WO2017223304A1

WO2017223304A1 - Implantable bone adjustment devices

Info

Publication number: WO2017223304A1
Application number: PCT/US2017/038732
Authority: WO
Inventors: Darren Wilson; Daniel Farley; Sied JANNA; Andrew Thompson
Original assignee: Smith & Nephew, Inc.
Priority date: 2016-06-23
Filing date: 2017-06-22
Publication date: 2017-12-28

Abstract

An orthopedic device (100) comprising a first body (160) having a first surface layer (106) configured to engage a second body (130), a second body (130) having a second surface layer (106) configured to engage a portion of the first surface layer of the first body, the second body configured to move relative to the first body, wherein at least one of the first surface layer and the second surface layer includes one or more ions from plasma-immersion ion implantation. In one form, the ions include one or more of carbon, oxygen, nitrogen, or argon. In one form, the surface layer treated by PIII has a hardness greater than 15 GPa, a thickness between 1 μm to 10 μm, and a coefficient of friction less than 0.30. The orthopedic device includes an intramedullary nail, endoscopic resection blade device, or other bone adjustment devices.

Description

IMPLANTABLE BONE ADJUSTMENT DEVICES

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims the benefit of U.S. Provisional Application Serial No.

62/354,069 filed June 23, 2016, the contents of which are incorporated herein by reference in their entirety.

TECHNICAL FIELD

[0002] The present disclosure generally relates to implantable bone adjustment devices, and more particularly, but not exclusively, relates to limb-lengthening intramedullary nails.

BACKGROUND

[0003] Implantable bone adjustment devices are occasionally used in orthopedic procedures to gradually adjust the position, orientation, geometry and/or length of a bone. One form of such a bone adjustment device is a limb-lengthening nail (LLN) which is implanted in the medullary canal of a long bone and subsequently manipulated to adjust the length of the bone. While currently-available LLN systems may be appropriate in particular situations, many of these products exhibit one or more shortcomings or disadvantages that render the product infeasible or contraindicated for certain procedures and/or patient populations.

[0004] One currently-available LLN is an internal telescopic nail including a one-way

lengthening mechanism activated by rotation. With this product, lengthening occurs with alternate rotations of the desired bone segment. The rotation of the bone segment results in an audible noise which indicates to the user the amount by which the bone has been lengthened. Due to the one-way lengthening mechanism, however, the product is incapable of reversing the lengthening or providing compression. Additionally, the nail has a large diameter, which renders the product unusable for many potential patients. Furthermore, the lengthening mechanism is occasionally painful to the patient.

[0005] Another available system includes a telescopic intramedullary rod that can be gradually extended by regular movement of the knee and ankle. Bone growth is monitored by measuring changes in the magnetic field of an embedded magnet in the system, as the poles of the magnet change orientation as the device lengthens. However, if the motion of the leg makes the device lengthen too quickly and the magnet switches poles twice between measurements, then the distraction is not recorded. This may lead to overly rapid growth, which can cause a number of issues, such as non-union of the regenerate, nerve damage, uncontrolled passive "run-away" lengthening, and a limited size range which excludes many potential patients. As with the above-described system, the distraction mechanism cannot be reversed, and compression is therefore not available.

[0006] Another telescopic implantable LLN is actuated by a small electric motor sealed within the implant device. The device is inductively powered through the skin with an external power unit. A small coil transducer protrudes from the end of the nail and is implanted in the soft tissue, close to the skin. Coupling the external unit with the implanted transducer activates the motor and begins the lengthening. Limitations of this system include a high cost and limited availability outside of Europe. Additionally, the implant has a large diameter, which in turn precludes its use in many potential patients.

[0007] Another available LLN includes an internal magnet which is connected to a screw shaft through a gear box. Rotating the magnet rotates the screw shaft and lengthens or shortens the telescopic nail. An external actuator is applied to the limb to rotate the internal magnet. The actuator has two magnets that are rotated by a motorized system while they are held against the limb at the level of the internal magnet in the nail. Drawbacks of this system include a high cost, limited magnetic coupling distance, limited weight bearing during lengthening, and reports of lengthening mechanism malfunction or breakage, possibly due to large resistive forces.

Additionally, the limited size of the prosthesis precludes its use in many potential patients.

[0008] In systems which utilize a magnetic coupling to manipulate the implant, the ability of the system to distract the bone against the forces of the bone callus and soft tissue is directly related to the strength of the magnetic coupling between the internal magnet of the nail and the magnet in the external actuation unit, as well as the resistive friction forces internal to the device. For patients with a large limb diameter, the distance between the nail and actuator reduces the coupling strength and distraction capability. Accordingly, certain conventional magnetically- actuated intramedullary LLN systems are contraindicated for patients with a large limb diameter.

[0009] Orthopedic implants and prosthetics are typically formed of a biocompatible metal.

Medical grade cobalt-chromium (CoCr) alloys such as cobalt-chromium-molybdenum (CoCrMo) are among the most suitable metallic biomaterials, particularly for weight-bearing implants. These alloys typically exhibit high mechanical properties, adequate corrosion resistance, and acceptable biocompatibility. Consequently, this alloy has occasionally been used for the construction of prosthetics for deformity correction and acquired trauma. While CoCr alloys have proven useful for external prosthetics and fixed implants, there are concerns over the use of this material for internal fixation devices having moving parts. One such concern relates to the generation of wear particles from the internal CoCr components which control the lengthening and shortening of the implant, such as mating threaded members. The formation of nanoscale wear debris from these internal mating surfaces could release chromium and cobalt ions into the host body and cause potential toxicity. For these reasons among others, a need remains for further improvements in this technological field.

SUMMARY

[0010] There is provided a bone adjustment device includes a first body configured for

attachment to a first bone segment, and a second body configured for attachment to a second bone segment. The first portion includes a rod having a first set of threads, and the second portion includes a block having a second set of threads. The first set of threads is engaged with the second set of threads such that relative rotation of the rod and the block causes axial displacement of the first and second bodies. At least one of the rod and the block includes an outer surface layer formed by one of plasma-immersion ion implantation (PHI) and plasma- immersion ion implantation and deposition (PIIID). The surface layer is formed on at least one of the sets of threads, and reduces friction between the engaged threads. The rod and the block may be formed of a cobalt-chromium (CoCr) alloy or other suitable materials.

