Plate mechanism for bone distraction

Abstract

To provide an adjustable implant configured to non-invasively guide bone growth in a patient.SOLUTION: The adjustable implant includes a first portion configured to couple to a first bone segment, and a second portion at least partially disposed within the first portion and configured to couple to a second bone segment. The adjustable implant includes a drive assembly configured to be transcutaneously actuated, and to drive rotation of a gear assembly configured to rotate about a first axis, and drive axial translation of the second portion along a second axis. Non-invasive actuation of the drive assembly therefore causes the adjustable implant to lengthen or retract along the second axis.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The subject matter described herein relates to adjustable implants, distraction and compression systems, and related methods. [Background technology]

[0002] Distraction osteogenesis allows two bone segments to be lengthened separately, allowing new bone tissue to form between the two bone segments. Distraction osteogenesis can be useful, for example, to increase the length of a bone (e.g., a femur, a tibia, etc.) at a predetermined rate (e.g., 1 millimeter per day), thereby allowing new bone tissue to form in the gap between the segments. One limitation of known devices, systems, and methods in the art of distraction osteogenesis is the size and / or shape of the known devices, which limit the implantation sites and / or distraction procedures that can be performed. Embodiments of the present disclosure aim to address these challenges, as well as other challenges generally associated with distraction osteogenesis devices, systems, and related methods. Summary of the Invention

[0003] All aspects, examples and features described below can be combined in any technically possible manner.

[0004] One aspect of the present disclosure provides an adjustable implant including a first portion configured to couple to a first bone segment, a drive assembly disposed within the first portion and configured to drive rotational movement about a first axis, a second portion configured to couple to a second bone segment and configured to translate axially relative to the first portion along a second axis, and a lead screw disposed at least partially within the first and second portions along the second axis, wherein the lead screw is rotatably coupled to the drive assembly such that rotational movement about the first axis drives rotational movement of the lead screw about the second axis, thereby axially translating the second portion relative to the first portion along the second axis.

[0005] Another aspect of the present disclosure provides an adjustable implant including a first portion configured to couple to a first bone segment, a gear assembly disposed in the first portion, a drive assembly rotatably engaged with the gear assembly and configured to rotate about a first axis, the drive assembly configured to drive rotational movement of the gear assembly about a second axis, a lead screw disposed at least partially within the first portion and extending along a third axis, and a second portion configured to couple to a second bone segment, the lead screw disposed at least partially within the second portion and rotatably coupled to the drive assembly such that rotational movement of the drive assembly about the first axis drives rotational movement of the gear assembly about the second axis and drives rotational movement of the lead screw about the third axis, thereby axially translating the second portion relative to the first portion along the third axis.

[0006] Another aspect of the present disclosure provides an adjustable implant including a first portion configured to couple to a first bone segment and a drive assembly disposed within the first portion and configured to rotate about a first axis. The drive assembly includes a drive portion configured to rotate about the first axis and a drive shaft rotatably coupled to the drive portion. The adjustable implant further includes a second portion configured to couple to a second bone segment and to translate axially relative to the first portion along the second axis, and a ratchet assembly at least partially disposed within the first and second portions. The ratchet assembly is configured to actuate axial translation relative to the first portion along the second axis and prevent retraction of the second portion relative to the first portion along the second axis in response to rotation of the drive assembly about the first axis.

[0007] Two or more aspects described in this disclosure, including aspects described in this summary section, may be combined to form implementations not specifically described herein.

[0008] The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims. [Brief explanation of the drawings]

[0009] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate certain aspects of the subject matter disclosed herein and, together with the specification, serve to explain some of the principles associated with the disclosed implementations. [Figure 1] 1 shows an assembled perspective view of one embodiment of an adjustable implant according to the present disclosure. [Figure 2] 2 shows an exploded perspective view of the adjustable implant of FIG. 1. [Figure 3] 2 shows a side cross-sectional view of the adjustable implant of FIG. 1. [Figure 4] 2 illustrates the gear assembly and lead screw of the adjustable implant of FIG. 1; [Figure 5] 1 illustrates one embodiment of an adjustable implant that includes two or more lead screws coupled with a gear assembly. [Figure 6] 1 illustrates one embodiment of an adjustable implant that includes two or more lead screws coupled with a gear assembly. [Figure 7] 1 shows an assembled perspective view of one embodiment of an adjustable implant including a worm gear according to the present disclosure. FIG. [Figure 8] 1 illustrates a top cross-sectional view of one embodiment of an adjustable implant including a ratchet assembly and a bidirectional plate according to the present disclosure. [Figure 9] 9 shows a cross-sectional perspective view of the adjustable implant of FIG. 8. [Figure 10] 9 shows an exploded cross-sectional perspective view of the adjustable implant of FIG. 8. [Figure 11] 1 illustrates a top cross-sectional view of one embodiment of an adjustable implant including a ratchet assembly according to the present disclosure. [Figure 12]1 illustrates the internal components of an external adjustment device for non-invasively adjusting a lengthening and compression device, according to an embodiment of the present disclosure. [Figure 13] 10A-10C illustrate external adjustment devices configured for adjusting distraction and compression devices implanted within the femur and tibia, respectively, in accordance with an embodiment of the present invention. [Figure 14] 10A-10C illustrate external adjustment devices configured for adjusting distraction and compression devices implanted within the femur and tibia, respectively, in accordance with an embodiment of the present invention. [Figure 15] 1 illustrates a method according to an embodiment of the present disclosure.

