Offset-adjustable neck length trial device and system for hip arthroplasty

Abstract

Improved hip arthroplasty trial devices and hip arthroplasty trial systems are described. The hip arthroplasty trial device has a head member having a central axis and defining an internal chamber, a head member opening for accessing the internal chamber, and a cavity extending inwardly from an outer surface of the head member. A rotatable member is disposed within the internal chamber along an axis between the central axis and one lateral portion of the head member. The cavity extends along an axis between the central axis and another opposing lateral portion of the head member. A spacer is disposed within the head member opening and is movable between a spacer first position and a spacer second position. Rotational movement of the rotatable member moves the spacer from the spacer first position to the spacer second position.

Description

Technical Field

[0001] Related Applications This application claims the benefit of U.S. Provisional Application No. 63 / 181,493, filed Apr. 29, 2021. The disclosure of this related application is incorporated herein by reference in its entirety.

[0002] This disclosure relates to the field of medical devices. More particularly, this disclosure relates to a hip arthroplasty trial device and a hip arthroplasty trial system.

Background Art

[0003] During hip arthroplasty when implanting the femoral head, surgeons currently use multiple head length options that must be individually tried to determine the desired offset amount between the femoral head and the femoral stem. With each trial, it is necessary to assemble and disassemble different head lengths to determine whether the desired offset amount has been achieved, resulting in the hip joint being removed and moved multiple times during the trial. This multiple trial approach for determining the desired offset amount between the femoral head implant and the femoral stem has significant drawbacks such as being complex, time-consuming, and tissue-destructive.

[0004] Hip arthroplasty is a highly complex procedure, often with limited space for manipulating components. To replace the trial device, undesirable movement of multiple trial devices in and out of such an environment is required. Even the operation of existing adjustable trial devices can be difficult considering the limited space available during surgery.

Summary of the Invention

Problems to be Solved by the Invention

[0005] Therefore, there is a need for a newly improved hip arthroplasty trial device and a hip arthroplasty trial system.

Means for Solving the Problems

[0006] Various trial devices and trial systems for hip arthroplasty are described herein.

[0007] An exemplary hip arthroplasty trial apparatus comprises a head member, a movable spacer positioned within an opening defined by the head member, a rotatable member defining a gear and a cam such that the cam translates the spacer when rotated, a drive gear having teeth that mesh with the teeth of the gear defined by the rotatable member, and a locking member.

[0008] Another exemplary hip arthroplasty trial apparatus comprises a head member; a spacer positioned and movable within an opening defined by the head member; a rotatable member defining a gear and a cam such that the cam translates the spacer when rotated; a drive gear having teeth that mesh with the teeth of the gear defined by the rotatable member; and a locking member. The drive gear is positioned between the central longitudinal axis of the head member and the proximal portion of the head member that defines the opening in which the spacer is positioned. The gear defined by the rotatable member is positioned between the central longitudinal axis of the head member and the distal portion of the head member.

[0009] Another example of a hip arthroplasty trial apparatus comprises a head member, a spacer, a rotatable member, a gear, an O-ring positioned on the spacer, and a locking member. The rotatable member defines a cam that translates the spacer when the rotatable member rotates. The head member comprises a separable first head member portion and a second head member portion. The rotatable member defines first and second bosses that seat in corresponding grooves in the first and second head member portions, respectively. The first boss defines a gear having teeth that mesh with the teeth of the gear defined by the rotatable member. The second boss defines a series of pockets that receive a projection defined by the locking member. The drive gear is positioned between the central longitudinal axis of the head member and the proximal portion of the head member that defines the opening in which the spacer is positioned. The gear defined by the rotatable member is positioned between the central longitudinal axis of the head member and the distal portion of the head member.

[0010] Another exemplary hip arthroplasty trial apparatus comprises a head member, a spacer positioned and movable within an opening defined by the head member, a rotatable member defining a gear and a cam such that the cam translates the spacer when rotated, and a locking member. The head member defines a cavity for accessing the gear defined by the rotatable member.

