Patent Description:
Some fractures of the radius occur in the part of the bone that is proximate the elbow, called the radial "head". Radial head fractures are common injuries that may result from an acute elbow injury. Fractures of the radial head are typically treated with a variety of surgical and non-surgical options depending upon the severity of the injury. For example, surgical options for more severe injuries to the radial head can include open reduction with internal fixation (ORIF), radial head resection, hemi-arthroplasty (e.g., radial head arthroplasty), and total arthroplasty (i.e., total elbow replacement).

Radial head arthroplasty involves resecting the fractured and damaged radial head and replacing the natural articulation surface with an artificial articulation surface of an implant. The articulating surface of the implant articulates with the natural cartilage surface of the capitellum of the distal humerus.

In radial head replacement procedures, a radial head prosthesis is implanted into the medullary canal of the proximal radius. The radial head may cooperate with an ulna or ulnar prosthesis to provide radioulnar joint articulation. The radial head may cooperate with a humerus or humeral prosthesis to provide radiohumeral joint articulation.

Prior to implantation of a radial head implant, a surgeon selects an implant having a size that properly fits the implant site of the particular patient. Many known systems include trial stems and trial heads the surgeon can assemble and use prior to final implantation to evaluate the fit for selecting the most appropriately sized implant. However, known systems do not offer a simple effective means for trying a plurality of different humeral head heights to determine the proper height for a final radial head implant. Exemplary systems include the following prior art devices:
<CIT> discloses an intramedullary fixation device for use in securing a trial in the medullary canal of a bone to determine the offset and orientation of a prosthetic implant for replacement of a joint articulating surface of the bone is disclosed. The fixation device comprises a body for receiving a trial and a fixation portion for engaging the trial. A system for use in surgical repair of a joint comprising a selection of prosthetic implants of various sizes, a selection of trials of various sizes corresponding to the sizes of the implants, a selection of fixation devices of various sizes corresponding to the sizes of the trials, a trial fixation device driver for inserting the fixation device and attached trial into the canal of a bone, and a trial device extractor for removing the fixation device from the resected bone is disclosed. Methods of using the fixation device and system of the invention are disclosed.

<CIT> discloses radial head implant apparatuses and methods. In one embodiment, a radial head implant can include a head portion for articular engagement with a humerus bone, a stem portion for engagement with a radius bone, and a shaft for engagement with the stem portion. The head portion can include an upper surface for engaging the humerus bone. The stem portion can have an axial opening for receiving at least a portion of the shaft, and a collar can be disposed around the stem portion at a proximal end thereof. An upper portion of the shaft can be configured for engaging the head portion, while a distal portion of the shaft can be elongated and cylindrical for axially fitting into and moving within the axial opening of the stem portion. Other embodiments are also disclosed for axial movement for a radial head implant. Various structures are disclosed for locking the shaft in position within the stem portion.

<CIT> discloses a prosthesis system for replacement of a head portion of a proximal radius. The system can include a first polymeric articulation component having a first locking portion and a metal head component having a second locking portion. The second locking portion can mate with the first locking portion to form a first locking mechanism to initially couple the first articulation component to the head component. The head component can define a locking channel. The system can also include a stem component having a protrusion receivable in the locking channel. The protrusion can define a bore, and the stem component can be adapted to be coupled to the radius. The system can also include a fastener received through the locking channel and into the bore to provide a second locking mechanism that couples the head component to the stem component.

<CIT> discloses a kit for use in a procedure for implantation of an orthopaedic joint prosthesis includes a head component of an orthopaedic joint prosthesis, which comprises a body part having a convex bearing surface, and a reverse face at which the head component can be connected to a mating component of the joint prosthesis, in which the head component has a chamfer surface extending around at least part of its periphery where the bearing and reverse faces come together, and a plurality of markings on the chamfer surface. The kit includes a trial head component which comprises a body part having a convex trial bearing surface and a reverse face, in which the trial head component has a plurality of markings on the trial bearing surface at or towards the interface between it and the reverse face. The transverse dimensions of the head component are approximately the same as the transverse dimensions of the trial head component, and in which the location of the markings on the chamfer surface around the periphery of the head component corresponds to the location of the markings on the trial bearing surface of the trial head component around its periphery.

