shown in FIG. 8 , the cross-sectional shape 325 of the hollow space 310 of the first magnetic member 306 may include a first engagement surface 322, and the cross-sectional shape 326 of the second magnetic member 308 may include a second engagement surface 324. The first engagement surface 322 is configured to engage the second engagement surface 324 when the second magnetic member 308 is at least partially disposed within the hollow space 310 of the first magnetic member 306. Thus, the second magnetic member 308 is configured to rotate in response to a force exerted by the first engagement surface 322 on the second engagement surface 324 upon rotation of the first magnetic member 306. This engagement is configured to cause the second magnetic member 308 to rotate at a speed equal to that of the first magnetic member 306 .

[0051] 8, the second magnetic member 308 has a cross-sectional shape 326 that is "D-shaped," and the hollow space 310 has a corresponding complementary cross-sectional shape 325. Other geometric shapes are contemplated, such that the female cross-sectional shape 325 and the male cross-sectional shape 326 may include, for example, a crescent, a semicircle, an irregular shape having at least one arc and at least one flat side, an irregular shape having at least one arc and at least two flat sides, an irregular shape having at least one arc and at least three flat sides, an irregular shape having at least one arc and at least four or more flat sides, a slotted circle or a pair of separated semicircles and corresponding flat sides, a cross or Phillips head, a mating pair of hexalobular shapes, or any other mating pair of keyed shapes capable of transmitting torque as described herein or known in the art.

[0052] In the embodiment of FIG. 8 , the mating pair of cross-sectional shapes 326, 326 may be asymmetric, but each of the rotational features of the joint 300 is oriented in a concentric or substantial arrangement and has no material offset relative to the axis of rotation. The driver 302, receiver 304, and first and second magnetic members 306, 308 are concentric or substantially related to one another. In some embodiments, the three-dimensional shape of the second magnetic member 308 can be conceptualized by starting with the embodiment having the geometry depicted in FIG. 7 , making a flat cut to remove a quantity of material therefrom, and adding that material to the interior surface of the first magnetic member 306, such that the first and second magnetic members 306, 308 collectively form a cylinder concentric with the driver 302 and receiver 304. In other embodiments, the flat surface forming, for example, the engagement surface 324, need not be made of magnetic material. For example, the second magnetic member 308 may include a magnet surrounded by a cladding or coating of a non-magnetic material, such as steel, which may contribute to the cross-sectional shape 326 and the aspect of one or more of the engagement surfaces 324 .

[0053] The first magnetic member 306 may be rotationally fixed to the driver 302 such that rotation of the driver 302 is configured to cause rotation of the first magnetic member 306. The second magnetic member 308 is rotationally fixed to the receiver 304 such that rotation of the second magnetic member 308 is configured to cause rotation of the receiver 304. The second magnetic member 308 is configured to rotate in response to rotation of the first magnetic member 306.

[0054] 8, the driver 302 and receiver 304 are rotationally locked relative to one another due to the geometric relationship and magnetic attraction between the first magnetic member 306 and the second magnetic member 308. However, similar to that described with respect to FIG. 7, the coupling between the first magnetic member 306 and the second magnetic member 308 allows axial movement at the joint 300 of the first magnetic member 306 relative to the second magnetic member 308.

[0055] 9 , similar to the embodiment of FIG. 7 , the junction 300 may include a first magnetic member 306 including a dipole magnet having a north pole 312 and a south pole 314, and a second magnetic member 308 which may include a dipole magnet having a north pole 316 and a south pole 318. The first magnetic member 306 and the second magnetic member 308 may be magnetically coupled to one another, for example, such that the north pole 316 of the second magnetic member 308 attracts the south pole 314 of the first magnetic member 306 and the north pole 312 of the first magnetic member 306 attracts the south pole 318 of the second magnetic member 308. As shown in FIG. 9 , the first magnetic member 306 and the second magnetic member 308 may each comprise a disk-shaped dipole magnet which may be coupled to the driver 302 and the receiver 304, respectively.

[0056] The embodiment of FIG. 9 may further include a friction reducing component or thrust bearing 328 disposed axially between the first magnetic member 306 and the second magnetic member 308 and configured to prevent the first magnetic member 306 and the second magnetic member 308 from contacting each other and to resist damage to the magnetic members 306, 308 when the magnetic members 306, 308 are pressed against each other.