[0011] Another exemplary hip arthroplasty trial apparatus comprises a head member, a spacer positioned and movable within an opening defined by the head member, a rotatable member defining a gear and a cam, such that the cam translates the spacer during rotation, and a locking member. The head member defines a cavity for accessing the gear defined by the rotatable member. The cavity is located between the longitudinal center of the head member and the proximal portion of the head member that defines the opening in which the spacer is positioned. The gear defined by the rotatable member is located between the central longitudinal axis of the head member and the distal portion of the head member.

[0012] Another example of a hip arthroplasty trial apparatus includes a head member having a central axis and defining an internal chamber, having an outer head member surface, a proximal head member portion, and a distal head member portion, wherein the outer head member surface defines a head member cavity extending into the head member along an axis between the central axis and the proximal head member portion, and the proximal head member portion defines a head member opening for accessing the internal chamber; a spacer disposed within the head member opening and movable between a first spacer position and a second spacer position; and a rotatable member disposed within the internal chamber along an axis between the central axis and the distal head member, defining a rotatable member gear and a cam, and in contact with the spacer such that the rotation of the rotatable member moves the spacer from the first spacer position to the second spacer position.

[0013] Another example of a hip arthroplasty trial apparatus includes a head member having a central axis and defining an internal chamber, having an outer head member surface, a proximal head member portion, and a distal head member portion, wherein the outer head member surface defines a head member cavity extending into the head member along an axis between the central axis and the proximal head member to a base wall defining a base wall opening, and the proximal head member portion defines a head member opening for accessing the internal chamber; a spacer disposed within the head member opening and movable between a first spacer position and a second spacer position; and a rotatable member disposed within the internal chamber along an axis between the central axis and the distal head member, defining a rotatable member gear and a cam, wherein the cam is in contact with the spacer such that the spacer moves from the first spacer position to the second spacer position by rotation of the rotatable member, and the rotatable member gear is partially disposed within the head member cavity.

[0014] An exemplary hip arthroplasty trial system comprises a hip arthroplasty trial device and a driver. The hip arthroplasty trial device comprises a head member, a spacer positioned and movable within an opening defined by the head member, a rotatable member defining a gear and cam of a rotatable member such that the cam translates the spacer when rotated, and a locking member. The head member defines a cavity for accessing the gear defined by the rotatable member. The driver comprises a handle, a body extending from the handle, and a driver gear positioned on the handle. The driver gear is sized and configured to be received in the cavity of the head member and has teeth sized and configured to mesh with the teeth of the gear defined by the rotatable member.

[0015] Another example of a hip arthroplasty trial system comprises a hip arthroplasty trial device and a driver. The hip arthroplasty trial device comprises a head member, a spacer positioned and movable within an opening defined by the head member, a rotatable member defining a gear and cam of a rotatable member such that the cam translates the spacer when rotated, and a locking member. The head member defines a cavity for accessing the gear defined by the rotatable member. The base of the cavity defines an opening. The driver comprises a handle, a body extending from the handle, a driver gear positioned on the handle, and an end projection extending from the body and extending axially beyond the driver gear, such that the driver gear is positioned axially between the end projection and the handle. The driver comprises a handle, a body extending from the handle, and a driver gear positioned on the handle. The driver gear is sized and configured to be received in the cavity of the head member and has teeth sized and configured to mesh with the teeth of the gear defined by the rotatable member. The terminal projection is sized and configured to be received by the opening defined by the base of the cavity defined by the head member.

[0016] Another example of a hip arthroplasty trial system comprises a hip arthroplasty trial device and a driver. The hip arthroplasty trial device comprises a head member, a spacer positioned and movable within an opening defined by the head member, a rotatable member defining a gear and a cam of a rotatable member such that the cam translates the spacer when rotated, and a locking member. The head member defines a cavity for accessing the gear defined by the rotatable member. The base of the cavity defines an opening. The driver comprises a handle, a body extending from the handle, a driver gear positioned on the handle, and an end projection extending from the body and extending axially beyond the driver gear, such that the driver gear is positioned axially between the end projection and the handle. The driver comprises a handle, a body extending from the handle, a driver gear positioned on the handle, and a projection extending perpendicular to the longitudinal axis of the body so as to move away from the body. The driver gear is sized and configured to be received in the cavity of the head member, and has teeth that are sized and configured to mesh with the teeth of the gear defined by the rotatable member. The terminal projection is sized and configured to be received in the opening defined by the base of the cavity defined by the head member.

