WO2021123994A1

WO2021123994A1 - Limb and joint sparing in mammals using patient-specific surgical guides and implant with textured muscle attachment zones.

Info

Publication number: WO2021123994A1
Application number: PCT/IB2020/061404
Authority: WO
Inventors: Vladimir Brailovski; Bernard Seguin; Anatolie Timercan; Bertrand Lussier; Yvan Petit
Original assignee: Socovar, L.P.; Colorado State University Research Foundation; Universite De Montreal
Priority date: 2019-12-16
Filing date: 2020-12-02
Publication date: 2021-06-24

Abstract

An endoprosthesis (300) including a scapular fixation (302) for attaching to the scapula (202), a humeral fixation (304) insertable in the medullary cavity (208) of a distal portion of the humerus (212) after the proximal portion thereof (210)has been excised, and a joint replica (306) extending therebetween.In some embodiments, the joint replica (306) is articulated. Also, an implant (300)including a textured muscle attachment zone (324,326,328).

Description

TITLE OF THE INVENTION

Limb and joint sparing in mammals using patient-specific surgical guides and implant with textured muscle attachment zones.

FIELD OF THE INVENTION

[0001] The present invention relates to the art of medical treatments. More specifically, the present invention is concerned with limb and joint sparing in mammals using patient-specific endoprostheses and surgical guides. The present invention is also concerned with implants incorporating textured muscle attachment zones.

BACKGROUND

[0002] There are medical conditions in dogs and other mammals that require amputation of the proximal humerus. Since the distal part of the affected leg is then no longer linked with bones to the torso, such amputations will typically require total amputation of the affected leg, which greatly reduces the quality of life of the patient. The whole leg can be replaced with a prosthesis, but such prostheses are barely functional, as they are not articulated. They are also cosmetically unappealing.

[0003] Accordingly, there is a need in the industry to provide novel limb sparing devices and methods. An object of the present invention is to provide such devices and methods. SUMMARY OF THE INVENTION

[0010] Is it proposed to use customized implants to replace an excised portion of the proximal humerus, for example in a dog. The shape and dimensions of the implant may be obtained through imaging techniques prior to a surgical intervention, with the use of any suitable technique to manufacture the customized implant, such as 3D printing or machining, among other possibilities. One may use either an image of the limb on which excision will occur, or a mirror image of the contralateral limb. Customized cutting, reaming and drilling guides are also used. This summary assumes that the proximal humerus is to be excised due to an osteosarcoma. However, the present invention is usable in other contexts and simple mention of osteosarcoma as an example in the present document should not be used to limit the scope of the invention unless explicitly claimed.

[0011] Generally speaking, the proposed method for limb sparing uses the following steps. While the proposed method herein is used in the context of dogs, this method is also applicable in other mammals, such as other pets and humans for example. Anatomically correct geometrical reconstruction is the first step for the design of the custom-made endoprosthesis. Commonly, in dogs suffering from osteosarcoma, both the affected and normal contralateral limbs are imaged simultaneously. The affected limb serves to determine the length of the excised portion of the humerus and to design the cutting, reaming and drilling guides. The unaffected limb is utilized to design the bone replica portion of the endoprosthesis. Subsequently, a mirrored image of the replica is generated to bridge the bone defect created during surgery. The mirrored geometry is then examined and, if necessary, adjusted to obtain the best possible fit between the bone replica and the remaining distal portion of the affected humerus. This step allows detecting and correcting anatomical differences between the normal contralateral and affected limbs. This approach originates from the circumstance that the tumour often results in deformations of the affected humerus; hence mirroring is then a designated solution for adequate implant design. However, if the affected humerus is still close to a non-pathological shape, an image of the affected humerus may be used instead. Patient-specific attachments are created to complete the endoprosthesis.

[0012] To form 3D models of both affected and contralateral limbs, starting from a CT study, image segmentation is carried out, for example using Mimics (Materialise NV, Belgium), a highly accurate contour detection tool to separate bony from surrounding soft tissue structures. The outer surface of the limbs is typically automatically created, using for example the marching cube algorithm. The resulting tessellated limb models are exported into a computer assisted design tool for post processing. For example, the design tool used is CATIA v5 (Dassault Systems, France), a highly performant CAD/CAM software. With the help of the CAD tool, the tessellated limb models are smoothed and filled to create three dimensional solid body models.

[0013] The design of the implant is accomplished in two concurrent or successive steps. First, personalized cutting, reaming and drilling guides are designed. These will be used respectively to guide cutting the proximal portion of the humerus, accurately reaming the medullary cavity of the remaining portion of the distal humerus and forming apertures for inserting screws or bolts that will secure the endoprosthesis to the humerus. Second, the personalized implant is designed. The design of these components is, for example, carried out entirely in the CAD environment. Subsequently, both components are manufactured, for example using 3D printing or a CNC controlled machine, among other possibilities. [0014] The cutting, reaming and fixing guides are highly advantageous in ensuring that the limb-sparing prosthesis will precisely fit the bone defect in terms of length, position and overall size. The cutting guide's shape is primarily influenced by the shape of the bone to excise and the cutting guide length depends on the resection margin established by the surgeon to prevent tumour recurrence. To create the cutting guide, the location at which osteotomy will occur is marked on the reconstructed affected limb geometry. Second, the profile of the cutting guide is drawn with the help of 2D sketches on the affected limb. The 3D solid model of the cutting guide is created using a multi-section solid extrusion feature. The 3D cutting guide extends beyond the osteotomy location and intersects with the limb. The distal end of the cutting guide extends into the supratrochlear foramen for added stability. At the osteotomy site, a cutting slot pocket feature, wide enough for the bone saw blade to pass, is provided. During surgery, the cutting guide will be aligned using the scapular spine, at or adjacent the acromion for example. Lastly, a Boolean type logical subtraction between the affected limb and the cutting guide will be performed to create a seamless geometrical fit between the limb and the cutting guide. This fit helps in (i) centering the guide’s cutting slot exactly at the osteotomy location and (ii) to lock the cutting guide in place while the veterinary surgeon performs the osteotomy. The drilling and reaming guides are similarly shaped to conform to the part of the humerus that will remain after excision. Notably, the drilling guide may abut against the proximal part of the lateral epicondyle and into the supratrochlear foramen.