[0057] Continuing with reference to the embodiment of FIG. 9, in certain embodiments, the second magnetic member 308 may be configured to rotate more slowly than the first magnetic member 306 in a manner similar to that described above with respect to the embodiment of FIG. 7. In some examples, the final gear stage is coupled to the first circular magnet (the rightmost one), and the lead screw is coupled to the second circular magnet (the leftmost one). For example, the rotation of the second magnetic member 308 may lag behind the rotation of the first magnetic member 306, either in speed or time of initiation of rotational motion. In this manner, the relationship between the first and second magnetic members 306, 308, can cushion the movement of the second magnetic member 308, such that even if the first magnetic member 306 rotates shortly after the driver 302 rotates, the second magnetic member 308 may tend to seek ideal alignment for a short period of time after the driver 302 rotates. In this manner, the magnetic relationship between the first magnetic member 306 and the second magnetic member 308 can act as a shock absorber to limit the application of sudden changes in force to the patient tissue, for example, during a distraction procedure.

[0058] 10A-10C illustrate another embodiment of a joint 300 configured to transmit torque from a driver 302 to a receiver 304. As shown in the embodiment of FIG. 10A, the joint 300 includes a receptacle 330 disposed on an end of the driver 302 that is open to the end of the driver 302 that mates with the receiver 304. The receptacle 330 is configured to receive an end portion of the receiver 304 therein. A first receptacle groove 332 and a second receptacle groove 334 are each disposed on an annular inner wall 336 of the receptacle 330. A first receiver groove 338 and a second receiver groove 340 may each be disposed on a radially outer surface 342 of the end portion of the receiver 304. The pair of grooves, consisting of the first receptacle groove 332 and the first receiver groove 338, are axially aligned such that when the end portion of the receiver 304 is disposed within the receptacle 330, the first receptacle groove 332 and the first receiver groove 338 mate to form a first annular space 344. Similarly, the pair of grooves, consisting of the second receptacle groove 334 and the second receiver groove 340, are axially aligned such that when the end portion of the receiver 304 is disposed within the receptacle 330, the second receptacle groove 334 and the second receiver groove 340 mate to form a second annular space 346. The first and second annular spaces 344 and 346 are axially spaced apart from one another along the axial extent of the interface between the receptacle 330 and the end portion of the receiver 304.

[0059] A first toroidal spring 348 is disposed within the first annular space 344 such that it is circumferentially disposed around the end portion of the receiver 304. The first toroidal spring 348 is canted in a first direction, as shown in FIG. 10B. A second toroidal spring 350 is disposed within the second annular space 346 and is also circumferentially disposed around the end portion of the receiver 304. The second toroidal spring is canted in a second direction opposite the first direction, as shown in FIG. 10C. In certain embodiments, the directions may be reversed, such that the first toroidal spring 348 is canted in the second direction as shown in FIG. 10C and the second toroidal spring 350 is canted in the first direction opposite the second direction as shown in FIG. 10B.

[0060] When used together as shown in FIG. 10A , the first and second coil springs 348, 350 act as an infinite ratchet. Rotating the driver 302 in one direction lays down the coils of one spring 348 or 350, while rotating the driver 302 in the opposite direction raises the coils of the other spring 348 or 350, resisting movement. As described above with respect to FIGS. 10B and 10C , the coil springs 348 and 350 are inserted in opposite directions to self-impede and lock the rotational movement of the receiver 304 disposed through the coil springs 348, 350. This interaction provides the advantage of ease of assembly while allowing torque transmission from the driver 302 to the receiver 304. Notably, the receiver 304 is only inserted axially through the coil springs 348, 350, limiting the need for precise alignment of the driver 302 and receiver 304. Additionally, this arrangement provides some flexibility, i.e., float or play, in the connection between the driver 302 and the receiver 304, overcoming any potential imperfections in the alignment of the driver 302, the receiver 304, and / or the driver 302 and the receiver 304 within the implant 100.

[0061] In some embodiments, the first toroidal spring 348 and the second toroidal spring 350 may comprise coil springs with a first end welded or otherwise attached to a second end. The coil springs 348, 350 may be made of, for example, stainless steel, more specifically, 17-7 stainless steel.

[0062] In certain embodiments, such as that shown in FIG. 10A , the first toroidal spring 348 and the second toroidal spring 350 may have the same diameter as the other coil spring. In other embodiments, the first toroidal spring 348 has a first diameter, and the second toroidal spring 350 has a second diameter different from the first diameter. In such embodiments, the first end of the receiver 304 may include a stepped diameter shaft having a first annular space 344 disposed in a first step and having a first diameter, and a second annular space 346 disposed in a second step and having a second diameter. In further embodiments, the end portion of the receiver 304 may further include a shaft and a collar disposed thereon. The combination of the shaft and collar may achieve the effect of a stepped diameter shaft. In such an embodiment, one of the first annular space 344 or the second annular space 346 may be disposed on the collar, and the other of the first annular space 344 or the second annular space 346 may be disposed on the shaft.

