Patent ID: 12226318

DETAILED DESCRIPTION OF THE DRAWINGS

FIGS.1and2illustrate perspective and front views (respectively) of an implantable medical device10ain the form of an ALIF device. In this regard, it is noted at the outset that the use of a reference numeral followed by a lower case letter and/or apostrophe in this specification typically indicates alternative embodiments of a general element identified by the reference numeral. Thus for example implantable medical device10ais similar to but not identical to implantable medical device10b. Further, references to an element identified only by the numeral refer to all embodiments of that element. Thus for example a reference to implantable medical device10is intended to include both the implantable medical device10aand the implantable medical device10b. In a similar manner, implantable medical device10acould include implantable medical devices10a′ and10a″ (not shown).

The implantable medical device10aincludes two components20a′,20a″ each having a respective body30a′,30a″. The bodies30a′,30a″ have a number of surfaces40a′,40a″ each with a contour42a′,42a″ that are configured to be complimentary to an anatomical surface of a specific patient. That is, the contours42a′,42a″ have been design for a certain patient. They are not complimentary in the generic sense, they have been designed for one patient in mind only. In this embodiment, the contours42a′,42a″ are configured to substantially match surfaces of a spinal bone/joint surface which are typically non-linear. In this regard, the surfaces40a′,40a″ are different to each other to substantially match different areas of the bone/joint surface they engage with.

With the above in mind, the contours42a′,42a″ are defined by modelling a bone or joint surface of a patient (typically based on a scan of the anatomical surface). A triangulated point (vertex) surface definition may then be developed with the assistance of the scan. Following this, the bodies30a′,30a″ are typically printed through additive manufacturing (i.e. 3DP) to capture a suitable shape. In addition, the contours42a′,42a″ in this embodiment are also separated by apertures44a′,44a″. The apertures44a′,44a″ assist in providing some compliance between the components20a′,20a″ and the bone or joint surface. That is, the apertures44a′,44a″ assist in forming protrusions or teeth adjacent thereto that improve stability by providing better grip between the components20a′,20a″ and bone/joint surface. The apertures44a′,44a″ may take various forms. For example, in one or more embodiments the apertures44a′,44a″ may be a recessed region or a channel.

The components20a′,20a″ also each include a part engaging surface50a′,50a″. The part engaging surfaces50a′,50a″ are respectively on an opposite side of bodies30a′,30a″ in comparison to the surfaces40a′,40a″. Side surface(s) respectively separate the surfaces40a′,40a″ from the part engaging surfaces50a′,50a″. The part engaging surfaces50a′,50a″ each include a first engaging surface52a′,52a″ and a second engaging surface54a′,54a″. The first engaging surfaces52a′,52a″ are offset to the second engaging surfaces54a′,54a″. In particular, the second surface54a′,54a″ is located further away from the surfaces40a′,40a″ in comparison to the first engaging surface52a′,52a″. This assists in providing an undulating surface, with ledges, that allows the components20a″,20a″ to securely engage with a component-engaging part60a(as discussed below).

The component-engaging part60ain this embodiment is in the form of a generic part. That is, the component-engaging part60amay be used amongst various patients and is used as a suitable spacer between the components20a′,20a″. The component-engaging part60acan therefore be swamped in and out, with other parts60of different sizes, to find a combination with components20that allows suitable engagement with the bone/joint surface. In this regard, the component-engaging part60aincludes a first engaging surface62band a second engaging surface64bthat respectively engage with the first engaging surfaces52a′,52a″ and the second engaging surfaces54b′,54b″. The engaging surfaces52a′,52a″,54b′,54b″,62b,64bare configured to interact to connect or secure the components20a′,20a″ to the component-engaging part60a.

FIG.3illustrates a traditional ALIF device8aengaging with a bone surface whilstFIG.4illustrates the implantable medical device10a. As shown inFIG.3, the generically formed ALIF device8ahas a surface that does not substantially complement the bone surface. This is further evident fromFIG.5illustrating a stress distribution of device8a. In particular, stress hot spots, which can lead to device or anatomical structure failure, can be seen towards the front edges of bone engaging with device8adue to its non-complimentary shape with the bone surface. In comparison, the implantable medical device10asuitably matches the bone surface, decreasing stress hot spots, increasing even low magnitude stress distribution, as well as increasing contact surface area and stability of the device-anatomy construct.

