Fixation device for orthopaedic prosthesis, heat treatment device for orthopaedic prosthesis and method of use

Abstract

This invention generally relates to apparatus and methods for securely joining modular orthopedic prosthesis components together by securing recesses and protrusions of the components together, particularly by securing protrusions present in one modular component to correspondingly configured recesses (i.e., holes or grooves) present in another modular component. Preferably, the protrusions are tapered, and the holes or grooves are correspondingly configured to provide a tight tolerance fit therewith. In a preferred embodiment, a fixation device is used for joining the components, the fixation device including a heat-resistant portion or area that shields the heated portion from its surrounding environment; the fixation device can be used to hold the orthopedic prosthesis component. In another preferred embodiment, the invention also includes a heat treatment device for providing appropriate heat treatment to the modular orthopedic prosthesis component (or a portion thereof). A method for utilizing the fixation device and heat treatment device during surgical implantation of a modular orthopedic prosthesis is also disclosed.

Description

[0001] This invention generally relates to apparatus and methods for securely joining components of a modular orthopedic prosthesis by fastening female parts to male parts of the components together, particularly by fastening male parts present in a modular component to correspondingly configured female parts (i.e., holes or grooves) present in another modular component. Preferably, the male parts are tapered, and the female parts are correspondingly configured to provide holes or grooves that fit closely to the male parts. In a preferred embodiment, a fixation device is used to join the components, the fixation device including a heat-resistant portion or area that shields the heated portion or component from its surrounding environment; the fixation device can be used to hold the components of the orthopedic prosthesis. In another preferred embodiment, the invention further includes a heat treatment device used to provide appropriate heat treatment to the components (or portions thereof) of the modular orthopedic prosthesis. Methods utilizing the fixation device and heat treatment device during surgical implantation of a modular orthopedic prosthesis are also disclosed.

[0002] Therefore, the present invention relates to an apparatus and method for assembling orthopedic prostheses from multiple components; particularly, the apparatus and method are especially suitable for use in conjunction with prostheses implanted in the human body to surgically replace at least partially the shoulder, elbow, hip, or knee joint. Such orthopedic prostheses are typically assembled from two or more component parts (e.g., an implantable stem fixed to bone and an implantable cup structure of appropriate size also implanted or fixed to bone). These two components, on their own (or in combination with other components), can operate as a replacement joint for the treated patient.

[0003] Examples of such orthopedic prostheses incorporating tapered portions are well-known, and in particular include US 8313531B2 "Interlocking Reverse Hip Prosthesis"; US 2014 / 0156011A1 "Modified Reverse Joint and Revision Prosthesis"; and US 2014 / 0200675 A1 "Lined Femoral Cup". These depict multi-part implantable orthopedic prostheses that include tapered portions (i.e., Morse tapers). It is readily apparent from these that certain components and portions of implantable orthopedic prostheses are typically constructed from durable materials (i.e., metals and / or metal alloys (collectively referred to as "metals")) that are biocompatible and expected to have a long service life. Such components of implantable orthopedic prostheses are typically formed or machined to very precise dimensions and tolerances. In some implementations, the surface areas or portions of components formed of metal / metal alloys may also have specific surface treatments, which may help in one or more ways, such as reducing corrosion or improving bone growth on the surface of such portions.

[0004] Modular orthopedic prostheses typically consist of components with "convex" portions (or elements) sized to fit into correspondingly sized cavities or openings ("recessed" portions or elements) of other components. In the operating room, surgeons are usually provided with multiple discrete components (which may be in the form of a "kit"), from which they can select during the surgical procedure. These components may vary in their respective sizes or configurations, for example, according to their function, and from these components, the surgeon can assemble an orthopedic implant with the appropriate configuration to be implanted into the patient. However, when multiple components are provided by the surgeon for assembly, this "modularity" often involves the subsequent release of metal debris into the patient's body, which can occur over periods of weeks, months, or years after the orthopedic implant is placed from the assembled modular components. This metal debris can be a cause of local inflammatory reactions, ultimately leading to osteolysis. The resulting pain and functional impairments often require subsequent, and sometimes extensive, surgical correction of the previously implanted orthopedic prosthesis formed by the assembled modular components and / or the significant clinical and functional limitations imposed on the patient.

[0005] It is also known in the art that micro-movement between a tapered protrusion and a correspondingly sized recess is a major culprit of “fretting corrosion” under both in vivo and in vitro conditions, even though both parts are typically machined metal parts manufactured to very tight tolerances. Fretting corrosion typically occurs at metal surfaces and damage to implanted orthopedic prostheses is usually caused under load and in the presence of repetitive motion and / or vibration. Such fretting corrosion occurring at or near the interfacial contact surface of a protrusion housed or connected within a correspondingly sized recess is particularly desirable to avoid. Such fretting corrosion can damage the protective oxide layer that may otherwise form or exist at the interfacial contact surface between parts, and such damage can trigger a corrosive cascade effect, wherein, in the presence of impurities and localized tissue fluid in the implanted modular orthopedic prosthesis region, such damage triggers galvanic corrosion by lowering the pH at or near the interfacial contact surface of a protrusion housed or connected within a correspondingly sized recess. This leads to the release of metal hydride ions, resulting in further damage to the interfacial contact surface.

[0006] However, during the assembly of components of implantable modular orthopedic prostheses, manual impact using a hammer is known, but this is not always satisfactory. It has been reported that manual impact is often insufficient to reduce or eliminate micro-movements between components due to cyclic loading during normal gait and other daily activities of the patient causing cantilever and movement. Furthermore, while the use of additional corresponding machining features (such as mating threads, splines, or other non-smooth machining features) in one or both of the interfacial contact surfaces of the tapered protrusions and correspondingly sized recesses may be considered a remedy, this requires additional machining and inherently increases the surface area, which in turn increases the likelihood and extent of galvanic corrosion caused by a decrease in pH at or near their interfacial contact surfaces. These disadvantages, along with the increased complexity in manufacturing and properly assembling orthopedic prostheses from modular components with such additional corresponding machining features, hinder the use of such modular components with non-smooth surfaces at the interfacial surface areas or interfacial contact surfaces of their protrusions and correspondingly sized recesses.