[0015] The endoprosthesis (i) serves to span the bone defect caused by the surgical en bloc resection of the osteosarcoma, (ii) guarantees adequate biomechanical functionality of the spared limb, and (iii) minimizes the risk of implant failure and infection. Hence, the patient-specific prosthesis plays an important role in improving the patient’s quality of life and function. In some embodiments, the endoprosthesis is a single rigid component. In other embodiment, the endoprosthesis is articulated to allow movements between the scapula and the humerus, recreating the preexisting thoracic limb joint.

[0016] The endoprosthesis incorporates three main functional components, namely a scapular fixation, a humeral fixation and a joint replica extending therebetween. When in place, the scapular fixation is secured to the scapula, the humeral fixation is inserted in the medullary cavity of the humerus and the joint replica extends where the excised bone was before excision.

[0017] The replica of the removed affected bone segment is created using a mirror image of the reconstructed normal contralateral solid limb model, obtained as described previously. At the distal flat contact surface of the replica, a scaled extrusion of a portion of the medullary cavity is created (intramedullary stem) to enable a more solid connection between the implant and the intact bone. The joint replica has an anatomically exact shape to facilitate attachment of the muscles that needed to be detached to perform the osteotomy. The 3D model of the scapular fixation is then generated, for example, with the help of a multi-section solid extrusion feature, followed by a Boolean type logical subtraction between the scapular fixation and the scapula, creating a seamless fit. Subsequently, the three components of the endoprosthesis are combined to form a single solid part with the help of a Boolean type logical addition. Lastly, mounting apertures, for example threaded countersunk hole features, are placed on the scapular fixation for locking screw placement during surgery. To enable a solid connection between the implant and the remaining humerus, at least one, for example three, screws from the lateral side pass through holes in the intramedullary stem, thereby acting similarly to an interlocking nail. [0018] The cutting guide and endoprosthesis are manufactured using any suitable method. For example, they are manufactured using two different additive manufacturing techniques. Prior to manufacturing, the solid 3D models of the cutting guide and endoprosthesis are surface tessellated and exported as separate .STL files. In some embodiments, the cutting guide is manufactured using fused deposition modelling (FDM), a cost-effective additive manufacturing technology capable of transforming biocompatible plastic materials. In some embodiments, the endoprosthesis is manufactured using laser powder bed fusion (LPBF), a versatile manufacturing technology capable of direct manufacturing of parts made of biocompatible metals. An EOS280 LPBF system can be utilized which uses a focused Nd-YAG laser to locally melt metal powder (e.g. stainless steel, Ti, Ni-Ti alloys, and Co-Cr allows) evenly spread on a movable building plate. To provide adequate implant stability while minimizing the implant weight and reduce the risk of excessive thermal stresses, a lattice structure can be implemented inside the replica of the removed bone. Upon completion of the manufacturing process, the endoprosthesis is cut off the building platform. Finally, all surfaces of the endoprosthesis may be finished using sand blasting followed by polishing. Such treatment results in a smooth and even surface that decreases the risk of bacterial adhesion and minimizes the risk of biofilm formation.

[0019] The present application cites many documents, the contents of which is hereby incorporated by reference in their entirety. The present patent application claims priority from US provisional patent applications 62948613 and 62948629, both files December 16, 2019, the contents of which is hereby incorporated by reference in its entirety.

[0020] In a broad aspect, there is provided an orthopaedic implant for replacing bone tissues to which a muscle was attached, comprising: a body shaped to replace the bone tissues, the body being provided with a muscle attachment zone configured and sized for reattaching the muscle thereto after the bone tissues are removed and the orthopaedic implant is implanted.

[0021] There may also be provided an orthopaedic implant wherein the muscle attachment zone includes a tridimensional porous structure including interconnected pores configured to be colonized by the muscle after the muscle is reattached to the muscle attachment zone.

[0022] There may also be provided an orthopaedic implant wherein the tridimensional porous structure extends from an underlying continuous bulk surface of the body.

[0023] There may also be provided an orthopaedic implant wherein the tridimensional porous structure includes zigzagging struts interconnected to each other at nodes.

[0024] There may also be provided an orthopaedic implant wherein the nodes form a tridimensional orthogonal grid.

[0025] There may also be provided an orthopaedic implant wherein the tridimensional porous structure has a porosity of between about 30% and about

80%.

[0026] There may also be provided an orthopaedic implant wherein the nodes are spaced apart centre-to centre from each other in a plane of the orthogonal grid by a distance of from about .25 to about 2.5 mm, an wherein the struts have a transversal cross-sectional area of from about .05 to about 1 mm².

[0027] There may also be provided an orthopaedic implant wherein the implant is further provided with suture apertures extending through the body for receiving a suture usable to secure the muscles to the orthopaedic implant until the tridimensional porous structure is colonized.

[0028] There may also be provided an orthopaedic implant wherein the implant has a substantially smooth surface outside of the muscle attachment zones.

[0029] There may also be provided an orthopaedic implant wherein the implant is metallic.

[0030] There may also be provided an orthopaedic implant wherein the implant is articulated.