FIGS.6and7illustrate a further implantable medical device10bin the form of an ALIF device. In a similar manner to the device10a, the device10bincludes two components20b′,20b″ located either side of a component-engaging part60b. The components20b′,20b″ each include a body30b′,30b″ having surfaces40b′,40b″ that are configured to be complementary to at least part of a bone or joint surface of a patient. The surfaces40b′,40b″ include contours42b′,42b″ that are non-linear in order to suitably engage the bone or joint surface. Furthermore, apertures44b′,44b″ render gaps in surfaces40b′,40b′ that assist in forming protrusions or teeth adjacent thereto.

FIG.7further illustrates the interaction between the first surfaces52b′,62band the second surfaces54b′,64b. In particular, the components20b′,20b″ are configured to be slid into a secure engagement with the component-engaging part60b. The geometry between the first surfaces52b′,52b″,62band the second surfaces54b′,54b″,64bassists in creating a frictional engagement therebetween. Catches, lips and/or notches may also assist in connecting the components20b′,20b″ to the component-engaging part60b. In further embodiments, it would be appreciated that the components20b′,20b″ may be secured to the component-engaging part60bwith, for example, one or more fasteners. In addition, it will also be appreciated that the sliding arrangement between the components20b′,20b″ and the component-engaging part60ballows the components20b′,20b″ or part60bto be readily replaced with different components/parts having a different size (i.e. height, angle etc.) or material.

FIG.8illustrates the different positions of the spine2aachieved through different height (termed size inFIG.8) and angled components20blocated between vertebral bodies3a,3b. The +2 mm component20b2maintains the same superior spinal alignment as the 0 mm component20b0but the additional displacement may be desirable if there is a canal and/or foraminal stenosis compressing the neurological structures but the sagittal balance of the spine is suitable. The angled device20b0adjusts the sagittal balance of the spinal level, which may be desirable in cases where a collapsed disc has reduced the interbody, or disc space, lordotic angle. In this regard,FIG.8shows that when the lordotic angle of the disc space is reduced, the centre of mass of the spine, and the thorax, shifts anteriorly. An anterior shift in the centre of mass of the thorax leads to muscloskeletal compensation throughout the thoracic and cervical spine and associated musculature, which can add to the clinical symptoms for the patient. On this basis, the components20bcan assist in finding a suitable compromise for this problem.

FIG.9illustrates a further implantable medical device10cin the form of an ALIF device. The medical device10cis substantially the same as device10bbut the overall height of10chas been reduced compared to10bby swapping generic middle part60bfor60c. Components20c′,20c″ are substantially the same as components20b′ and20b″, respectively. In other words, and as evident fromFIG.8,FIG.9is further illustrating potential uses of the same components20with, for example, a different component-engaging part60c.

FIG.10illustrates an implantable medical device10din the form of an expandable cage. The device10dincludes two components20d′,20d″, acting as endplates, on either end of a component-engaging part60d. The components20d′,20d″ each have a body30d′,30d″ with respective surfaces40d′,40d″. Component20d′ is shown further inFIG.11. In this regard, it is noted that the surface40d′ has a contour42d′ that is somewhat convex in some regions, and somewhat concave in other regions. Furthermore, apertures44d′ in the form of channels separate the contours42d′ in order to assist with securing the component20d′ with the bone or joint surface.

The components20d′,20d″ include part engaging surfaces50d′,50d″. As shown inFIG.11, the part engaging surfaces50dinclude a plurality of first engaging surfaces52d′ in the form of a number of protrusions. The protrusions extend from a substantially linear surface and away from the surface40d′. The protrusions are configured to engage with the component-engaging part60din order to assist in securely connecting thereto. In particular, the protrusions form part of a click-in mechanism, including a click-in lip, and the protrusions prevent rotation about the component-engaging part60d.

The component-engaging part60dis shown further inFIGS.12and13. The component-engaging part60dincludes a body62d, a rotating portion64dand a (linear) movement portion66d. The rotating portion64dis configured to allow the components20d′,20d″ to rotate about the body62d. This allows the components20d′,20d″ to find an angle, whether rotating about the axial direction of the body62dand/or in a sagittal/transverse plane to the axial direction of the body62d, to suitably engage the discs3e,3fof the spine2c. In addition, the movement portion66dallows a portion of the component-engaging part60dto expand and retract in order to establish a suitable distance between the vertebral endplates3e,3f. The movement portion66dmay be adjusted via, for example, a screw. Accordingly, the components20d′,20d″ can be adjusted between the vertebral endplates3e,3fto find suitably engagement therewith.