[0007] The present invention solves and overcomes the above-mentioned shortcomings of the prior art.

[0008] In one aspect, the present invention provides an improved orthopedic prosthesis assembled from modular components, which is intended to prevent or substantially reduce fretting corrosion caused by micromovements within the implanted orthopedic prosthesis.

[0009] On the other hand, the present invention provides an improved orthopedic prosthesis assembled from modular components, which is expected to exhibit little or no micromovement between the assembled protrusions and recesses.

[0010] On the other hand, the present invention provides a method for assembling such an improved orthopedic prosthesis from discrete modular components, at least one component having a protrusion and at least one component having a concave component of a corresponding size suitable for receiving and retaining the protrusion, wherein the assembled prosthesis does not exhibit or reduces fretting corrosion caused by micromovements within the implanted orthopedic prosthesis.

[0011] In another aspect, the present invention provides a method for assembling such an improved orthopedic prosthesis from discrete modular components, at least one component having a protrusion and at least one component having a concave component of a corresponding size suitable for receiving and retaining the protrusion, wherein the assembled prosthesis does not exhibit or reduces micromovement between the assembled protrusion and concave portion.

[0012] In another aspect, devices for assembling such modified orthopedic prostheses as described herein and methods for using said devices are provided.

[0013] Another aspect of the invention is a surgical method comprising the steps of securely attaching components forming a modular orthopedic prosthesis within the body of a human patient.

[0014] These and other aspects of the invention will become more apparent from the following description and drawings.

[0015] The inherent property of metals (and / or metal alloys) is their tendency to change shape and volume in response to changes in temperature through heat transfer. The expansion and contraction of components due to heat is widely used to mate metal parts together, such as the thermal riveting of structural steel components in buildings. In other mechanical applications, the diameter of a small-diameter hole in a metal bushing can be increased by heating, which then allows it to mate around a circular shaft, and subsequent cooling achieves a “contraction fit.” Such “contraction fits” of mechanical components are known in machinery; typically, metal parts require a sufficient heating time to cause adequate expansion, subsequently allowing the formation of an assembly, i.e., the insertion or removal of a heated metal part with another element or component.

[0016] The inventors have discovered that micromovements between smooth surface protrusions and correspondingly sized recesses of components in a modular implantable orthopedic prosthesis can be substantially or completely eliminated, and this significantly reduces corrosion of the contact surfaces of these contacts. This can be achieved using a device and a corresponding method. Such a result can occur by pre-treating one or more components or portions of a modular implantable orthopedic prosthesis before assembling them with one or more additional components or portions thereof. However, such assembly occurs when the heat-treated portion or component has an elevated temperature relative to another unheat-treated component during assembly, causing shrinkage of the heat-treated portion or component. This heat pretreatment provides a significant reduction in in vitro (particularly in vivo) fretting corrosion between the interfacial contact surfaces of the assembled modular implantable orthopedic prosthesis elements by substantially or completely eliminating “micromovements” between the protrusions and recesses of two or more assembled components of the prosthesis. During the assembly of an implantable orthopedic prosthesis from two or more components (e.g., modular components), as the heat-pretreated component and / or portion thereof cools from its previously elevated temperature applied to it via the heat pretreatment step to ambient temperature, the heat pretreatment of at least one of the components and / or portions and the resulting thermal expansion allows for a mechanically secure “shrink-fit” type engagement subsequently formed between the portion and / or component and the unpretreated portion or component. Such ambient temperatures can be between approximately 50°F and 100°F (approximately 10°C to 38°C), the latter slightly exceeding “normal” human body temperature. This thermal shrinkage in the previously heat-pretreated component or portion provides shrinkage of the component or portion, and thus allows for a mechanically secure “shrink-fit” type engagement between them, thereby providing considerable contact pressure at the interfacial contact surfaces between them, typically exceeding the contact pressure typically generated at the interfacial contact surfaces from manual impacts of the implantable orthopedic prosthesis alone (e.g., tapping or hammering the mating modular components or portions together).

[0017] Such results are particularly evident in the fact that the mating parts of the modular components of the implantable orthopedic prosthesis are joined between a tapered protrusion and a correspondingly sized recess (i.e., a hole or cavity that receives the tapered protrusion).

[0018] Such results are particularly evident in the fact that the mating parts of the modular components of the implantable orthopedic prosthesis are joined between a non-conical protrusion and a correspondingly sized recess (i.e., a hole or cavity that receives the non-conical protrusion).

[0019] In a preferred embodiment, the tapered protrusion may be a truncated conical element or a tapered shank. The tapered configuration can be any configuration complementary to the dimensions of a correspondingly sized recess, which is preferably a hole or cavity that receives the tapered protrusion and forms a “shrink-fit” engagement with it. The angle of the tapered protrusion relative to the central axis of the shank or protrusion may vary, but advantageously has an angle of about 0.5 to 5 degrees, preferably about 1 to 3 degrees. Conventional configurations of such tapered protrusions are preferred, including one or more of Morse tapers, Jacobs tapers, Brown & Sharpetaper tapers, and Jarno tapers, with Morse tapers, especially those with an angle of about 1 to 5 degrees, being particularly preferred. The outer wall surface of the tapered protrusion or protrusion may be a smooth surface, but optionally may include a coating or a roughened surface, which may facilitate contact with the interface of the hole or cavity receiving the tapered protrusion. Preferably, the tapered outer wall surface does not include splines or threaded elements machined therein.