[0031] There may also be provided an orthopaedic implant wherein the implant is an endoprosthesis for replacing an excised proximal portion of a humerus to which muscles were attached, the humerus defining a medullary cavity, the endoprosthesis being securable to both a remaining portion of the humerus and a scapula, the scapula defining a scapular spine defining two side surfaces and terminated by an acromion, the endoprosthesis including: a scapular fixation securable to the scapula; a humeral fixation insertable in the medullary cavity; and a joint replica extending therebetween for replacing the excised proximal portion, the muscle attachment zone being provided in the joint replica.

[0032] There may also be provided an orthopaedic implant wherein the joint replica includes a replica scapular portion and a replica humeral portion articulated to each other, the muscle attachment zone being provided in the humeral portion.

[0033] The orthopaedic implant as defined in claim 13, wherein the replica scapular portion is formed integrally with the scapular fixation and the replica humeral portion is formed integrally with the humeral fixation.

[0034] There may also be provided an orthopaedic implant wherein the replica scapular portion and the replica humeral portion are articulated to each other through a ball-and-socket joint allowing rotation in all planes.

[0035] There may also be provided an orthopaedic implant wherein the scapular fixation includes a pair of arms securable to the scapula.

[0036] There may also be provided an orthopaedic implant wherein the arms define an acromion receiving recess.

[0037] There may also be provided an orthopaedic implant wherein growth factors are provided at the muscle attachment zone.

[0038] There may also be provided an orthopaedic implant wherein the growth factors include a collagen matrix.

[0039] In another broad aspect, there is provided an endoprosthesis usable in a patient for replacing an excised proximal portion of a humerus to which muscles were attached, the humerus defining a medullary cavity, the endoprosthesis being securable to both a remaining portion of the humerus and a scapula, the scapula defining a scapular spine defining two side surfaces and terminated by an acromion, the endoprosthesis comprising: a scapular fixation securable to the scapula; a humeral fixation insertable in the medullary cavity; and a joint replica extending therebetween for replacing the excised proximal portion.

[0040] There may also be provided an endoprosthesis wherein the scapular fixation is securable adjacent to or directly to the scapular spine.

[0041] There may also be provided an endoprosthesis wherein the scapular fixation includes two arms extending from the joint replica, the arms each defining an arm bone facing surface configured and sized to abut against and conform to a respective one of the side surfaces.

[0042] There may also be provided an endoprosthesis wherein an acromion recess is defined at an origin of the two arms, the acromion recess being configured and sized for receiving the acromion thereinto.

[0043] There may also be provided an endoprosthesis wherein the arms are substantially parallel to each other.

[0044] There may also be provided an endoprosthesis wherein the arms each define mounting apertures extending therethrough for receiving fasteners thereinto to fasten the arms to the scapula.

[0045] There may also be provided an endoprosthesis wherein each arm include from 4 to 12 mounting apertures. [0046] There may also be provided an endoprosthesis wherein the mounting apertures are substantially perpendicular to the arm bone facing surface.

[0047] There may also be provided an endoprosthesis wherein the bone facing surfaces of each arm are substantially perpendicular to each other.

[0048] There may also be provided an endoprosthesis wherein the arms define chamfered free ends.

[0049] There may also be provided an endoprosthesis wherein the joint replica is substantially elongated and the humeral fixation includes a stem extending coaxially with the joint replica.

[0050] There may also be provided an endoprosthesis wherein the stem is provided with stem apertures extending laterally therethrough.

[0051] There may also be provided an endoprosthesis, wherein the joint replica defines a muscle attachment zone configured and sized for reattaching thereto at least one of the muscles.

[0052] There may also be provided an endoprosthesis wherein the muscle attachment zones is provided with suture apertures through which a suture may be inserted to secure the at least one of the muscles to the endoprosthesis.

[0053] There may also be provided an endoprosthesis wherein the muscle attachment zone is described above. [0054] There may also be provided an endoprosthesis wherein, when the endoprosthesis is in use, the muscle attachment zone is located at a position substantially similar or adjacent to an insertion of the at least one of the muscles muscle prior to excision.

[0055] There may also be provided an endoprosthesis wherein the muscle attachment zone is configured and located for attaching thereto a deep pectoral.

[0056] There may also be provided an endoprosthesis wherein the muscle attachment zone is provided substantially opposed to the arms on the joint replica, with part of the muscle attachment zone being generally in axial alignment with the arms, so that once the prosthesis is implanted in the patient, the muscle attachment zone faces laterally outwardly relative to the patient.

[0057] There may also be provided an endoprosthesis wherein the muscle attachment zone is configured and located for attaching thereto at least one of a superficial pectoral and a medial triceps.

[0058] There may also be provided an endoprosthesis wherein the muscle attachment zone is configured and located for attaching thereto the superficial pectoral and the medial triceps.

[0059] There may also be provided an endoprosthesis wherein the muscle attachment zone is provided adjacent the humeral fixation, so that once the prosthesis is implanted in the patient, the muscle attachment zone faces laterally outwardly relative to a patient. [0060] There may also be provided an endoprosthesis wherein the muscle attachment zone is configured and located for attaching thereto at least one of a brachialis, a triceps accessory and a lateral triceps.

[0061] There may also be provided an endoprosthesis wherein the muscle attachment zone is configured and located for attaching thereto the brachialis, the triceps accessory and the lateral triceps.

[0062] There may also be provided an endoprosthesis wherein the muscle attachment zone is adjacent the arms, opposed to a region of the joint replica substantially longitudinally opposed to the arms on the joint replica, so that once the prosthesis is implanted in the patient, the muscle attachment zone faces laterally inwardly relative to a patient.

[0063] There may also be provided an endoprosthesis wherein the muscle attachment zone is configured and located for attaching thereto a supraspinatus.