[0010] It should be noted that the drawings of the subject matter are not necessarily to scale. The drawings are intended to depict only typical aspects of the subject matter and therefore should not be considered as limiting the scope of the disclosed subject matter. In the drawings, like numbers represent like elements between the drawings. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present disclosure describes various embodiments of adjustable implants, distraction and compression systems, and related methods. Such embodiments include, for example, an adjustable implant having a first portion configured to couple to a first bone segment of a patient and a second portion configured to couple to a second bone segment. The second portion may be at least partially disposed within the first portion and configured for axial translation relative to the first portion along an axis. The first and second portions of the adjustable implant may include one or more apertures configured to receive fixation anchors therein, for example, to couple the first and second portions of the adjustable implant to the first and second bone segments, respectively. The adjustable implant may include a drive assembly configured to drive rotational movement of a lead screw to move the second portion relative to the first portion, thereby adjusting the distance between the first and second bone segments to perform distraction osteogenesis. The adjustable implant may be configured to be externally controlled by an external adjustment device and, therefore, may be non-invasively adjustable in such embodiments.

[0012] As shown in FIG. 1 , the adjustable implant 100 includes a first portion 102 and a second portion 104 at least partially disposed within the first portion 102. For example, the first portion 102 can be a housing, and the second portion 104 can be a movable rod at least partially disposed within the housing. The illustrated first portion 102 and second portion 104 each include a plate shaped and sized to engage a bone segment of a patient. The first portion 102 is configured to be secured to bone at a first location (e.g., the first bone segment), and the second portion 104 is configured to be secured to bone at a second location (e.g., the second bone segment). The first portion 102 and second portion 104 can each include one or more fixation openings 106 configured to receive one or more fixation screws therein. The fixation screws can be configured to couple the first portion 102 and second portion 104 to bone at the first and second locations, respectively. In some embodiments, the one or more fixation openings 106 comprise internally threaded set screw holes for mating with the threads on the head of a fixation screw, as described herein. One or both of the first portion 102 and the second portion 104 can be configured for extramedullary attachment to bone.

[0013] To allow bone growth, i.e., lengthening, the bone can be pre-separated or intentionally cut or broken to create this separation (e.g., by osteotomy), and the bone is divided into a first segment and a second segment. The cutting can be performed before implanting and securing the adjustable implant 100, or can be performed after implanting the adjustable implant 100 (e.g., by using a flexible Gigli saw). As described herein, the implant 100 is configured such that the second portion 104 can be distally or proximally retracted (e.g., for compression) and / or lengthened (e.g., for limb lengthening) relative to the first portion 102 along the longitudinal axis (A2). The adjustable implant 100 is configured to enable controlled and precise translation of the second portion 104 relative to the first portion 102 via non-invasive remote control, thereby enabling controlled and precise translation of the second bone segment coupled to the second portion 104 relative to the first bone segment coupled to the first portion 102.

[0014] Over the course of limb lengthening treatment, the bone is periodically distracted, creating new separations where bone formation can occur. "Periodic distraction" is meant to indicate that limb lengthening occurs regularly or periodically (which may be approximately daily or every few days). An exemplary distraction rate is 1 millimeter per day, although other distraction rates may also be used. That is, a typical distraction regimen may include increasing the length of the adjustable implant 100 by approximately 1 millimeter per day. This may be accomplished, for example, by four distraction sessions per day, each resulting in a 0.25 mm distraction. The adjustable implant 100 includes a drive assembly 110 configured to drive rotational motion about an axis (A1), allowing the second portion 104 to telescope from the first portion 102, thus separating the first and second segments of the bone from one another. As shown in FIG. 1, the rotational axis A1 may be orthogonal to the axis A2. In an alternative embodiment of the present disclosure, the rotational axes A1 and A2 form an oblique angle, as disclosed in more detail below.

[0015] Referring to FIG. 2 , the adjustable implant 100 includes a drive assembly 110 at least partially disposed within or coupled to the first portion 102. The drive assembly 110 includes a drive section 112 configured to drive rotational motion of the drive section 112 about a rotation axis A1. The drive section may take any of a variety of forms, such as a motor or an externally driven rotating permanent magnet. The illustrated drive assembly 110 further includes a drive shaft 114 extending proximally from and rotatably coupled to the drive section 112. The drive section 112 and drive shaft 114 may be axially fixed within the first portion 102 by one or more mechanical hardware components, such as one or more bearings 116. In the illustrated embodiment, the drive section 112 includes a rotating permanent magnet configured to rotate with an externally applied magnetic field. An external adjustment device 400 (see FIG. 12) including external magnets 414, 416 can be configured to actuate rotation of the drive unit 112 in either a first direction or a second direction about the rotation axis A1 of the drive unit 112.