[0063] 11A-11O, various joints 300 are provided that include any of several complementary geometric features configured to translate rotation from a driver 302 to a receiver 304. Such joints 300 may be configured to include geometric features similar to those of FIG. 8 described above. However, in joints 300 as illustrated in FIGS. 11A-11O, the first member 406 and the male member 408 may be made from a non-magnetic material.

[0064] 11A , the female member 406 may include a hollow space 410 therein that may have a cross-sectional shape 425 configured to provide a complementary fit with the cross-sectional shape 426 of the male member 408. The cross-sectional shape 425 of the hollow space 410 of the female member 406 may include a first engagement surface 422, and the cross-sectional shape 426 of the male member 408 may include a second engagement surface 424. The first engagement surface 422 is configured to engage the second engagement surface 424 upon rotation of the female member 406 in response to rotation of the driver 302 when the male member 408 is at least partially disposed within the hollow space 410 of the female member 406.

[0065] In various embodiments described herein, two or more engagement surfaces 422, 424 may be present on the cross-sectional shape 425, 426 of the male member 408 and the hollow space 410 of the female member 406. Regardless of the number of engagement surfaces, the male member 408 is configured to rotate in response to a force exerted by the first engagement surface 422 on the second engagement surface 424. This engagement is configured to cause the male member 408 to rotate at a speed equal to the speed of the female member 406.

[0066] As shown in FIG. 11A, the male member 408 may have a cross-sectional shape 426 that is "D-shaped" including arcs and flats (see also FIG. 11B), with the hollow space 410 having a corresponding complementary cross-sectional shape 425. Other geometric shapes are also contemplated, as illustrated in FIGS. 11C-11O. Each of FIGS. 11B-11I, 11N, and 11O illustrates an exemplary shape that may be used as the cross-sectional shape 426, which may be configured to matingly engage with a corresponding complementary cross-sectional shape 425 of the hollow space 410 in the female member 406 (FIGS. 11A, 11I). The female cross-sectional shape 425 and the male cross-sectional shape 426 may include any now known or later developed mating or keyed shape capable of transmitting torque, including, for example, a crescent, semicircular, or "D-shape" (FIG. 11B), an irregular shape having two flat sides and one or more arcuate sides (FIG. 11C), an irregular shape having three flat sides and one or more arcuate sides (FIG. 11D), an irregular shape having four flat sides and one or more arcuate sides (FIG. 11E), a regular or irregular hexagon (FIG. 11F), a slotted circle mated with a flat blade feature (FIG. 11G), a cross or Phillips head (FIG. 11H), a hexalobe (FIG. 11I), or a keyed geometric shape (FIGS. 11J, 11K, 11L, 11M, 11N, and 11O). Any of the aforementioned geometric features may be formed as an extrusion of the depicted geometry to form the male member 408. The male member 408 may then be disposed within a complementary shaped hollow space or opening 410 within the female member 406. As discussed in connection with certain other embodiments, such as the embodiment of Figures 7 and 8, the geometric engagement of the male member 408 and female member 406 rotationally locks the driver 302 to the receiver 304 but allows axial movement of the male member 408 and female member 406 relative to one another.

[0067] As shown in FIGS. 11J-11M, a guide ball (FIGS. 11J, 11K, 11L) or a guide pin (FIG. 11M) may be used to transfer torque from the driver to the receiver. In such embodiments, the female member 406 (FIG. 11L) includes an axial slot guide 430. The axial slot guide 430 includes at least one slot 431 (FIG. 11M) extending radially through the thickness of the first member 406 from the inner wall 407 defining the hollow space 410 to the radially outward surface 405. In one particular embodiment, the axial slot guide 430 includes two such slots 431, each spaced approximately 180 degrees apart from the other relative to the diameter of the female member 406.

[0068] An axial slot guide 430 including a slot 431 extends axially from the end face 411 (FIG. 11M) of the female member 406 that mates with the male member 408 to a location midway along the axial extent of the female member 406. The male member 408 may include a ball feature 433 (FIGS. 11J-11L) or a pin feature 432 (FIG. 11M) that extends radially outward from the male member 408 in a direction perpendicular to the axis of rotation. The ball 433 or pin 432 may be positioned near the end of the male member 408 that mates with the female member 406 and / or along the axial length of the male member 408. In embodiments including only one slot 431 in the female member 406, the ball 433 or pin 432 may extend radially outward from the male member 408 in one direction. In embodiments including two slots 431 as shown in Figure 11M, a pair of pins 432 may extend radially outward in opposite directions from the male member 408. Other arrangements are possible, such as arrangements in which the pins 432 and slots 431 engage at different angles, e.g., 90 degrees, or arrangements in which the balls 433 extend in more than one radial direction.