[0064] There may also be provided an endoprosthesis wherein the muscle attachment zone is adjacent the arms, substantially parallel thereto.

[0065] There may also be provided an endoprosthesis wherein wherein the endoprosthesis is made of a single integrally extending piece of material.

[0066] There may also be provided an endoprosthesis wherein wherein the joint replica is articulated.

[0067] There may also be provided an endoprosthesis wherein wherein the joint replica includes a replica scapular portion and a replica humeral portion articulated to each other.

[0068] There may also be provided an endoprosthesis wherein the replica scapular portion is formed integrally with the scapular fixation and the replica humeral portion is formed integrally with the humeral fixation.

[0069] There may also be provided an endoprosthesis wherein the replica scapular portion and the replica humeral portion are articulated to each other through a ball-and-socket joint allowing rotation in all planes.

[0070] There may also be provided an endoprosthesis wherein the replica scapular portion defines a scapular end surface opposed to the scapular fixation in which a sphere cap shaped scapular recess is formed; the replica humeral portion defines a humeral end surface opposed to the medullar fixation; a stem terminated by a head extends from the humeral end surface, the head defining a head distal surface shaped like a portion of an outer surface of a sphere and having a radius of curvature substantially similar that of the scapular recess; the head abuts against the scapular recess and is rotatable relative thereto.

[0071] There may also be provided an endoprosthesis wherein the head has a larger diameter than a transversal section of the stem.

[0072] There may also be provided an endoprosthesis further comprising a pair of retaining cap positioned between the humeral end surface and the scapular end surface and shaped so to conform to the shape of the humeral and scapular end surfaces, the retaining caps defining a stem receiving aperture receiving the stem thereinto so that the stem is movable in the stem receiving aperture to articulate the joint replica, the stem receiving aperture defining a neck of a diameter smaller than a diameter of the head adjacent the head.

[0073] There may also be provided an endoprosthesis further comprising a polymer insert between the retaining caps and the humeral end surface.

[0074] There may also be provided an endoprosthesis further comprising a polymer insert between the scapular recess and the head.

[0075] There may also be provided an endoprosthesis wherein the retaining caps are secured to the humeral end surface.

[0076] In yet another broad aspect, there is provided a kit for implanting an endoprosthesis to replace an excised proximal portion of a humerus having a medullary cavity, comprising: a prosthesis as described above; a cutting guide to guide a cut made to excise the proximal portion of the humerus; a reaming guide to guide reaming of the medullary cavity after excision of the proximal portion of the humerus; a drilling guide to guide drilling of lateral apertures through a remaining distal portion of the humerus.

[0077] In yet another broad aspect, there is provided a method of using an orthopaedic implant to replace excised bone tissues in a patient, the bone tissues having one or more muscles attached thereto prior to excision, the orthopaedic implant including one or more muscle attachment zones provided with a porous textured surface, the method comprising: sectioning the one or more muscles; excising the excised bone tissues; positioning the orthopaedic implant at a position substantially similar to the position of the excised bone tissues prior to excision; and securing at least some of the one or more muscles to the one or more muscle attachment zones so that the muscles are in register with the porous textured surface.

[0078] There may also be provided a method further comprising colonizing the porous textured surface with the muscles.

[0079] There may also be provided a method further comprising providing muscle growth factors at the textured porous surface.

[0080] There may also be provided a method wherein the muscles are secured with a suture to secure the muscles prior to completion of colonization. A prosthesis, comprising: a scapular fixation for attaching to the scapula, a humeral fixation insertable in the medullary cavity of a distal portion of the humerus after the proximal portion thereof has been excised, and a joint replica extending therebetween.

[0081] In yet another broad aspect, there is provided an implant usable adjacent muscle tissues, comprising: a body, the body being provided with a muscle attachment zone configured and sized for attaching the muscle tissues thereto, the muscle attachment zone including a tridimensional porous structure including interconnected pores configured to be colonized by the muscle tissues after the muscle tissues are abutted thereagainst.

[0082] Other objects, advantages and features of the present invention will become more apparent upon reading of the following non-restrictive description of preferred embodiments thereof, given by way of example only with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0083] Figure 1 , in a flowchart, illustrates a limb sparing method in dogs in accordance with an embodiment of the present invention;

[0084] Figure 2, in a perspective view, illustrates some anatomical features of a mammal thoracic limb relevant to the present invention;

[0085] Figure 3, in a perspective view, illustrates an endoprosthesis usable in the method of FIG. 1 ;

[0086] Figure 4, in an alternative perspective view, illustrates the endoprosthesis of FIG. 3;

[0087] Figure 5, in a side elevation view, illustrates a cutting guide usable in the method of FIG. 1 ;

[0088] Figure 6, in a top elevation view, illustrates the cutting guide of FIG. 5;

[0089] Figure 7, in a perspective view, illustrates a reaming guide usable in the method of FIG. 1 ;

[0090] Figure 8, in an alternative perspective view, illustrates the reaming guide of FIG. 5; [0091] Figure 9, in a top elevation view, illustrates a drilling guide usable in the method of FIG. 1 ;

[0092] Figure 10, in a top elevation view, illustrates the cutting guide of FIG. 5 mounted to a patient;

[0093] Figure 11 , in a top elevation view, illustrates the reaming guide of FIG. 5 mounted to a patient;

[0094] Figure 12, in a top elevation view, illustrates the endoprosthesis of FIG. 3 mounted to a patient;

[0095] Figure 13, in a side elevation view, illustrates the endoprosthesis of FIG. 3 mounted to a patient;

[0096] Figure 14, in a lateral view, illustrates the drilling guide of FIG.9 mounted to the endoprosthesis and to the patient

[0097] Figure 15, in a schematic view, illustrates the endoprosthesis of FIG. 3 mounted to a patient and the attachment of muscles thereto;