[0011] There is provided an orthopedic device comprising a first body having a first surface layer configured to engage a second body; a second body having a second surface layer configured to engage a portion of the first surface layer of the first body, the second body configured to move relative to the first body, wherein at least one of the first surface layer and the second surface layer includes one or more ions from plasma-immersion ion implantation.

[0012] In some embodiments, the first surface layer treated by the plasma-immersion ion

implantation may have a hardness greater than 15 GPa.

[0013] In some embodiments, the second surface layer may include one or more ions from the plasma-immersion ion implantation process.

[0014] In some embodiments, the first surface layer or the second surface layer may have a thickness between 1 μηι to 10 μιη.

[0015] In some embodiments, the one or more ions may be any one or more of carbon, oxygen, nitrogen, or argon ions to reduce friction between the first surface layer and the second surface layer.

[0016] In some embodiments, the one or more ions may be any one or more of molybdenum, titanium, tungsten, or tantalum ions to reduce friction between the first surface layer and the second surface layer.

[0017] In some embodiments, the orthopedic device may be an intramedullary nail, the first body includes a block defining an internally threaded opening that includes the first surface layer, the second body includes a threaded rod that includes the second surface layer, the threaded rod arranged such that a portion of the threaded rod is rotatably engaged by the threaded opening in the block wherein the first surface layer is configured to contact the second surface layer.

[0018] In some embodiments, the threaded rod may be coupled to the second body to rotate relative thereto without relative axial movement, an inner magnet may be received by the first body and coupled to the threaded rod for rotation therewith, the threaded rod passing through the block and threadedly engaging with the internal threads of the threaded opening such that rotation of the inner magnet and the threaded shaft relative to the block causes relative axial movement between (a) the inner magnet, the threaded shaft, and the second body, and (b) the first body.

[0019] In some embodiments, the orthopedic device may be an intramedullary nail, the first body includes a compression screw that includes the first surface layer, the second body includes a lag screw that includes the second surface layer, wherein the lag screw is arranged such that a portion of the lag screw is rotatably engaged with the compression screw wherein the first surface layer is configured to contact the second surface layer.

[0020] In some embodiments, the orthopedic device may be an endoscopic resection blade

device, the first body includes an outer tubular member having an opening that defines an edge that includes the first surface layer, the second body includes an inner tubular member having a cutting surface that includes the second surface layer, the inner tubular member rotatably received in the outer tubular member and arranged such that the cutting surface engages with the edge of the opening to cut tissue positioned there between.

[0021] In some embodiments, the first body may be a compression screw that includes the first surface layer, the second body may include a plate that defines a locking hole that includes the second surface layer, the compression screw is rotatably received in the locking hole wherein the first surface layer is configured to contact the second surface layer.

[0022] In some embodiments, the first body and the second body may be formed of one or more of cobalt-chromium, stainless steel, or titanium alloy.

[0023] In some embodiments, the coefficient of friction of either the first surface layer or the second surface layer may be less than 0.30 or less than 0.20. [0024] In some embodiments, the plasma-immersion ion implantation may include plasma- immersion ion implantation and deposition, the first body includes a coating deposited on the first body by the plasma-immersion ion implantation and deposition.

[0025] In some embodiments, the coating may be a diamond-like carbon material.

[0026] Further features and advantages of at least some of the embodiments of the present

invention, as well as the structure and operation of various embodiments of the present invention, are described in detail below with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG. 1 illustrates a front view of a system according to one embodiment which includes an intramedullary nail having an adjustable length and an actuating mechanism.

[0028] FIG. 2 illustrates a side view of the system illustrated in FIG. 1.

[0029] FIG. 3 illustrates a cross-sectional view of the intramedullary nail shown in FIG. 1 in a retracted configuration.

[0030] FIG. 4 illustrates a cross-sectional view of the intramedullary nail shown in FIG. 1 in an extended configuration.

[0031] FIG. 5 illustrates a front view of the intramedullary nail shown in FIG. 1 in an extended configuration.

[0032] FIG. 6 illustrates a cross-sectional view of the intramedullary nail shown in FIG. 5 in an extended configuration.

[0033] FIG. 7a illustrates a front view of a threaded block which forms a portion of the

intramedullary nail shown in FIG. 1.

[0034] FIG. 7b illustrates a side view of the threaded block shown in FIG. 7a.

[0035] FIG. 7c illustrates a cross-sectional view of the threaded block shown in FIG. 7a taken along line 7c-7c.

[0036] FIG. 7d illustrates a perspective view of the threaded block shown in FIG. 7a.

[0037] FIG. 8 illustrates the intramedullary nail shown in FIGS. 1-6 implanted in a bone in a retracted state.

[0038] FIG. 9 illustrates the intramedullary nail shown in FIGS. 1-6 implanted in a bone in an expanded state.

[0039] FIG. 10 is a schematic illustration of a plasma-immersion ion implantation system which may be used in certain embodiments.

[0040] FIG. 11 illustrates a bone adjustment device according to a second embodiment.

[0041] FIG. 12 illustrates a bone adjustment device according to a third embodiment.

[0042] FIGS. 13 and 14 illustrate a bone adjustment device according to a third embodiment.

[0043] FIGS. 15 and 16 illustrate a surgical cutting instrument according to one embodiment. DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS

[0044] For the purposes of promoting an understanding of the principles of the invention,

reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alterations and further modifications in the described embodiments, and any further applications of the principles of the invention as described herein are contemplated as would normally occur to one skilled in the art to which the invention relates.

[0045] With reference to FIGS. 1-6, a system 90 according to one embodiment includes a

telescoping intramedullary (IM) nail 100 and an actuator or actuation unit 200. The IM nail 100 includes a longitudinal axis 102 that spans along the length of the IM nail 100. The IM nail 100 includes an outer body 110, a nail portion or inner body 120 mounted in the outer body 110, and a threaded rod 130 mounted in and coupled to the inner body 120. The outer body 1 10 has a proximal end 1 12 opposite a distal end 1 14. The inner body 120 has a proximal end 122 opposite a distal end 124. The threaded rod 130 has a proximal end 132 opposite a distal end 134. The IM nail 100 also includes an inner magnet 140 seated in the outer body 1 10 and coupled to the proximal end 132 of the threaded rod 130, a distal block 150 coupled to the inner body 120 and the distal end 134 of the threaded rod 130, and a threaded block 160 coupled to the outer body 110 and engaged with the threaded rod 130.

