Self-powered, sensor-enabled component of a joint replacement prosthesis

Abstract

A sensor-enabled component of a joint replacement prosthesis comprises a housing, a plurality of electric generators, and a displacement transmission post disposed between each electric generator and the housing. The sensor-enabled component contacts another component of the prosthesis such that there is a load transmission between the sensor-enabled component and the other component. Each electric generator comprises a piezoelectric generator or a triboelectric generator and includes spaced-part first and second electrode plates and configured to generate an electrical output based on relative movement between the spaced-apart first and second electrode plates. Each displacement transmission post is configured to transmit a motion caused by an external force acting on the outer surface of the housing to the associated electric generator to cause relative movement of the second electrode plate with respect to the first electrode plate of one or more of the plurality of electric generators.

Description

SELF-POWERED, SENSOR-ENABLED COMPONENT OF A JOINT REPLACEMENT PROSTHESISCROSS-REFERENCE, PRIORITY CLAIM

[0001] This application claims priority to U.S. Provisional Application No. 63 / 553,061, filed February 13, 2024.BACKGROUND

[0002] loint replacement has become a common procedure for reducing the patient’s pain. However, the satisfaction rate after joint replacement is still a main challenge, often requiring a repetition of the surgery. Augmenting conventional prosthetic implants to smart implants utilizing implantable sensors can significantly enhance satisfaction rates by eliminating invasive diagnostics to monitor hidden conditions within the human body to increase patient care and reduce medical procedure. Under daily activities, multiple loads may be transferred to the replaced joints, and the magnitude of these loads depends on body weight and the joints’ kinematics, where it can reach eight times the body weight. Therefore, such loading conditions could significantly affect the implant lifespan and fatigue and lead to the loosening of prostheses and implant wear, hence negatively impacting patient comfort and reducing implant life span. Information about joint loads is lacking from conventional prosthetic implants. Researchers have demonstrated smart implant systems for postoperatively sensing and monitoring the joint functionality (e.g., hip joint) under daily activities for extending the lifespan of the implants and consequently increasing overall patient satisfaction rates. In addition, data from such so-called “smart implants” can be used in vitro to define load conditions for testing and verification of implant performance and enhance projections about functionality and lifespan.

[0003] A challenge associated with conventional smart implants stems from the need to provide power to the implant’s sensors. Such power may come from internal stored energy devices, e.g., batteries, which require periodic re-charging and / or replacement. Alternatively, power may come from external devices, which are inconvenient.

[0004] Therefore, there is a need for self-powered, smart prosthetic implants that can measure loads on implants in real-time for noninvasive diagnostic capabilities.SUMMARY

[0005] The following presents a simplified summary in order to provide a basic understanding of some aspects described herein. This summary is not an extensive overview of the claimed subject matter. It is intended to neither identify key or critical elements of the claimed subject matter nor delineate the scope thereof. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is presented later.

[0006] Triboelectric energy harvesting generates power from contact and separation of materials with opposite tendencies to lose or gain electrons (contact electrification and electrostatic induction). Similarly, piezoelectric energy harvesting generates power from the compression, elongation, and / or bending (which may include both compression and elongation) of piezoelectric materials. The greater the load applied to the energy harvester, the greater the area of contact achieved in the triboelectric harvester or the greater the strain in the piezoelectric material, and hence the more electricity that can be generated. This proportionality between the loads applied and the electricity generated makes triboelectricity and piezoelectricity well-suited for self- powered load sensor applications, and each energy harvester functions as a load sensor. In addition, high efficiency, lightweight, low fabrication costs, and biocompatibility are other advantages of triboelectric and piezoelectric energy harvesters.