[0017] Another example of a hip arthroplasty trial system comprises a hip arthroplasty trial device. The hip arthroplasty trial device comprises a head member having a central axis and defining an internal chamber, and having an outer head member surface, a proximal head member portion, and a distal head member portion, wherein the outer head member surface defines a head member cavity extending into the head member to a base wall defining a base wall opening along an axis between the central axis and the proximal head member, and the proximal head member portion defines a head member opening for accessing the internal chamber; a spacer positioned within the head member opening and movable between a first spacer position and a second spacer position; and an internal chamber along an axis between the central axis and the distal head member. A rotatable member disposed within a head member cavity comprises a rotatable member comprising a rotatable member gear and a cam, wherein the cam contacts a spacer such that the spacer moves from a first spacer position to a second spacer position by the rotation of the rotatable member, and the rotatable member gear is partially disposed within the head member cavity; and a driver comprising a handle, a body extending from the handle, and a driver gear disposed on the body and spaced axially apart from the handle, wherein the driver gear is sized and configured to be removablely disposed within the head member cavity and to mesh with the rotatable member gear.

[0018] The experimental apparatus and experimental system for hip arthroplasty described in the embodiment can be further understood by referring to the following detailed description and attached drawings. [Brief explanation of the drawing]

[0019] [Figure 1] This shows the first example of a trial device for hip replacement surgery that is detachably attached to the femoral stem.

[0020] [Figure 2] Figure 1 is an exploded perspective view of the experimental hip arthroplasty device and femoral stem shown.

[0021] [Figure 3]It is an exploded perspective view of the head member of the hip joint forming trial device shown in FIG. 1.

[0022] [Figure 4] It is a perspective view of the rotatable member of the hip joint forming trial device shown in FIG. 1.

[0023] [Figure 5] It is a perspective view of the spacer of the hip joint forming trial device shown in FIG. 1.

[0024] [Figure 6] It is a cross-sectional view of the spacer of the hip joint forming trial device shown in FIG. 1 along the central longitudinal axis.

[0025] [Figure 7] It is a perspective view of the drive gear of the hip joint forming trial device shown in FIG. 1.

[0026] [Figure 8] It is another perspective view of the drive gear of the hip joint forming trial device shown in FIG. 1.

[0027] [Figure 9] It is a perspective view of the washer of the hip joint forming trial device shown in FIG. 1.

[0028] [Figure 10] It is another perspective view of the washer of the hip joint forming trial device shown in FIG. 1.

[0029] [Figure 11] It is a partial cross-sectional view of the hip joint forming trial device shown in FIG. 1 disposed on the femoral stem.

[0030] [Figure 12] It is a top view of the hip joint forming trial device shown in FIG. 1 removably attached to the partially shown femoral stem. The hip joint forming trial device is shown in the first position.

[0031] [Figure 12A] Figure 12 is a cross-sectional view of the hip arthroplasty device and femoral stem shown along line 12A-12A.

[0032] [Figure 13] Figure 1 is a top view of a hip arthroplasty trial device, which is detachably attached to a partially shown femoral stem. The hip arthroplasty trial device is shown in the second position.

[0033] [Figure 13A] Figure 13 is a cross-sectional view of the hip arthroplasty device and femoral stem shown along line 13A-13A.

[0034] [Figure 14] Figure 1 is a top view of a trial hip arthroplasty device, detachably attached to a partially shown femoral stem. The trial hip arthroplasty device is shown in the third position.

[0035] [Figure 14A] Figure 14 is a cross-sectional view of the hip arthroplasty device and femoral stem shown along line 14A-14A.

[0036] [Figure 15] This is a top view of the hip arthroplasty trial device shown in Figure 1, which is detachably attached to a partially shown femoral stem. The hip arthroplasty trial device is shown in position 4.

[0037] [Figure 15A] Figure 15 is a cross-sectional view along line 15A-15A of the hip arthroplasty device and femoral stem shown.

[0038] [Figure 16]The first example of a trial system for hip arthroplasty is shown. The trial device for hip arthroplasty in the trial system is detachably attached to the femoral stem.