As also shown inFIG.13, the implantable medical device10dmay form part of a system. This system may further include a fixation assembly110aincluding screws112a′,112a″ and rods114a. In this embodiment, the fixation system110ais located on an opposite side of the spine2acompared to the implantable medical device10d. Based on the present invention, it will be appreciated that the screws112a′,112a″ may include a component that provides a surface that suitably matches part of the vertebrae3e,3fit is designed to engage with. Once the screws112a′,112a″ are in place, the rod114acan be connected therebetween to assist in fixing movement of the spine.

As further appreciated below, mechanical disc replacement devices can broadly be classified into two groups: i) biasing based mid-section devices (i.e. springs/elastomers); and ii) floating block mid-section devices.FIG.14illustrates a front view of two cervical vertebrae3g,3h, as in their planned post-operative position, for an implantable medical device10ein the form of a disc replacement mechanism. The vertebral endplate surfaces of the vertebrae3g,3hinclude contours. A triangulated mesh is used to model the surfaces that correspond to the surfaces40e′,40e″ inFIG.14.FIG.15shows a subsequent model of the component10e, which is a floating block mid-section disc replacement device type. The device10efurther includes a plurality of protrusions in the form of teeth46a′,46a″ that are configured to pierce respective vertebral endplates of the vertebrae3g,3h. This is shown further inFIG.16where the teeth46a′,46a″ are shown to have punctured through the bone surface of the vertebrae3g,3h.

The device10ealso includes a component-engaging part60ethat is in the form of a floating component. The floating component is an off-the-shelf product that is configured to connect with the components20e′,20e″. The floating of the component-engaging part60eallows for suitable movement between the vertebral bodies3g,3h. In this regard, the matching of the contours in surfaces42e′,42e″ to the anatomical contours of the vertebral endplates of the vertebrae3g,3hpermit components20e′,20e″ to be customised. This reduces the need for surgical preparation, meaning that less bone is removed to fit the device10e, as well as increasing the contact surface area of the device10ewith the anatomy. Leaving the bone substantially intact assists in: i) reducing the chance of subsidence of the device10einto the vertebral body; and ii) increasing the force needed for the teeth to pull out through the bone.

FIG.17illustrates an implantable medical device10fin the form of a posterior lumbar interbody fusion (PLIF) cage. The device10facts as a one piece interbody fusion, or spacer, device whilst, for example, the device10eacts as a floating block mid-section disc replacement device. The device10fincludes components20f′,20f″ on either side of the component-engaging part60f. The components20f′,20f″ are connected in an integral manner to the component-engaging part60f. This is in contrast to the embodiments above where the other components20typically retain separable bodies after being secured. The component-engaging part60fincludes a lattice geometry that remains constant when different components20f′,20f″ are associated therewith.

The components20f′,20f″ include respective bodies30f′,30f″ that have surfaces40f′,40f″ with contours42f′,42f″ configured to match and engage with vertebral bodies3i,3jof the spine2e. This is shown further inFIG.18. The components20f′,20f″ includes part engaging surfaces50f′,50f″ that suitably connect with the portion of the component-engaging part60f.

As shown further inFIG.19, and in a similar manner toFIG.13, the implantable medical device10fmay form part of a system. In this embodiment, this system includes a fixation assembly110bhaving screws112b′,112b″ and rods114b. Once the screws112b′,112b″ are in place, the rod114bcan be connected therebetween to assist in fixing movement of the spine. In this regard, the combination of the device10f, screws112b′,112b″ and rods114bprovide a solution for positioning the spine2eto ultimately improve patient comfort.

With the above in mind, inserting the implantable medical devices10into a patient requires retrieving the components20. Potentially, a number of component engaging parts60may be on hand and, through a process of elimination, it can be determined which component engaging part60will restore the patient's anatomy in the appropriate manner. Furthermore, the component parts20may be interchanged to find a suitable combination. Once the components20and engaging part60is selected, they are secured together. In the present embodiments, the connection between the components20and the component-engaging part60relies on a frictional arrangement including a click-in mechanism. In further embodiment, it would be appreciated that the components20may be fastened to the component-engaging parts60.