[0098] Figure 16, in a schematic view in with an alternative orientation, illustrates the endoprosthesis of FIG. 3 mounted to a patient and the attachment of muscles thereto;

[0099] Figure 17, in a perspective exploded view, illustrates an alternative endoprosthesis usable in the method of FIG. 1 ; [00100] Figure 18, in a lateral view, illustrates movements in a first plane of the endoprosthesis of FIG. 17;

[00101] Figure 19, in a cranio-caudal view, illustrates movements in a second plane of the endoprosthesis of FIG. 17;

[00102] Figure 20 illustrates a step in assembly of the endoprosthesis of FIG. 17;

[00103] Figure 21 illustrates an other step in assembly of the endoprosthesis of FIG. 17;

[00104] Figure 22 illustrates yet another step in assembly of the endoprosthesis of FIG. 17;

[00105] Figure 23, in a cutaway view, illustrates the endoprosthesis of FIG. 17.

[00106] Figure 24, in a lateral view, illustrates the endoprosthesis of FIG. 17 mounted to a patient and the attachment of some muscles thereto;

[00107] Figure 25, in a lateral view, illustrates an alternative endoprosthesis usable in the method of FIG. 1 ;

[00108] Figure 26, in a perspective view, illustrates pores in a plane of a tridimensional porous structure part of a texture of the endoprosthesis of FIG. 25;

[00109] Figure 27, in a top elevation view, illustrates pores of the tridimensional porous structure;

[00110] Figure 28, in a perspective view, illustrates a triangulation of the surface of struts forming part of the tridimensional porous structure; and

[00111] Figure 29, in a perspective view with shading, illustrates the pores and struts of part of the tridimensional porous structure.

DETAILED DESCRIPTION

[00112] The present invention relates to limb sparing methods and devices, and in some embodiments to joint sparing methods and devices. With reference to FIG. 1 , the present invention implements a method 100 in which part of an affected limb bone is amputated and replaced by an endoprosthesis. The method starts at step 105. Then, at step 110, images of the affected limb and, if necessary, of the contralateral limb are acquired. The images are acquired using an imaging modality that allows creation of a 3D model of both limbs adjacent the portion of the affected limb, such as CT imaging, as performed in step 115. More specifically, in step 115, an affected limb 3D model is created, and a contralateral limb 3D model is created. These 3D models are used as basis for manufacturing respectively an endoprosthesis (in part from the mirror image of the contralateral limb 3D model and in part from the affected limb 3D model) and the cutting, reaming and drilling guides (from the affected limb 3D model), at step 120. After manufacturing, all these manufactured parts are then sterilized. Finally, at step 125, a surgical procedure is performed in which the cutting guide is positioned on the affected limb, directly on the bone, part of the affected bone is removed using surgical instruments, such as a surgical saw, and the prosthesis is secured to the remaining portion of the bone after reaming. If one or more muscle attachment zones are provided, as described below, one or more muscles can also be attached at step 125. Finally, the method ends at step 130.

[00113] FIG. 2 illustrates some canine anatomical structures relevant to the method 100. The humerus 200 is articulated with the scapula 202, which defines a scapular spine 204 terminated adjacent the humerus 200 by an acromion 206. The humerus 200 defines a medullary cavity 208 and humerus proximal and distal portions 210 and 212. The humerus proximal portion 210 is adjacent the scapula 202. Similar structures are present in other mammals on which the method 100 can be performed.

[00114] FIGS. 3 and 4 illustrates an implant in the form of an endoprosthesis 300 in accordance with an embodiment of the present invention. The endoprosthesis 300 replaces the humerus proximal portion 210 that is removed when the method 100 is performed. The endoprosthesis 300 includes a scapular fixation 302, a humeral fixation 304 and a joint replica 306 extending therebetween. In some embodiments, the endoprosthesis 300 is made of a single integrally extending piece of material, but a prosthesis made of many assembled components is also within the scope of the present invention.

[00115] The scapular fixation 302 is configured and shaped to be secured to the scapula 202, for example adjacent to or directly to the scapular spine 204. For example the scapular fixation 302 includes two arms 314 and 316 defining respective arm bone facing surfaces 315 and 317 configured and sized to each abut and conform to a respective one of the side surfaces of the scapular spine 204. An acromion recess 318 is defined at an origin from which the two arms 314 and 316 extend and receives the acromion 206 thereinto when the scapular fixation 302 is secured to the scapula 202. The arms 314 and 316 are typically substantially parallel to each other. Mounting apertures 320 extend through the arms 314 and 316, for example between 4 and 12 mounting apertures for each of the arms 314 and 316. The mounting apertures 320 are typically substantially perpendicular to the surface of the scapular spine 204 against which the arm 314 or 316 in which they are formed abuts, and therefore perpendicular to the arm bone facing surfaces 315 and 317. Also, in some embodiments, the mounting apertures 320 of the arm 314 are substantially perpendicular to the mounting apertures 320 of the other arm 316. In use, fasteners, such as locking screws 322, are inserted through the mounting apertures 320 and in the scapula 202. The arms 314 and 316 may be chamfered at their free end.

[00116] The joint replica 306 has a shape substantially similar to the shape the portion of the humerus 200 that it replaces. This is achieved for example by having the joint replica 306 having the shape of a mirror image of the contralateral humerus, or of the excised portion if the latter is not deformed by the disease requiring the surgical intervention. The joint replica 306 defines muscle attachment zones for attaching muscles thereto, either directly or through their ligaments. For example, first, second and third muscle attachment zones 324, 326 and 328 are defined, the third muscle attachment zone 328 being only visible in FIG. 3.