[0016] Rotation in a first direction may correspond to extension of the adjustable implant 100, and rotation in a second direction may correspond to retraction of the adjustable implant 100. For example, the drive portion 112 may be configured to rotate in a first direction about rotation axis A1 corresponding to distal translation (e.g., extension) of the second portion 104, and to rotate in a second direction opposite the first direction corresponding to proximal translation (e.g., retraction, as in a compression procedure) of the second portion 104 along axis A2. Alternatively, the adjustable implant may include a motor configured to rotate in response to an electrical signal (e.g., as provided by an external device). The motor may be electrically coupled to a power source, such as an implantable battery or a charging capacitor, to drive rotation of the drive shaft 114. The power source may be configured for percutaneous charging using an external power source.

[0017] As further shown in FIGS. 1-3 , adjustable implant 100 further includes a gear assembly 120 ( FIGS. 2-3 ) rotatably coupled to drive shaft 114 of drive assembly 110. Gear assembly 120 may include multiple gears (e.g., one or more output gears, ring gears, sun gears, compound planetary gears, etc.) configured to engage with one another to transfer rotational motion from drive assembly 110 about axis A1 to rotational motion of lead screw 138 about axis A2, thereby translating second portion 104 along axis A2, as disclosed in more detail below. Gear assembly 120 may include, for example, multiple compound planetary gears 126 disposed about axis A1 and rotatably coupled to drive shaft 114, such that rotational motion of drive portion 112 rotates multiple compound planetary gears 126 about axis A1. In the embodiment shown in FIGS. 2-3 , gear assembly 120 includes one planetary gear stage, but it should be understood that any number of stages may be implemented in various embodiments within the scope of this disclosure. Each of the one or more gear stages in gear assembly 120 may provide a gear reduction ratio, such as a 66:1 gear reduction ratio. Each compound planetary gear 126 includes a first gear 126A that is rotatably coupled to a second gear 126B extending proximally from the first gear 126A, such that rotational motion of drive shaft 114 coupled to sun gear 124 causes first gear 126A to rotate as a group about axis A1, thereby causing second gear 126B to rotate as a group about axis A1. The first gear 126A of each compound planetary gear is disposed within first ring gear 122, and the second gear 126B of each compound planetary gear 126 is disposed within second ring gear 130.

[0018] 2 and 3, the first ring gear 122 of the gear assembly 120 is rotatably fixed to the first portion 102. The first ring gear 122 includes a first cavity 122A configured to receive the drive portion 112 therein, a second cavity 122B opposite the first cavity 122A along the axis A1, and an opening 123 configured to receive the drive shaft 114 therein and allow communication between the first cavity 122A and the second cavity 122B. The first ring gear 122 is configured to engage the cover 118 to retain the drive portion 112 within the first cavity 122A. The second cavity 122B includes an inner surface having a plurality of gear teeth 125 configured to rotatably engage a first gear 126A of each compound planetary gear 126 disposed therein. The first gear 126A of each compound planetary gear 126 may be configured to rotatably engage the plurality of gear teeth 125 in the second cavity 122B and to rotatably engage a first sun gear 124 coupled to the drive shaft 114, such that rotation of the drive shaft 114 rotates the first sun gear 124, thereby causing the first gear 126A of each compound planetary gear 126 to orbit about the first sun gear 124 within the second cavity 122B. Rotational motion of the first gear 126A of the plurality of compound planetary gears 126 thereby causes rotational motion of a second gear 126B extending proximally from the first gear 126A about axis A1. The second gear 126B of each compound planetary gear 126 may be configured to be received within and rotatably engage the second ring gear 130. The second ring gear 130 includes a cavity 130A configured to receive the second gear 126B therein. The cavity 130A includes an inner surface having a plurality of gear teeth 131 configured to rotatably engage the second gear 126B of each compound planetary gear 126 disposed therein. The second gear 126B orbits about and is rotatably engaged with a second sun gear 128, which is rotatably coupled to the distal end of the drive shaft 114. The second sun gear 128 is configured to support the second gear 126B but does not provide torque to any gears or components of the gear assembly 120 (e.g., the second sun gear 128 is an "idle gear").The rotational movement of second gear 126B thereby rotates second ring gear 130 about axis A1. Second ring gear 130 is rotatably coupled to bevel output gear 132 (FIGS. 3-4), such that rotation of second ring gear 130 rotates bevel output gear 132 about axis A1. Thus, rotation of drive section 112 rotates drive shaft 114, which in turn rotates first sun gear 124, which in turn rotates multiple compound planetary gears 126, which in turn rotates second ring gear 130, which in turn rotates bevel output gear 132.