[0007] An energy harvester as describe herein is designed to be placed inside a component of a joint replacement prosthesis, such as the femoral head of a prosthetic hip implant, the humoral head of a prosthetic shoulder implant, or the femoral end of a prosthetic knee implant. To accommodate the magnitude and direction of the joint forces, the component acts as a unit that contains multiple energy harvesters uniformly distributed along the component, where each harvester is acting as a separate generator (load sensor) and responsible for sensing the force magnitude acting at that location. The energy harvester may comprise a triboelectric generator comprising a moving electrode plate and a fixed electrode plate with a bonded Polydimethylsiloxane (PDMS) layer. Both electrode plates may be made of suitable conductive, preferably light-weight, and biocompatible material, such as Titanium, Stainless Steel, Aluminum, Cobalt Chromium, and their alloys, or other biocompatible materials commonly used in implants, and are separated by resilient spacers, such as mechanical springs. Alternatively, the energy harvester may comprise a piezoelectric generator comprising a first electrode plate and a second electrode plate with a piezoelectric material sandwiched between the electrode plates. Bothelectrode plates may be made of suitable conductive, preferably light-weight material, such as Titanium, Stainless Steel, Aluminum, Cobalt Chromium, and their alloys.

[0008] Under activities of the joint incorporating the prosthetic implant with the load sensors (energy harvesters), the loads will be transferred to a sensor-enabled component, incorporating one or more energy harvesters, and from the component to the energy harvester(s), resulting in periodic relative motion between each harvester’s electrode plates. This periodic motion will generate a periodic electrical signal that is proportional to the amount of relative displacement of the harvester’s plates, which is proportional to the magnitude of the load. The load magnitude and location(s) over the surface of the sensor-enabled component can be resolved and calibrated to characterize the load state of the joint.

[0009] The design described herein enables the implementation of multiple triboelectric or piezoelectric energy generators into a joint replacement prosthetic having complex shapes, motions, and load paths.

[0010] Other features and characteristics of the subject matter of this disclosure, as well as the methods of operation, functions of related elements of structure and the combination of parts, and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate various embodiments of the subject matter of this disclosure. In the drawings, like reference numbers indicate identical or functionally similar elements.

[0012] FIG. 1 is an exploded perspective view of a conventional hip replacement prosthesis (on the left-hand side) and a perspective view of the assembled hip replacement prosthesis (on the right-hand side).

[0013] FIG. 2 is an exploded perspective view of a sensor-enabled component of a prosthetic hip implant supported on the neck of the prosthetic implant.

[0014] FIG. 3 is a top view of a base of the sensor-enabled component.

[0015] FIG. 4 is a transverse cross-sectional view of the base along the line A-A in FIG. 3.

[0016] FIG. 5 is a perspective view of the sensor-enabled component with the housing omitted from the figure.

[0017] FIG. 6 is a see-through side view of the sensor-enabled component.

[0018] FIG. 7 is an exploded perspective view of the base of the sensor-enabled component and a single displacement transmission post.

[0019] FIG. 8 is a perspective view of a piezoelectric energy generator.

[0020] FIG. 9 is a perspective view of a triboelectric energy generator.

[0021] FIG. 10 is a cut away side view of the housing of the sensor-enabled component with no load applied to the component.

[0022] FIG. 11 is a cut away side view of the housing of the sensor-enabled component with an external load applied to the component.

[0023] FIG. 12 is a perspective view of a hip replacement prosthesis incorporating an alternate embodiment of a sensor-enabled component.

[0024] FIG. 13 is a partial, perspective cut away view of the hip replacement prosthesis and the alternate embodiment of the sensor-enabled component.

[0025] FIG. 14 is a perspective view of the sensor-enabled component of FIG. 13.

[0026] FIG. 15 is an exploded perspective view of the sensor-enabled component of FIG.14.

[0027] FIG. 16 is a partial transverse cross-sectional view of the hip replacement prosthesis and the alternate embodiment of the sensor-enabled component.

[0028] FIG. 17 is a perspective view of a sensor assembly of the alternate embodiment of the sensor-enabled component.

[0029] FIG. 18 is an exploded perspective view of the sensor assembly.DETAILED DESCRIPTION

[0030] While aspects of the subject matter of the present disclosure may be embodied in a variety of forms, the following description and accompanying drawings are merely intended to disclose some of these forms as specific examples of the subject matter. Accordingly, the subject matter of this disclosure is not intended to be limited to the forms or embodiments so described and illustrated.Definitions

[0031] Unless defined otherwise, all terms of art, notations and other technical terms or terminology used herein have the same meaning as is commonly understood by one of ordinary skill in the art to which this disclosure belongs. All patents, applications, published applications and other publications referred to herein are incorporated by reference in their entirety. If a definition set forth in this section is contrary to or otherwise inconsistent with a definition set forth in the patents, applications, published applications, and other publications that are herein incorporated by reference, the definition set forth in this section prevails over the definition that is incorporated herein by reference.