[0046] The outer body 110 is at least partially hollow, and accommodates a portion of the inner body 120, which extends through the distal end 1 14 of the outer body 110. The outer and inner bodies 1 10, 120 are dimensioned such that the outer and inner bodies 110, 120 are able to move axially along the longitudinal axis 102 with respect to one another. The outer body 1 10 also houses the inner magnet 140, which may be mounted in a casing or carrier to facilitate the coupling of the inner magnet 140 to the threaded rod 130. As described in further detail below, the inner magnet 140 may be rotated about the longitudinal axis 102 of the IM nail 100 by the actuation unit 200. Each of the outer body 1 10 and the inner body 120 includes a plurality of fastener openings 108 structured to receive fasteners for coupling the bodies 1 10, 120 to the patient's bone. [0047] The inner magnet 140 is coupled to the threaded rod 130, which extends through the proximal end 122 of the inner body 120. The threaded rod 130 also extends through a bearing 103 which engages an inner wall 116 of the outer body 1 10. Similarly, a bearing 104 may be coupled to a proximal end of the inner magnet 140 in order to facilitate rotation of the inner magnet 140 within the outer body 110. The distal end 134 of the threaded rod 130 is engaged with the distal block 150, which is coupled to the inner body 120. The distal block 150 permits rotation of the threaded rod 130 with respect to the inner body 120, and couples the inner body 120 and threaded rod 130 for joint movement along the longitudinal axis 102. For example, the distal block 150 may be coupled or affixed to the inner body 120 such that the threaded rod 130 and end cap 152 mounted thereon can rotate freely without altering the position of the distal end 134 of the threaded rod 130 with respect to the inner body 120. The threaded rod 130 also extends through the threaded block 160, which is coupled to the outer body 110.

[0048] With additional reference to FIGS. 7a, 7b, 7c, and 7d, the threaded block 160 includes a proximal end 162 and a distal end 164. The threaded block 160 also includes an opening 163 formed in the proximal end 162, and a threaded bore 165 extending through at least a portion of the length of the block 160. The threaded bore 165 includes a set of internal threads 166 formed therein. The threaded block 160 is mounted on and rotationally coupled to the outer body 110. For example, a notch 1 15 as illustrated in FIG. 5 may be formed in the distal end 1 14 of the outer body 110, and the threaded block 160 may be mounted in the notch 115.

[0049] The threaded rod 130 includes a set of external threads 136 which extend along the full length or a partial length of the threaded rod 130. In one embodiment, the external threads 136 extend along the length of the threaded rod 130 but do not extend along the distal end 134. The external threads 136 are configured to engage with the set of internal threads 166 formed in the threaded bore 165 of the block 160. As noted above, the threaded rod 130 is axially coupled to the inner body 120 and is axially and rotationally coupled to the inner magnet 140, and the threaded block 160 is engaged with the threaded rod ISO and axially and rotationally coupled to the outer body 110. As a result, rotation of the inner magnet 140 causes relative movement of the outer and inner bodies 1 10, 120 along the longitudinal axis 102. As described in further detail below, at least one of the threaded rod 130 and block 160 is subjected to a plasma- immersion ion implantation (PHI) treatment to form surface layers 106 which improve the hardness and lubricity of the engaged threads 136, 166, respectively, of the threaded rod 130 and block 160.

[0050] FIG. 3 illustrates the IM nail 100 in a retracted or contracted state, and FIG. 4 illustrates the IM nail 100 in an extended or distracted state. The IM nail 100 may be moved between the contracted and distracted states by rotating the inner magnet 140 with the actuation unit 200. More specifically, rotation of the magnet 140 causes rotation of the threaded rod 130 and movement of the threaded block 160 and outer body 110 along the axis 102, thereby adjusting the length of the IM nail 100. As is evident from a comparison of FIGS. 3 and 4, the

longitudinal positions of the distal block 150, end cap 152, and distal end 134 of the threaded rod 130 with respect to the inner body 120 remain unchanged. The inner body 120 has an elongated slot 126 which enables the threaded block 160 to slide along the inner body 120 during relative movement of the bodies 1 10, 120 along the longitudinal axis 102.

[0051] The actuation unit 200 includes a pair of housings 210, an arcuate body 220 connecting the housings 210, and a pair of outer magnets 240 mounted in the housings 210. In FIGS. 1 and 2, the actuation unit 200 is illustrated in a position in which it partially surrounds the IM nail 100, such that the outer magnets 240 are positioned on opposite sides of the inner magnet 140. The magnets 140, 240 may, for example, be neodymium magnets. With the outer magnets 240 positioned on opposite sides of the inner magnet 140, and with each of the outer magnets 240 having an inward-facing side of one polarity aligned with a side of the inner magnet having the opposite polarity, the inner magnet 140 is magnetically coupled to the actuation unit 200. Thus, rotation of the actuation unit 200 about the longitudinal axis 102 results in a torque being applied to the inner magnet 140. As a result of the torque, the inner magnet 140 rotates about the longitudinal axis 102, thereby causing rotation of the threaded rod 130 and either distraction or contraction of the IM nail 100.

[0052] In certain forms, the arcuate body 220 may include an adjustment device which permits relative movement of the housings 210 in a direction transverse to the longitudinal axis 102. In such embodiments, the distance 92 between the inner magnet 140 and the outer magnets 240 may be adjustable in order to accommodate limbs of varying diameters. For example, the housings 210 may be moved further apart from one another in order to accommodate a limb having a larger diameter, and may be moved toward one another to increase the strength of the magnetic coupling when the limb has a smaller diameter. [0053] In the illustrated form, the outer magnets 240 are fixedly mounted in the housings 210, and rotation of the inner magnet 140 is achieved by rotating the actuating device 200 about the longitudinal axis 102. In other embodiments, the outer magnets 240 may be rotatably mounted in the housings 210. In such forms, rotation of the inner magnet 140 may be achieved by rotating the outer magnets while the actuating device 200 remains stationary, as described, for example, in U.S. Patent No. 8,777,947 to Zahrly et al.