[0019] As shown in FIG. 4 , the bevel output gear 132 of the gear assembly 120 is further configured to rotatably engage the lead screw 138, thereby rotating the lead screw 138 about axis A2, which in turn drives translation of the second portion 104 along axis A2. As shown, the lead screw 138 includes a shaft extending between a first end having a bevel gear 140 configured to rotatably engage the gear assembly 120 and a second end configured to be received within the second portion 104. The lead screw 138 further includes an externally threaded portion 142 disposed on a radially outward surface of the shaft that is configured to threadably engage with the internal threads 136 of the cavity 108 in the second portion 104. Rotation of the lead screw 138 translates the second portion 104 relative to the first portion 102 along the externally threaded portion 142 of the lead screw 138. Rotation of the lead screw 138 about axis A2 in a first direction may correspond to extension of the adjustable implant 100, and rotation in a second direction may correspond to retraction of the adjustable implant 100. The rotation axis A1 of the gear assembly 120 forms an angle, which may be orthogonal or oblique, with respect to the rotation axis A2 of the lead screw 138, for example. In one example, the minimum angle between A1 and A2 is greater than n degrees, where n is any integer between 1 and 90 degrees, inclusive. In some embodiments, the lead screw 138 is configured to drive the first portion 102 from the second portion 104 by rotating within a nut secured to an inner surface adjacent the cavity 108 of the second portion 104 in which the lead screw 138 is disposed. Thus, the lead screw 138 is indirectly mechanically coupled to the drive assembly 110, such that rotation of the drive 112 results in rotation of the lead screw 138. Thus, rotation of drive portion 112 rotates drive shaft 114, which in turn rotates bevel output gear 132 of drive assembly 110 about axis A1, which in turn rotates lead screw 138 about axis A2, driving axial translation of first portion 102 and then second portion 104 relative to first portion 102.

[0020] In another embodiment, as shown in FIGS. 5 and 6 , the adjustable implant 100 includes two or more lead screws rotatably coupled to a gear assembly. In such an embodiment, each of the two or more lead screws includes a bevel gear configured to rotatably engage a bevel output gear of the gear assembly. The number of lead screws rotatably engaged with the gear assembly may be determined by the size and shape of the implant, the number of gear teeth on the bevel output gear, and / or the size and shape of each lead screw. The present disclosure is not limited to the number of lead screws shown in the drawings, but encompasses any number of lead screws disposed within the adjustable implant that translate axially in response to rotation of a gear assembly oriented at an angle relative to the lead screws. In some embodiments, the two or more lead screws may be partially disposed within two or more portions of the adjustable implant (e.g., extension and compression rods) that are configured to translate axially relative to another portion (e.g., a housing similar to the first portion 102 shown in FIGS. 1-3 ). Thus, rotation of the drive assembly drives rotational movement of each of the two or more lead screws, thereby axially translating the two or more portions of the adjustable implant relative to the housing along the respective rotational axes of the two or more lead screws. In some embodiments, each lead screw of the two or more lead screws is substantially identical. In other embodiments, one or more lead screws has a different size and / or shape than another one of the lead screws.

[0021] 5, adjustable implant 100 includes two lead screws 138A, 138B that mate with bevel output gear 132 and are configured to rotate about the same axis A2, thereby axially translating two portions (not shown) in opposite directions along axis A2. Thus, rotation of bevel output gear 132 drives rotation of bevel output gears 140A, 140B of lead screws 138A, 138B, which in turn axially translates respective portions of adjustable implant 100 along axis A2 in opposite directions via external threads 142A, 142B.

[0022] 6, the adjustable implant includes a first lead screw 138A, a second lead screw 138B, and a third lead screw 138C that mate with a bevel output gear 132 and are configured to rotate about axes A2, A3, and A4, respectively. Each lead screw 138A, 138B, 138C has a respective bevel gear 140A, 140B, 140C configured to mate with the bevel output gear 132. Thus, rotation of the bevel output gear 132 drives rotation of the bevel output gears 140A, 140B, 140C of the lead screws 138A, 138B, 138C, which in turn axially translates each portion of the adjustable implant 100 in different directions along the respective axes A2, A3, A4 via the external threads 142A, 142B, 142C. Each axis A2, A3, A4 is perpendicular to the rotational axis A1 of the bevel output gear 132 and forms an angle (e.g., an oblique angle, a right angle, etc.) with respect to the other lead screw axes (i.e., θ 34 and θ 24 ).

[0023] 5 and 6, first portion 102 (e.g., the portion of the adjustable implant on which drive portion 112 and gear assembly 120 are held) may be configured to be fixed directly to bone (e.g., by having one or more fixation openings 106) or may not be directly connected to bone (e.g., by not having fixation openings 106). In an exemplary implementation, two or more lead screws 138 translate respective components fixed to bone (e.g., by having fixation openings) relative to the first portion.