[0032] Unless otherwise indicated or the context suggests otherwise, as used herein, “a” or “an” means “at least one” or “one or more.”

[0033] References in the specification to “one embodiment,” “an embodiment,” a “further embodiment,” “an example,” “an exemplary embodiment,” “some aspects,” “a further aspect,” “aspects,” etc., indicate that the embodiment, example, or aspect described may include a particular feature, structure, or characteristic, but every embodiment encompassed by this disclosure may not necessarily include the particular feature, structure, or characteristic or combination thereof. Moreover, such phrases are not necessarily referring to the same embodiment, example, or aspect. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, such feature, structure, or characteristic is also a description in connection with other embodiments, examples, or aspects with which it is not incompatible, whether or not explicitly described.

[0034] This description may use various terms describing relative spatial arrangements and / or orientations or directions in describing the position and / or orientation of a component, apparatus, location, feature, or a portion thereof or direction of movement, force, or other dynamic action. Unless specifically stated, or otherwise dictated by the context of the description, suchterms, including, without limitation, top, bottom, above, below, under, on top of, upper, lower, left, right, in front of, behind, beneath, next to, adjacent, between, horizontal, vertical, diagonal, longitudinal, transverse, radial, axial, clockwise, counter-clockwise, forward, backward, sideward, sideways, etc., are used for convenience in referring to such component, apparatus, location, feature, or a portion thereof or movement, force, or other dynamic action represented in the drawings and are not intended to be limiting.

[0035] Unless otherwise indicated, or the context suggests otherwise, terms used herein to describe a physical and / or spatial relationship between a first component, structure, or portion thereof and a second component, structure, or portion thereof, such as, attached, connected, fixed, joined, linked, coupled, or similar terms or variations of such terms, shall encompass both a direct relationship in which the first component, structure, or portion thereof is in direct contact with the second component, structure, or portion thereof or there are one or more intervening components, structures, or portions thereof between the first component, structure, or portion thereof and the second component, structure, or portion thereof.

[0036] Unless otherwise stated, any specific dimensions mentioned in this description are merely representative of an exemplary implementation of a device embodying aspects of the disclosure and are not intended to be limiting.

[0037] To the extent used herein, the terms “about” or “approximately” apply to all numeric values and terms indicating specific physical orientations or relationships such as horizontal, vertical, parallel, perpendicular, concentric, or similar terms, specified herein, whether or not explicitly indicated. This term generally refers to a range of numbers, orientations, and relationships that one of ordinary skill in the art would consider as a reasonable amount of deviation to the recited numeric values, orientations, and relationships (i.e., having the equivalent function or result) in the context of the present disclosure. For example, and not intended to be limiting, this term can be construed as including a deviation of ±10 percent of the given numeric value, orientation, or relationship, provided such a deviation does not alter the end function or result of the stated value, orientation, or relationship. Therefore, under some circumstances as would be appreciated by one of ordinary skill in the art a value of about or approximately 1% can be construed to be a range from 0.9% to 1.1%.

[0038] To the extent used herein, the term “adjacent” refers to being near (spatial proximity) or adjoining (physical contact). Adjacent objects or portions thereof can be spaced apart from one another or can be in actual or direct physical contact with one another. In someinstances, adjacent objects or portions thereof can be coupled to one another or can be formed integrally with one another.

[0039] To the extent used herein, the terms “substantially” and “substantial” refer to a considerable degree or extent. When used in conjunction with, for example, an event, circumstance, characteristic, or property, the terms can refer to instances in which the event, circumstance, characteristic, or property occurs precisely as stated as well as instances in which the event, circumstance, characteristic, or property occurs to a close approximation, such as accounting for typical tolerance levels or variability of the embodiments described herein.