[0039] [Figure 17] Figure 16 is an exploded perspective view of the trial system for hip arthroplasty and the femoral stem.

[0040] [Figure 18] Figure 16 is an exploded perspective view of the head member of the hip arthroplasty trial device in the hip arthroplasty trial system shown.

[0041] [Figure 19] Figure 16 is a perspective view of the driver of the trial system for hip arthroplasty.

[0042] [Figure 20] Figure 16 is a side view of the driver of the trial system for hip arthroplasty.

[0043] [Figure 21] Figure 16 is an end view of the driver of the trial system for hip arthroplasty.

[0044] [Figure 22] Figure 16 is a side view of the hip arthroplasty trial device of the hip arthroplasty trial system shown. The hip arthroplasty trial device is detachably attached to the femoral stem, which is partially shown.

[0045] [Figure 23] Figure 16 is a partial cross-sectional view of the hip arthroplasty trial device of the hip arthroplasty trial system shown. The hip arthroplasty trial device is detachably attached to the femoral stem, which is partially shown.

[0046] [Figure 24]Figure 16 is a top view of the hip arthroplasty trial system. The hip arthroplasty trial device is detachably attached to the partially shown femoral stem. The driver and the hip arthroplasty trial device are each shown in their respective first positions.

[0047] [Figure 24A] Figure 24 is a cross-sectional view along line 24A-24A of the hip arthroplasty device and femoral stem shown.

[0048] [Figure 25] Figure 16 is a top view of the hip arthroplasty trial system. The hip arthroplasty trial device is detachably attached to the partially shown femoral stem. The driver and the hip arthroplasty trial device are shown in their respective second positions.

[0049] [Figure 25A] Figure 25 is a cross-sectional view along line 25A-25A of the hip arthroplasty device and femoral stem shown.

[0050] [Figure 26] Figure 16 is a top view of the hip arthroplasty trial system. The hip arthroplasty trial device is detachably attached to the partially shown femoral stem. The driver and the hip arthroplasty trial device are shown in their respective third positions.

[0051] [Figure 26A] Figure 26 is a cross-sectional view along line 26A-26A of the hip arthroplasty device and femoral stem shown.

[0052] [Figure 27]Figure 16 is a top view of the hip arthroplasty trial system. The hip arthroplasty trial device is detachably attached to the partially shown femoral stem. The driver and the hip arthroplasty trial device are shown in their respective fourth positions.

[0053] [Figure 27A] Figure 27 is a cross-sectional view of the hip arthroplasty trial device and femoral stem shown along line 27A-27A. [Modes for carrying out the invention]

[0054] The following detailed description and accompanying drawings illustrate exemplary hip prosthetic devices and hip prosthetic systems. These descriptions and drawings are provided to enable those skilled in the art to fabricate and use hip prosthetic devices and hip prosthetic systems according to these embodiments. They are not intended to limit the scope of the claims in any way.

[0055] Figures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 12A, 13, 13A, 14, 14A, 15, and 15A show an example of a hip arthroplasty trial device 10 or its components used in hip arthroplasty. Figures 1, 2, 11, 12, 12A, 13, 13A, 14, 14A, 15, and 15A show the hip arthroplasty trial device 10 detachably attached to a femoral stem 11. The hip arthroplasty trial device 10 comprises a head member 12, a spacer 14, a rotatable member 16, a drive gear 18, a washer 20, an O-ring 22, and a locking member 24.

[0056] As best illustrated in Figures 2 and 3, the head member 12 comprises a separable first head member portion 30 and a second head member portion 32, which collaboratively define an internal chamber 34 in which the rotatable member 16 is located. The first head member portion 30 and the second head member portion 32 also collaboratively define an opening 36, which provides access to the internal chamber 34 in which the spacer 14 is located. The first head member portion 30 defines a series of posts 38 that are removably received by a series of fitting chambers 40 defined by the second head member portion 32. The posts 38 and the chambers 40 friction-fit, enabling the first head member portion 30 and the second head member portion 32 to snap together to form the head member 12.