<CIT> discloses a prosthesis trial system includes at least one head member having an outer surface and a cavity configured to mate with an exterior surface of a stem member. The prosthesis trial system further includes at least one shell member having an inner surface configured to mate with the outer surface of the at least one head member.

<CIT> discloses a kit for use in performing a trial reduction injoint arthroplasty is provided. The kit includes a trial stem assembly including a first component, a second component selectably moveable with respect to the first component, and a fastener for securing the first component to the second component. The kit also includes an articulating trial component removeably fixedly secured to the trail stem assembly and a driver for cooperation with the fastener to secure the first component to the second component. The kit also includes a handle. The handle has a first feature for permitting the driver to pass through the handle and a second feature for orientably connecting the handle to the articulating trial component.

<CIT> discloses a radial head replacement system includes a radial head replacement, an apparatus for guiding the resection of a radial head, and a kit including bone plug and bone plug insertion instrument. The radial head replacement has a separate adjustable head portion that may be secured on an implanted stem such that the implanted radial head replacement smoothly interfaces with the capitellum of the humerus. In another form, the radial head replacement uses crossed bone screws that serve to more securely anchor the stem of the radial head replacement in the medullary canal of the radius. The resection guide includes a movable cutting guide which ensures a precise resection of the radial head and thereby allows for better positioning of the implanted radial head replacement. The bone plug limits the travel of bone cement beyond the area of affixation of the stem portion of a radial head replacement to the radius.

<CIT> discloses a modular prosthesis system for replacement of a head portion of a radius. The prosthesis system includes a head component having a first connection portion that connects to a second connection portion and a collar component having the second connection portion and a third connection portion. The system also includes a stem component including a fourth connection portion that connects with the third connection portion, the stem component having a stem anchoring portion that connects to the radius. The collar component provides the modular geometry to the prosthesis without having to have an increased number of head components and stem components with variable lengths and angles.

<CIT> discloses a radial head trial device for replacement of a proximal radial head includes a stem component having a center longitudinal axis extending between a proximal end and a distal end, a head component axially and removably attachable to the stem component, wherein the head component is interchangeable with a selection of other head components each axially and removably attachable to the stem component, an anti-rotation feature, and a recess, wherein the anti-rotation feature is structured to be received in the recess to prohibit rotation of the head component relative to the stem component.

<CIT> and <CIT> disclose radial head prostheses.

What is needed in the art is a trial radial head implant device and system that allows less joint distraction and a simpler device for confirming final implant height.

The invention relates to an orthopedic trial implant assembly as defined in the appended claims. Embodiments, examples or aspects in the following disclosure which do not fall under the scope of the claims are presented for illustration purposes only and do not form part of the invention.

In accordance with one example of the present disclosure, an orthopedic trial implant assembly can include at least one radial trial implant and at least one spacer. The radial trial implant can include a head body that defines a proximal head body surface and a distal head body surface opposite the proximal head body surface substantially along a longitudinal direction. The head body can have a height that extends from the proximal head body surface to the distal head body surface along the longitudinal direction. The radial trial implant can further include a stem that extends from the head body along a distal direction that is substantially defined by the longitudinal direction. The at least one spacer can be configured to removably attach to the radial trail implant along a direction substantially perpendicular to the longitudinal direction so as to define a composite head including the head body and a spacer head of the spacer. The composite head defines a proximal composite head surface and a distal composite head surface opposite the proximal composite head surface along the longitudinal direction, and the composite head defines a composite head height from the proximal composite head surface to the distal composite head surface. One of the proximal composite head surface and the distal composite head surface can be defined by the head body, and the other of the proximal composite head surface and the distal composite head surface can be defined by the spacer head. In one example, the composite head height is greater than the head body height.