[0040] To the extent used herein, the terms “optional” and “optionally” or the term “may” (e.g., as in the phrase “may include,” “may comprise,” “may produce,” “may provide,” or similar phrases) mean that the subsequently described, component, structure, element, event, circumstance, characteristic, property, etc. may or may not be included or occur and that the description includes instances where the component, structure, element, event, circumstance, characteristic, property, etc. is included or occurs and instances in which it is not or does not.

[0041] To the extent used herein, the terms “first” and “second” preceding the name of an element (e.g., a component, apparatus, location, feature, or a portion thereof or a direction of movement, force, or other dynamic action) are used for identification purposes to distinguish between similar elements, and are not intended to necessarily imply order, nor are the terms “first” and “second” intended to preclude the inclusion of additional similar elements. Furthermore, use of the term “first” preceding the name of an element (e.g., a component, apparatus, location, feature, or a portion thereof or a direction of movement, force, or other dynamic action) does not necessarily imply or require that there be additional, e.g., “second,” “third,” etc., such element(s).

[0042] To the extent used herein, the terms or phrases “configured to,” “adapted to,” “operable to,” “constructed and arranged to,” and similar terms mean that the object of the term or phrases includes, constitutes, or otherwise encompasses the requisite structure(s), mechanism(s), arrangement(s), component(s), material(s), algorithm(s), circuit(s), programming, etc. to perform a specified function, task, or tasks or achieve a specified output or characteristic, either automatically or perpetually or selectively when called upon to do so.

[0043] All possible combinations of elements and components described in the specification or recited in the claims are contemplated and considered to be part of this disclosure. It should be appreciated that all combinations of the foregoing concepts and additional concepts discussed in greater detail herein (provided such concepts are not mutually inconsistent) arecontemplated as being part of the unique subject matter described herein. In particular, all combinations of claimed subject matter appearing at the end of this disclosure are contemplated as being part of the inventive subject matter disclosed herein.Exemplary Embodiments

[0044] For purposes of illustration in this disclosure, devices, components, assemblies, and techniques disclosed herein are described the context of their incorporation and implementation in a total hip replacement (THR) prosthetic implant. Devices, components, assemblies, and techniques disclosed herein may, however, be implemented in any of a variety of joint replacement prosthetics, including hip replacement prosthetics, shoulder replacement prosthetics, and knee replacement prosthetics. Accordingly, devices, components, assemblies, and techniques described herein need not be limited to implementation in any particular prosthetic joint implant.

[0045] A conventional hip replacement prosthesis 100 is shown in FIG. 1. The prosthesis 100 includes a femoral stem 102, a neck 104, a femoral head 106, an acetabular component (cup) 108, and a liner 110 positioned between the acetabular component 108 and the femoral head 106. Liner 110 may be formed of a plastic, such as polyethylene.

[0046] A sensor-enabled component is shown in FIGS. 2-7. The sensor-enabled component 200, which, in the illustrated embodiment, is the femoral head of a prosthetic hip implant, includes a base 220 supported on an end of the neck 104 of the prosthetic implant, a housing 202 positioned over the base 220, and a plurality of displacement transmission posts 280, each including a rotatable bearing 286 and positioned between an outer surface of the base 220 and an inner surface of the housing 202. Note that in FIGS. 6 and 7, a single displacement transmission post 280 is shown and a number of displacement transmission post 280 are omitted from the figure for clarity.

[0047] Referring to FIGS. 3 and 7, base 220 includes an outer surface 224 and a bottom, or support, surface 222 attached to and supported on a portion of the prosthesis, such as a distal end of the neck 104, as shown in FIGS. 2, 5, and 6, or on a distal end of the femoral stem. One or more anchor tabs 238 (four shown in FIG. 3) may be provided for securing the base 220 to the remainer of the prosthetic implant. Base 220 may be made from a suitable, biocompatible material, such as Titanium, Stainless Steel, Aluminum, Cobalt Chromium, and their alloys, or other biocompatible materials commonly used in implants. Referring to FIGS. 3, 6 and 7, a number of generator pockets 226 are formed in the outer surface 224 of the base 220. Each generator pocket 226 may comprise a recess (circular in the illustrated embodiment) with a first portion 234 and asecond portion 236 coaxially-arranged with respect to, and deeper than, the first portion 234. An electrical generator (or energy harvester), as will be described below, is positioned within the second portion 236 of the generator pocket 226. A number of grooves 230 and / or holes 232 may be formed within the generator pocket 226 (e.g., in a bottom surface of the second portion 236, as shown) to accommodate one or more wires connected to the electrical generator positioned within the second portion 236. As shown in FIG. 4, base 220 may include internal channels (indicated by arrows) extending from wire holes 232 within the generator pockets 226 to accommodate wires from the generators.