[0057] The spacer 14 is positioned within the opening 36 and is movable relative to the head member 12 between a first spacer position, a second spacer position, a third spacer position, and a fourth spacer position. As best shown in Figures 5 and 6, the spacer 14 has a first spacer end 70, a second spacer end 72, and a spacer body 74 defining a spacer passage 76 and a plurality of spacer grooves 78. The spacer passage 76 extends from the first spacer end 70 to the second spacer end 72 and tapers from the second spacer end 72 to the first spacer end 70. Each of the plurality of spacer grooves 78 extends into the spacer body 74 and is located away from the first spacer end 70.

[0058] The rotatable member 16 defines a cam 42 which translates the spacer 14 when the rotatable member 16 rotates. The rotatable member 16 defines a first boss 44 and a second boss 46 which seat in corresponding grooves of the first head member portion 30 and the second head member portion 32, respectively. The first boss 44 defines a gear 48 having teeth 50 that mesh with the teeth 52 of the drive gear 18. The second boss 46 defines a series of pockets 54, each of which is sized and configured to receive projections 56 defined by the locking member 24.

[0059] The drive gear 18 defines teeth 52 which are sized and configured to mesh with the teeth 50 of the gear 48 defined by the rotatable member 16. As best shown in Figure 8, the first side surface 47 of the drive gear 18 defines a circumferential projection 49 extending from the first side surface 47, which is sized and configured to be received by an opening 72 in the base wall 70 of the cavity 66 defined by the head member 12. The drive gear 18 also defines a passage 53 partitioned by a wall 55 which has a structure that is sized and configured to receive and engage a driver.

[0060] The rotatable member 16 having drive gears 18 and 48 allows for an offset arrangement of the adjustment mechanism, thereby rotating the rotatable member 16 to move the cam 42 and ultimately translate the spacer 14. As best shown in Figure 11, gear 48 is located on an axis 61 between the central axis 58 of the head member 12 and the distal portion 60 of the head member 12, and drive gear 18 is located on an axis 63 between the central axis 58 of the head member 12 and the proximal portion 62 of the head member defining the opening 36. This arrangement of the drive gear 18, which is offset from the central axis 58 extending through the head member 12, is advantageous in that it allows greater access to the adjustment mechanism in the relatively confined space available when using the hip arthroplasty trial device 10 during a hip arthroplasty procedure, and allows for on-site adjustment with all hip arthroplasty components assembled. Furthermore, this offset arrangement of the drive gear 18 and rotatable member 16, in which the drive gear is on one axis 61 offset to one side from the central axis 58, and the rotatable member and gear 48 are on the other axis 63 offset to the other side from the central axis 58, is important for using the hip arthroplasty trial device 10 over a variety of head sizes, including small head sizes (e.g., 28 mm head, 32 mm head). This structural configuration brings adjustability to hip arthroplasty trial devices that have not been able to have an adjustment mechanism until now. Current adjustable head trial devices have a centrally located cam, which cannot be placed within small head sizes.

[0061] As best shown in Figures 1, 2, and 3, the outer surface 64 of the head member 12 defines a cavity 66 to allow access to the drive gear 18. An optional washer 20 is positioned in the cavity 66 to hold the drive gear 18 in place. The cavity 66 is sized and configured to receive a driver that defines a structure that engages with the drive gear 18 and rotates the drive gear 18, resulting in rotation of the rotatable member 16 and translation of the spacer 14, such as a Torx® screwdriver or other suitable screwdriver. Also, as best shown in Figures 12, 13, 14, and 15, the outer surface 64 is mostly spherical, but defines facets 68 at the location where the outer surface 64 forms the cavity 66.

[0062] During use, a screwdriver is inserted into the cavity 66 and engages with the drive gear 18, causing it to rotate clockwise. This rotation of the drive gear 18 causes the gear 48 of the rotatable member 16 to rotate counterclockwise. Since the gear 48 is defined by the rotatable member 16, the rotation of the gear 48 causes the rotatable member 16 and the cam 42 to rotate, resulting in a relative movement of the spacer with respect to the head member 12. When the drive gear 18 is rotated in this way, the spacer 14 moves from the first spacer position relative to the head member 12 shown in Figures 12 and 12A to the second spacer position relative to the head member 12 shown in Figures 13 and 13A. When the drive gear 18 is rotated further in this manner, the spacer 14 moves from the second spacer position to the third spacer position relative to the head member 12 shown in Figures 14 and 14A. Similarly, as the drive gear 18 is rotated further in this manner, the spacer 14 moves from the third spacer position to the fourth spacer position relative to the head member 12, as shown in Figures 15 and 15A.