The following detailed description will be better understood when read in conjunction with the appended drawings, in which there is shown in the drawings example embodiments for the purposes of illustration. It should be understood, however, that the present disclosure is not limited to the precise arrangements and instrumentalities shown. In the drawings:.

Corresponding reference characters indicate corresponding parts throughout the several views. The exemplary embodiments set forth herein are not to be construed as limiting the scope of the invention in any manner.

The present invention will be discussed hereinafter in detail in terms of various exemplary embodiments according to the present disclosure with reference to the accompanying drawings. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be obvious, however, to those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known structures are not shown in detail in order to avoid unnecessary obscuring of the present invention.

Thus, all of the implementations described below are exemplary implementations provided to enable persons skilled in the art to make or use the embodiments of the disclosure and are not intended to limit the scope of the invention, which is defined by the claims. As used herein, the word "exemplary" or "illustrative" means "serving as an example, instance, or illustration. " Any implementation described herein as "exemplary" or "illustrative" is not necessarily to be construed as preferred or advantageous over other implementations. Moreover, in the present description, the terms "upper", "lower", "left", "rear", "right", "front", "vertical", "horizontal", and derivatives thereof shall relate to the invention as oriented in <FIG>.

It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the inventive concepts defined in the appended claims.

Referring now to <FIG>, an orthopedic trial implant assembly <NUM> can be configured as a radial trial implant assembly configured to be implanted in the proximal radius. The orthopedic trial implant assembly <NUM> includes a radial trial implant <NUM> and a radial trial spacer <NUM> that is configured to be removably attached to the radial trial implant <NUM>. The radial trial implant <NUM> and the radial trial spacer <NUM> can be made of any suitable plastic or other suitable material.

As illustrated in <FIG>, the radial trial implant <NUM> includes a head body <NUM> and a stem <NUM> that extends out from the head body <NUM>. In one example, the stem <NUM> can be monolithic with the head body <NUM>. Alternatively, the stem <NUM> can be separate from the head body <NUM> and attached to the head body <NUM>.

The head body <NUM> defines a proximal head body surface <NUM> and a distal head body surface <NUM> that is opposite the proximal head body surface <NUM> substantially along a longitudinal direction. For instance, the distal head body surface <NUM> is spaced from the proximal head body surface <NUM> in a distal direction that is defined by the longitudinal direction. Conversely, the proximal head body surface <NUM> is spaced from the distal head body surface <NUM> in a proximal direction that is opposite the distal direction and defined by the longitudinal direction. Thus, the term "distal," "distally," and derivatives thereof as used herein refer to a direction from the proximal head body surface <NUM> to the distal head body surface <NUM>. The term "proximal," "proximal," and derivatives thereof as used herein refer to a direction from the distal head body surface <NUM> to the proximal head body surface <NUM>.

The term "substantially" and "approximate" and derivatives thereof as used herein recognizes that the referenced dimensions, sizes, shapes, directions, or other parameters can include the stated dimensions, sizes, shapes, directions, or other parameters and up to ±<NUM>%, including ±<NUM>%, ±<NUM>%, and ±<NUM>% of the stated dimensions, sizes, shapes, directions, or other parameters.

In one example, the proximal head body surface <NUM> can define an articular surface that can be configured to cooperate with an ulna or ulnar prosthesis to provide radioulnar joint articulation. The proximal head body surface <NUM> can cooperate with a humerus or humeral prosthesis to provide radiohumeral joint articulation. In this regard, the proximal head body surface <NUM> can be a concave surface. The distal head body surface <NUM> can be a substantially flat surface. It should be appreciated, of course, that the proximal head body surface <NUM> and the distal head body surface <NUM> can be shaped in any suitable manner as desired. The stem <NUM> can extend out from the distal head body surface <NUM> along the distal direction.