[0069] In use, the male member 408 is inserted into the hollow space or opening 410 of the female member 406 and rotationally positioned so that the ball 433 or pin 432 is aligned with the slot 431 of the axial slot guide 430. With the ball 433 or pin 432 aligned with the slot 431, the male member 408 may be inserted into the female member 406. The ball or pin 432 fits closely within the width of the slot 431, so that when the driver 302 rotates the female member 406, the walls of the slot 430 exert a rotational force on the ball 433 or pin 432 disposed therein, causing the male member 408 carried by the ball 433 or pin 432 to rotate. The closer the fit between the ball 433 or pin 432 and the walls of the slot 431, i.e., the smaller the gap between the ball 433 or pin 432 and the walls of the slot 431, the faster and more accurate the torque transmission.

[0070] 11N illustrates an embodiment of joint 300 in which keyway 414 and key 418 are used to rotationally lock the driver to the receiver for torque transmission. In such an embodiment, female member 406 may be in the form of a sleeve attached to the driver and may include a hollow space 410 therein that opens to the end opposite the connection to driver 302.

[0071] The hollow space 410 may have a substantially circular cross-sectional shape configured to receive the male member 408. At one or more locations along the circumference of the inner wall 407 of the hollow space or opening 416, the opening may further include a keyway 414 extending axially along the opening 410 and fluidly connected with the portion of the opening 410 having the substantially circular cross-sectional shape. The keyway 414 may be in the form of, for example, a groove, channel, or other recessed shape disposed on the inner wall 407.

[0072] The male member 408 may have a substantially circular cross-sectional shape and may be configured to be received within the opening 410 of the female member 406. At one or more locations around the circumference of the radially outer surface 405 of the male member 408, the male member 408 may include a keyway 415 extending axially along the outer surface 405. The keyway 415 may be in the form of, for example, a groove, channel, or other recessed shape and may correspond in shape and dimension to the keyway 414 on the opening 410. When the male member 408 is inserted into the opening 410, the male member 408 may rotate freely within the opening 410 without a key.

[0073] In use, the keyways 414, 415 may be rotationally aligned with one another. In this position, as shown in FIG. 11N, the keyways 414 and 415 together form a single keyway into which a key 418 may be disposed. The key 418 may be positioned with one end in the keyway 414 of the female member 406 and the other end in the keyway 415 of the male member 408. When the key 418 is positioned in both keyways 414, 415, the male member 408 and the female member 406 may translate relative to one another but are rotationally locked relative to one another by the presence of the key 418 in the keyways 414, 415. The closer the fit between the key 418 and the keyways 414, 415, i.e., the smaller the gap between the key 418 and the keyways 414, 415, the faster and more accurate the torque transmission.

[0074] Figure 11O depicts a joint 300 similar to the joint of Figure 11N. In the embodiment of Figure 11O, the joint 300 includes a pair of keyways 414 and a pair of keys 418 for rotationally locking the driver to the receiver for transmitting torque. In such an embodiment, the female member 406 may be in the form of a sleeve that is attached to the driver and may include a hollow space 410 therein that opens to the end opposite the connection to the driver 302.

[0075] The hollow space 410 may have a substantially circular cross-sectional shape configured to receive the male member 408. At one or more locations along the circumference of the inner wall 407 of the hollow space or opening 416, the opening may further include a first keyway 414 extending axially along the opening 410 and fluidly connected with the portion of the opening 410 having the substantially circular cross-sectional shape. The keyway 414 may be in the form of, for example, a groove, channel, or other recessed shape disposed on the inner wall 407. The second keyway 414 may extend axially along the opening 410 and fluidly connected with the portion of the opening 410 having the substantially circular cross-sectional shape. The two keyways 414 may be radially spaced apart from one another by, for example, about 90 degrees, about 180 degrees (as shown in FIG. 11O), about 270 degrees, or other measures intermediate between the aforementioned exemplary angular measurements. Similar to the first keyway 414, the second keyway 414 may also be in the form of a groove, channel, or other recessed shape disposed on the inner wall 407, for example.

[0076] The male member 408 may have a substantially circular cross-sectional shape and may be configured to be received within the opening 410 of the female member 406. At one or more locations around the circumference of the radially outer surface 405 of the male member 408, the male member 408 may include a pair of keyways 415 extending axially along the outer surface 405. The keyways 415 may be in the form of, for example, a groove, channel, or other recessed shape and may correspond in shape and dimension to the keyways 414 on the opening 410. The two keyways 415 may be radially spaced apart from one another by, for example, about 90 degrees, about 180 degrees (as shown in FIG. 11O), about 270 degrees, or other intermediate degrees between the aforementioned exemplary angular measurements. When the male member 408 is inserted into the opening 410, the male member 408 may freely rotate within the opening 410 without the keys 418.