[0063] The inclusion of gear 48 and drive gear 18, the offset arrangement of drive gear 18, and the faceted structure of the outer surface 64 of head member 12 work together to provide significant advantages compared to existing adjustable hip arthroplasty trial devices. For example, the hip arthroplasty trial device 10 can be adapted to short neck trunnions of varying sizes depending on the manufacturer. This allows the hip arthroplasty trial device 10 to be used with a wider variety of femoral stems, which is expected to increase its adoption rate. Furthermore, the overall structure of the hip arthroplasty trial device 10 is suitable for structures made of disposable parts such as plastic components, eliminating the need for disassembly, cleaning, sterilization, and reuse required for existing devices.

[0064] Figures 16, 17, 18, 19, 20, 21, 22, 23, 24, 24A, 25, 25A, 26, 26A, 27, and 27A show an example of a hip arthroplasty trial system 100 or its components used in hip arthroplasty. The hip arthroplasty trial system 100 includes a hip arthroplasty trial device 110 and a driver 180. Figures 16, 17, 22, 23, 24, 24A, 25, 25A, 26, 26A, 27, and 27A show the hip arthroplasty trial device 110 of the hip arthroplasty trial system 100, which is detachably attached to the femoral stem 111.

[0065] The hip arthroplasty trial device 110 is the same as the hip arthroplasty trial device 10 described above, except as detailed below. Thus, the hip arthroplasty trial device 110 comprises a head member 112, a spacer 114, a rotatable member 116, an O-ring 122, and a locking member 124. The head member 112 comprises a separable first head member portion 130 and a second head member portion 132 that cooperatively define an internal chamber 134 in which the rotatable member 116 is located. The first head member portion 130 and the second head member portion 132 also cooperatively define an opening 136 for accessing the internal chamber 134 in which the spacer 114 is located. The first head member portion 130 defines a series of posts 138 that are removably received by a series of fitting chambers 140 defined by the second head member portion 132. The post 138 and the chamber 140 are friction-fitted such that the first head member portion 130 and the second head member portion 132 snap together to form the head member 112.

[0066] Spacer 114 is positioned within the opening 136 and is movable relative to the head member 112 between a first spacer position, a second spacer position, a third spacer position, and a fourth spacer position. Rotatable member 116 defines a cam 142 which is configured to translate spacer 114 when the rotatable member 116 rotates. Rotatable member 116 defines a first boss 144 and a second boss 146 which seat in corresponding grooves of the first head member portion 130 and the second head member portion 132, respectively. The first boss 144 defines a gear 148 having teeth 150 that mesh with the teeth 188 of the driver gear 186, as will be described in detail below. The second boss 146 defines a series of pockets 154, each sized and configured to receive projections 156 defined by the locking member 124.

[0067] As best illustrated in Figure 22, the outer surface 164 of the head member 112 defines a cavity 166 to allow access to the gear 148 of the rotatable member 116. The cavity 166 is sized and configured to receive the driver gear 186 so that the teeth 188 of the driver gear 186 can mesh with the teeth 150 of the gear 148 of the rotatable member 116. Thus, the driver gear 186 is detachably positioned within the cavity 166 and is sized and configured to mesh with the gear 148 of the rotatable member 116. The arrangement of the cavity 166 results in an offset arrangement of the adjustment mechanism, which causes the rotatable member 116 to rotate in order to move the cam 142 and ultimately translate the spacer 114. As best illustrated in Figure 22, the gear 148 is positioned between the central axis 158 of the head member 112 and the distal portion 160 of the head member 112, and the cavity 166 is positioned between the central axis 158 and the proximal portion 162 of the head member 112 defining the opening 136. This arrangement of the cavity 166, offset from the central axis 158 extending through the head member 112, is advantageous at least in that it allows offset access for the driver 180 and driver gear 186, which facilitates adjustment within the limited space available during use of the hip arthroplasty trial system 100. The base wall 170 of the cavity 166 defines an opening 172 having a size and configuration to receive the terminal projection 190 of the driver 180.