In one example, the distal head body surface <NUM> can be substantially smooth. Alternatively, in accordance with the invention and as illustrated in <FIG>, the distal head body surface <NUM> can define a plurality of cutting teeth <NUM> that are configured to planarize the radius as the head body <NUM> is rotated about its central axis that is oriented along the longitudinal direction. The cutting teeth <NUM> can extend distally, and can be monolithic with the distal head body surface <NUM>. Alternatively, the cutting teeth <NUM> can be separate from the radial trial implant <NUM> and attached to the distal head body surface <NUM>. The cutting teeth <NUM> can be circumferentially arranged about the distal head body surface <NUM>. In one example shown in <FIG>, the teeth can be shaped as segments of swept spirals. Thus, the teeth <NUM> can be referred to as swept spiral teeth. Alternatively, as illustrated in <FIG>, the cutting teeth <NUM> can be are oriented straight and linear. Further, the cutting teeth <NUM> can be oriented radially as they extend about the distal head body surface <NUM>. In one example, the cutting teeth <NUM> can intersect each other at the central axis of the head body <NUM>.

Referring again to <FIG>, the head body <NUM> can further include at least one side wall <NUM> that extends from the proximal head body surface <NUM> to the distal head body surface <NUM>. The at least one side wall can define an outer perimeter of the head body <NUM> in a plane that is oriented perpendicular to the longitudinal direction. The at least one side wall <NUM> can be configured as a single substantially cylindrical side wall <NUM>. The cylindrical side wall <NUM> can extend along a central axis that is oriented along the longitudinal direction. Alternatively, the at least one side wall <NUM> can be defined by a plurality of connected walls that define the outer perimeter of the head body <NUM>. Further, the side wall <NUM> can be substantially flat along the longitudinal direction from the proximal head body surface <NUM> to the distal head body surface <NUM>. As will be described in more detail below, the head body <NUM> can define a channel <NUM> that extends into the at least one side wall <NUM> that is configured to receive the spacer <NUM> so as to removably attach the spacer <NUM> to the radial trial implant <NUM>.

The head body <NUM> defines a height H1 that extends from the proximal head body surface <NUM> to the distal head body surface <NUM> substantially along the longitudinal direction. It is envisioned that the height H1 of the head body <NUM> may be less than the gap <NUM> between the proximal radius <NUM> (see <FIG>) and a complementary articulating surface <NUM> that can be defined by one or both of the ulna and humerus. In such instances, it may be desirable to attach the spacer <NUM> to the radial trial implant <NUM> so as to increase the height of the head body <NUM>.

Referring now to <FIG> and <FIG>, the spacer <NUM> includes a spacer head <NUM> that includes a proximal spacer head surface <NUM> and a distal spacer head surface <NUM> that is opposite the proximal spacer head surface <NUM> and spaced from the proximal spacer head surface <NUM> along the distal direction. In one example, the proximal spacer head surface <NUM> can define an articular surface that can be configured to cooperate with an ulna or ulnar prosthesis to provide radioulnar joint articulation. The proximal spacer head surface <NUM> can cooperate with a humerus or humeral prosthesis to provide radiohumeral joint articulation. In this regard, the proximal spacer head surface <NUM> can be a concave surface. The distal spacer head surface <NUM> can be a substantially convex surface. Accordingly, the distal spacer head surface <NUM> can be configured to nest with the proximal head body surface <NUM> when the spacer <NUM> is attached to the radial trial implant <NUM>. It should be appreciated, of course, that the proximal spacer head surface <NUM> and the distal spacer head surface <NUM> can be shaped in any suitable manner as desired.

The spacer <NUM> can further include at least one side wall <NUM> that extends from the proximal spacer head surface <NUM> to the distal spacer head surface <NUM>. The at least one side wall <NUM> can define an outer perimeter of the spacer head <NUM> in a plane that is oriented perpendicular to the longitudinal direction. The at least one side wall <NUM> can be configured as a single substantially cylindrical side wall <NUM>. The cylindrical side wall <NUM> can extend along a central axis that is oriented along the longitudinal direction. The central axis of the cylindrical side wall <NUM> of the spacer can be parallel with or coincident with the central axis of the cylindrical side wall <NUM> of the trial radial prosthesis <NUM>. Alternatively, the at least one side wall <NUM> can be defined by a plurality of connected walls that define the outer perimeter of the spacer head <NUM>. Further, the side wall <NUM> can be substantially flat along the longitudinal direction from the proximal spacer head surface <NUM> to the distal spacer head surface <NUM>.