[0054] FIGS. 8 and 9 illustrate the IM nail 100 implanted in a bone 300 having a medullary canal 301. The bone 300 has a proximal portion 310 and a distal portion 320, and a gap 302 that separates the proximal and distal bone portions 310, 320. The gap 302 may be formed, for example, during an osteotomy procedure in which the bone 300 is severed for purposes of lengthening the bone 300 over time. The IM nail 100 is received in the medullary canal 301 and is coupled to the bone 300. More specifically, the outer body 1 10 is coupled to the proximal bone portion 310, and the inner body 120 is coupled to the distal bone portion 320. By way of example, the bodies 110, 120 may be coupled to the respective bone portions 310, 320 by fasteners 109 such as screws or pins, which may be received in or otherwise engaged with the openings 108.

[0055] As noted above, both distraction and compaction of the outer and inner bodies 1 10, 120 with respect to each other is possible. Thus, with the IM nail 100 implanted in the bone 300, the segmented portions of the bone may be distracted or compacted as necessary by rotation of the threaded rod 130 and inner magnet 140, thereby enabling both lengthening and shortening of the bone 300. In other words, the telescoping ability allows the IM nail 100 to both distract and contract the bone portions 310, 320, to which the outer and inner bodies 110, 120 are coupled. During lengthening, the IM nail is transitioned from the retracted state (FIG. 8) to the expanded state (FIG. 9), thereby lengthening the bone 300. The IM nail 100 may be transitioned from the retracted state to the expanded state gradually over a given period of time, such that an ossified region 306 forms as the bone 300 lengthens and heals.

[0056] In the illustrated form, the IM nail 100 is made of ASTM F-1537 Co-Cr-Mo alloy. After implantation of the IM nail 100 in the medullary canal 301 of the bone 300, the system 90 is capable of providing incremental osteogenic distraction via callus manipulation. The external actuation unit 200 is used at various times, per physician instructions, to non-invasively lengthen or shorten the implanted IM nail 100. Relative displacement of the telescoping outer and inner bodies 1 10, 120 is accomplished with the threaded rod 130. The threaded rod 130 mates with the threaded block 160 in the outer body 1 10, and is contained within the inner body 120 such that rotation of the threaded rod 130 will result in extension or compression of the IM nail 100. As noted above, rotation of the rod 130 is driven by magnetic coupling with the external actuation unit 200.

[0057] As will be appreciated, the ability of the system 90 to distract the IM nail 100 against the forces of the bone callus and soft tissue is determined in part by the strength of the magnetic coupling between the inner magnet 140 and the outer magnets 240. For patients with a large limb diameter, the distance 92 between the inner magnet 140 and outer magnets 240 reduces the strength of the magnetic coupling, which limits the amount of torque that can be applied to the threaded rod 130 and inner magnet 140 by the actuation unit 200. The ability of the system 90 to distract the nail also depends in part upon the resistive frictional forces internal to the IM nail 100, such as friction between the engaged threads 136, 166, respectively, of the threaded rod 130 and threaded block 160.

[0058] As described in further detail below, at least one of the threaded rod 130 and threaded block 160 is surface-treated with a plasma immersion ion implantation (PHI) technique which generates surface layers 106 having improved lubricity and/or hardness characteristics. As a result of the improved lubricity, friction between the surfaces of the mating threads 136, 166 is reduced. This reduction in friction reduces the torque required to lengthen the nail 100, thereby reducing the required strength of the magnetic coupling. As a result, the system 90 may be used with patients having a larger limb diameter, for whom the coupling distance 92 between the inner and outer magnets 140, 240 may be increased as compared to patients having a smaller limb diameter. The improved lubricity and/or hardness of the surface layers 106 also reduces the wear on the engaged threads 136, 166, thereby reducing the amount of debris (e.g., Co and/or Cr ions) resulting from such wear.

[0059] FIG. 10 illustrates one example of a system 400 which may be utilized to apply the PHI treatment to a part 402 such as the threaded rod 130 or the threaded block 160. The system 400 includes a chamber 410 having an intake 412 for introduction of one or more gases 413, and an exhaust 414 connected to a pump 416 which generates a partial vacuum in the chamber 410. The part 402 is seated on and electrically connected to a holder 420, which is positioned in the chamber 410 and is connected to a high-voltage pulse generator 430. A radio frequency (RF) antenna 440 faces the holder 420 and is connected to an RF generator 450, for example via a matching box 460.

[0060] During operation, plasma 470 is introduced to and/or generated within the chamber 410.

In the illustrated form, the plasma 470 is generated within the chamber by the antenna 440, which excites the introduced gas 413 to a plasma state. Additionally, the pulse generator 430 provides high- voltage electrical pulses to the holder 420, which transmits the pulses to the part 402. As a result of the electrical charge, the part 402 attracts ions 472 from the plasma 470 such that the ions 472 become implanted or embedded in the surface of the part 402, thereby generating a treated surface layer 403 on the part 402. The part 402 may be immersed in and entirely surrounded by the cloud of plasma 470. In such forms, the ions 472 may be implanted into the whole surface of the part 402 simultaneously, thereby forming strong bonds at the molecular level. With the part 402 immersed, all external surfaces of the part 402 are exposed to the plasma 470, thereby obviating the need to adjust the position of the part 402 during the implantation process.

[0061] As will be appreciated, the material properties of the treated surface layer 403 (e.g., the surface layers 106 of the threads 136, 166) depend in part upon the bulk material of which the part 402 is formed, and in part upon the operational parameters of the PHI process. In certain forms, the bulk material and/or operational parameters may be selected to provide the surface layer 403 with one or more desired properties such as tribological characteristics, thickness, hardness, lubricity, corrosion resistance, hydrophilicity, cohesion between the layer 403 and substrate, cytocompatability, ion release, anti-microbial properties, and/or other desired characteristics. For example, the bulk material and/or parameters may be selected such that the surface layer 403 has a hardness greater than 15GPa, such as in the range of 15GPa to 20GPa. As another example, the bulk material and/or parameters may be selected such that the surface layer 403 has a thickness in the range of 1 micrometer (μηι) to 5μπι, in the range of 3μιη to 5μιτι, in the range of 3μηι to 7μηι, in the range of 5μιτι to ΙΟμηι, or of about 5μηι (e.g., in the range of 4μηι to 6μπι). As another example, the bulk material and/or parameters may be selected such that the surface layer 403 has a coefficient of friction, μ, in the range of 0.10 to 0.35, and more particularly, is in the range of 0.10 to 0.30.