[0024] 7 , a perspective view of another embodiment of an adjustable implant 200 is shown, including a drive assembly 210 having a worm gear 216 configured to rotatably engage a gear assembly 220. As shown, adjustable implant 200 includes a first portion 202 configured to be secured to a patient's bone at a first location and a second portion 104 disposed at least partially within first portion 202, configured to be secured to bone at a second location (e.g., a second bone segment). Adjustable implant 200 is configured to enable controlled and precise translation of second portion 204 relative to first portion 202 via non-invasive remote control, and thus enable controlled and precise translation of the second bone segment coupled to second portion 204 relative to the first bone segment coupled to first portion 202. In contrast to the embodiment shown in FIGS. 1-3 , the drive assembly 210 of the adjustable implant 200 includes a driver 212 (e.g., a rotating permanent magnet) configured to drive rotational motion of a drive shaft 214 about axis A5, thereby rotating a gear assembly 220 about axis A1. The drive shaft 214 includes a worm gear 216 configured to mate with an input gear 222 of the gear assembly 220, which in turn rotates a plurality of planetary gears 226 of the gear assembly 220 about axis A1, thereby rotating an output gear 232 of the gear assembly 220 about axis A1. Similar to the gear assembly 120 described with respect to FIGS. 1-4 , the gear assembly 220 is configured to transfer rotational motion from the drive assembly 210 to a lead screw (not shown) disposed within the first portion 202, details of which are omitted herein for the sake of brevity. It should be noted that other gear assembly designs configured to transfer rotational motion from the drive assembly 210 to the lead screw are also contemplated within the scope of the present invention.Thus, rotation of drive portion 212 rotates drive shaft 214 about axis A5, which in turn rotates worm gear 216 about axis A5, which in turn rotates input gear 222 about axis A1, which in turn rotates planetary gears 226 about axis A1, which in turn rotates output gear 232 about axis A1, which in turn rotates the lead screw about axis A2, which in turn axially translates second portion 204 relative to first portion 202 along axis A2. In some embodiments, axis A5 of drive assembly 210 is orthogonal to axis A1 of gear assembly 220. In other embodiments, axis A5 of drive assembly 210 forms an oblique angle with axis A1 of gear assembly 220.

[0025] As shown in FIGS. 8-10 , another embodiment of an adjustable implant 300 includes a first portion 302 (e.g., a housing) configured to receive a second portion 304 and a third portion 305 therein. Two or more of the portions 302, 304, 305 may comprise plates shaped and sized to engage a patient's bone at a respective location. For example, the first portion 302 may (but need not) be configured to be secured to a bone at a first location (e.g., a first bone segment). The second portion 304 may be configured to be secured to a bone at either the first location or a second location (e.g., the first bone segment or the second bone segment). The third portion 305 may be configured to be secured to a bone at either a second location or a third location (e.g., the second bone segment or the third bone segment). Each portion 302, 304, 305 may further include one or more fixation openings 306 configured to receive one or more fixation screws configured to couple each portion 302, 304, 305 to a respective location on the bone. As described herein, the second portion 304 is configured to extend in a first direction relative to the first portion 302 along the longitudinal axis (A6), and the third portion 305 is configured to extend in an opposite second direction relative to the first portion 302 along the longitudinal axis A6. The adjustable implant 300 is configured to enable controlled, precise translation of the second portion 304 and the third portion 305 relative to the first portion 302, and thus, the second and third bone segments relative to the first bone segment, along the longitudinal axis A6, via non-invasive remote control.

[0026] 9-10, additional internal features of the adjustable implant 300 are shown. The adjustable implant 300 includes a drive assembly 310 at least partially disposed within the first portion 302 (FIG. 8). The drive assembly 310 includes a drive portion 312, such as a rotary permanent magnet or a motor, configured to drive rotational movement of the drive portion 312 about a rotation axis A8. The drive assembly 310 further includes a drive shaft 314 extending proximally from and rotatably coupled to the drive portion 312. The drive portion 312 and the drive shaft 314 may be axially fixed within the first portion 302 by one or more mechanical hardware components. The drive assembly 310 may further include a drive portion output gear 316 disposed along the drive shaft 314. As shown in FIGS. 9-10, the drive portion 312 may include a rotary permanent magnet configured to rotate with an externally applied magnetic field. An external adjustment device 400 (see FIG. 12 ), including external magnets 414, 416, can be configured to actuate rotation of the drive portion 312 in either a first direction or a second direction about the drive portion 312's rotation axis A8. Rotation in at least one of the first or second directions can correspond to extension of the second portion 304 and the third portion 305 relative to the first portion 302, for example, along axis A6. Alternatively, the adjustable implant 300 can include a motor configured to rotate in response to an electrical signal (e.g., as provided by an external device). The motor can be electrically coupled to a power source, such as a battery or a charging capacitor, to drive rotation of the drive shaft. The power source can be configured for percutaneous charging using an external power source.

[0027] As further shown in FIGS. 9-10 , adjustable implant 300 further includes a gear assembly 320 rotatably coupled to drive assembly 310 via driver output gear 316. Gear assembly 320 includes multiple gears (e.g., input gear, output gear, etc.) configured to engage with one another to transfer rotational motion from drive 312 about axis A8 to ratchet assembly 330 disposed along axis A6. Ratchet assembly 330 thereby actuates axial translation of second portion 304 and third portion 305 relative to first portion 302, as described herein. Gear assembly 320 may include, for example, an input gear 322 rotatably coupled to drive shaft 314, an output gear 324 configured to rotatably engage input gear 322, and an eccentric shaft 326 configured to rotatably engage output gear 324. Thus, rotation of drive portion 312 rotates drive shaft 314, which in turn rotates input gear 322, which in turn rotates output gear 324, which in turn rotates eccentric shaft 326. Eccentric shaft 326 is coupled to ratchet assembly 330 such that rotation of eccentric shaft 326 actuates ratchet assembly 330.