The spacer head <NUM> defines a spacer head height H2 that extends from the proximal spacer head surface <NUM> to the distal spacer head surface <NUM> substantially along the longitudinal direction. It is envisioned that the spacer head height H2 can be less than the height H1 of the head body <NUM>. The spacer <NUM> is configured to be removably attached to the radial trial implant <NUM> such that the spacer head <NUM> and the head body <NUM> define a composite head <NUM> having a composite head height H3 (see <FIG>) that is greater than the height H1 of the head body <NUM>. For instance, the composite head height H3 can be substantially equal to the sum of the height H1 of the head body <NUM> and the spacer head height H2, as shown in <FIG>.

With continuing reference to <FIG> and <FIG>, the spacer <NUM> can include an attachment member <NUM> that is configured to attach to a complementary attachment member of the radial trial implant <NUM>. In particular, the complementary attachment member of the radial trial implant <NUM> can be configured as the channels <NUM>. The attachment member <NUM> of the spacer <NUM> can be received in the channel <NUM> so as to attach the spacer2 <NUM> to the radial trial implant <NUM>. In other examples, it is envisioned that the attachment member of the radial trial implant <NUM> can be received in a channel of the spacer <NUM> so as to removably attach the spacer <NUM> to the radial trial implant <NUM>.

Referring now to <FIG> generally, the attachment member <NUM> can include an extension member <NUM> that extends from the spacer head <NUM>. In particular, the extension member <NUM> can extend substantially distally from the spacer head <NUM>. In one example, the extension member <NUM> can extend substantially distally from the distal spacer head surface <NUM>. Thus, the extension member <NUM> can have a first end that extends out from the distal spacer head surface <NUM>, and the extension member <NUM> can extend from the first end to a second end substantially along the longitudinal direction. The extension member <NUM> is sized to be received in a proximal portion <NUM> of the channel <NUM> that can be open to the proximal head body surface <NUM>. In particular, the channel <NUM> can extend through the proximal head body surface <NUM> along the proximal direction.

The attachment member <NUM> can further include an attachment tab <NUM> that extends from the extension member <NUM>. In particular, the attachment tab <NUM> can extend out from the extension member <NUM> along a first direction that is substantially perpendicular to the longitudinal direction. For instance, the attachment tab <NUM> can extend out from the second end of the extension member. The attachment tab <NUM> is configured to be slidingly inserted into a distal portion <NUM> of the channel <NUM> along the first direction that is substantially perpendicular to the longitudinal direction. When the attachment tab <NUM> is inserted into the channel <NUM>, the distal spacer head surface <NUM> can face or abut the proximal head body surface <NUM>. The distal portion <NUM> of the channel <NUM> can be open to the proximal portion <NUM> of the channel <NUM> along the longitudinal direction. The attachment tab <NUM> can be disposed such that the spacer <NUM> defines a gap <NUM> that extends from the attachment tab <NUM> to the spacer head <NUM>, and in particular to the distal spacer head surface <NUM>, along the longitudinal direction. When the attachment member <NUM> is inserted into the channel <NUM>, the gap <NUM> can receive a portion of the head body <NUM> that includes the proximal head body surface <NUM> and an opposed inner surface <NUM> that defines a proximal end of the distal portion <NUM> of the channel <NUM>.