[0020] In a preferred method of the invention, before assembly onto the protrusion, the recess or a portion thereof is first subjected to a heat treatment step, wherein sufficient energy (preferably thermal energy) is supplied to the recess or portion such that at least one dimension (preferably the width dimension of the hole or cavity sized to receive the protrusion) is at least slightly larger than that of the same hole or cavity at room temperature (i.e., 68°F (20°C)). The relative amount or percentage increase of at least one dimension (e.g., preferably the width or other sized portion of the recess suitable for receiving the protrusion) does not need to be particularly large and the relative increase (or more) in size can be as small as 0.00001% to as high as 5%. Only the increase of at least one dimension of the recess (i.e., the hole or cavity) due to the heat treatment step (e.g., by heating) is needed to reversibly expand that dimension so that after the heat treatment step and when the recess returns to room temperature, it substantially (i.e., within 99.99%-100%) returns to its original size. By way of non-limiting example, at least one dimension of the recessed part may be the diameter of a portion of a hole or cavity at one or more of its parts (such as at its entrance or edge for insertion into the protrusion), or may be the diameter or lateral length at a point perpendicular to a portion of the hole or cavity somewhere between its ends, or between its open ends, or between one of its open ends and closed ends, whichever is appropriate. Heat treatment may be provided by any method, but is preferably provided by the heat treatment apparatus described below. Once joined with an unheat-treated part or portion thereof, the heat-treated part or portion thereof may be cooled and restored to a reduced temperature by rinsing or immersing with a liquid (such as a sterile saline composition) or sterile water. Ideally, during their assembly, the heat-treated part or portion is held at an elevated temperature relative to the unheat-treated part or portion used to form the component, such that a thermal “shrinkage fit” occurs upon subsequent cooling of the heat-treated part or portion. In a preferred embodiment, the heat-treated portions or components are at least about 10°C hotter than the untreated portions or components to which they are joined, and more preferably (in increasing order of preference) at least 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 120°C, 140°C, 160°C, 180°C, 200°C, 220°C, and 240°C. In a preferred embodiment, the heat-treated portions or components are heated to a temperature in the range of about 220°C to 275°C, more preferably in the range of about 240°C to 260°C, and particularly preferably at a temperature of about 250°C.

[0021] It should also be clearly understood that a hole or cavity does not need to have a geometry that is symmetrical about a central axis; such a geometry may occur if the hole or cavity has a circular, cylindrical, or truncated conical cross-section. It should be recognized that recessed parts may also include holes or cavities with asymmetrical geometries, and thus these recessed parts can be used; convex parts and portions thereof may also have asymmetrical geometries. Such include elliptical, oval, and other cavities. A hole may have straight walls, meaning that the cross-sectional geometry remains constant from the opening end of the hole to its other end or another distal opening. However, a hole may also have an asymmetrical geometry, i.e., the cross-sectional geometry may change from the opening end of the hole, or from the opening end of the cavity, to its other end and another distal opening. Such holes and cavities may have distal ends that are flattened, or may be non-flattened, but this is not mandatory. In fact, other irregular geometries may also exist.

[0022] As noted, the amount of heat energy supplied to the component or part thereof during the heat treatment step needs to be sufficient to induce adequate thermal expansion of the modular component or part thereof, thereby causing reversible thermal expansion and resulting in a compressive shrinkage fit between the convex and concave portions of the component. The amount of energy required to achieve this goal will depend on several factors, including but not limited to: the properties of the metal, the coefficient of thermal expansion of the metal of the part or component being treated, the mass of the component or part to be treated, the dimensions and geometry of the component and / or its portion, and the presence of any surface coatings or surface treatments on the component or part undergoing the heat treatment step. As will be readily understood, these factors play a role in determining the amount of energy introduced into the modular component or part to be treated to produce a satisfactory degree of thermal expansion, thereby allowing it to be placed. Preferably, the physical forces applied to the respective component or part thereof (such as physical compression or impact) will vary particularly from the component and / or part being treated, but this can be determined by conventional experimental or empirical techniques. For example, the component or part thereof can be heated, and attention should be paid to the heating time and energy, and to the satisfactory time and energy required to produce a satisfactory amount of thermal expansion. Subsequently, similar or related components or portions may undergo the same heat treatment process to produce a similar satisfactory degree of thermal expansion. When a component or portion experiences the desired or satisfactory amount of thermal expansion, it may be joined or bonded to a corresponding component or portion that has not yet undergone a heat treatment step, such that the cooled, heat-treated component or portion forms a shrinkage fit. Furthermore, heat treatment may be provided by any method, such as by exposing the heat-treated component or portion to a suitable energy source. Non-limiting examples include: induction heating, immersion in a heated liquid bath (such as boiling water or other sterile solutions), heating to a sufficient temperature in an oven, heating under pressure (such as in an autoclave), immersion in a heated bed of granular or particulate material, or by other methods or by using other means not expressly described herein. However, it is advantageous to provide heat treatment by a heat treatment apparatus as described below. Furthermore, after joining with another component or portion thereof, cooling may be facilitated by providing the joined component and / or portion thereof with a cold, sterile flushing fluid readily available in an operating room.

[0023] The apparatus and method of the present invention are particularly suitable for assembling devices and methods for securely joining two or more components of a modular orthopedic prosthesis together by fixing the protrusions and recesses of two or more components, especially in cases where the modular orthopedic prosthesis is used to replace the shoulder, elbow, knee, and particularly the hip of a human patient. Non-limiting examples of such prostheses include:

[0024] 1) Surgically implantable hip prostheses, wherein the femoral implant includes a stem or shaft having a portion embedded within the femur and a ball (or similarly configured three-dimensional geometry) extending from said stem or shaft. The hip prosthesis also includes a complementary acetabular cup implantable in the pelvis, comprising a cavity or socket (or other three-dimensional geometry that may include a concave surface corresponding to the portion of the ball) that contacts the portion of the ball extending from the stem or shaft of the femoral implant. An interface surface is defined between the ball and the acetabular cup when they contact each other. The femoral ball can be secured to the recess (hole and / or cavity) via a protrusion using the apparatus and methods of the present invention. In such implantable hip prostheses, an implantable femoral stem is typically provided, the implantable hip prosthesis comprising a recess and a femoral ball having an extending protrusion, the femoral ball being first processed using the apparatus of the present invention and can be secured to the femoral stem, which may have already been implanted in the femur of a patient. Non-limiting examples of this kind are known in the art, such as US 5462563, US 8323346 and US 9005306.