[0028] 8-10 , the ratchet assembly 330 includes a first ratchet arm 332A and a second ratchet arm 332B, each of which is disposed within the first portion 302 and rotatably coupled to the eccentric shaft 326. The first ratchet arm 332A and the second ratchet arm 332B are configured to rotate within the first portion 302 about the eccentric shaft 326 in response to rotation of the drive assembly 310, thereby axially translating the second portion 304 and the third portion 305, respectively, along axis A6 ( FIG. 8 ) relative to the first portion 302. The first ratchet arm 332A includes a first end coupled to the first ratchet 334A and a second end rotatably coupled to the eccentric shaft 326. The second ratchet arm 332B includes a first end coupled to the second ratchet 334B and a second end rotatably coupled to the eccentric shaft 326. As shown in FIG. 10 , the ratchet assembly 330 further includes a first linear rack 336A disposed on the second portion 304 and a second linear rack 336B disposed on the third portion 305. The first linear rack 336A and the second linear rack 336B may each have a plurality of ratchet teeth 337 configured to engage the first ratchet 334A and the second ratchet 334B, respectively, to incrementally drive axial translation along the axis A6. The ratchet assembly 330 further includes a first pawl 338A configured to engage the first linear rack 336A and a second pawl 338B configured to engage the second linear rack 336B. First pawl 338A and second pawl 338B are dimensioned to allow extension of second portion 304 and third portion 305, respectively, in a first direction along axis A6, but prevent retraction of second portion 304 and third portion 305, respectively, in a second direction opposite the first direction. Ratchet assembly 330 may further include mechanical hardware, such as springs 340, configured to position ratchets 334A, 334B and / or pawls 338A, 338B within ratchet teeth 337 of respective linear racks 336A, 336B in the absence of rotational motion from drive assembly 310.Thus, rotation of the drive portion 312 rotates the drive shaft 314, which in turn rotates the input gear 322, which in turn rotates the output gear 324, which in turn rotates the eccentric shaft 326, which in turn actuates the ratchet assembly 330 to cause axial translation of the second portion 304 and the third portion 305 relative to the first portion 302 along axis A6.

[0029] As shown in Figure 11, in some embodiments, the adjustable implant 300 includes a ratchet assembly 330 configured to actuate axial translation of the second portion 304 relative to the first portion 302. In contrast to the embodiments shown in Figures 8-10, the adjustable implant 300 of Figure 11 does not include a third portion 305 and associated components of the ratchet assembly 330 configured to engage the third portion 305.

[0030] 12-14 illustrate an external adjustment device 400 configured to enable non-invasive adjustment of an adjustable implant 100, 200, 300 by applying a moving magnetic field to rotate a drive unit 112, 212, 312 within the adjustable implant 100, 200, 300, as described. The external adjustment device 400 may also be referred to as an external remote controller or external remote control device and may operate similarly with respect to the drive assembly 110, 210, 310 of the adjustable implant 100, 200, 300. FIG. 12 illustrates the internal components of the external adjustment device 400, showing the drive unit 112 of the adjustable implant 100 (representative of the drive units 112, 212, 312 and implant systems 100, 200, 300 disclosed herein) without the remainder of the assembly for clear reference. The internal operating components of the external adjustment device 400 may, in certain embodiments, be similar to those described in U.S. Patent Application Publication No. 2012 / 0004494, incorporated herein by reference. A motor 402 with a gearbox 404 outputs to a motor gear 406. The motor gear 406 engages and rotates a central (idle) gear 408, which has a suitable number of teeth to rotate a first magnet gear 410 and a second magnet gear 412 at the same rotational speed. A first magnet 414 and a second magnet 416 rotate in conjunction with the first magnet gear 410 and the second magnet gear 412, respectively. Each magnet 414, 416 is held within a respective magnet cup 418 (partially shown). An exemplary rotational speed may be 60 RPM or less. This speed range limits the amount of current density induced in body tissue and fluids and may be configured to meet international guidelines or standards. 12, the south pole 422 of the first magnet 414 faces in the same direction as the north pole 424 of the second magnet 416, and similarly, the first magnet 414 has a north pole 426 that faces in the same direction as the south pole 428 of the second magnet 416. When these two magnets 414, 416 rotate together in sync, they apply complementary and additive moving magnetic fields to the radially polarized drive member 112, which has a north pole 432 and a south pole 434. Magnets with multiple north poles (e.g., two) and multiple south poles (e.g., two) are also contemplated in each of the devices.When the two magnets 414, 416 rotate in a first rotational direction 442 (e.g., counterclockwise), magnetic coupling causes the drive 112 to rotate in an opposite second rotational direction 444 (e.g., clockwise). The direction of rotation of the motor 402 and the corresponding direction of rotation of the magnets 414, 416 are controlled by buttons 446, 448. One or more circuit boards 452 contain control circuitry for both sensing and controlling the rotation of the magnets 414, 416.