The attachment member <NUM> can further include a retention member <NUM> that can releasably secure to the radial trial implant <NUM>. In particular, the retention member <NUM> can releasably secure to a complementary retention member of the head body <NUM> in the channel <NUM>. In one example, the retention member <NUM> can be press-fit in the channel <NUM>, and in particular in the distal portion <NUM> of the channel <NUM>. The press-fit engagement can be removed when a sufficient force is applied to the spacer <NUM> along a second direction that is opposite the first direction, thereby causing the spacer <NUM> to be removed from the radial trial implant <NUM>. The second direction can be referred to as a removal direction. The first direction can be referred to as an attachment direction.

Referring now to <FIG> and <FIG>, when the attachment member <NUM> is inserted into the channel <NUM> in the first direction, the spacer head <NUM> can face or abut the head body <NUM> of the trial radial implant <NUM>. In particular, the distal spacer head surface <NUM> can face or abut the proximal head body surface <NUM>. Thus, the orthopedic trial implant assembly <NUM> can define a composite head <NUM> that includes the head body <NUM> and the spacer head <NUM>. The composite head <NUM> can define a proximal composite head surface <NUM> and a distal composite head surface <NUM> opposite the proximal composite head surface <NUM> along the longitudinal direction. In particular, the distal composite head surface <NUM> is spaced from the proximal composite head surface <NUM> substantially in the distal direction. Conversely, the proximal composite head surface <NUM> is spaced from the distal composite head surface <NUM> in the proximal direction.

The composite head <NUM> defines the composite head height H3 that extends from the proximal composite head surface <NUM> to the distal composite head surface <NUM> substantially along the longitudinal direction. One of the proximal composite head surface <NUM> and the distal composite head surface <NUM> is defined by the head body <NUM>, and the other of the proximal composite head surface <NUM> and the distal composite head surface <NUM> is defined by the spacer head <NUM>. In one example, the proximal spacer head surface <NUM> defines the proximal composite head surface <NUM>, and the distal head body surface <NUM> defines the distal composite head surface <NUM>. While the spacer head <NUM> is disposed proximal of the head body <NUM> in one example, it is envisioned that the spacer <NUM> can alternatively attach to the head body <NUM> such that the spacer head <NUM> is disposed distal of the head body <NUM>. In this regard, the proximal spacer head surface <NUM> can face the distal head body surface <NUM>. Further, the proximal head body surface <NUM> can define the proximal composite head surface <NUM>, and the distal spacer head surface <NUM> can define the distal composite head surface <NUM>.

Referring now to <FIG>, the orthopedic trial implant assembly <NUM> can include a plurality of spacers <NUM>, such as a first spacer 24a and a second spacer 24b. Each of the plurality of spacers <NUM> can be selectively and removably attached to the radial trial implant <NUM>. That is, each the spacers <NUM> can be attached to the radial trial implant <NUM> in the manner described above. Further, each of the spacers <NUM> can be removed from the radial trail implant in the manner described above.

The first spacer 24a can be attached to the radial trial implant <NUM> in the manner described above so as to define a first composite head 70a. The second spacer 24b can be attached to the radial trial implant <NUM> in the manner described above so as to define a second composite head 70b. Each of the spacers <NUM> of the plurality of spacers <NUM> can have different spacer heights substantially along the longitudinal direction as described above. For instance, the first spacer 24a can define a first spacer height HS1. Thus, when the first spacer 24a is attached to the radial trial implant <NUM> in the manner described above, the spacer head <NUM> of the first spacer 24a and the head body <NUM> can combine to define a first composite head 70a having a first composite head height. The first spacer 24a can be removed from the radial trial implant <NUM>, and the second spacer 24b can be attached to the radial trail implant <NUM>, such that the spacer head <NUM> of the second spacer 24b and the head body <NUM> can combine to define a second composite head 70b having a second composite head height. The second spacer 24b can define a second spacer height HS2 that is different than HS1. For instance, the second spacer height HS2 can be greater than the first spacer height HS1. Thus, the height of the resulting first composite head 70a can be different than the height of the resulting second composite head 70b. For instance, the height of the second composite head 70b can be greater than the height of the first composite head 70a. It is appreciated that the respective attachment members <NUM>, including the extension members <NUM> and the attachment tabs <NUM>, of the differently sized spacers <NUM> can be sized and shaped identical to each other, within manufacturing tolerances, such that the attachment members <NUM> can removably attach to the same radial trial implant <NUM>.