[0025] 2) Modified implantable hip prostheses, sometimes referred to as “reverse cup” types. In this type, the femoral implant includes a stem or shaft having a portion embedded within the femur, and a femoral cup extending from said stem or shaft, the femoral cup including a cavity or fossa. The hip prosthesis also includes a complementary acetabular cup implantable in the pelvis, said acetabular cup including a ball (or similarly configured three-dimensional geometric surface) at least partially present therein. An interface surface is defined between the cavity or fossa of the femoral cup and the ball of the acetabular cup when they contact each other. Non-limiting examples are also known in the art, such as: US8313531, US 8845743, US 8992627, US 9119724.

[0026] In another aspect, devices for assembling such modified orthopedic prostheses as described herein and methods for using said devices are provided.

[0027] According to a method of the present invention, thermal expansion of a modular component or a portion thereof occurs within or near the positioning of a human patient. To facilitate this, a fixation device is provided comprising a heating element and a heat-resistant portion or region that shields the heating element from human tissue within or near the positioning of the human patient. Furthermore, the fixation device can be used to hold a portion or modular component of an orthopedic prosthesis while simultaneously providing heat to the portion or modular component, and can assist in placing the heated portion or modular component within the human patient. An exemplary fixation device is disclosed and described with reference to the accompanying drawings, wherein:

[0028] Figure 1A cross-sectional view of a fastening device is depicted, which can be used to hold or removably retain modular components within it and facilitates impact resistance to the retained modular components.

[0029] Figure 2 yes Figure 1 A perspective view of the fixing device.

[0030] Figure 3 A cross-sectional view depicting an alternative embodiment of the fixing device is shown.

[0031] Figure 4 A cross-sectional view of another embodiment of the fixing device is depicted.

[0032] Figure 5 A cross-sectional view of another embodiment of the fixing device is shown.

[0033] Figure 6 A view of another embodiment of the fixing device is shown.

[0034] Figure 7 This is a cross-sectional view of a heat treatment apparatus according to a preferred embodiment, showing its use for directly heating a conical cavity present within a modular component (i.e., a sphere).

[0035] Figure 8 This is a cross-sectional view of a heat treatment apparatus according to a preferred embodiment, which is substantially as follows: Figure 3 The description in the figure only includes an extension, and its use here is shown for heating the conical cavity present in the modular component (i.e., the orthopedic conical component).

[0036] Figure 9 This is a partial cross-sectional view of an alternative embodiment of the fixed device and the handheld heat treatment device, showing direct heating of the conical cavity within the modular component (i.e., the ball).

[0037] Various other objects, features, and incidental advantages of the invention will become fully apparent when considered in conjunction with the accompanying drawings, as the same reference characters in several views designate the same or similar parts, and wherein:

[0038] Turning now descriptively to the accompanying drawings, in which similar reference characters denote similar elements in several views, the drawings illustrate certain preferred embodiments of the invention.

[0039] exist Figure 1 and Figure 2The preferred fixing device A is depicted, comprising an impact handle 1 connected at its distal end 1a to a cylindrical heat-resistant impact body 2. The impact handle has a proximal end 1b and an intermediate shaft 1c extending to the distal end 1a, which includes a threaded end 1e. The handle 1 is secured to the impact body 2 via the threaded end 1e through a set of mating threads 28. Although not depicted in the figure, the impact handle 1 can be secured to the impact body 2 by any other suitable configuration or means (i.e., by using a friction-fitting distal end 1a instead of the threaded end 1e, which can fit into a suitably sized socket, or other configurations). The impact body 2 extends further distally from the threaded end 1e to form a protective circular thermal skirt 6 extending and terminating at a base 6a. Between the base 6a and the threads 28, the impact body 2 defines a cavity 31, within which a modular component or portion thereof that has undergone the heat treatment described above is configured and removably held. In the depicted embodiments, the cavity 31 is typically hemispherical in shape because the specific embodiments are designed to accommodate the articulated metal ball 4 as a modular component. Similarly, the configuration of the base 6a is substantially circular, accommodating such an articulated metal ball 4. (Also available from...) Figure 1 and Figure 2 As can be seen, the articulated metal ball 4 includes a conical cavity 5 as a concave portion, which is configured to receive a corresponding convex portion (i.e., a Morse cone (not shown)).

[0040] The impact body 2 and its extended skirt 6 are made of a heat-resistant material that can effectively withstand temperatures of at least 275°C (but preferably exceeding 275°C) without deforming or melting. Non-limiting examples of such materials may include resins, composites, ceramics, polymers, glass fibers, or combinations thereof. Preferably, it is an impact-resistant material reinforced with different materials (i.e., fibers, rovings, threads, microparticles) that allows an impact force to be applied to the proximal end 1b of the impact handle 1, such impact force being provided by a hammer or other manually operated striking tool, or by a power source (i.e., electric, hydraulic, and / or pneumatic) (i.e., an electrically driven impact hammer or similar tool). To keep the ball 4 fixed within the impact chamber 31 after heating, in the depicted embodiment, a rod 3 with claw ends 29 is also provided. The rod 3 is located on a portion of the skirt 6, and the claw ends 29 extend through an opening 7 that extends through the skirt 6, thereby bringing the claw ends 29 into contact with a portion of the ball 4. The rod 3 is pivotable about the pin 30; located between the pin 30 and the proximal end 3a of the rod 3 is a spring 8 located in the cylindrical cavity 9. The spring 8 is an expansion spring that is biased outward to abut against a part of the rod 3, thereby pushing the claw end 29 inward and against the ball 4.