[0068] As best shown in Figures 24, 25, 26, and 27, the outer surface 164 is mostly spherical, but facets 168 are defined at the locations where the outer surface 164 forms the cavity 166.

[0069] As best shown in Figures 19, 20, and 21, the driver 180 is an elongated member having a handle 182, a body 184 extending from the handle 182, and a driver gear 186 positioned on the body 184 and axially spaced from the handle 182. As best shown in Figure 23, the driver gear 186 defines teeth 188 having a size and configuration that meshes with the teeth 150 of a gear 148 defined by a rotatable member 116. A terminal projection 190 extends axially from the body 184 beyond the driver gear 186 so that the driver gear 186 is positioned axially between the terminal projection 190 and the handle 182. The terminal projection 190 is sized and configured to be received by an opening 172 in the base wall 170 of the cavity 166 to ensure proper seating of the driver gear 186 within the cavity 166 during use of the hip arthroplasty trial system.

[0070] The driver 180 also includes a projection 192 that extends perpendicular to the longitudinal axis of the body 184, away from the body 184. As best shown in Figures 24, 25, 26, and 27, the projection 192 provides a visual indicator, namely the rotational position of the driver 180 relative to its initial position, to the user of the hip arthroplasty trial system. For example, in Figure 24, the driver 180 is in a first position, or initial driver position, where the driver gear 186 is positioned within the cavity 166 and meshes with the gear 148 of the rotatable member 116. Rotation has not yet begun, and the spacer 114 is maintained in its first spacer position, as best shown in Figure 24A. The projection 192 is in the first rotational position. In Figure 25, the driver 180 has rotated to a second driver position, with the driver gear 186 rotated. As a result, the gear 148 of the rotatable member 116 rotates, causing the cam 142 to move, which in turn translates the spacer 114 to its second spacer position, as best shown in Figure 25A. The projection 192 is in the second rotational position, offset 90 degrees from the first rotational position. In Figure 26, the driver 180 has rotated to the third driver position, further rotating the driver gear 186. As a result, the gear 148 of the rotatable member 116 rotates further, causing the cam 142 to move further, which in turn translates the spacer 114 to its third spacer position, as best shown in Figure 26A. The projection (not visible in Figure 26) is in the third rotational position, offset 180 degrees from the first rotational position. In Figure 27, the driver 180 has rotated to the fourth driver position, further rotating the driver gear 186. As a result, the gear 148 of the rotatable member 116 rotates further, causing further movement of the cam 142, which in turn translates the spacer 114 to its fourth spacer position, as best shown in Figure 27A. The projection 192 is in the fourth rotational position, offset 270 degrees from the first rotational position.

[0071] All components of the hip prosthesis device and hip prosthesis system can be formed from any suitable material. However, it should be noted that the structural configuration of the hip prosthesis device described herein facilitates the use of plastic in the device, making it suitable for disposable use and eliminating the need for disassembly, cleaning, sterilization, and reuse required in existing devices.

[0072] Those skilled in the art will understand, considering the overall teachings of this disclosure, that various modifications and alternatives can be developed to the embodiments described and illustrated. Accordingly, the disclosed structural arrangements are illustrative and not limit the scope of the invention, which is given to the entire scope of the appended claims and all equivalents.

Claims

1. A head member having a central axis, defining an internal chamber, and comprising a head member outer surface, a head member proximal portion, and a head member distal portion, wherein the head member outer surface defines a head member cavity extending into the head member along an axis between the central axis and the head member proximal portion, and the head member proximal portion defines a head member opening for accessing the internal chamber, A spacer is provided within the opening of the head member and is movable between a first spacer position and a second spacer position. A rotatable member disposed within the internal chamber along the axis between the central axis and the distal portion of the head member, comprising a rotatable member gear and a cam, wherein the cam contacts the spacer such that the spacer moves from the first spacer position to the second spacer position as a result of the rotation of the rotatable member, A drive gear disposed within the head member cavity, which meshes with the rotatable member gear such that the rotation of the drive gear causes the rotation of the rotatable member; A trial device for hip arthroplasty, comprising the above features.