[00117] The first muscle attachment zone 324 is provided substantially opposed to the arms 314 and 316 on the joint replica 306, with part of the first muscle attachment zone 324 being generally in axial alignment with the arms 314 and 316. Thus, once the endoprosthesis 300 is implanted, the first muscle attachment zone 324 faces laterally outwardly relative to the patient, adjacent to the scapula 202. The second muscle attachment zone 326 also faces laterally outwardly and is provided closer to the humeral fixation 304 than the first muscle attachment zone 324. The third muscle attachment zone 328 is generally opposed to the first muscle attachment zone 324, adjacent the scapular fixation 302, and faces laterally inwardly once the endoprosthesis 300 is implanted. Other suitable muscle attachment zones may be provided in alternative embodiments. The first, second and third muscle attachment zones 324, 326 and 328 are provided with suture apertures 330 through which a suture may be inserted to secure muscles to the endoprosthesis 300. Typically, the muscle attachment zones are located at a position substantially similar or adjacent to an insertion of the muscles to secure thereto prior to excision, so that the endoprosthesis 300 may have biomechanical properties similar to that of the humerus prior to excision.

[00118] The humeral fixation 304 takes the form of a stem extending coaxially with an elongated joint replica 306, at its distal end, and is dimensioned to be inserted in the medullary cavity 208 of the remaining portion of the humerus 200. In some embodiments, the humeral fixation 304 is provided with stem apertures 332 extending laterally therethrough to allow longitudinal immobilization of the humeral fixation in the humerus 200 using suitable fasteners.

[00119] An example of a cutting guide 400 usable in the method of FIG. 1 is shown in FIGS. 5 and 6. While any suitable cutting guide may be manufactured, the cutting guide 400 shown in FIGS. 5 and 6 is well suited to guide removal of the humerus proximal portion 210 in dogs and other similar animals.

[00120] The cutting guide 400 includes a cut guiding portion 402, an opposed mounting portion 404 and a linking portion 406 therebetween, which are typically integrally formed together. The cut guiding portion 402 is configured to abut against the humerus 200 adjacent the cut location where the humerus 200 is to be cut during surgery. For example, the cut guiding portion 402 defines a slit 408 through which the blade 700 of a saw 702 (shown in FIG. 10) can be inserted to cut through the humerus 200. Thus, the slit 408 is configured, sized and positioned to be substantially adjacent the cut location when the cutting guide 400 is operatively mounted to the humerus 200 and scapula 202. The slit 408 is typically generally perpendicular to the humerus 200 when the cutting guide 400 is mounted thereto, but other orientations are within the scope of the invention.

[00121] As better seen in FIG. 6, the mounting portion 404 defines a pair of mounting arms 410 and 412 substantially parallel to each other extending from a head receiving portion 414, which itself extends from the linking portion 406. The mounting arms 410 and 412 are configured to conform to part of the scapular spine 204 and the head receiving portion conforms to part of the shape of the humeral head. The linking portion 406 takes any suitable shape and typically conforms to the surface of the humerus proximal portion 210.

[00122] More specifically, the cutting guide 400 is delimited by a cutting guide peripheral surface 416. The cutting guide peripheral surface 416 defines a bone facing portion 418, better seen in FIG. 5, which faces the humerus 200 and scapula 202 when the cutting guide 400 is mounted thereto. The bone facing portion 418 has a shape, configuration and dimensions so that is conforms to the shape of the humerus 200 and scapula 202. Typically, the bone facing portion of the cutting guide 400 is designed to prevent as much as possible collision with the tumour, while permitting precision positioning at prior to cutting. Thus, when the cutting guide 400 is mounted to the humerus 200 and scapula 202, there is only one precise relative position between the cutting guide 400 and the humerus 200 and scapula 202 that results in a precise fit therebetween. This ensures that the cutting guide 400 will not move easily relative to the humerus 200 when the latter is cut, and ensures also that the slit 408 is precisely positioned at the right location prior to cutting.

[00123] In some embodiments, the cutting guide 400 includes one or more K-wire apertures 420. The K-wire apertures 420 are formed in the cutting guide 400 and configured, positioned and sized to receive each a K-wire (not shown in the drawings) thereinto such that the K-wire can be inserted in the humerus 200 and/or the scapula 202 before cutting. For example, two K-wire apertures 420 are provided adjacent the slit 408 and a K-wire aperture 420 is provided in each of the mounting arms 410 and 412.

[00124] The reaming guide 422, seen in FIGS. 7 and 8, includes a bone receiving portion 424 and a spacing portion 426 extending axially from each other. The bone receiving portion 424 defines a bone receiving cavity 428 conforming in shape to the shape of the proximal end of the distal remaining humerus 200 after excision of the humerus proximal portion 204. The bone receiving cavity 428 is typically manufactured so that it substantially snugly fit to the humerus 200. The spacing portion 426 extends from the bone receiving portion 424 and defines a passageway 431 axially therethrough leading to the bone receiving cavity 428.The passageway 431 is sized to receive therethrough a reamer 708 (seen in FIG. 11). The medullary cavity 408 may be enlarged to conform to the diameter and length of the humeral stem 304 so it may be fitted snugly within the reamed medullary cavity 408.

[00125] Referring to FIG. 9, the drilling guide 430 is used to drill lateral apertures through the remaining humerus 200, after excision, in register with the stem’s apertures 332. The drilling guide 430 is configured to fit at only a predetermined location on the remaining part of the humerus 200, using a custom bone-facing surface. Drilling guide apertures 432 extend through the drilling guide 430, towards the bone-facing surface and are positioned so as to be in register with the stem apertures 332 when properly positioned. A drill bit can then be used to drill through the humerus and the stem apertures 332 to form apertures in the humerus 200, allowing insertion of bicortical screws 322 or bolts therethrough. The drilling guide 430 is typically secured to the endoprosthesis 330 to ensure alignment with the stem apertures 332. For example, the drilling guide 430 defines at its proximal end two mounting tabs 429 that are inserted each in a corresponding drilling guide mounting recess 333 formed in the endoprosthesis 300.