[0041] Although not in Figure 1 and Figure 2As shown, but those skilled in the art will readily understand, one or more additional similar rods 3 and corresponding openings 7, pins 30, and springs 8 in cavities 9 can advantageously be provided to provide additional rods that can provide additional support and retention for the ball 4. Figure 3 This embodiment is illustrated in cross-sectional view, showing an additional fixing device A with an impact handle 1 connected at its distal end 1a to a cylindrical heat-resistant impact body 2, wherein the distal end 1a is tapered and forms an interference fit with a corresponding tapered cavity 2a present in the impact body 2. This allows the impact handle 1 to be separated from the impact body 2 without requiring any rotation between them. The figure depicts the functions and... Figure 1 The spring 8 is similar to the leaf spring 8a, but differs in that the leaf spring 8a is biased against the outer wall 2a of the impact body 2. When two such rods 3 are placed radially opposite each other as shown, this facilitates the release of the ball 4 by pressing the two ends 3a of the rods 3 together (e.g., against the spring 8a). The provision of multiple rods 3 can provide improved retention of the ball 4 (or other components) within the cavity 31.

[0042] Moreover, although not in Figure 1 and Figure 2 As shown, but will be readily understood by those skilled in the art, lever 3 may be omitted, and instead, a chuck may be provided, wherein the elements of the chuck are extended, and when the chuck is in the first position, one or more portions of ball 4 are gripped, while when the chuck is in the second position, the elements of the chuck retract to release ball 4. Figure 4 The cross-sectional view shows such an embodiment, depicting an additional fixing device A. As shown, the distal end 1a of the handle (only a portion of it is shown) is connected to a portion of the cylindrical heat-resistant impact body 2 via a set of intermediate mating threads 28. Here, the extended skirt 6 is omitted, and is partially replaced by pivot plates 40, each having a lower end 40a and an upper end 40b pivotable about an annular ring 41, which holds the pivot plates 40 in place relative to the impact body 2. A collet 50 spans the circumference of the impact body 2 and has an internal mating thread 50a that engages correspondingly with a surface thread 2c present on the impact body 2, such that when the collet 50 rotates, it causes the inclined portion 50c of the collet 50 to move toward or away from the upper end 40b, which in turn causes the lower end 40a to pivot toward or away from the ball 4 present in the cavity 31. The selective placement of the chuck ring 50 through such rotation allows for controllable clamping pressure on portions of the ball 4, which may be desirable in certain situations. It should be understood that... Figure 4 The use of such components shown can also be applied to other heat-treated parts besides ball 4, which is depicted for illustrative purposes.

[0043] Moreover, although not in Figure 1 and Figure 2 As shown, but will be readily understood by those skilled in the art, the rod 3 may be omitted, and instead, a portion of the cavity 31 may be lined with an elastic compressible material configured and / or sized to removably hold the ball 4 (or other heat-treated component) within the cavity 31, but after the ball 4 is attached to another unheat-treated component, the impact body 2 may be withdrawn, thereby causing sufficient deformation of the elastic compressible material so that the ball 4 (or other heat-treated component) is released from the cavity 31. As a non-limiting example, such a loop or ring of elastic compressible material may be adapted within the cavity 31 near or overlapping the base 6a. Figure 5 A cross-sectional view shows an embodiment of such a fixation device A. In this embodiment, a handle 1 (only a portion of which is shown) is surrounded by an impact body bore 2d passing through it, which allows the impact body 2 to slide along an axis 1c; this facilitates the engagement of a conical (or other shaped) distal end 1a into a conical cavity 5, which is configured to receive a corresponding protrusion (i.e., a Morse cone) of a heat-treated component, shown here as a handle 4a that can be used for implantation into bone (e.g., the femur, tibia, or other bones in the human body). The cavity 31 of the impact body 2 includes an internal lining 60 of a deformable elastic material, which may be at least partially compressible and / or elastically deformable, and in this case may help retain the heat-treated component within the impact body 2. Although understood as optional (but included in the preferred embodiment) in the depicted embodiments, the distal end 1a includes a surface liner 61 of deformable elastic material at its surface. The surface liner 61 may be at least partially compressible and / or elastically deformable, and in this case, may help retain the heat-treated component within its cavity 5. The inner liner 60 and the surface liner 61 may be the same or different deformable elastic materials. Figure 5 In this embodiment, the non-spherical shape of the handle 4a is securely held by the fixation device A at least by an inner lining 60 of deformable elastic material and a handle 1 engaged in the cavity 5 (recess). The impact body hole 2d allows for selective placement of the impact body 2 and the skirt 6 during surgery (i.e., during the initial insertion of the handle 4a). It may be advantageous to hold the skirt 6 in a position that shields the heat-treated portion of the handle 4a from nearby tissues within the patient's body, but the skirt 6 can be lifted away if desired or necessary to allow unobstructed view of the handle 4a, and once observation is complete, the skirt 6a can be returned to its previous position.

[0044] exist Figure 1 and Figure 2 In another configuration, not shown but readily understood by those skilled in the art from the following description, the opening 6b of cavity 31 ( Figure 2The size of the impact body 2 is slightly smaller than the maximum or widest dimension of the ball 4 (or other heat-treated component) so that it is held within the cavity. However, the impact body 2 has at least one movable portion extending through the skirt 6 so that the impact body 2 can be configured to increase the size of the opening 6b to allow the ball 4 (or other heat-treated component) to be released from the cavity. For example, the impact body 2 may be formed of two or more component parts that hold the ball 4 (or other heat-treated component) when these component parts are assembled, but allow the ball 4 (or other heat-treated component) to be released through the opening 31 when partially disassembled, after the ball 4 (or other heat-treated component) has been engaged to an unheat-treated component or part thereof. In a simple embodiment, the impact body is formed of two halves movable between an "open" and a "closed" position, such as Figure 6 As shown in the partial cross-sectional view with dashed lines, the impact body 2 is formed by two halves 2', 2" which, when in the closed position as shown, grip the heat-treated component (here, the portion of the handle 4a held by complementary, at least partially compressible and / or elastically deformable clamping) at least by their heat-treated portions, and in this case, help to retain the heat-treated component in complementary cavities 31', 31" which together define cavity 31 when the impact body 2 is in the closed position. The complementary cavities 31', 31" formed of compressible material 60 operate to at least clamp the heat-treated portion of the handle 4a. In this position, the impact body 2 can be used to place the component (here, the handle 4a) into the body, and then the two halves 2', 2" can be hinged open, such as around pin 30, to release the handle 4a from within the impact body 2.