2. The trial apparatus for hip arthroplasty according to claim 1, wherein the head member cavity has a base wall that defines the base wall opening.

3. The experimental apparatus for hip arthroplasty according to claim 2, wherein the drive gear has a first side surface that defines a circumferential projection extending into the base wall opening.

4. The experimental apparatus for hip arthroplasty according to claim 3, further comprising a washer positioned on the drive gear within the cavity of the head member.

5. The trial apparatus for hip arthroplasty according to claim 2, wherein the rotatable member gear is partially arranged within the cavity of the head member.

6. The trial apparatus for hip arthroplasty according to claim 2, wherein the outer surface of the head member defines a facet.

7. The trial apparatus for hip arthroplasty according to claim 6, wherein the head member cavity extends from the facet into the head member.

8. The trial apparatus for hip arthroplasty according to claim 2, wherein the head member has a separable first head member portion and a second head member portion.

9. A head member having a central axis, defining an internal chamber, and comprising a head member outer surface, a head member proximal portion, and a head member distal portion, wherein the head member outer surface defines a head member cavity extending into the head member along the axis between the central axis and the head member proximal portion to a base wall defining a base wall opening, and the head member proximal portion defines a head member opening for accessing the internal chamber, A spacer is provided within the opening of the head member and is movable between a first spacer position and a second spacer position. A rotatable member disposed within the internal chamber along the axis between the central axis and the distal portion of the head member, comprising a rotatable member gear and a cam, wherein the cam contacts the spacer such that the spacer moves from the first spacer position to the second spacer position by the rotation of the rotatable member, and the rotatable member gear is partially disposed within the cavity of the head member, A trial device for hip arthroplasty, comprising the above features.

10. The trial apparatus for hip arthroplasty according to claim 9, wherein the outer surface of the head member defines a facet.

11. The trial apparatus for hip arthroplasty according to claim 10, wherein the head member cavity extends from the facet into the head member.

12. The trial apparatus for hip arthroplasty according to claim 9, wherein the head member comprises a detachable first head member portion and a second head member portion.

13. The first head member portion defines the post, The trial apparatus for hip arthroplasty according to claim 12, wherein the second head member portion defines a recess having a size and configuration for receiving the post.

14. A trial system for hip arthroplasty comprising a trial device and driver for hip arthroplasty, The aforementioned trial device for hip arthroplasty, A head member having a central axis, defining an internal chamber, and comprising a head member outer surface, a head member proximal portion, and a head member distal portion, wherein the head member outer surface defines a head member cavity extending into the head member along the axis between the central axis and the head member proximal portion to a base wall defining a base wall opening, and the head member proximal portion defines a head member opening for accessing the internal chamber, A spacer is provided within the opening of the head member and is movable between a first spacer position and a second spacer position. A rotatable member disposed within the internal chamber along the axis between the central axis and the distal portion of the head member, comprising a rotatable member gear and a cam, wherein the cam contacts the spacer such that the spacer moves from the first spacer position to the second spacer position by the rotation of the rotatable member, and the rotatable member gear is partially disposed within the cavity of the head member, Equipped with, The driver comprises a handle, a body extending from the handle, and a driver gear positioned on the body at an axial distance from the handle, wherein the driver gear is sized and configured to be removablely disposed within the head member cavity and to mesh with the rotatable member gear. A trial system for hip arthroplasty.

15. The trial system for hip arthroplasty according to claim 14, wherein the main body of the driver defines an end projection that extends axially beyond the driver gear so as to be separated from the main body, and the driver gear is positioned axially between the end projection and the handle.

16. The hip arthroplasty trial system according to claim 15, wherein the terminal projection is sized and configured such that it is positioned within the base wall opening.

17. The aforementioned body has a longitudinal axis, The trial system for hip arthroplasty according to claim 16, wherein the driver further comprises a projection extending perpendicular to the longitudinal axis so as to separate from the main body.

18. The trial system for hip arthroplasty according to claim 17, wherein the outer surface of the head member defines a facet.

19. The trial system for hip arthroplasty according to claim 18, wherein the head member cavity extends from the facet into the head member.

Images