Modular offset stem implants

Description

INTRODUCTION

Various modular stem implants are currently available for knee replacement procedures. Some tibial implants, for example, incorporate a component that provides an offset to address anatomical mismatch between the patient's intramedullary canal and the center of the proximal tibia.

Although the existing modular implants can be satisfactory for their intended purposes, modular implants that provide additional anatomical flexibility are still desirable.

SUMMARY

The present teachings provide a modular device for coupling a stem to an end component of an implant. The device includes a plurality of rotatably interconnectable intermediate components for coupling the stem to the end component, such that each intermediate component can be rotated for selectively changing a total offset between the stem and the end component by a relative offset.

The present teachings also provide a modular device for coupling a stem to an end component of an implant, and including a first component rotatably coupled to the end component at a first relative offset, and a second component rotatably coupled to the stem at a second relative offset, wherein the first and second components are rotatably coupled therebetween.

The present teachings further provide a modular implant that includes an end component, a stem, and a plurality of rotatably interconnectable intermediate components for coupling the stem to the end component, and providing at least two relative offsets.

The present teachings also provide a modular implant that includes an end component having a center axis, a stem having a stem axis, and a plurality of rotatably interconnectable intermediate components coupling the stem to the end component, such that the center axis and the stem axis can be selectively offset relative to one another by a total offset within a predetermined range.

The present teachings provide a method for coupling a stem to an end component of a modular implant. The method includes providing a plurality of modular intermediate components, wherein at least two components of the group comprising the end component and the intermediate components are configured for eccentric coupling, sequentially coupling the plurality of intermediate components between the end component and the stem, and selectively rotating at least one intermediate component to change a total offset between the stem and the end component.

Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

FIG. 1 is an exploded sectional view of a modular implant according to the present teachings;

FIG. 1A is an exploded isometric view of a modular implant according to the present teachings;

FIG. 1B is an assembled view of the modular implant shown in exploded view in FIG. 1;

FIG. 2 is an exploded sectional view of a modular implant according to the present teachings;

FIG. 3 is an exploded sectional view of a configuration of a modular implant according to the present teachings;

FIG. 4 is a perspective environmental view of a modular implant according to the present teachings; and

FIGS. 5A and 5B are perspective environmental views of a modular implant according to the present teachings.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. For example, although the present teachings are illustrated for tibial implants in knee surgery, the present teachings can be used for any other orthopedic procedures that require implants that include a stem received in a long bone, such as, for example, femoral implants and shoulder implants.

Referring to FIGS. 1, 1A and 2, an exemplary modular implant 100 according to the present teachings includes an end component 102 and a stem 104. Although the end component 102 is illustrated as a tibial tray for a proximal tibial implant, the end component 102 can also be a body or neck or trunnion for a distal femoral implant, or an end component for a humeral implant.

The end component 102 can be coupled with the stem 104 by a plurality of modular intermediate components 106, such as those indicated by reference numbers 106a-106d in FIGS. 1 and 2. It will be appreciated that although two intermediate components 106 are illustrated in each of the implants of FIGS. 1 and 2, a greater number of intermediate components 106 can be used. Adjacent intermediate components 106 can be coupled to one another or to the stem 104 or to the end component 102 by Morse taper or taper lock connections in various combinations of male/female tapers or other type of appropriate connections.

Referring to FIG. 1, for example, the end component 102 can include a male taper 112, which can be received in a female taper 114 of the first intermediate component 106a. The first intermediate component 106a can also include a male taper 116, which can be received in a female taper 118 of the second intermediate component 106b. The second intermediate component 106b can also include another female taper 120 which can receive a male taper 122 of the stem. The second intermediate component 106b can be constructed as an integral adapter having the two taper locks 118, 120 sequentially positioned along a longitudinal direction defined by the implant 100, as shown in FIG. 1, or as two distinct components modularly coupled.

Referring to FIG. 2, the end component 102 can include a female taper 130, which receives a male taper 132 of the first intermediate component 106c. The first intermediate component 106c can also include a female taper 134, which can receive a male taper 136 of the second intermediate component 106d. The second intermediate component 106d can also include a female taper 138 which can receive the male taper 122 of the stem. In this aspect, each intermediate component 106c, 106d can include both male and female tapers, 132, 134, and 136, 138, with the female tapers 134, 138 defined in interior surfaces of the respective male tapers 132, 136.