[0062] The following materials with or without PHI treatment were all tested and it was found that by subjecting the bulk material to the PHI treatment improved the coefficient of friction, μ, over the bulk materials that were not subjected to PHI treatment. For example, the bulk material being CoCr having PHI treatment with the gas 413 being one of oxygen, nitrogen, or oxygen and nitrogen duplex has reduction of coefficient of friction, μ, of 0% to 33%, 20% to 63%, or 0% to 44%, respectively. In another example, the bulk material being stainless steel with PHI treatment with the gas being one of nitrogen or oxygen and nitrogen duplex have a reduction of coefficient of friction, μ, of 53% to 66% or 3% to 17%. In another example, the bulk material being

Ti6A14V with PHI treatment with the gas being oxygen or nitrogen has reduction of coefficient of friction, μ, of 0% to 16% for either treatment. In yet another example, the bulk material being Ti6A14V, Type II Anodized, with PHI treatment with the gas being oxygen or nitrogen has reduction of coefficient of friction, μ, of 9% to 28% or 0% to 33%.

[0063] Processing parameters of the system 400 include the base and working pressures within the chamber 410, duration and frequency of the pulses generated by the pulse generator 430, density of the ions 472 within the plasma 470, implantation voltage, duration of implantation, ion dose, acceleration voltage, and the composition of the introduced gas 413. Another operating parameter is the source of the plasma 470, which determines the type of ions 472 which will be present in the plasma 470. As described in further detail below, the source of the plasma 470 may include at least one metal and/or at least one gas, which may be included in the introduced gas 413. Illustrative examples of metal-gas combinations which may be used as the source of the plasma 470 include TIN and Ti(Ta⁺⁵)0₂.

[0064] In certain embodiments, the source of the plasma 470 may include one or more metals, such as molybdenum, titanium, tungsten, tantalum, and carbon. In such forms, the system 400 may be operated according to the following parameters: an implantation voltage in the range of 10 kilovolts (kV) to 50kV, an arc pulse duration of about 280 microseconds (μ8), a pulse repetition rate of about 33 Hertz (Hz), a discharge velocity of about 80 volts (V), an arc peak

5 3 current of about 300 amps (A), a base gas pressure in the range of 10^" Pascals (Pa) to 10^" Pa, an implantation time in the range of one to two hours, and a temperature in the range of 300 degrees Celsius (°C) to 450°C. In certain forms, the gases 413 may include one or more of oxygen (O- PIII), water vapor (H₂O-PIII), nitrogen (N-PIII), and carbon (C-PIII), combinations creating oxide, nitrides (CrN and Cr₂N) being dominating and carbide phases respectively. Argon gas can be blended to enhance the cohesion between substrate and films. Diamond-like carbon thin films can be achieved via acetylene (C₂H₂) gas to produce the carbon plasma for film deposition. [0065] In certain embodiments, the source of the plasma 470 may be the gas 413, which may include one or more of oxygen, nitrogen, and water vapor. In such forms, the system 400 may be operated according to the following parameters: an implantation voltage in the range of lOkV to 50kV, a pulse width in the range of 30μ8 to 100μ8, a pulse repetition rate of about 300Hz, a discharge velocity of about 80 V, a discharge current of about 1 A, a base gas pressure of about 7xl0^"6 Torr, a working pressure of about 5x10^"4 Torr, an implantation time in the range of one to two hours, and a temperature in the range of 300°C to 450°C.

[0066] In one embodiment, the source of the plasma 470 may be the gas 413, which may include nitrogen (N₂), and the system 400 may be operated according to the following parameters: an implantation voltage in the range of lOkV to about 50 kV, the dose is on the order of about

1x10 1 at/cm 2 to about 5x1017 at/cm 2 and the bulk material includes one or more of CoCr, titanium, or stainless steel. In another embodiment, the gas 413, which may include oxygen (0₂), and the system 400 may be operated according to the following parameters: an

implantation voltage in the range of lOkV to about 50 kV, the dose is on the order of about

18 2 ·

1x10 at/cm , and the bulk material includes one or more of CoCr, titanium, or stainless steel. In another form, the gas 413, which may include a dual treatment of nitrogen (N₂) and oxygen (0₂), and the system 400 may be operated according to the following parameters: an

implantation voltage in the range of lOkV to about 50 Kv, the doses for each of nitrogen and oxygen is on the order of about 5xl0^!7 at/cm², and the bulk material includes one or more of CoCr or titanium. In one embodiment, the source of the plasma 470 may be the gas 413, which may include nitrogen (N₂), and the system 400 may be operated according to the following parameters: an implantation voltage in the range of lOkV to about 50 kV, the dose is on the order

16 2 17 2 * of about 5x10 at/cm to about 5x10 at/cm and the bulk material includes titanium.

[0067] For gas-based PHI, oxygen implantation has shown an enhanced formation of chromium oxides, while chemical segregations had led to a diffusion of Co into deeper surface levels.

Correspondingly, an improved corrosion resistance has been observed in accordance with the known behavior of passivating Cr₂0₃ layers on stainless steel. The opposite effect has been found to occur for nitrogen implantation, where trapping of nitrogen by Cr reduces the mobility of Cr, even at reduced temperatures. Nitrogen PHI has also been found to reduce wear of CoCr, but is associated with increased release of Co ions. It has also been found that PHI process temperature (and the corresponding release of Co ions) correlates with the cytocompatibility of the material. Therefore, the two competing concerns (i.e. reduction of wear and increase in release of Co ions) may need to be taken into consideration when evaluating the clinical applicability of nitrogen-implanted CoCr.

[0068] The dose of the implanted ion may be optimized by adjusting the plasma parameters, such as plasma density, pulse width, applied bias voltage and repetition frequency. Typically, it is on the order of 1 to 10 mA/cm . In another form, the dose is on the order from 1x10 to about 5xl0'° at/cm . In one form, the dose is 1x10 at/cm for the gases 413 including nitrogen (N₂₎ and/or oxygen (0₂). A pulsed high voltage may be used to reduce substrate heating as well as to control charging. In certain embodiments, pulse lengths are in the range of 2μ8 to 100 8 at working frequencies from 100Hz up to 3kHz. The substrate temperature can be controlled by varying the implant parameters, and may range from ambient or room temperature to 600°C without additional heating. Self-regulating charge control achieved by the alternating attraction of ions and electrons enables one to process not only conductive, but also insulating surfaces. Certain PHI processes are conducted at very low gas pressure to achieve high impact energy, for example, lower than 0.1 mTorr, and so energy loss and charge transfer/neutralization arising from ion collisions are minimal. Hence, a high intensity plasma source such as an electron cyclotron resonance (ECR) plasma source may be necessary for high ion dose dc-PIII. Nitride phases have been found to give rise to the superior micro-hardness and tribological properties. Ion concentration increases with ion dose but decreases with acceleration voltage.