Once the component(s)20are secured to the component-engaging part60, the device10is implanted into the patient. During this process, the component-engaging part60may be adjusted to allow the component(s)20to suitably engage the bone or joint surface. For example, the rotating portion64dof the component-engaging part60dmay be rotated, from a first position to a second position, in order achieve a required angle/height for the surfaces40of the component(s)20to substantially engage and complement the bone or joint surface. Similarly, the movement portion66dmay be shifted, in a substantially longitudinal direction, to allow engagement with the associated surfaces of the vertebrae3.

The implantable medical devices10provide a personalised device that can be manufactured and provided at a reduced cost, due to the use of (generic) component-engaging parts60, whilst maintaining the benefits of personalised devices in terms of device-anatomy fit. Due to the common interface between the components20and the component-engaging parts60, there is the potential to swap the (generic) component-engaging parts60at the time of surgery. Furthermore, different components20may be on hand allowing for other suitable combinations. This gives, for example, surgeons much more flexibility in treatment options. By way of example, if a different amount of height/angle is required for ALIF device60b, the surgeon can choose from a number of other component-engaging parts60that can assist in providing a suitable solution (as shown inFIG.8). In other words, the implantable medical devices10give surgeons more flexibility over some critical dimensions. This assists in avoiding problems where: i) anatomy has changed between medical imaging and surgery; or ii) the anatomy changes during the procedure.

Furthermore, the implantable medical devices10assist in reducing the amount of metal alloys implanted into a patient's body as any, or all, parts of the device10can be made out of non-metallic materials (e.g. polymers, organic tissues). This reduces the potential adverse immune-response and rejection of the device10. Moreover, post scanning of the device, potentially with CT and/or MRI scans, is more readily available and other forms of therapy become possible (e.g. beam therapies for some cancer patients). The use of different (non-metallic) materials also allows the modulus of the device10to be varied to suit a patient's needs. For example, a reduced overall stiffness of the assembled device can be used for a patient with reduced bone density to help prevent the onset of subsidence of the device into the adjacent bone anatomy.

The implantable medical devices10also reduce the volume of 3D printed material that is needed to produce a personalised medical device, which reduces the cost per unit of personalised devices as 3D printing manufacturing costs are based on the volume of material to be manufactured. Accordingly, the embodiments of the present invention reduce the overall cost of producing personalised devices as the ‘generic’ part60of the device10can be mass produced using traditional manufacturing methods (which take advantage of ‘economy-of-scale’ production). The embodiments of the present disclosure also reduce the number of personalised components20that need to be supplied for the treatment of each patient, obviating the need to manufacture multiple devices for a single patient and thereby reducing the costs and waste associated with production of patient specific devices.

In addition, it would be appreciated that the present invention has a range of medical applications. For example, in a dental application, a patent specific crown, designed to complement opposing teeth, may be attached with a generic part which is designed to be embedded in a mandibular bone. Further, it is to be understood that the present invention is also applicable to other total joint replacement devices whose design consists of a floating mid-section and anatomy interfacing sections. Such devices effectively include devices designed for any other synovial joint where arthroplasty is suitable including, but not limited to: total facet replacement/arthroplasty (spine); total knee arthroplasty; total hip arthroplasty; total ankle arthroplasty; ‘re-surfacing’ hip and knee arthroplasty; and total/partial shoulder and elbow arthroplasty.

In this specification, adjectives such as first and second, left and right, top and bottom, and the like may be used solely to distinguish one element or action from another element or action without necessarily requiring or implying any actual such relationship or order. Where the context permits, reference to an integer or a component or step (or the like) is not to be interpreted as being limited to only one of that integer, component, or step, but rather could be one or more of that integer, component, or step etc.

The above description of various embodiments of the present invention is provided for purposes of description to one of ordinary skill in the related art. It is not intended to be exhaustive or to limit the invention to a single disclosed embodiment. As mentioned above, numerous alternatives and variations to the present invention will be apparent to those skilled in the art of the above teaching. Accordingly, while some alternative embodiments have been discussed specifically, other embodiments will be apparent or relatively easily developed by those of ordinary skill in the art. The invention is intended to embrace all alternatives, modifications, and variations of the present invention that have been discussed herein, and other embodiments that fall within the spirit and scope of the above described invention.

In this specification, the terms ‘comprises’, ‘comprising’, ‘includes’, ‘including’, or similar terms are intended to mean a non-exclusive inclusion, such that a method, system or apparatus that comprises a list of elements does not include those elements solely, but may well include other elements not listed.