[00126] The endoprosthesis 300 and the cutting, reaming and drilling guides 400, 422 and 430 may be used as follows. First, the muscles attached to the humerus proximal portion 210 are detached from the humerus 200. Then, as seen in FIG. 10, the cutting guide 400 is mounted to the humerus 200 and scapula 202 and the saw 702 is used to cut the humerus 200 at the location of the slit 408 so that the humerus proximal portion 210 may be removed.

[00127] Then, as seen in FIG. 11 , the reaming guide 422 is inserted on the remaining portion of the humerus 200 so that the medullary cavity 408 (not shown in FIG. 11 ) may be reamed using the drill 708.

[00128] Then, as seen in FIGS. 12 and 13, the endoprosthesis 300 is mounted to the scapula 202 and the humerus 200. More specifically, the scapular fixation 302 is mounted to the scapula 202 and the humeral fixation 304 is inserted in the reamed medullary cavity 408. Screws 322 may be used to secure the arms 314 and 316 to the scapula, after which the drilling guide 430 is positioned on the endoprosthesis 300 and the humerus 200, as seen in FIG. 14, and the drill 708 is used to drill through the humerus 200 to reach the drilling apertures 432, after which the drilling guide 430 is removed and screws 322 are inserted in the stem apertures 332, through the humerus 200, to secure the endoprosthesis 300 to the humerus 200. Custom-made screws 322 are preferably used for the latter step. Typically, these screws 322 are a few millimetres longer than the diameter of the humerus portion through which they are inserted.

[00129] Finally, the muscles that were sectioned from the humerus originally are reattached to the endoprosthesis 300 using sutures 334. For example, referring to FIG. 15, the deep pectoral 216 is secured to the first muscle attachment zone 324, the superficial pectoral 218 and medial triceps 220 are secured to the second muscle attachment zone 326 and, referring to FIG. 16; finally the brachialis 219, triceps accessory 222 and the lateral triceps 224 are secured to the third muscle attachment zone 328. It should be noted that some of the sectioned muscle may be left unattached in some embodiments.

[00130] FIG. 17 illustrates an alternative endoprosthesis 500 similar to the endoprosthesis 300 and only the differences therewith are described herein. The endoprosthesis 500 includes an articulated bone replica. Therefore, the endoprosthesis 500 includes a bone replica scapular portion 506, typically formed integrally with the scapular fixation 502 and a bone replica humeral portion 507, typically formed integrally with the scapular fixation 504. The bone replica scapular and humeral portions 506 and 507 are articulated to each other, for example through a ball-and-socket joint allowing rotation in all planes, as illustrated in FIGS. 18 and 19. In alternative embodiment, movement along only one direction could be possible if a hinge joint is provided. [00131] For example, the ball-and-socket joint is formed as follows. The bone replica scapular portion 506 defines a scapular end surface 534, opposed to the arms 514 and 516 in which a scapular recess 536 is formed. The scapular recess 536 is sphere cap shaped. Two threaded apertures 538 are also formed in the scapular end surface 534. The remainder of the scapular end surface 534 is for example substantially planar, but other configurations are within the scope of the invention.

[00132] Complementarily, the bone replica humeral portion 507 defines a humeral end surface 540 shaped similarly to a portion of a sphere. A stem 542 extends from the humeral end surface 540 and is terminated by a head 544 shaped similarly to a sphere from which a cap has been removed. The radius of curvature of the head 544 is substantially similar to the radius of curvature of the scapular recess 536 and, when the endoprosthesis 500 is assembled, the head 544 abuts against the scapular recess 536 and may rotate thereinto. The head 544 is larger transversally than the transversal section of the stem 542, in some embodiments by having a larger diameter than the stem 542.

[00133] Retaining caps 546 and 548 are used to secure the head 544 in the scapular recess 536. The retaining caps 546 and 548 are configured to together define a stem receiving aperture 550, seen in FIG. 23, in which the stem 542 is received. The stem receiving aperture 550 is larger than the stem 542 so that the stem 542 may move thereinto to allow rotations of the bone replica scapular and humeral portions 506 and 507 relative to each other. The dimensions of the stem receiving aperture 550 limit the range of motion of the endoprosthesis 500.

[00134] More specifically, the retaining caps 546 and 548 are each secured to the bone replica scapular portion 506, for example through screws 552 each inserted in a respective cap aperture 553 extending through each of the retaining caps 546 and 548. The retaining caps 546 and 548 as shaped so that they conform to the shape of the scapular and humeral end surfaces 534 and 540 where they abut thereagainst. Also, the retaining caps 546 and 548 are also shaped to provide a large contact area where they abut, for example through planar surfaces. Finally, the retaining caps are shaped such that when they are secured to the bone replica scapular portion, the head 544 cannot be removed from the scapular recess. That is for example the case when the stem receiving aperture 550 defines a neck of a diameter smaller than the diameter of the head 544 at the junction between the stem 542 and the head 544.

[00135] More specifically, each of the caps 546 and 548 defines a humeral facing surface 554, facing the humeral end surface 540 and an opposed scapular facing surface 555, facing the scapular end surface 534. Each of the caps 546 and 548 also defines a cap facing surface 556, facing the cap facing surface 556 of the other cap 546 or 548. The cap facing surface 556 defines a recessed portion 558, so that the two recessed portions 558 together define the stem receiving aperture 550. In some embodiments, the above-mentioned surfaces merge into each other. In other embodiments, the caps 546 and 548 define an intermediate surface between the humeral and scapular facing surfaces 554 and 555.