[0077] In use, the pair of keyways 414, 415 may be rotationally aligned with one another. In this position, as shown in FIG. 11O, the keyways 414 and 415 together form a single keyway into which a key 418 may be disposed. The key 418 may be positioned with one side within the keyway 414 of the female member 406 and the other side within the keyway 415 of the male member 408. When the key 418 is positioned within both keyways 414, 415, the male member 408 and the female member 406 may translate relative to one another but are rotationally locked relative to one another by the presence of the key 418 within the keyways 414, 415. The closer the fit between the key 418 and the keyways 414, 415, i.e., the smaller the clearance between the key 418 and the keyways 414, 415, the faster and more accurate the torque transmission.

[0078] 11A-11O, the driver 302 and receiver 304 are rotationally locked relative to one another due to the geometric relationship between the female member 406 and male member 408. In the embodiments of Figures 11A-11O, regardless of the symmetry or asymmetry of the cross-sectional shape of a particular male member 408 and corresponding opening 410, each of the rotational features of the joint 300 is oriented in a substantially concentric arrangement with no offset relative to the axis of rotation. The driver 302, receiver 304, and the female member 406 and male member 408 are in a concentric relationship to one another.

[0079] 12 illustrates an embodiment of a joint 300 utilizing a pin and shank-sleeve connection. In such an embodiment, the female member 406 may be in the form of a sleeve attached to the driver 302 and may include a hollow space 410 therein that opens at an end opposite the connection to the driver 302. The hollow space 410 may have a cross-sectional shape configured to provide a complementary fit with the cross-sectional shape of a portion of the male member 408. At an end opposite the end where the male member is coupled to the receiver 304, the male member 408 may include a shank 412 having a pin 432 extending in a direction perpendicular to the axis of rotation. The female member 406 may include an opening 410 having a cross-sectional shape configured to matingly receive the shank 412 and pin 432 therein. The pin 432 may be disposed at a point along the axial extent of the shank 412 so that, in use, the end of the shank 412 may be inserted into the opening 410 regardless of rotational orientation, but insertion of the pin and portion of the shank beyond the pin 432 requires rotational alignment of the pin 432 with the contours of the opening 410. With the pin 432 and opening 410 aligned, the shaft 412 and pin 432 of the male member 408 may be inserted into the opening 410 of the female member 406. The pin 432 fits closely within the cross-sectional shape of the opening 410, so that when the driver 302 rotates the female member 406, the inner wall 407 of the opening 410 exerts a rotational force on the pin 432 disposed therein, rotating the male member 408 carried by the pin 432. The tighter the fit between the pin 432 and the wall 407 of the opening 410, ie, the smaller the gap between the pin 432 and the wall 407 of the opening 410, the faster and more accurate the torque transmission will be.

[0080] 13A and 13B illustrate an embodiment of a joint 300 that utilizes a set screw and a rod having a non-circular cross-sectional shape, e.g., a D-shape, to rotationally lock the driver 302 to the receiver 304 for torque transmission. In such an embodiment, the male member 408 may have a non-circular cross-sectional shape having at least one arcuate surface 434 and at least one flat surface 436. In the embodiment illustrated in FIG. 13A, the male member 408 may include a D-shaped cross-sectional shape, similar to FIG. 11B. The female member 406 may be in the form of a sleeve attached to the driver and may include a hollow space 410 therein that opens to the end opposite the connection to the driver 302. Unlike the embodiment of FIG. 11A , in which the female member 406 has a round outer diameter and only the cross-sectional shape of the opening 410 corresponds to the cross-sectional shape of the male member 408, in FIG. 13A , the female member 406 and the opening 410 therein have a cross-sectional shape that includes at least one arcuate surface and at least one flat surface, including an arcuate surface 434 and a flat surface 436, that corresponds to the cross-sectional shape of the male member 408. The opening 410 is configured to receive the male member 408 therein. Engagement between the inner surface of the opening 410 and the outer surface of the male member 408 causes the male member 406 and female member 408, and their respective coupled driver 302 and receiver 304, to be rotationally locked together and transmit torque from the driver to the receiver in a manner similar to that described in connection with FIGS. 8 and 11A-11B. Once the male member 408 has been inserted to a desired axial position within the opening 410, a set screw 438 can be inserted into an aperture 440 in the flat surface of the female member 406, thereby locking the axial position of the male member 408 relative to the female member 406.