[0048] Referring to FIGS. 2 and 6, housing 202 may include a convex outer surface 204, a concave inner surface 206, and a plurality of bearing holes 210 formed through the housing. Housing 202 may be made from a suitable, biocompatible material, such as Titanium, Stainless Steel, Aluminum, Cobalt Chromium, and their alloys, or other biocompatible materials commonly used in implants. The housing 202 is larger than the base 220, thereby defining a hollow inner chamber 208 enclosing the base 220 and a gap 228 between the outer surface 224 of the base 220 and the inner surface 206 of the housing 202.

[0049] FIG. 7 is an exploded perspective view of the base 220 of the sensor-enabled component 200 and a single displacement transmission post 280. Displacement transmission post 280 may be made from a suitable, biocompatible material, such as Titanium, Stainless Steel, Aluminum, Cobalt Chromium, and their alloys, or other biocompatible materials commonly used in implants. The displacement transmission post 280 comprises a recess 288 at its distal end 284 for receiving a bearing 286, which may be spherical as shown or a roller (cylindrical) bearing as appropriate to the application. Displacement transmission post 280 may be generally cylindrical, as shown, and may include an annular flange 290 near a proximal end 282 and a cylindrical extension 292 extending below the flange 290 to the proximal end 282. The transverse width (e.g., diameter) of the annular flange 290 is no greater than the transverse width (e.g., diameter) of the first portion 234 of the generator pocket 226 but is larger than the transverse width (e.g., diameter) of the second portion 236 of the generator pocket 226 so that the flange 290 may fit into the first portion 234 of the generator pocket 226 but not into the second portion 236. The transverse width (e.g., diameter) of the extension 292 is not greater than the transverse width (e.g., diameter) of the second portion 236 generator pocket 226 so that the extension 292 made fit into the second portion 236.

[0050] FIG. 8 is a top perspective view of a piezoelectric energy generator 240. Piezoelectric energy generator 240 includes a first electrode plate 242 and a second electrode plate244 with an inter-plate gap 246 between first plate 242 and second plate 244. Each of first and second electrode plates 242, 244 may be of any suitable shape, such as, for example, circular, oval, polygon (e.g., square, rectangle, hexagon). First and second electrode plates 242, 244 may be formed of any suitable conductive, biocompatible material, such as Titanium, Stainless Steel, Aluminum, Cobalt Chromium, and their alloys, or other conductive biocompatible materials commonly used in implants. To reduce the risk of electrical contact between the electrode plate 242 and the base 220, the generator 240 may be electrically isolated from the base 220, for example, with a thin, non-conductive, biocompatible polyethylene layer, similar to the polyethylene liner materials commonly used in prosthetic implants. The inter-plate gap 246 is filled with a piezoelectric filler material 248, such as Lead zirconate titanate (PZT), barium titanate, and lead titanate, that is in contact with both the first electrode plate 242 and the second electrode plate 244 so that any relative movement between first and second electrode plates 242, 244 produces a proportional strain in the piezoelectric filler material 248 to thereby generate an electric signal proportional to the amount of relative movement.

[0051] FIG. 9 is a top perspective view of a triboelectric energy generator 260. Triboelectric energy generator 260 includes a first electrode plate 262 and a second electrode plate 266 with an inter-plate gap 270 between first plate 262 and second plate 266. Each of first and second electrode plates 262, 266 may be of any suitable shape, such as, for example, circular, oval, polygon (e.g., square, rectangle, hexagon). First and second electrode plates 262, 266 may be formed of any suitable conductive, biocompatible material, such as Titanium, Stainless Steel, Aluminum, Cobalt Chromium, and their alloys, or other conductive biocompatible materials commonly used in implants. A top surface of first electrode plate 262 is coated with a layer 264 of Polydimethylsiloxane (PDMS), so that relative movement between first and second electrode plates 262, 266 generates an electric signal proportional to the amount of relative movement.