Referring to FIGS. 1 and 2, the modular intermediate components 106a, 106b, and 106c, 106d and the end component 102 can be selectively structured for eccentric coupling that provides at least two relative offsets 140, such as first and second relative offsets 140a, 140b, and 104c, 140d for the corresponding implants 100 shown in FIGS. 1 and 2. It will be appreciated that when more than two additional intermediate components 106 are coupled between the end component 102 and the stem 104, additional relative offsets 140 can be provided, as desired. The relative offsets 140 of the implant 100 can be all of equal size (width) or can have variable sizes. Further, the relative offsets 140 can be all oriented toward a single direction (unilateral) to provide a total offset that is the sum of the relative offsets or can have variable orientations (multilateral) resulting in a total offset of 0 or less than the sum of the relative offsets as described below. Because of the taper lock connections, the orientation of each intermediate component can be readily changed by rotation. Once a desired orientation is selected, that particular orientation can be secured by using self-locking tapers or various methods and devices known in the art, such as, for example, screws, washers or other locking devices.

Referring to FIG. 1, the first relative offset 140a can be formed, for example, by offsetting center axes A and B of the female tapers 114, 118 of the first and second intermediate components 106a, 106b, respectively. It will be appreciated that in the exemplary illustration of FIG. 1, the axis B is also the axis of the male taper 116 and the first intermediate component 106a is structured for eccentric coupling by including eccentrically arranged female and male tapers 114, 116. The second relative offset 140b can be defined by offsetting center axes B and C of the female tapers 118 and 120 of the second intermediate component 106b.

Referring to FIG. 2, the first relative offset 140c can be defined, for example, by offsetting a center axis F of the female taper 130 of the end component 102 from a center axis D of the female taper 134 of the first intermediate component 106a. The second relative offset 140d can be defined by offsetting center axes D and E of the female tapers 134 and 138 of the first and second intermediate components 106c, 106d respectively. As illustrated in FIG. 2, each the first and second intermediate component 106c, 106d include female and male tapers that are offset, such that the first and second intermediate component 106c, 106d are configured for eccentric coupling. It is further noted that the axis F is also the center axis of the male taper 132 of the first intermediate component 106c, and that the axis D is also the center axis of the male taper 136 of the second intermediate component.

It should be appreciated that the number, arrangement and orientation of the intermediate components 106 can be varied to achieve a total offset of desired width and orientation between the end component 102 and the stem 104. The total offset is the result of relative offsets 140, such as those illustrated by reference numerals 140a, 140b, 140c, 140d in FIGS. 1 and 2. For example, each relative offset 140a, 140b can be 2.5 mm in width, for a total offset of 5 mm when the relative offsets 140a, 140b are unilaterally arranged, as shown in FIG. 1. The same relative offsets 140a, 140b can be arranged in opposite directions, 180° apart, to provide a total offset of 0 mm, or at two directions defining other angles, to provide a 2.5 mm offset in each of those directions. Similarly, the relative offsets 140 can be unequal. For example, the offset 140c can be 2.5 mm and the offset 140d can be 1 mm, providing a total offset of 3.5 mm for unilaterally arranged offsets, and 1.5 mm for opposing offsets. The relative offsets 140 can be created by offsetting the center axes of the male and/or female tapers of adjacent components 106 relative to one another or between an intermediate component 106 and the end component 102 or the stem 104. Further, the relative offsets can be arranged at infinite rotational directions (360°) about the stem 104, can be indexable, or can be directionally fixed by adding a key to the corresponding taper lock connections.

Referring to FIG. 3, in one aspect, the end component 102 can include an eccentric female taper 150 that provides an offset 140e between a center axis G of the end component 102 and a center axis H of the female taper 150. The end component 102 can be selectively coupled either directly to the stem component 104, as shown in FIG. 3, or indirectly by using appropriately sized intermediate components 106, such as those illustrated in FIG. 2.

Referring to FIGS. 4, 5A and 5B, various exemplary environmental views of the modular implant 100 are illustrated. In FIG. 4, the modular implant 100 are shown implanted in the tibia of a knee. In FIG. 5A, the modular implant 100 is shown in hip replacement. In FIG. 5B, the modular implant 100 is shown generally implanted into a long bone.

The foregoing discussion discloses and describes merely exemplary arrangements of the present invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims, that various changes, modifications and variations can be made therein without departing from the spirit and scope of the invention as defined in the following claims.