[0045] Reference Figure 6 In one embodiment, the compressible material 60 may be a material that exhibits good thermal properties but very low compressibility. Alternatively, the compressible material 60 may be replaced by a rigid thermal insulation material that is sufficiently shock-resistant such that when the component portion is clamped within the complementary cavities 31', 31" of the impact body 2, the impact force applied via the handle 1 or otherwise transmitted to the component portion can be transferred to the component portion.

[0046] On the other hand, the present invention provides in Figure 7 and Figure 8 An embodiment of the heat treatment apparatus B depicted above. The heat treatment apparatus applies thermal expansion to a component or part thereof. (Refer to...) Figure 7Heat treatment is provided within the cavity 5 of the articular ball implant 4. Inductive heating is provided by an electromagnetic unit (typically designated "E"); this is "dry heat" because no liquid or gaseous heat transfer medium is required. The electromagnetic unit E is encapsulated in a housing 27. A primary electromagnetic coil 17 wound around an iron core 19 generates a strong current in a secondary coil 18, which is delivered by a low-resistance and / or high-current conduit 15 electrically connected to a heating element 16. The heating element 16 is located within a heating core 14 (here, having a convex conical configuration). The low-resistance and / or high-current conduit 15 passes through a thermal base 11 that insulates the heating core 14 and the ball 4 from the primary electromagnetic coil 17. The heating core 14 is formed of a heat-transferring (or conductive) material; however, it does not need to be thermally conductive itself, but only needs to effectively transfer heat from the heating element 16 to the outer surface 14a of the heating core 14. The heating core 14 is configured to be slidably inserted into the conical cavity 5 of the articular ball implant 4. However, preferably, the size of the heating core 14 is slightly smaller than the size of the conical cavity 5 to avoid the connection between the two components.

[0047] The depicted heat treatment apparatus B also includes a variable closed-circuit thermostat 12, which operates by controlling the duration required to reach the desired temperature to control the temperature and / or may also limit the maximum operating temperature of the heating core 14. Since it is readily recognized that different modular components with different configurations and qualities require different heating parameters, the control circuit 20 and / or the variable closed-circuit thermostat 12 can be used to establish desired heating parameters suitable for a particular modular component. Also shown, but optionally in some embodiments, is an audiovisual aid (such as lamp 22) that illuminates and emits an audible signal (e.g., a “beep”) to alert the operator that the heating process has reached the desired temperature, indicating that the joint ball 4 (or other modular component) has reached the desired amount of thermal expansion and is ready to be removed from apparatus B. When this state is reached, the control circuit 20 may also be programmed to automatically shut off the current flowing to the primary coil, or the operator of the apparatus may simply change the position of switch 24 to the “off” position to shut off the current flowing to the primary coil.

[0048] In use, once the ball joint 4 is inserted into the heating core 14, the heating cavity 10 is covered with the cover 9 to avoid unnecessary heat loss and the associated extended time, which is necessary to provide sufficient heat to the ball joint 4. The operation of the electromagnetic unit E is initiated by powering the unit via a power source, for example, by wall current (e.g., 110-130V AC or 220-230V AC) supplied via a conventional plug 20a. Heating is initiated by moving the switch 24 to the operating position, activating the control unit 20, which in turn activates the primary electromagnetic coil 17. This causes current to flow through the secondary coil 18 and to the heating core 14, which reaches a suitable temperature to generate the desired amount of thermal expansion in the cavity 5 of the ball 4. Advantageously, the heating core is operated to reach a temperature of approximately 200°F-500°F (93°C-260°C), preferably approximately 250°F-400°F (120°C-205°C).

[0049] The heating of the ball 4 (or other modular components or portions thereof) can be enhanced by establishing a vacuum within the heat treatment apparatus B; this can be achieved, for example, by providing a vacuum valve 32 having a pipe 32a extending into the interior of the chamber 10 of the heat treatment apparatus B. The vacuum valve 32 can be opened and connected to a suitable vacuum source (not shown) to evacuate air from the chamber 10 via the pipe 32a and the vacuum valve 32 during, but preferably before, energizing the electromagnetic unit E. When relatively large and / or heavy modular components (i.e., such as...) are to be processed within the heat treatment apparatus B... Figure 8 This can be particularly useful when (as described above).

[0050] Optionally, the heating of the ball 4 (or other modular components or portions thereof) can be enhanced by first establishing a vacuum within the heat treatment apparatus B and then filling the chamber 10 with an inert or rare gas; this can be achieved, for example, by providing a vacuum valve 32 having a pipe 32a extending into the interior of the chamber 10 of the heat treatment apparatus B. The vacuum valve 32 can be opened and connected to a suitable vacuum source (not shown) to evacuate air from the interior 10 via the pipe 32a and the vacuum valve 32. Subsequently, during, but preferably before, energizing the electromagnetic unit E, an inert or rare gas is introduced into the chamber 10. The amount of inert or rare gas that can be provided is such that the low pressure is equal to or less than 1 atmosphere (equal to or less than 101000 Pa) or the increased pressure, i.e., more than 1 atmosphere (more than 101000 Pa). When relatively large and / or heavy modular components (i.e., such as...) are to be processed within the heat treatment apparatus B... Figure 8 This can be particularly useful when (as described above).

[0051] Instead of the following induction heating device: which includes an electromagnetic unit (in Figure 7 , Figure 8 The electromagnetic unit (usually designated "E") has a primary electromagnetic coil 17 wound around an iron core 19, which generates a strong current in a secondary coil 18. This strong current is delivered by a low-resistance and / or high-current conduit 15 electrically connected to the heating element 16. It should be clearly understood that in any embodiment of the heat treatment apparatus B of the present invention, other devices and apparatuses providing "dry heat" may be used instead, regardless of their specific characteristics. Figure 7 and Figure 8 The static configuration shown here still has reference to be made later. Figure 9 The heat treatment apparatus discussed is a handheld configuration. Preferably, it is powered by an electric current or power source and does not involve any method of chemical combustion, as the latter introduces a particularly dangerous fire risk. For example, a resistance heater, an electric heating coil, and / or a thermistor can be used instead.