[0069] In certain embodiments, additional surface modification treatments may be utilized, such as application of either hydrogen peroxide or alkali treatment of the parts with PHI treatment to enhance the functionality of the parts. In certain embodiments, plasma polymerisation and grafting can be used to create lubricous coatings for the internal CoCr components of the limb lengthening nail 100 (e.g., silanes, 1,3,5,7 tetramethylcyclotetrasiloxane and grafting of N- trimethylsilylallylamine or 2-methylacryloyloxyethyl phosphorylcholine).

[0070] In certain embodiments, the PHI technique may take the form of a plasma-based ion

implantation and deposition or plasma-immersion ion implantation and deposition (PIIID) technique. Although standard PHI is a versatile technique which facilitates simultaneous and consecutive ion implantation, it can have limited processing depth. Adding coatings to the surface modification using PIIID may enhance the applicability of plasma immersion processing. For example, simultaneous deposition and ion implantation can improve the hardness of the surface and the adhesion between the deposited layer and the substrate due to mixing effects. In PIIID, the workpiece 402 may be directly placed in the plasma and biased to high negative voltage as an active part of the system. Under certain conditions, PIIID may be a more attractive option because of the low cost and capability of modifying complicated shapes. Additionally, diamond-like carbon (DLC) materials offer high hardness and chemical inertness, and can be deposited using PIIID-type techniques. In certain embodiments, PHI or PIIID may be used in combination with another form of surface treatments, such as plasma-assisted chemical vapor deposition (PACVD) and/or plasma-assisted physical vapor deposition (PAPVD).

[0071] The diamond-like carbon (DLC) materials can be used as a coating material to impart some of the properties of diamond, such as hardness, wear resistance, slickness and smoothness, to a material upon which it is coated. The diamond-like carbon (DLC) materials can be any of its known forms, i.e. pure tetrahedral amorphous carbon with all sp³ bonded carbon atoms, or one of the other forms containing sp³ and sp² bonded carbon atoms. The DLC materials can also include a filler(s) such as hydrogen and metal. In yet further embodiments or other aspects, the DLC material selected for coating a surface can have different properties from the DLC coating being applied to an opposing surface. For example, a first DLC coating having a first set of properties is applied to the outer or first surface of the outer or first body and a second DLC coating having a second set of properties is applied to the inner or second surface of the inner or second body, where the first and second set of properties are different from each other.

[0072] As will be appreciated, PHI retains certain advantages of beam-line ion implantation, such as the ability to introduce multiple elements at concentrations exceeding the solubility limits of conventional alloys. For example, multiple oxide and nitride species at high

concentrations can be implanted to create a special alloy in the near surface region. The plasma 470 can be generated in a suitably designed vacuum chamber 410 with the help of various plasma sources, which may yield plasma 470 with the highest density of ions 472 and lowest contamination level.

[0073] As a result of the PHI treatment, friction between the threaded rod 130 and threaded

block 160 is reduced. This reduced friction reduces the amount of Co and Cr ions generated by the internal components during operation of the IM nail 100, and also reduces the sliding frictional losses between the engaged threads 136, 166, thereby providing more efficient actuation. With a more efficient lengthening mechanism, the coupling distance between the internal magnet 140 and magnets 240 of the external actuation unit 200 can be increased while still providing sufficient torque for distraction of the IM nail 100 against the resistive forces of the bone callus and soft tissue. Larger actuation distances 92 allow for use of the nail 100 in patients with large limb diameters, who may have previously been limited to treatment with infection-prone external systems. Additionally, PHI allows for treatment of complex internally threaded geometries that are difficult to address with other surface treatment techniques such as vapor deposition.

[0074] It has been found that when used to treat the threaded rod 130 and threaded block 160 in the manner described above, the PHI process is simple and cost competitive, and offers advantages such as high efficiency, large area, batch processing, low risk of processing defects, and small instrument footprint, while retaining the favorable bulk attributes of the material. In contrast to certain surface coating techniques (e.g., physical vapor deposition and plasma spraying), the PHI process produces a gradual transitional zone in the alloy near the surface, which decreases the possibility of delamination from torsional forces exerted on the threaded rod 130. Moreover, PHI carried out at higher doses and lower energies provides an economical treatment for enhanced mechanical performance at a mass production scale without affecting the bulk properties. In addition to lubricity, PHI treatment may also be used to enhance other properties of the material, such as corrosion resistance and osseointegration due to the increase in hydrophilicity and oxide thickness.

[0075] As is evident from the foregoing, by generating the surface layers 106 the above- described PHI treatment may reduce the risk of generating cobalt and chromium ions, and may improve the tribological properties of the surfaces of the nail 100. This surface treatment may also improve biocompatibility and reduce the torque required to lengthen the nail 100, thereby enabling the system 90 to be utilized for patients with larger limb diameter. While the PHI treatment has been described as being applied at least one of the threaded rod 130 and the threaded block 160, it is to be appreciated that the PHI treatment may be applied to additional components of the nail 100 (e.g., the outer body 1 10 and/or the inner body 120) in order to form surface layers 106 on such components. In certain embodiments, the PHI treatment is applied to both the threaded rod 130 and the threaded block 160 such that each set of threads 136, 166 includes a ΡΙΙΙ-generated surface layer 106. [0076] Some medical implants are made of CoCrMo alloy. The biocompatibility of CoCrMo alloy is related closely to the material's excellent corrosion resistance, which is imparted by a thin passive oxide film that forms spontaneously on the alloy surface. Dopants such as nitrogen and oxygen may be introduced via a PHI or PIIID technique in order to increase the

biocompatibility of the alloy and minimize leakage of undesirable elements.