[0031] FIGS. 13 and 14 show an external adjustment device 400 for use with a device placed on the femur (FIG. 13) or tibia (FIG. 14). The external adjustment device 400 has a first handle 454 for carrying or securing the external adjustment device 400, for example, for stabilizing it relative to the upper leg 456 (as in FIG. 13) or the lower leg 457 (as in FIG. 14). An adjustable handle 458 is rotatably attached to the external adjustment device 400 at pivot points 460, 462. The pivot points 460, 462 may have easily lockable / unlockable mechanisms, such as spring-loaded brakes, ratchets, or locking screws, to allow the adjustable handle 458 to be adjusted to a desired angle relative to the housing 464 and to lock the orientation. In FIG. 13, the adjustable handle 458 is configured so that the top portion 466 of the loop 468 rests against the housing 464. In this position, the patient 470 can grasp one or both of the grips 472, 474 while the adjustment procedure (e.g., moving the bone between 0.10 mm and 1.50 mm) is performed. It is contemplated that the procedure may be a distraction procedure for a bone distraction device or a distraction plate attached externally to the bone. Referring to FIG. 14 , when the adjustable implant 100 is implanted in the tibia, the adjustable handle 458 can be repositioned to allow the patient 470 to grasp the top portion 466 so that the magnet region 476 of the external adjustment device 400 is held above the portion of the adjustable implant 100 including the drive unit 112. In either case, the patient 470 can clearly view the control panel 478, which includes the display 482. In a configuration different from the two directional buttons 446, 448 in FIG. 12 , the control panel 478 includes a start button 484, a stop button 486, and a mode button 488. Using the control circuitry contained on circuit board 452, the surgeon can store important information related to the specific aspects of each particular patient. For example, in some patients, the implant may be placed antegrade in the tibia. In other patients, the implant may be placed either antegrade or retrograde around the femur. In each of these three cases, it may be desirable to move the bone either distal to proximal or proximal to distal.By having the ability to store this type of patient-specific information within the external adjustment device 400, the external adjustment device 400 can be configured to automatically prompt the magnets 414, 416 to rotate in the correct direction, while the patient simply places the external adjustment device 400 in the desired position and presses the start button 484. The maximum allowable bone transport length per day and the maximum allowable bone transport length per session can also be entered and stored by the surgeon for safety purposes. These can also be added via an SD card, USB device, or wireless input. An additional feature is a camera located on the portion of the external adjustment device 400 that is placed on the skin. For example, the camera can be located between the first magnet 414 and the second magnet 416. The skin directly overlying the implanted drive unit 112 can be marked with indelible ink. A live image from the camera is then displayed on the display 482 of the control panel 478, allowing the user to position the first magnet 414 and the second magnet 416 directly over the marked area on the skin. On the display 482, crosshairs can be superimposed on the live image, allowing the user to align a mark on the skin between the crosshairs and thus optimally position the external adjustment device 400.

[0032] Other external adjustment devices may be used to cause actuation of the extension devices described herein. Examples of such external conditioning devices include those described in U.S. Patent No. 8,382,756, filed November 20, 2009; U.S. Patent No. 9,248,043, filed June 29, 2011; U.S. Patent No. 9,078,711, filed June 6, 2012; U.S. Patent Application No. 14 / 698,665, filed April 28, 2015; U.S. Patent Application No. 14 / 932,904, filed November 4, 2015; U.S. Patent Application No. 16 / 004,099, filed December 12, 2016; and International Application No. PCT / US2020 / 017338, filed February 7, 2020, all of which are incorporated by reference herein as if set forth in their entireties.

[0033] The examples described herein may benefit from techniques described in other applications. In one example, the maintenance feature described in U.S. Patent No. 10,405,891 (filed September 8, 2017 as U.S. Patent Application No. 15 / 699,711, incorporated herein by reference in its entirety for all purposes) may be adapted for use with the examples herein. In one example, the modified keeper mechanism described in U.S. Patent Application No. 17 / 806,552 (filed June 13, 2022, incorporated herein by reference in its entirety for all purposes) may be adapted for use with the examples herein.

[0034] In some embodiments, the present disclosure provides a method of post-operative distraction osteogenesis by non-invasively actuating an actuator of a distraction device implanted in a patient. Actuating the actuator of the distraction device can be performed percutaneously through intact skin. The method can further include implanting the distraction device in the patient and implanting one or more fixation anchors to couple the distraction device to a bone segment of the patient. The method can include forming one or more incisions in the patient and implanting the distraction device or fixation anchors through the one or more incisions. The method can further include rotating one or more external magnets of an external adjustment device to rotate one or more internal magnets of the distraction device, thereby non-invasively actuating the actuator post-operatively. For example, as shown in FIG. 15 , a method 1500 of the present disclosure may include step 1510 of implanting an adjustable implant into a first bone segment and a second bone segment, step 1520 of actuating a drive assembly about a first axis, step 1530 of extending the second bone segment relative to the first bone segment along a second axis, and step 1540 of allowing continued bone growth.

[0035] While the above implementations relate primarily to external magnetically driven adjustable implant systems, other drive systems can also be used. For example, in addition to or instead of magnet-based drives, one or more of the drive elements can take the form of an implanted electric motor. The implanted electric motor can be powered by an external power source (e.g., via a radio frequency link, via ultrasonic energy transmission technology, via an inductive connection, via another technology, or via a combination thereof) or by an implanted power source (e.g., a battery or charging capacitor that can be charged by an external power source). The implanted power source can be within the implant (e.g., within its housing) or can be separate from the implant and coupled to the implant via a cable.