Referring now to <FIG>, the orthopedic trial implant assembly <NUM> can be configured to identify a size of a permanent implant that is to be implanted in the proximal radius <NUM>. The term "permanent" implant indicates that the implant is not intended to be removed prior to completion of the surgical procedure. In particular, as illustrated at <FIG>, the radial trial spacer <NUM> is coupled to the proximal radius. In particular, the stem <NUM> of the radial trial spacer <NUM> is inserted into the medullary canal of the proximal radius <NUM> such that the head body <NUM> is disposed in the gap <NUM>. In some examples, the stem has been previously sized to fit into the medullary canal using a sounder that abuts the cortical bone in the medullary canal to determine the appropriate diameter or alternative cross-sectional dimension of the stem. In some examples, the stem can be sized to be loosely received in the medullary canal. When the head body <NUM> includes the cutting teeth <NUM> described above with respect to <FIG>, rotation of the radial trial spacer <NUM> about its central longitudinal axis can cause the cutting teeth to remove bone from the proximal radius, thereby planarizing the proximal radius. Thus, the head can be seated on a planar surface defined by the proximal radius. As illustrated in <FIG>, the head body <NUM> does not span the entirety of the gap <NUM> from the proximal radius <NUM> to the complementary articulating surface <NUM>.

Thus, as illustrated in <FIG>, one of the radial trial spacers <NUM> having a known height can be selected. Because the height of the corresponding spacer head <NUM> is known, and the height of the head body <NUM> is known, the resulting height of the resulting composite head can be easily calculated. As shown in <FIG>, the first trial spacer 24a can be aligned with the radial trial implant <NUM>, such that a sliding movement of the first trial spacer 24a in the first direction causes the first trial spacer 24a to be attached to the radial trial implant <NUM>, as shown in <FIG>. However, in <FIG>, it is observed that the height of the first composite head 70a is less than the height of the gap <NUM> along the longitudinal direction. Thus, the first composite head 70a fails to extend from the proximal radius <NUM> to the complementary articulation surface <NUM> (see <FIG>).

Accordingly, referring to <FIG>, the first trial spacer 24a can removed from the radial trial implant <NUM> by moving the first trial spacer 24a in the second direction with respect to the radial trial implant <NUM>. Advantageously, the radial trial implant <NUM> can remain coupled to the proximal radius while the first trial spacer 24a is removed. Otherwise said, the first trial spacer 24a can be removed from the radial trail implant <NUM> without removing the radial trial implant <NUM> from the proximal radius <NUM>.

Referring now to <FIG> in particular, once the first trial spacer 24a has been removed, the second trial spacer 24b can be attached to the radial trial implant <NUM> in the manner described above. Because the height of the corresponding spacer head <NUM> of the second trial spacer 24b is known, and the height of the head body <NUM> is known, the resulting height of the resulting second composite head 70b can be easily calculated. As illustrated in <FIG>, the second composite head <NUM> extends substantially from the proximal radius <NUM> to the opposed complementary articular surface <NUM> (see <FIG>). Thus, the height of the second composite head 70b is substantially equal to the height of the gap <NUM> along the longitudinal direction. Accordingly, referring now to <FIG>, a permanent radial implant <NUM> among a kit of permanent implants can be selected having a head height that is substantially equal to, or corresponding best to, the height of the second composite head 70b and therefore the height of the gap <NUM>. Referring again to <FIG>, the second trial spacer <NUM> can be removed from the radial trial implant <NUM>, and the radial trial implant can be removed from the proximal radius. Next, the selected permanent radial implant <NUM> can be selected and implanted in the proximal radius <NUM>. In particular, a stem of the permanent radial implant <NUM> can be inserted into the medullary canal, and the head of the permanent radial implant <NUM> can articulate about the complementary articulating surface defined by one or both of the ulna and the distal humerus. The permanent radial implant <NUM> can be made from titanium, alloys thereof, stainless steel, alloys thereof, or any suitable biocompatible metal or other material.