[0077] Although CoCr alloys have been proven to be safe for use in internal implants, CoCr implants may be more susceptible to bacteria than certain other materials. This is because CoCr alloys are less readily colonized by the cells of the host, and are consequently more easily colonized by bacteria. To combat this issue, anti-microbial properties can be achieved by implanting metallic dopant species such as copper, zinc and silver, and combinations thereof into the surfaces of the internal and external surfaces through PIIID treatment. It is believed that Ag and CrCo will form micro-galvanic couples owing to the different potentials when immersed in an electrolyte solution. The cathodic reaction may form a proton-depleted region between the bacterial membrane and CoCr substrate, which may disrupt the synthesis of adenosine triphosphate and lead to bacteria death.

[0078] The PHI process may be utilized to create desired bioactive surface chemistry for dental and orthopaedic implants by doping the implant surface with ions such as Ca and P ions (the basic ions of hydroxyapatite). The PHI process can also be tailored to improve the adhesion and release kinetics of pharmaceutical agent such as triclosan and bronopol from implantable devices. For example, PHI treatment could prevent an initial toxically high release of the drug, and allowing the incorporation of a higher amount of the drug and an extended action.

[0079] FIG. 1 1 illustrates a bone adjustment device 500 according to another embodiment. The device 500 includes an IM nail 510, a compression screw 520, and a lag screw 530. The device 500 may be implanted in a fractured bone such as a femur. The rack and pinion design of the device 500 allows for the compression screw 520 and lag screw 530 to compress the fracture while controlling rotation of the fracture segments. As the smaller lag screw 530 reaches the nail 510, it engages the compression screw 520, thereby starting active linear compression. The sliding action of these two screws 520, 530 ensures adequate compression of the fracture, which aids the healing process. The engagement surfaces of the screws 520, 530 are subjected to a PHI treatment such as that described above, thereby increasing lubricity and hardness and reducing friction and wear between the mating threads. [0080] FIG. 12 illustrates a bone adjustment device 600 according to another embodiment. The device 600 utilizes dynamic hip screws, which are femoral head-sparing "pin and plate" orthopedic devices, and which may also be used for femoral neck fractures. The device 600 includes a lag screw 610 and a plate 620. Following reduction, the fracture is internally fixed by applying a large lag screw 610 through the femoral neck, which is held laterally by a lateral femoral plate. The lag screw 610 can slide in the plate 620 along the longitudinal axis of the femoral neck, allowing compression of the fracture, which aids in the healing process. If sliding has taken place, the lateral end of the lag screw 610 may protrude laterally from the plate 620. As with the embodiments described above, the lag screw 610 and/or the plate 620 are subjected to a PHI treatment, thereby improving the tribological compatibility and ensuring adequate compression of the fracture.

[0081] FIGS. 13 and 14 illustrate a system 700 according to another embodiment, which

includes at least one compression screw 710 and a plate 720. The system 700 may, for example, be used to treat femoral fractures. With this system 700, one or more of the compression screws 710 are implanted in the fully extended position to give surgeon the same procedural feel as traditional screws. The compression screw 710 has dual medial and lateral threads 712 and a blunt tip 714 to increase pull-out strength in osteoporotic bone. The plate 720 is equipped with one or more locking holes 722 and one or more non-locking screw holes 724 in a plate shaft 726. The locking plate 720 is designed to provide more support than standalone screws. As with the embodiments described above, the compression screw 710 and/or the locking plate 720 are subjected to a PHI treatment, thereby improving the tribological compatibility and ensuring adequate compression of the fracture.

[0082] FIGS. 15 and 16 illustrate a surgical cutting instrument 800 according to another

embodiment. Such a surgical cutting instrument includes an elongate outer tubular member 811 coupled at a proximal end 812 to a major hub component 813. A distal end 814 of the outer tubular member 81 1 includes an opening 815 which forms a cutting port or window.

[0083] The surgical cutting instrument 800 further includes an elongate inner tubular member 820, more readily illustrated in FIG. 16. The inner tubular member 820 is coupled at a proximal end 821 to a minor hub component 822, and includes a distal end 823 having a cutting edge 824. The minor hub 822 and inner tubular member 820 are rotatably received in the major hub 813 and outer tubular member 81 1 , respectfully, such that the distal ends of the inner and outer tubular members abut, and so that the cutting edge 824 is positioned adjacent the opening 815 so the cutting edge can engage bodily tissue/bone for purposes of cutting same.

[0084] The opening 815 in the distal end of the outer tubular member 81 1 extends through the side and end walls to produce an edge which, in use, cooperates with the cutting edge 824 of the inner tubular member 820. The opening 820 and cutting edge or edges 824 can have any number of configurations as are known in the art or hereinafter developed, depending on their intended use, as long as the configurations are suitable for cooperating with each other to provide a surgical blade or the like that is suitable for cutting tissue and/or bone. In exemplary

embodiments, the opening and cutting edge or edges can combine or cooperate to form surgical trimmers, meniscal cutters, end cutters, side cutters, full radius cutters, synovial resectors, whiskers, open end cutters, arthroplasty burrs, slotted whiskers, tapered burrs, or oval burrs.

[0085] In use, the inner tubular member 820 is rotatably driven within the outer tubular member 81 1 such that the cutting edge 824 engages body tissue through the cutting port or window formed by opening 820. The cut or processed tissue is aspirated through the lumen of the inner tubular member and to exit the surgical cutting instrument via transverse bore 825, which communicates with a suction passage in the handpiece.

[0086] As with the embodiments described above, the outer tubular member 811 and the inner tubular member 820 are subjected to a PHI treatment, thereby increasing lubricity and hardness and reducing friction and wear between the outer tubular member 81 1 and the inner tubular member 820. In yet a further aspect or embodiment, both the outer surface of the inner tubular member 820 and the inner surface of the outer tubular member 811, or all of the exposed surfaces of the inner tubular member 820 and the outer tubular member 81 1 are subjected to a PHI treatment. In other embodiments, the cutting edge and/or opening or cutting port or window are subjected to the PHI treatment.

[0087] In one embodiment, an orthopedic device comprises a threaded portion and a mating surface, wherein the threaded portion and/or mating surface has been treated via PHI to increase hardness to 15-20 GPa and reduce friction with the mating surfaces.

