AU2019100983A4 - A Pelvic Implant - Google Patents

Abstract

The invention relates to a pelvic implant having a hemispherical acetabular cup portion and one or more projections extending outwardly from the acetabular cup portion; a projection extending from the acetabular cup at a first end to a flange connection member at a second end of the projection, the flange connection member adapted for connection to the contralateral pubis of a pelvis; wherein the flange connection member has an internal surface adapted to abut patient bone and an external surface adapted to abut soft tissue, wherein the connecting member is shaped such that the internal surface is at least partially concave such that when in position, the connection flange wraps at least partially from the medial aspect of the contralateral pubis on to the pubic crest; and wherein the connection flange member includes two or more screw apertures. rtrli r-I LLI)

Description

A Pelvic Implant

Field of Invention

This invention relates to a pelvic implant. More specifically, the invention relates to a pelvic implant designed for attachment to the contralateral pubis.

Background to the Invention

Successful placement and attachment of an orthopaedic implant to patient bone is essential in securing successful patient outcomes for people undergoing bone replacement surgery.

The success of an orthopaedic implant is largely determined by how well the implant integrates and connects with the surrounding tissue. Much research is being undertaken to determine the most effective way of designing an implant to ensure the implant remains stable and effective over the long term.

In acetabular implant design for standard hip replacements, flanges immediately surrounding the cup add commonly connect to the ischium and ilium to provide additional stability to the hip implant.

For implants having a greater need to stabilisation, changes in flange sizes can be made to suit specific patient requirements, but implant design must incorporate even stabilisation around the acetabular to ensure the implants are viable long term.

When pelvic regions in addition to the acetabular cup are being replaced, either due to deterioration, accident or disease, larger implants are required. With this comes the requirement for additional stabilisation to ensure success of the surgery and improve long term patient outcomes. Typically, pelvic implants are designed for connection to the ilium, ischium and or pubic ramus, as surgically these regions are more accessible, and provide adequate

2019100983 30 Aug 2019 stabilisation. In some instances however, particularly for larger implants or for patients with significant deterioration of the pelvis, connection of the implant to the contralateral pubis following removal of the pubic symphysis is preferable. Surgical access to the contralateral pubis is particularly difficult due to the amount of soft tissue, nerves and blood vessels present in the region making successful connection of pelvic implants in this region less preferable. It would be an advantage to develop a pelvic implant that may be successfully and more easily attached to the contralateral pubis region, improving long term success rates for implant patients.

Object of the Invention

It is an object of the invention to provide a pelvis implant incorporate a stable attachment means for connecting to the contralateral pubis.

It is an alternative embodiment of the invention to provide the public with a useful choice.

Summary of the Invention

According to a first aspect of the invention, there is provided a pelvic implant having a hemispherical acetabular cup portion and one or more projections extending outwardly from the acetabular cup portion; a projection extending from the acetabular cup at a first end to a flange connection member at a second end of the projection, the flange connection member adapted for connection to the contralateral pubis of a pelvis;

wherein the flange connection member has an internal surface adapted to abut patient bone and an external surface adapted to abut soft tissue, wherein the connecting member is shaped such that the internal surface is at least partially concave such that when in position, the connection flange wraps at least partially from the medial aspect of the contralateral pubis on to the pubic crest; and wherein the connection flange member includes two or more screw apertures.

2019100983 30 Aug 2019

In preferred embodiments, the length of the projection is greater than its width.

More preferably, the flange connection member includes two screw apertures, the screw apertures aligned such that screws received within the apertures extend out through the concave internal surface substantially perpendicular to one another.

Preferably, the connection flange includes an alignment flange, hook or tab.

In further embodiments, the pelvic implant further includes a second projection extending from the acetabular cup portion, the second projection taking the form of a flange.

Further aspects of the invention, which should be considered in all its novel aspects, will become apparent to those skilled in the art upon reading of the following description which provides at least one example of a practical application of the invention.

Brief Description of the Drawings

One or more embodiments of the invention will be described below by way of example only, and without intending to be limiting, with reference to the following drawings, in which:

Figure 1 shows a rear perspective view of a pelvic implant having a connection flange member in one embodiment of the invention;

Figure 2 shows the pelvic implant of Figure 1 from a side perspective view;

Figure 3 shows the pelvic implant of Figures 1 and 2 from a rear perspective view showing the internal surface of the flange connection member.

2019100983 30 Aug 2019

Detailed Description of Preferred Embodiments of the Invention

The pelvic implant of the present invention is described in further detail below and with reference to Figures 1-3.

The pelvic implant with flange connection member may be applied to implants having a selection of other flanges extending from and supporting the acetabular cup portion of the implant. The designs shown herein relate to a single pelvic implant design, but the invention may be applied to other designs utilising the contralateral pubis as a connection point for the implant.