[0052] As generally described herein, such resistive heaters, electric heating coils, and / or thermistors can be incorporated into the heating core 14. Furthermore, the current flowing to such resistive heaters, electric heating coils, and / or thermistors can be controlled via a thermostat 12, which operates to interrupt the current flow to such resistive heaters, electric heating coils, and / or thermistors when the desired temperature of the heating core 14 is reached. Advantageously, using such a thermostat 12 to control the current simplifies the control circuit 20, reducing it to a power supply, resistive heater, electric heating coil, and / or thermistor connected in series with the thermostat 12, which operates to interrupt the operation of the resistive heater, electric heating coil, and / or thermistor when the desired temperature is reached.

[0053] Once ball 4 (or other modular components or parts thereof) has reached the desired temperature and undergone sufficient thermal expansion, a fixing device (such as fixing device A) can be used. Figures 1 to 6The ball 4 is removed from the heat treatment device B, which can be used to attach the heated ball 4 (or other modular component) to another modular component or part thereof, which may be external to the human body but is preferably implanted inside the human body. To remove the ball 4, the protective cover 23 is lifted and removed to expose the chamber 10. The fixation device A is inserted so that the heat-treated ball 4 is fully inserted into and held therein in the cavity 31. This is achieved by the engagement of the claw end 29 of the rod 3. The heat-treated ball 4 is quickly removed and provided to the surgeon performing the operation on the side of the open surgical wound, who then attaches the heat-treated ball 41 (or other heat-treated modular component or part thereof) to another unheat-treated modular component or part thereof already present in the open surgical wound. Engagement may require simply inserting the corresponding protrusions and recesses of the modular components together (when one part is in a state of thermal expansion) and releasing the lever and withdrawing the fixation device A. However, optionally and often preferably, before the fixation device A is released from the heat-treated modular component or part thereof (here, ball 4), an impact force, such as that from a surgeon's hammer or a power source, can be used to drive the heat-treated modular component or part thereof into an unheat-treated modular component or part thereof already present in an open surgical wound. This provides a greater degree of compression to these elements, such that the heat-treated modular component or part thereof, once cooled and thermally contracted, achieves a greater degree of compression compared to the case without an impact force. During this placement, the heat-resistant skirt 6 extending beyond ball 4 keeps surrounding tissue from contacting the heated articular ball 4.

[0054] Optionally, but preferably, as just described above, after the heat-treated modular component or a portion thereof has been joined to or into an unheat-treated modular component or a portion thereof, if desired, the fixation device A or at least the impact body 2, detachable from the impact handle 1, is held in place to provide uninterrupted thermal protection to tissue within the surgical wound proximal to the joined component. The “contraction fit” between the joined components is achieved by cooling the joined components, by causing the heat-treated component or a portion thereof to thermally shrink and decrease in at least one dimension. The impactor and / or impact body 2 can then be removed, and if desired, further cooling of the joined component and its portion can be continued using additional flushing fluid.

[0055] It is worth noting that, given the sufficiently high temperature of the heat treatment, the heat-treated parts or sections, as well as chamber 10, sterilize any living materials and pathogens such as bacteria and viruses.

[0056] Figure 8 The alternative embodiments of the present invention are described. Figure 3 Optional configuration of heat treatment unit B. Figure 8In place of the articular ball 4, the modular component is a modified proximal femoral implant comprising a conical cavity (Morse conical cavity). To accommodate the larger size of the modified proximal femoral implant, the heating chamber 10 is enlarged using an extension 26. Therefore, given the larger mass and different configurations of the modified proximal femoral implant (which is typically not spherical), it is foreseeable that the heat treatment device B will have to operate according to different schemes (i.e., different heat settings and / or heating times) to achieve the desired degree of thermal expansion of the conical cavity of the modified proximal femoral implant.

[0057] Figure 9 This is a partial cross-sectional view of an alternative embodiment of both the fixation device A and the handheld heat treatment device B, showing direct heating of the conical cavity 5 within the modular component (i.e., the articular ball implant 4). However, it should be understood that the handheld heat treatment device B can also be used to heat treat different modular components. Figure 9 The handheld heat treatment device B shown in the image is... Figure 7 , Figure 8 Several advantages are offered by the heat treatment apparatus described herein. One such advantage is the portability provided by the handheld heat treatment device B, as it can be taken very close to open surgical wounds, and it not only means providing initial heat treatment to modular components to provide a satisfactory degree of thermal expansion, but also allows for reheating of modular components if placement requires additional time, or if the degree of thermal expansion is undesirably reduced before connection with other mating modular components. Secondly, the handheld heat treatment device B also allows for heat treatment of modular components that are already ready to be inserted and held within the fixation device A. This allows unnoticed or previously untreated modular components to be placed into the fixation device A first, and then heat treatment can be performed within a portion of the fixation device to achieve the desired degree of thermal expansion of the modular component. Thus, the need to remove the heat treatment device B (such as...) Figure 7 , Figure 8 The step of transferring the heat-treated module components within the (middle) unit. However, the fixed heat treatment device B (such as...) Figure 7 , Figure 8 The benefits of this approach are undeniable, particularly according to the described embodiments, where the processing of modular components takes place within a closed cavity, which can also be filled with a specific gas and / or subjected to reduced pressure. This can provide faster heating than is achievable using a handheld heat treatment device B.

[0058] like Figure 9As shown, the fixing device A and the impact handle 1 (partially shown) are secured to the encapsulated impact body 2 by a set of mating threads 28. In this embodiment, the impact body 2 is housed within a housing 70, within which the impact body 2 and the thermal skirt 6 are adapted. As previously described with reference to other embodiments, the impact body 2 and the thermal skirt 6 are formed of a heat-resistant material that can effectively withstand temperatures of at least 275°C (but preferably more than 275°C) without deformation or melting. It is also preferred that the structural material of the housing 70, formed of a heat-resistant material, is desirable; metals, resins, composites, ceramics, polymers, glass fibers, or combinations thereof are considered, which may optionally, but in some cases, preferably include reinforcing materials such as fibers, rovings, wires, or microparticles. However, it should be noted that the thermal insulation properties of the impact body 2 and the thermal skirt 6 do not imply that the structural material of the housing 70 has equal or higher heat resistance.