[0052] First and second electrode plates 262, 266 of generator 260 are separated by a plurality of resilient spacers 272, each of which may comprise a mechanical spring, such as a leaf spring or a helical spring. The number of resilient spacers 272 and the strength of each spacer 272 (e.g., spring constant) may be tailored to the particular prosthetic application and anticipated load conditions.

[0053] An electric generator (e.g., piezoelectric generator 240 or triboelectric generator 260) is seated within the second portion 236 of each generator pocket 226 of the base 220. Each electric generator has a transverse width (e.g., diameter) that is not larger than the transverse width (e.g., diameter) of the second portion 236, so that the generator fits within the second portion 236.The electric generator 240, 260 is fixed within the second portion 236 of each generator pocket 226, so that one of the electrode plates (e.g., first electrode plate 242 of generator 240 or first electrode plate 262 of generator 260) is fixed with respect to the base 220 and the opposite electrode plate is movable with respect to the base and the fixed electrode plate.

[0054] A displacement transmission post 280 is placed in contact with the second electrode plate 244 of the electrode generator 240 or the second electrode plate 266 of the electrode generator 240, and spans the gap 228 between the base 220 and the inner surface 206 of the housing 202. The rotatable bearing 286 positioned in the recess 288 formed in the distal end 284 of each displacement transmission post 280 extends through a corresponding bearing hole 210 formed in the housing 202 so that a top portion of the rotatable bearing 286 projects above the outer surface 204 of the housing 202. The rotatable bearings 286 projecting through the housing 202 engage a contacting component of the prosthetic implant to provide relatively frictionless translation of the sensor-enable component 200 with respect to the engaging component of the prosthetic implant. For example, where the sensor-enabled component 200 comprises the femoral head of a hip replacement prosthesis, the projecting rotatable bearings 286 permit rotation of the femoral head with respect to an acetabular component of the prosthetic implant.

[0055] The extension 292 of each displacement transmission post 280 has a width corresponding to the width of the second plate 244 of the generator 240 or the second plate 266 of the generator 260. As noted above, the width of the annular flange 290 of the post 280 corresponds to the width of the first portion 234 of each generator pocket 226. Thus, each displacement transmission post 280 is mounted for longitudinal movement. Accordingly, as a longitudinal force is applied to each displacement transmission post 280, the post 280 is able move in longitudinally to compress the generator 240, 260, as the annular flange 290 is able to move into the first portion 234 of the associated generator pocket 226.

[0056] FIG. 10 is a cut away side view of the sensor-enabled component 200 with no load applied to the component. FIG. 11 is a cut away side view of the sensor-enabled component 200 with an external load F applied to the component. As can be seen in FIG. 10 (which shows only a single displacement transmission post 280), with no load applied to the component 200, the rotatable bearing 286 of the displacement transmission post 280 projects through associated bearing hole 210 the housing 202. The energy generator (triboelectric energy generator 260(1), as shown) is uncompressed, thereby generating no current. As shown in FIG. 11 (which also shows only a single displacement transmission post 280), with load F applied to the rotatable bearing 286, the bearing 286 recedes into the associated bearing hole 210, the annular flange 290 of thedisplacement transmission post 280 recedes into the first portion 234 of the associated generator pocket 226 of the base 220, and the extension 292 of the displacement transmission post 280 recedes into the second portion 236 (extension 292 is not visible in FIG. 11) of the associated generator pocket 226. The energy generator (triboelectric energy generator 260(2), as shown) is compressed, thereby generating a current proportional to the amount of compression of the generator and thus to the magnitude of the force F. The compression of the electric generator (240 or 260) results in an electric signal that is proportional to the amount of compression of the generator (240 or 260). The signal can be calibrated to a particular load magnitude.