[0036] In the above specification and claims, phrases such as "at least one of" or "one or more of" may be followed by a conjunctive list of elements or features. The term "and / or" may appear in a list of two or more elements or features. Unless otherwise implicitly or explicitly contradicted by the context in which it is used, such phrases are intended to refer to any of the listed elements or features individually, or any of the listed elements or features in combination with any of the other listed elements or features. For example, the phrases "at least one of A and B," "one or more of A and B," and "A and / or B" are each intended to mean "A only, B only, or A in combination with B." A similar interpretation is intended for lists containing more than two items. For example, the phrases "at least one of A, B, and C," "one or more of A, B, and C," and "A, B, and / or C" are intended to mean "A only, B only, C only, a combination of A and B, a combination of A and C, a combination of B and C, or a combination of A, B, and C," respectively. Use of the term "based on" above and in the claims is intended to mean "based at least in part on," allowing for unrecited features or elements.

[0037] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, terms such as “first,” “second,” etc., do not denote 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 of quantity, but rather denote the presence of at least one of the referenced items. It will be further understood that, as used herein, the terms “comprises” and / or “comprising” specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. As used herein, “substantially” refers primarily, most often, to what is fully specified, or any slight deviation that provides the same technical advantages as the present disclosure. Furthermore, an embodiment or implementation described herein as “exemplary” should not be construed as preferred or advantageous over other embodiments or implementations, for example. Rather, it is intended to reflect or illustrate that the embodiment is an "exemplary" embodiment.

[0038] The implementations described in the foregoing description do not represent all implementations consistent with the subject matter described herein. Rather, they are merely some examples consistent with aspects related to the described subject matter. While several variations have been described in detail herein, other modifications or additions are possible. In particular, additional features and / or variations may be provided in addition to those described herein. For example, the above implementations may be directed to various combinations and subcombinations of the disclosed features and / or combinations and subcombinations of one or more features in addition to those disclosed herein. Additionally, the logic flow illustrated in the accompanying drawings and / or described herein does not necessarily require the particular order shown or sequential order to achieve desirable results. The scope of the following claims may include other implementations or embodiments.

Claims

1. 1. An adjustable implant, comprising: a first portion configured to couple to a first bone segment; a drive assembly disposed within the first portion and configured to drive rotational movement about a first axis; a second portion coupled to a second bone segment and configured for axial translation relative to the first portion along a second axis; a lead screw disposed at least partially within the first portion and the second portion along the second axis; a third portion coupled to a third bone segment and configured to translate axially relative to the first portion along a third axis; a second lead screw disposed at least partially within the first portion and the third portion along the third axis; the lead screw is coupled to the drive assembly for rotation therewith, such that rotational motion about the first axis drives rotational motion of the lead screw about the second axis, thereby axially translating the second portion relative to the first portion along the second axis; the second lead screw is configured to engage the drive assembly for rotation therewith to drive rotational movement of the second lead screw about the third axis, thereby axially translating the third portion relative to the first portion along the third axis.

2. The adjustable implant of claim 1 , wherein the first axis is orthogonal to the second axis.

3. The adjustable implant of claim 1 , wherein the first axis and the second axis form an oblique angle.

4. The drive assembly includes: a drive configured to rotate about the first axis in a first direction corresponding to proximal translation of the second portion and in a second direction corresponding to distal translation of the second portion; 10. The adjustable implant of claim 1, comprising: a drive shaft coupled to the drive portion for rotation therewith.

5. 5. The adjustable implant of claim 4, wherein the drive portion comprises a rotating permanent magnet configured to be rotated by an externally applied magnetic field.

6. 5. The adjustable implant of claim 4, further comprising a gear assembly coupled to the drive shaft for rotation therewith, the gear assembly configured to engage the lead screw for rotation therewith to drive rotational movement of the lead screw about the second axis.

7. 7. The adjustable implant of claim 6, wherein the gear assembly comprises a bevel output gear and the lead screw comprises a bevel gear configured to mate with the bevel output gear.

8. The gear assembly includes: a first ring gear fixed to the first portion; a first sun gear disposed within the first ring gear and coupled to the drive shaft for rotation therewith; a second sun gear coupled to the distal end of the drive shaft for rotation therewith; a plurality of compound planetary gears disposed about the first axis, each compound planetary gear including a first gear configured to engage the first sun gear and a second gear configured to engage the second sun gear; a second ring gear configured to receive the second gear of the plurality of compound planetary gears and engage the second gear for rotation therewith; 8. The adjustable implant of claim 7, wherein the bevel output gear is coupled to the second ring gear for rotation therewith, such that rotation of the second ring gear about the first axis causes rotation of the bevel output gear about the first axis, and rotation of the bevel output gear about the first axis drives rotational motion of the lead screw about the second axis.

9. 9. The adjustable implant of claim 8, wherein the first ring gear comprises a first cavity configured to receive the drive portion therein, a second cavity configured to receive the first gear of the plurality of compound planetary gears therein, and an opening dimensioned to receive the drive shaft therein and allow communication between the first cavity and the second cavity.

10. A first fixation anchor configured to couple the first portion to the first bone segment; a second fixation anchor configured to couple the second portion to the second bone segment; 10. The adjustable implant of claim 1, wherein the first portion and the second portion each include a receiving opening configured to receive the first fixation anchor and the second fixation anchor, respectively, therein.

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