It is recognized that different patients will have differently sized proximal radii. Therefore, a kit can be provided that includes a plurality of radial trial implants <NUM> (see <FIG>) that have different sizes and can be selected for implantation into an appropriately sized proximal radius. Further, each of the radial trial implants <NUM> can be configured to be removably attached to the same trial spacers. Thus, the radial trial implants <NUM> can have substantially identically sized channels that receive the trial spacers. The radial trail implants <NUM> can have at least one size or shape that is different from at least one other of the radial trial implants <NUM>. For instance, the stems <NUM> can be sized differently from each other. In one example, the stems <NUM> of the radial trial implants <NUM> can define different cross-sectional dimensions so as to define the different sizes. The stems <NUM> can be cylindrical or tapered, and thus the cross-sectional dimensions can be defined by respective diameters of the stems. The cross-sectional dimensions are measured at a constant distance from the distal head body surface <NUM> in the distal direction.

Thus, at least some of the stems of the radial trial implants of the kit are cross-sectionally sized differently with respect to other stems of the radial trial implants of the kit along a direction that is substantially perpendicular to the longitudinal direction. For instance, at least some of the stems of the radial trial implants are cross-sectionally sized differently with respect to other stems of the radial trial implants in a plane that is oriented substantially perpendicular to the longitudinal direction. Further at least some of the head bodies of the radial trial implants of the kit can be cross-sectionally sized differently with respect to other head bodies of the radial trial implants of the kit along a direction that is substantially perpendicular to the longitudinal direction.

It is further envisioned that the kit can include a plurality of the spacers <NUM> having different spacer head heights as described above. Each of the spacers <NUM> of the kit can be configured to attach to each of the radial trial implants <NUM> of the kit. For instance, the attachment members <NUM> of the spacers <NUM> of the kit can all be substantially equally sized and shaped, and all of the slots <NUM> of the radial trial implants <NUM> of the kit can be substantially equally sized and shaped.

Claim 1:
An orthopedic trial implant assembly (<NUM>) (<NUM>) configured to be implanted in a proximal radius, comprising:
at least one radial trial implant (<NUM>) including:
a head body (<NUM>) that defines a proximal head body surface (<NUM>) and a distal head body surface (<NUM>) opposite the proximal head body surface (<NUM>) substantially along a longitudinal direction, and the head body (<NUM>) has a height (H3) that extends from the proximal head body surface (<NUM>) to the distal head body surface (<NUM>) along the longitudinal direction; and
a stem (<NUM>) that extends from the head body (<NUM>) along a distal direction that is substantially defined by the longitudinal direction; and
at least one spacer (<NUM>) that is configured to removably attach to the radial trail implant (<NUM>) along a direction substantially perpendicular to the longitudinal direction so as to define a composite head (<NUM>) including the head body (<NUM>) and a spacer head (<NUM>) of the spacer (<NUM>), wherein the composite head (<NUM>) defines a proximal composite head surface (<NUM>) and a distal composite head surface (<NUM>) opposite the proximal composite head surface (<NUM>) along the longitudinal direction, and the composite head (<NUM>) defines a composite head height (H1) from the proximal composite head surface (<NUM>) to the distal composite head surface (<NUM>),
wherein one of the proximal composite head surface (<NUM>) and the distal composite head surface (<NUM>) is defined by the head body (<NUM>), and the other of the proximal composite head surface (<NUM>) and the distal composite head surface (<NUM>) is defined by the spacer head (<NUM>), and
wherein the composite head height (H1) is greater than the head body height (H3), characterized in that
the distal head body surface (<NUM>) defines a plurality of cutting teeth (<NUM>) configured to planarize the radius as the head body (<NUM>) is rotated about its central axis that is oriented along the longitudinal direction.