[0057] By measuring electrical signal (i.e., loads) at each of a plurality of electrical generators distributed over the surface of the housing 202, a load distribution over the sensor- enabled component can be resolved and characterized by the load magnitude and generator position of each electrical generator. Generator loads can be transmitted (e.g., wirelessly) to an external data logger and communicated to a computer executing a load resolving algorithm.

[0058] A hip replacement prosthesis 300 incorporating an alternative embodiment of a sensor-enabled component is shown in FIG. 12. Again, for purposes of illustration the alternative embodiment of the sensor-enabled component is described in the context of its incorporation and implementation in a total hip replacement (THR) prosthetic implant. The alternative embodiment of the sensor-enabled component may, however, be implemented in any of a variety of joint replacement prosthetics, including hip replacement prosthetics, shoulder replacement prosthetics, and knee replacement prosthetics. The prosthesis 300 includes a femoral stem 302, a neck 304, a femoral head 306, and acetabular component (cup) 308.

[0059] As shown in FIGS. 13 - 16, a sensor-enabled component 400 may be encased within the femoral head 306 of the prosthetic hip implant 300. In this regard, femoral head 306 functions as the housing 202 of sensor-enabled component 200 described above. In FIGS. 13 and 15, only one half (hemisphere) of the femoral head 306 is shown. In this regard, In one example, sensor-enabled component 400 includes a core 402, which is hollow and may be spherical in shape and which is mounted to the neck 304, a support shroud 420, which may be hemispherical in shape and which is radially spaced from the core 402, and a plurality of sensor assemblies 440, each extending through the support shroud 420 and into the core 402. Core 402 and support shroud 420 may be made from a suitable, biocompatible material, such as Titanium, Stainless Steel, Aluminum, Cobalt Chromium, and their alloys, or other biocompatible materials commonly used in implants.

[0060] As shown in FIG. 15, support shroud 420 includes a plurality of sensor openings 422 through which an associated sensor assembly 440 extends, and each sensor opening 422 may be surrounded by an annular ridge 424, e.g., to restrict seepage of fluid material into the opening 422 and into the core 402.

[0061] As shown in FIG. 16, the sensor assemblies 440 extending through the support shroud 420 are in contact with an inner surface of the femoral head 306, which is in direct or indirect contact with the acetabular component 308. Accordingly, forces transmitted between the femoral head 306 and the acetabular component 308 will be transmitted to one or more of the sensor assemblies 440.

[0062] As shown in in FIGS. 17 and 18, each sensor assembly 440 comprises a contact roller 442 (e.g., a metal ball bearing) rotatably seated in a roller base 444 disposed at one end of a connecting rod 446. Connecting rod 446 may be made from a suitable, biocompatible material, such as Titanium, Stainless Steel, Aluminum, Cobalt Chromium, and their alloys, or other biocompatible materials commonly used in implants. Connecting rod 446 extends through a guide tube 406 extending through a wall of the core 402 in a fixed relationship with respect to the core wall. A spring 448 surrounds the connecting rod 446 and is positioned between an inner surface of the connecting shroud 420 and an outer edge of the guide tube 406. A generator base 408 is disposed at an end of the guide tube 406 within an interior space of the core 402. A generator 460 is housed in the generator base 408 such that the generator 460 is exposed to the connecting rod 406 extending through guide tube 406. Generator 460 may be a piezoelectric generator 240 or a triboelectric generator 260 as described above. To reduce the risk of electrical contact between an electrode plate of the generator 460 and the core 402, connecting rod 446, and other conductive components, the generator 460 may be electrically isolated from such conductive components, for example, with a thin, non-conductive, biocompatible polyethylene layer, similar to the polyethylene liner materials commonly used in prosthetic implants.

[0063] Spring 448 biases the connecting rod 446 radially outwardly so that the end of the connecting rod is not in contact with the generator 460. When a force having a component in a longitudinal direction with respect to the connecting rod 446 is applied to the roller 442, via the femoral head 306, the connecting rod 446 is pushed through the guide tube 406 into contact with the generator 460. Connecting rod 446 therefore functions as a displacement transmission post as it is supported for longitudinal movement and transmits a displacement (force) applied by the femoral head 306 to the roller 442 to the generator 460.