The exemplified invention shown in Figures 1 - 3 shows implant 100 having an acetabular cup portion 10 formed as a hemispherical or semi-hemispherical cup, and projection 20 extending from cup 10 at a first end. Projection 20 terminates with flange connection member 30 at a second end of the projection, with connection member 30 being shaped and connected to the medial and superior aspect of the contralateral pubis of a patient. The shape of the connection member 30 may alter depending on the anatomy of the patient and it is envisaged that patient specific implants will be manufacture red and used with variations on the flange connection member 30 described herein.

Additional projections 40 may extend from cup 10 in opposing or alternative directions to projection 20, providing both stability for the acetabular cup and replacement of pelvic bone that has been or must be removed due to disease or damage. These projections may vary in shape and size depending on patient requirement and preferably incorporate a number of screw apertures for receiving screws at pre-determined angles, enabling the connection of implant to surrounding bone.

Flange connection member 30 includes concave internal surface 31 which contacts directly with and partially wraps around the contralateral pubis to secure implant 100 in position. The overall shape of the flange in individual implants will change depending on a number of factors

2019100983 30 Aug 2019 including the specific anatomy of the patient, the orientation of the implant within the patient and the availability of healthy bone to receive connection screws.

In the preferred embodiment shown in Figures 1-3, connection flange 30 is shaped such that the flange wraps from the medial aspect of the contralateral pubis - formally where the pubic symphysis was present before resection - on to the superior aspect of the pubis or pubic crest. Projection B of connection flange 30, as seen in Figure 2, is formed to enable location of the projection B on the medial aspect of the contralateral pubis where the pubic symphysis has been resected. Projection A is shaped such that it extends along the superior aspect of the pubic crest before terminating posterior of the pubic tubercle.

Connection flange 30 must be large enough to receive a number of connection screws for maintaining connection flange 30 in position, but small enough such that ease of insertion and positioning in maintained. The size is determined from the anatomy of the patient.

Screw apertures 33-35 are positioned in pre-determined positions connection flange 30 and are adapted to receive both a drill guide and orthopedic bone screws. In preferred embodiments a first and second screw apertures 33, 34 are positioned on the superior portion of projection A to direct screws into the inferior pubic ramus, and a third screw aperture 35 positioned on the medial portion opposing projection B to direct a screw towards the superior pubic ramus.

When bone screws are received within apertures 33-35, the screw in 35 is inserted into patient bone substantially perpendicular to screws received in aperture 33, 34. This screw arrangement is most preferably to maximise connection strength of the implant to the pubis and encourage bone ingrowth into the implant by reducing stress- shielding as much as possible.

Internal surface 31 of connection flange 30 is preferred formed with one or more regions of porous mesh scaffold to increase bone growth into the implant over time.

The implant of the present invention is preferably integrally formed using additive manufacturing technologies, in particular EBM manufacturing which achieves a preferred surface finish on manufactured implants.

2019100983 30 Aug 2019

The preferred porous mesh scaffold for use in the present invention is a three-dimensional modified dodecahedron structure with an individual unit cell structure of between 1.0 mm and 3.0mm. Maintaining unit cell size is important to increase the chances of effective osseointegration with the implant. If unit cell size is too small, the three-dimensional scaffold becomes difficult to clean and sterilise prior to use. If the unit cell size becomes too large, the structure loses mechanical integrity and osseointegration may also not be achieved as readily with a more spacious three-dimensional scaffold structure.

As would be clear to a person skilled in the art, the style of three-dimensional scaffold structure discussed above is not intended to be limiting and it is envisaged that other formations of three-dimensional scaffold that are mechanically sound may be used in the method and products of the present invention.

Screw apertures 33-35 are not intended to include three-dimensional scaffold as would be clear to a person skilled in the art.

The entire disclosures of all applications, patents and publications cited above and below, if any, are herein incorporated by reference.

Reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that that prior art forms part of the common general knowledge in the field of endeavour in any country in the world.

Where in the foregoing description reference has been made to integers or components having known equivalents thereof, those integers are herein incorporated as if individually set forth.

It should be noted that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the invention and

Claims (5)

1. A pelvic implant having a hemispherical acetabular cup portion and one or more projections extending outwardly from the acetabular cup portion;

at least one projection extending from the acetabular cup at a first end to a flange connection member at a second end of the projection, the flange connection member adapted for connection to the contralateral pubis of a pelvis;

wherein the flange connection member has an internal surface adapted to abut patient bone and an external surface adapted to abut soft tissue, wherein the connecting member is shaped such that the internal surface is at least partially concave such that when in position, the flange connection member wraps at least partially around the medial and superior aspects of the contralateral pubis; and wherein the connection flange member includes two or more screw apertures.

2. The implant of claim 1, wherein the length of the projection is greater than its width.

3. The implant of claim 1 or 2, wherein the flange connection member includes two screw apertures, the screw apertures aligned such that screws received within the apertures extend out through the concave internal surface substantially perpendicular to one another.

4. The implant as claimed in any one of claims 1-3, wherein the connection flange includes an alignment flange, hook or tab.

5. The pelvic implant substantially as described herein with reference to the accompanying figures.