[0081] 14A and 14B illustrate an embodiment of a joint 300 that utilizes a T-slot to rotationally lock a driver to a receiver for torque transmission. In such an embodiment, the torque receiver may include a male member 408 disposed on an end thereof and configured to mate with a corresponding complementary female member 406 coupled to the driver. In some embodiments, the male member 408 may be disposed on the end of the lead screw 160. As shown in FIG. 14B, the male member 408 may include a feature having a T-shaped cross-section that includes a disk-shaped member 448 coupled to the receiver by an axially extending shaft 450.

[0082] As shown in FIG. 14A , the female member 406 may be in the form of a substantially cylindrical member 442 attached at one end to the driver and may include an opening 410 therein that opens to the end opposite the connection to the driver 302. The opening 410 may comprise a T-slot configured to complement and receive the T-shaped feature of the male member 408. To form the T-slot, the opening 410 may include an axially extending slot portion 444 that opens at one end to the end of the female member 406 that mates with the complementary male member 408 and at the other end to a transverse slot portion 446 that is perpendicular to the axially extending slot portion 444 and extends across the axis of rotation of the female member 406. The transverse slot portion 446 is open at one or both ends of the slot portion 446, i.e., across the diameter of the female member 406. This allows the male member 408, having a T-shaped configuration, to be inserted laterally relative to the female member 406. This configuration contrasts with certain other configurations described herein in which the male members 308, 408 are inserted axially into the female members 306, 406 (see, e.g., FIGS. 7, 8, 10A-10C, 11A-11O, and the like). Once the male member 408, including the disk 448 and shaft 450, is inserted laterally into the T-shaped slot, including the axially and laterally extending portions 444, 446, further lateral movement of the male member 408 is constrained by circumferentially disposed components within the implant. The male member 408 is also limited in axial movement by the axial constraint imposed on the movement of the disk 448 by the walls of the lateral slot portion 446. The closer the fit between the width 452 of the disc 448 and the width 454 of the lateral slot portion 446, the smaller the gap between the disc 448 and the walls of the lateral slot portion 446, and the less lateral movement is permitted. Less lateral movement results in faster and more accurate torque transfer from the driver to the receiver. The closer the fit between the thickness 456 of the disc 448 and the depth 458 of the lateral slot portion 446, the smaller the axial gap between the disc 448 and the walls of the lateral slot portion 446, and the less axial movement is permitted.

[0083] FIGS. 15A and 15B illustrate an embodiment of a joint 300 that utilizes a spline 360 ​​(FIGS. 15A and 15B) and a retaining ring 362 (FIG. 15A) to rotationally lock a driver to a receiver for torque transmission. In such an embodiment, the joint 300 includes a spline 360 ​​on one end and a lead screw 160 on the opposite end. The joint 300 can transmit torque between them. The spline 360 ​​can be a specially formed portion of the joint 300 component or a fastener coupled thereto. The spline can effectively change the cross-sectional shape of the torque-receiving or transmitting end of the lead screw 160 to have a non-circular cross-section to facilitate the transmission of torque to or from another component. In the illustrated embodiment, the spline 360 ​​can have an elliptical cross-sectional shape configured to mate with an elliptical receiver. Also illustrated is a spline 360 ​​having a rounded shape with two flats for mating with another part having complementary features. The cross-sectional shape of the spline 360 ​​can contribute to torque transmission. As shown in FIG. 15B, a recess 364 may be disposed between the spline 360 ​​and the lead screw 160, which may be configured to receive a retaining ring 362 (FIG. 15A). The retaining ring 362 may be configured to maintain the relative position of the moving parts.

[0084] FIG. 16 illustrates an embodiment of a joint 300 utilizing a three-pin coupling to rotationally lock a driver to a receiver for torque transmission. In such an embodiment, a first member 506 is coupled at one end to a driver 302, e.g., the output of a final gear stage. At the other end, the first member 506 is configured to mate with a receiver, e.g., a lead screw 160. The first member 506 may include three pins 504 extending axially from an end configured to mate with the end of the lead screw 160. The three pins 504 may be equidistant and symmetrically positioned around the end of the first member 506. The lead screw 160 may include a set of three holes 510 disposed on an end face 508 of the lead screw 160, each hole 510 configured to receive a corresponding pin 504. More or fewer pins 504 and corresponding holes 510 may be used, but symmetry may be maintained regardless of the number of pins 504 and holes disposed about the end face of the first member 506 and the end face 508 of the lead screw 160. The pins 504 may be axially inserted into the holes 510, thereby rotationally locking the first member 506 to the lead screw 160, thereby transmitting torque from the driver to the lead screw. The closer the fit of the pins 504 within the holes 510, the faster and more accurate the transmission of torque.