[0088] In another embodiment, an orthopedic device comprises a threaded portion and a mating surface, wherein the threaded portion or mating surface has an outer surface layer up to 5μηι thick and is implanted with C, O or N ions to reduce friction with the mating surfaces. [0089] In another embodiment, a length adjustable intramedullary nail system comprises an intramedullary nail including an outer body, an inner body having a portion received by the outer body, a threaded shaft coupled to the inner body to rotate relative thereto without relative axial movement, wherein the threaded shaft has been impregnated by PHI to increase hardness and reduce friction, an inner magnet received by the outer body and coupled to the threaded shaft for rotation therewith, and a threaded block coupled to the outer body and having internal threads impregnated by PHI to increase hardness and reduce friction, the threaded shaft passing through the threaded block and threadedly engaging with the internal threads such that rotation of the inner magnet and the threaded shaft relative to the threaded block causes relative axial movement between a) the inner magnet, the threaded shaft and the inner body and b) the outer body.

[0090] In another embodiment, a length adjustable intramedullary nail system comprises an

intramedullary nail including a proximal outer body, a distal body having a portion received by the proximal outer body, a threaded shaft coupled to the distal body to rotate relative thereto without relative axial movement, wherein the threaded shaft has an outer surface layer up to 5μηι thick implanted with C, O or N ions, an inner magnet received by the proximal outer body and coupled to the threaded shaft for rotation therewith, and a threaded block coupled to the proximal outer body and having internal threads and an outer surface layer up to 5μπι thick implanted with C, O, or N ions, the threaded shaft passing through the threaded block and threadedly engaging with the internal threads such that rotation of the inner magnet and the threaded shaft relative to the threaded block causes relative axial movement between a) the inner magnet, the threaded shaft and the distal body and b) the proximal outer body.

[0091] In another embodiment, a method comprises forming a first body configured for

attachment to a first bone portion, and forming a second body configured for attachment to a second bone portion, wherein forming the first body includes forming a block having a first set of threads, and performing plasma-immersion ion implantation on the block, thereby generating a first surface layer on the first set of threads, wherein forming the second body includes forming a rod having a second set of threads structured to matingly engage the first set of threads, and performing plasma-immersion ion implantation on the rod, thereby generating a second surface layer on the second set of threads, and wherein the first and second surface layers are structured to reduce friction between engaged threads. In certain embodiments, the block and the rod are formed of a cobalt-chromium alloy. In other embodiments, performing plasma-immersion ion implantation includes performing plasma-immersion ion implantation and deposition.

[0092] While the invention has been illustrated and described in detail in the drawings and

foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the inventions are desired to be protected.

[0093] It should be understood that while the use of words such as preferable, preferably,

preferred or more preferred utilized in the description above indicate that the feature so described may be more desirable, it nonetheless may not be necessary and embodiments lacking the same may be contemplated as within the scope of the invention, the scope being defined by the claims that follow. In reading the claims, it is intended that when words such as "a," "an," "at least one," or "at least one portion" are used there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. When the language "at least a portion" and/or "a portion" is used the item can include a portion and/or the entire item unless specifically stated to the contrary.

Claims

WHAT IS CLAIMED IS:

1. An orthopedic device comprising:

a first body having a first surface layer configured to engage a second body;

a second body having a second surface layer configured to engage a portion of the first surface layer of the first body, the second body configured to move relative to the first body, wherein at least one of the first surface layer and the second surface layer includes one or more ions from plasma-immersion ion implantation.

2. The orthopedic device of claim 1, wherein the first surface layer treated by the plasma- immersion ion implantation has a hardness greater than 15 GPa.

3. The orthopedic device of any preceding claim, wherein the second surface layer includes one or more ions from the plasma-immersion ion implantation process.

4. The orthopedic device of any preceding claim, wherein the first surface layer or the second surface layer has a thickness between 1 μηι to 10 μηι.

5. The orthopedic device of any preceding claim, wherein the one or more ions include any one or more of carbon, oxygen, nitrogen, or argon ions to reduce friction between the first surface layer and the second surface layer.

6. The orthopedic device of any preceding claim, wherein the one or more ions include any one or more of molybdenum, titanium, tungsten, or tantalum ions to reduce friction between the first surface layer and the second surface layer.

7. The orthopedic device of any preceding claim, wherein the orthopedic device includes an intramedullary nail, the first body includes a block defining an internally threaded opening that includes the first surface layer, the second body includes a threaded rod that includes the second surface layer, the threaded rod arranged such that a portion of the threaded rod is rotatably engaged by the threaded opening in the block wherein the first surface layer is configured to contact the second surface layer.

8. The orthopedic device of claim 7, wherein the threaded rod is coupled to the second body to rotate relative thereto without relative axial movement, an inner magnet received by the first body and coupled to the threaded rod for rotation therewith, the threaded rod passing through the block and threadedly engaging with the internal threads of the threaded opening such that rotation of the inner magnet and the threaded shaft relative to the block causes relative axial movement between

(a) the inner magnet, the threaded shaft, and the second body, and

(b) the first body.

9. The orthopedic device of any of claims 1 -6, wherein the orthopedic device includes an intramedullary nail, the first body includes a compression screw that includes the first surface layer, the second body includes a lag screw that includes the second surface layer, wherein the lag screw is arranged such that a portion of the lag screw is rotatably engaged with the compression screw wherein the first surface layer is configured to contact the second surface layer.

10. The orthopedic device of any of claims 1-6, wherein the orthopedic device includes an endoscopic resection blade device, the first body includes an outer tubular member having an opening that defines an edge that includes the first surface layer, the second body includes an inner tubular member having a cutting surface that includes the second surface layer, the inner tubular member rotatably received in the outer tubular member and arranged such that the cutting surface engages with the edge of the opening to cut tissue positioned therebetween.

11. The orthopedic device of any of claims 1 -6, wherein the first body includes a

compression screw that includes the first surface layer, the second body includes a plate that defines a locking hole that includes the second surface layer, the compression screw is rotatably received in the locking hole wherein the first surface layer is configured to contact the second surface layer.

12. The orthopedic device of any of claims 1-1 1 , wherein the first body and the second body are formed of one or more of cobalt-chromium, stainless steel, or titanium alloy.

13. The orthopedic device of any of claims 1-12, wherein the coefficient of friction of either the first surface layer or the second surface layer is less than 0.30 or less than 0.20.

14. The orthopedic device of any of claims 1-13, wherein the plasma-immersion ion implantation includes plasma-immersion ion implantation and deposition, the first body includes a coating deposited on the first body by the plasma-immersion ion implantation and deposition.

15. The orthopedic device of any of claims 1-14, wherein the coating is a diamond-like carbon material.