[0064] In an unloaded state, the energy generator 460 is uncompressed, thereby generating no current. When a load is applied to the roller 442 pushing the connecting rod 446 into contact with the generator 460, the generator 460 is compressed, thereby generating a current proportional to the amount of compression of the generator and thus to the magnitude of the force applied to the roller 442. The compression of the electric generator 460 results in an electric signal that is proportional to the amount of compression of the generator 460, and the signal can be calibrated to a particular load magnitude.

[0065] While the subject matter of this disclosure has been described and shown in considerable detail with reference to certain illustrative examples, including various combinations and sub-combinations of features, those skilled in the art will readily appreciate other embodiments and variations and modifications thereof as encompassed within the scope of the present disclosure. Moreover, the descriptions of such examples, combinations, and sub-combinations is not intended to convey that the claimed subj ect matter requires features or combinations of features other than those expressly recited in the claims. Accordingly, the scope of this disclosure is intended to include all modifications and variations encompassed within the scope of the following appended claims.

Claims

CLAIMS1 A sensor-enabled component of a joint replacement prosthesis, wherein the sensor-enabled component contacts another component of the prosthesis such that there is a load transmission between the sensor-enabled component and the other component, the sensor-enabled component comprising: a housing; a plurality of electric generators disposed internally of the housing, each electric generator comprising a piezoelectric generator or a triboelectric generator and including spaced-part first and second electrode plates and configured to generate an electrical output based on relative movement between the spaced-apart first and second electrode plates, wherein the first electrode plate is fixed and the second electrode plate is movable with respect to the first electrode plate; and a displacement transmission post disposed between the second electrode plate of each electric generator and an inner surface of the housing, wherein each displacement transmission post is supported for longitudinal movement for transmitting a motion caused by an external force acting on an outer surface of the housing to the electric generator to cause relative movement of the second electrode plate with respect to the first electrode plate of one or more of the plurality of electric generators.2 The sensor-enabled component of claim 1, further comprising a base, wherein the housing is positioned over the base, and wherein the first electrode plate of each electric generator is supported on the base.3 The sensor-enabled component of claim 1, further comprising a rotatable bearing disposed in a distal end of each displacement transmission post.4 The sensor-enabled component of claim 3, wherein each rotatable bearing projects through an associated opening formed in the housing.5 The sensor-enabled component of claim 2, wherein the base includes generator pocket associated with each electric generator, wherein each generator pocket comprises a recess with a first portion and a second portion coaxially-arranged with respect to, and deeper than, the first portion, and wherein the associated electrical generator is positioned within the second portion of the generator pocket, and wherein each displacement transmission post comprises an annular flange near a proximal end thereof and a cylindrical extension extending below the annular flange to the proximal end, and wherein the annular flange fits into the first portion of the associatedgenerator pocket but not into the second portion of the generator pocket and the extension fits into the second portion of the generator pocket.6 The sensor-enabled component of claim 1, comprising a hollow core; and a support shroud disposed at a spaced apart position from the hollow core, wherein each electric generator is disposed within an interior space of the hollow core, and wherein each displacement transmission post extends through a wall of the hollow core and through a wall of the support shroud.7 The sensor-enabled component of claim 6, comprising a guide tube associated with each displacement transmission post extending through the wall of the hollow core, wherein each displacement transmission post comprises a connecting rod extending through the guide tube.8 The sensor-enabled component of claim 7, wherein each displacement transmission post comprises a contact roller and a roller base disposed at an end of the connecting rod within which the contact roller is rotatably seated, and wherein the roller base of each displacement transmission post is positioned outside of on an outer surface of the support shroud.9 The sensor-enabled component of claim 8, comprising a spring surrounding the connecting rod of each displacement transmission post, wherein spring is disposed between the associated guide tube and an inner surface of the support shroud.10 The sensor-enabled component of claim 8, wherein each displacement transmission post comprises a generator bases disposed at an end of the connecting rod opposite the roller base and within which the associated electric generator is housed.11 The sensor-enabled component of claim 1, wherein the housing forms a femoral head of a hip replacement prosthesis.

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