[0085] 17 illustrates an embodiment of a joint 300 utilizing a plate having radially disposed ridges on a mating surface to rotationally lock the driver to the receiver for torque transmission. In such an embodiment, a first member 606 is coupled at one end to the driver 302, e.g., the output 198 of the final gear stage. At the other end, the first member 606 includes an annular plate 603 having a plurality of ridges 604 disposed on an end surface of the annular plate 603. A second member 608 may be coupled at one end to the torque-receiving component 304 and may include at an opposite end an annular plate 609 having a plurality of ridges 610 disposed on an end surface of the annular plate 609. The ridges 604 and 610 are configured to engage with each other to transmit torque.

[0086] The ridges 604 disposed on the plate 603 extend radially outward at the end face of the annular plate 603, with valleys 605 between each radially extending ridge 604. The ridges 604 may be spaced apart at regular intervals around the circumference of the annular plate 603. In some embodiments, the ridges 604 may include a chamfer 607 on one edge of each of the ridges 604 in the same direction. The ridges 604 may omit the chamfer 607 on the other edge of the ridges 604 and instead have a straight 90-degree angle. In other embodiments, the chamfer 607 may be omitted entirely, and the edges of the ridges 604 facing both directions of rotation may be straight, e.g., have a 90-degree angle. In certain embodiments, the ridges 604 may also be angled or pie-slice shaped to reduce spacing near the inner diameter of the annular plate 603. The ridges 610 on the annular plate 609 of the second member 608 are arranged in substantially the same manner as described above with respect to the ridges 604 on the annular plate 603 .

[0087] In use, annular plate 603 including ridges 604 mates with annular plate 609 including ridges 610. Ridges 604 are configured to mate with ridges 610 such that chamfers 607, if present on ridges 604, engage with corresponding complementary chamfers on ridges 610 on plate 609. If chamfers 607 are not present on ridges 604, the 90-degree angles of ridges 604 are configured to engage with corresponding 90-degree angles on ridges 610. First member 606 is configured to rotate as driver 302 rotates. If ridges 604 have not yet contacted ridges 610 and traverse the valleys between ridges 610 before engaging ridges 610, a delay may occur between the start of rotation of first member 606 and the start of rotation of second member 608. Nevertheless, once ridges 604 and 610 begin to engage, rotation of first member 606 causes second member 608 to rotate due to forces on the engaging and mating surfaces of ridges 604, 610. As a result, second member 608 rotates at the same speed as driver 302 and first member 606.

[0088] FIG. 18A illustrates an embodiment of a joint 300 in which a spring-loaded / magnetic clutch 700 is used as both the drive mechanism and the parking brake. The clutch may permit selective disengagement. For example, an external magnet (not shown) may be used to engage or disengage the clutch. Any one or more of the joints 300 described elsewhere herein can be modified with such features. For example, the mechanism may be in a default connected or disconnected state. Such a default state can be achieved using a spring 702 or other feature to prompt the default connected or disconnected state. The force of the spring 702 can be selected to be overcome by external actuation. For example, the presence or absence of an external magnet can cause physical movement of one or both sides 704, 706 of the joint (or a bridging component between the two joints) to establish or disengage the joint. Such a feature can advantageously resist undesired torque transmission across the joint. One or both of the components 704, 706 can be magnets themselves or can be configured to be affected by a magnetic field induced by an external component. In some cases, the implant may include an actuator for making or breaking the connection.

[0089] Each of the aforementioned torque transmission joints may be used to transmit torque in distraction and compression systems, including, for example, intramedullary, extramedullary, and spinal distraction and compression systems and implants. They may also be used to transmit torque in combination with any driver of rotational motion, including permanent magnets, motors, or other drivers driven by externally generated magnetic fields. They may also be used in combination with any other feature of such implants, as understood in the art.

[0090] As used herein, terms such as "first," "second," and the like do not denote any order, quantity, or importance, but rather are used to distinguish one element from another, and the terms "a" and "an" herein do not denote a limitation on quantity, but rather denote the presence of at least one of the referenced items. The modifier "about" used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., includes the degree of error associated with measuring the particular quantity). The suffix "(s)," as used herein, is intended to include both the singular and the plural of the term it modifies, thereby including one or more of that term (e.g., metal includes one or more metals). Ranges disclosed herein are inclusive and independently combinable (e.g., the range "up to about 25 mm, or, more specifically, about 5 mm to about 20 mm" includes the endpoints and all intermediate values ​​of the range "about 5 mm to about 25 mm").

[0091] While various embodiments have been described herein, it will be understood from the specification that various combinations of elements, variations, or improvements therein may be made by one skilled in the art and are within the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is not intended that the invention be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but the invention is intended to include all embodiments falling within the scope of the appended claims.