[0059] The fixing device A in this embodiment includes one or more inner springs 8b, which are located within the inner cavity 31 and biased toward the centerline, or biased toward the position of the module component when the module component is present in the cavity 31. Preferably, there are two or more inner springs 8b, such as... Figure 9 As shown, the components are radially positioned relative to each other within cavity 31 so that they can each contact the surface of the modular component with the corresponding portion of the impact body 2. The modular component is held within cavity 31 and impact body 2 by their spring force. Optionally, but preferably, there are also corresponding channels 6c, one of which is located below the corresponding inner spring 8b. These corresponding channels 6c are recessed into portions of impact body 2 and provide space within which the spring 8b can fully retract to allow insertion and removal of the modular component from cavity 31. Advantageously, as shown, the contour of the inner springs 8b includes a portion, preferably a wavy shape, that approximates the corresponding portion of the surface of the modular component and thus forms a good interfacial contact with it, thereby providing improved retention of the modular component. It should also be understood that although inner springs 8b are shown, one, two, three, or any other number may be provided similarly, as desired or necessary.

[0060] It should be understood that the features of the fixing device A shown in any of the accompanying drawings can be used interchangeably and can also be combined in a single fixing device A. Therefore, the depicted embodiments of fixing device A are illustrative but not limiting examples.

[0061] Figure 9A handheld heat treatment device B is also depicted, which can be used to provide direct heating of a conical cavity 5 within a modular component. Such a handheld heat treatment device B includes a cylinder 14b with a heating core 14 at one end, the heating core 14 being insertable into the cavity 5 of an articular ball implant 4. The cylinder 14b extends into a housing 14c having a grip portion 14d adapted for holding by a surgeon or other person. A switch 24 extends from the grip portion 14d; the operator of the device can easily change the position of the switch between an "on" and "off" position to actuate the handheld heat treatment device B, thereby energizing the heating core 14 and providing heat treatment to the cavity 5 of the modular component. Figure 7 and Figure 8 As with other devices, the heating core 14 may be in indirect physical contact with a portion of the modular component (i.e., ball 4), or may be separated from it by a small air gap. The handheld heat treatment device B may include one or more audiovisual aids (such as lamp 22) that illuminate and emit audible signals (e.g., a “beep”) to alert the operator that the heating process has reached the desired temperature, indicating that the joint ball 4 (or other modular component) has reached the desired amount of thermal expansion and that the heating core 14 is ready to be removed from the cavity 5. When this state is reached, a variable closed-loop thermostat 12 within the cylinder 14b near the proximal end of the heating core 14 may be activated to control the temperature and / or limit the maximum operating temperature of the heating core 14 by controlling the duration required to reach the desired temperature. In addition, the control circuit (not shown, but which may be integrated into the housing 14c and / or the power / control unit 20b) may also be programmed to automatically shut off the power to the heating core 14, or the operator of the device may simply release the switch 24, which moves the switch 24 to the "off" position and thus terminates the heating of the heating core 14.

[0062] Although not in Figure 9 As shown, however, it should be understood that the components of the control circuit 20 may reside within the housing 14c and / or the power supply / control unit 20b to which it is electrically connected. Although not shown in Figure 9 As shown, but it should still be understood that all operating elements can be incorporated into housing 14c, in which case the cable can terminate in plug 20a that can be connected to a suitable power source.

[0063] Further discussion regarding the uses and operation of the invention should be apparent from the foregoing description. Furthermore, regarding the foregoing description, it should be recognized that optimal dimensional relationships of parts of the invention, including variations in size, material, shape, form, function, and manner of operation, assembly, and use, are obvious and apparent to those skilled in the art, and all equivalent relationships shown in the drawings and described in the specification are intended to be covered by the invention. Therefore, the foregoing is considered merely an illustration of the principles of the invention.

[0064] Furthermore, since many modifications and variations will readily occur to those skilled in the art, it is not intended to limit the invention to the exact structures and operations shown and described, and accordingly, all suitable modifications and equivalents may be made that fall within the scope of the invention.

Claims

1. A heat treatment apparatus adapted to apply thermal expansion to a portion or component of a modular orthopedic prosthesis having a conical cavity, said heat treatment apparatus comprising: A heating core with a convex conical configuration is slidably inserted into the conical cavity, and the size of the heating core is slightly smaller than the size of the conical cavity to avoid adhesion between the heating core and a part or component of the modular orthopedic prosthesis. The heating core is heated by a heating element, which is an electromagnetic unit, a resistance heater, an electric heating coil, or a thermistor. The electromagnetic unit includes a primary electromagnetic coil and a secondary electromagnetic coil. The electromagnetic unit, resistive heater, electric heating coil, or thermistor is used to heat a portion or component of the modular orthopedic prosthesis to apply thermal expansion to that portion or component.

2. The heat treatment apparatus according to claim 1, wherein the heating element generates heat in the range of 93°C to 260°C.

3. The heat treatment apparatus according to claim 2, wherein the heating element generates heat in the range of 120°C to 205°C.

4. The heat treatment apparatus according to claim 1, further comprising a housing.

5. The heat treatment apparatus according to claim 4, further comprising a chamber for containing gas or a vacuum.

6. The heat treatment apparatus according to claim 5, wherein the chamber is pressurized to more than 1 atm.

7. The heat treatment apparatus according to claim 1, wherein it is a handheld heat treatment apparatus.

8. The heat treatment apparatus according to claim 7, further comprising a handheld grip.

9. The heat treatment apparatus according to any one of claims 1 to 8, further comprising one or more audiovisual aids.

10. The heat treatment apparatus according to any one of claims 1 to 8, wherein the convex cone is a Morse cone.

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