Claims

1. An implant, a biocompatible housing; Driver and A receiver and a joint configured to transmit torque from the driver to the receiver, the joint comprising: a first magnetic member rotationally fixed to the driver, the first magnetic member comprising a dipole magnet, and configured such that rotation of the driver causes rotation of the first magnetic member; a second magnetic member rotationally fixed to the receiver, the second magnetic member configured such that rotation of the second magnetic member causes rotation of the receiver; 10. An implant, wherein the first magnetic member is configured to attract the second magnetic member, and the second magnetic member is configured to rotate in response to rotation of the first magnetic member.

2. The implant of claim 1 , wherein the second magnetic member is configured to rotate more slowly than the first magnetic member.

3. The implant of claim 2 , wherein the second magnetic member comprises a dipole magnet.

4. The implant of claim 3 , wherein the first magnetic member is magnetically coupled to the second magnetic member.

5. The implant of claim 3 , wherein the first magnetic member comprises a disc-shaped dipole magnet and the second magnetic member comprises a disc-shaped dipole magnet.

6. The implant of claim 5 , further comprising a component disposed between the first magnetic member and the second magnetic member, the component comprising a thrust bearing or a friction reducing component.

7. The implant of claim 3 , wherein the first magnetic member comprises a cross-sectional shape configured to provide a complementary fit with a cross-sectional shape of the second magnetic member.

8. 8. The implant of claim 7, wherein the second magnetic member is at least partially disposed within the first magnetic member in a male-female arrangement, and the first and second magnetic members are substantially axially aligned.

9. the first magnetic member further comprises a barrel shape and the second magnetic member further comprises a solid cylindrical shape; The implant of claim 8 , wherein the first magnetic member and the second magnetic member are arranged substantially concentrically.

10. The implant of claim 1 , wherein the second magnetic member comprises a magnetic material.

11. The implant of claim 10 , wherein the first magnetic member comprises a cross-sectional shape configured to provide a complementary fit with a cross-sectional shape of the second magnetic member.

12. 12. The implant of claim 11, wherein the second magnetic member is at least partially disposed within the first magnetic member in a male-female arrangement, and the first and second magnetic members are substantially axially aligned.

13. the first magnetic member further comprising a first engagement surface, and the second magnetic member comprising a second engagement surface; 12. The implant of claim 11, wherein the second magnetic member is configured to rotate in response to a force exerted by the first engagement surface on the second engagement surface.

14. 14. The implant of claim 13, wherein the second magnetic member comprises a cross-sectional geometry selected from a semicircular shape, an irregular shape having at least one arc and one flat side, an irregular shape having at least one arc and two flat sides, an irregular shape having at least one arc and three flat sides, an irregular shape having at least one arc and four flat sides, a slotted circle, a cross or Phillips head, a hexalobular shape, and a keyed shape.

15. An implant, a biocompatible housing; Driver and A receiver and a joint configured to transmit torque from the driver to the receiver, the joint comprising: a receptacle disposed at an end of the driver and configured to receive an end portion of the receiver therein; a first receptacle groove and a second receptacle groove, each disposed on an annular inner wall of the receptacle; a first receiver groove and a second receiver groove, each disposed on a radially outer surface of the end portion of the receiver, a first receiver groove and a second receiver groove, the first receptacle groove and the first receiver groove mating to form a first annular space and the second receptacle groove and the second receiver groove mating to form a second annular space when the end portion of the receiver is disposed within the receptacle; a first toroidal spring disposed within the first annular space and inclined in a first direction; a second toroidal spring disposed within the second annular space and angled in a second direction opposite the first direction.

16. 16. The implant of claim 15, wherein the first toroidal spring and the second toroidal spring each comprise a coil spring having a first end welded to a second end.

17. 16. The implant of claim 15, wherein the first toroidal spring and the second toroidal spring have the same diameter.

18. 16. The implant of claim 15, wherein the first toroidal spring has a first diameter and the second toroidal spring has a second diameter different from the first diameter.

19. the first end of the receiver comprises a stepped diameter shaft; 19. The implant of claim 18, wherein the first annular space having the first diameter is disposed in a first step and the second annular space having the second diameter is disposed in a second step.

20. the end portion of the receiver further comprising a shaft and a collar disposed thereon; 19. The implant of claim 18, wherein one of the first annular space or the second annular space is disposed on the collar and the other of the first annular space or the second annular space is disposed on the shaft.

21. An implant, a biocompatible housing; Driver and A receiver and a joint configured to transmit torque from the driver to the receiver, the joint comprising: a first member rotationally fixed to the driver, the first member configured such that rotation of the driver causes rotation of the first member; a second member rotationally fixed to the receiver, the second member configured such that rotation of the second member causes rotation of the receiver; The implant, wherein the second member is configured to rotate in response to rotation of the first member.

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