[00136] In some embodiments, one or more polymer inserts 560 is (are) provided between the retaining caps 546 and 548 and the humeral end surface 540, and/or between the scapular recess 536 and the head 544. These polymer inserts 560 are typically relatively thin and selected to facilitate articulation of the endoprosthesis 500. [00137] FIGS. 20 to 22 illustrate various steps in the assembly of the endoprosthesis 500. In some embodiments, the endoprosthesis 500 is assembled after attachment to the humerus 200 and scapula 202. In other embodiments, the endoprosthesis 500 is assembled first and then secured to the humerus 200 and scapula 202.

[00138] As seen in FIG. 24, in some embodiments, the endoprosthesis 500 also defines a fourth muscle attachment zone 529 for attaching the supraspinatus 236 thereto. This fourth muscle attachment zone 529 is for example in prolongation of the first muscle attachment zone 526, so that is presents a surface that is generally parallel to the arms 514 and 516. Also, the infraspinatus 238 may be secured, through its tendon, to an interference screw 539 screwed in the endoprosthesis 500.

[00139] In some embodiments, as seen in the endoprosthesis 600 of FIG. 25, muscles may be directly attached to the endoprosthesis 600 and integrated to the endoprosthesis 600. The endoprosthesis 600 may be similar to the endoprostheses 300 and 500, except that the endoprosthesis 600 defines textured muscle attachment zones 624, 626 and 628. The muscle attachment zones 624, 626 and 628 are adjacent apertures, as in the prostheses 300 and 500, but also include a texture 603 that promotes integration and growth of reattached muscles so that these muscles can pull on the endoprosthesis 600.

[00140] For example, the muscle attachment zones 624, 626 and 628 are covered with a texture 603 having a unit cell 604, shown in FIG. 26. That is, the unit cell 604 is repeated over the whole texture volume 603. Many layers of unit cells are typically provided. The unit cell 604 may be repeated identically over the whole surface, or many different unit cells, for example of different dimensions, may be used. The unit cells 604 defines an open 3D structure through which muscles can grow after reattachment, so that eventually the muscles are attached permanently to the endoprosthesis 600 and integrated thereto, with the suture 334 no longer providing a structural role.

[00141] For example the unit cell 604 includes a pair of substantially orthogonal elongated wires 606 and 608 and a closed loop 610. The wires 606 and 608 of adjacent unit cells 604 are in prolongation of each other. The wires 606 and 608 are not rectilinear but consist of a plurality of segments that are angled relative to each other in a plane generally perpendicular to the surface that is covered by the texture 603, to form a zigzag pattern in 3D. The loop 610 may have any suitable shape, for example a generally square shape, with zigzagging edges. The loop 610 is for example centred relative to the intersection of the wires 606 and 608. In some embodiments, the wires 606 and 608 are shaped such that their intersection is raised above the surface of the remainder of the endoprosthesis 600, so as to create gap that will be colonized by the muscles.

[00142] The texture 603 can be manufactured separately from the remainder of the endoprosthesis 600 and then applied thereto, or the texture 603 can be manufactured through 3D printing along with the remainder of the prosthesis 600. In this later case, the loop 610 and the wires 606 and 608 extend integrally from each other. Using metal sintering or other similar 3D printing techniques, the texture 603 may be metallic. In some embodiments, the remainder of the endoprosthesis 600 had a substantially smooth surface outside of the muscle attachment zones 624, 626 and 628, but having other types of surface, depending on the specific application, is possible in alternative embodiments. [00143] In some embodiments, growth factors and other compositions promoting colonization by muscle cells of the texture 603 may be provided. For example, a membrane including growth factors, such as the Vetrix (TM) BioSIS (TM) membrane, a collagen matrix derived from porcine tissues, may be provided on the texture 603 before the muscles are superposed thereonto directly, followed by suturing. Other manners of providing growth factors, such as coating the texture 603 with growth factors when manufactured so that the growth factors are eluted after implantation, or applying a cream or gel incorporating the growth factors to the texture 603 prior to muscle attachment are also possible. In yet other embodiments, the texture 603 may be provided with stem cells that will promote attachment of the muscles thereto after differentiating into appropriate tissues, such as muscle or tendon tissue.

[00144] With reference to FIGS. 27 to 29, another manner of describing the texture 603 is to consider that the muscle attachment zone includes a tridimensional porous structure 700 including interconnected pores 702 configured to be colonized by the muscle after the muscle is reattached to the muscle attachment zone. Typically, the tridimensional porous structure 700 extends from an underlying continuous bulk surface 704 of the body, seen in FIG. 25.

[00145] In some embodiments, the tridimensional porous structure includes zigzagging struts 706. The struts 706 may be rectilinear and angled relative to each other, to zigzag, or the struts 706 themselves may include bends. Purely rectilinear struts 706 extending from each axially from each other are also usable in alternative embodiments. The struts 706 are interconnected to each other at nodes 708. In some embodiments, the nodes 708 form a tridimensional orthogonal grid, for example a cubic grid. Therefore, the structure seen in FIG. 27 would be seen similarly if the texture 700 is cut in the three orthogonal planes in which the pores are aligned with each other. However, the nodes 708 may also be distributed in any other suitable manner.

[00146] In a specific example of implementation, the tridimensional porous structure 700 has a porosity (fraction of volume that is empty) of between about 30 and about 80%, the nodes 708 are spaced apart centre-to centre from each other in a plane of the orthogonal grid by about 0.25 to 2.5 mm, and the struts 706 have a transversal cross-sectional area of about 0.05 to 1 mm². The struts have any suitable cross-sectional configuration, such as polygonal or cylindrical, among other possibilities.

[00147] It should be noted that while the muscle attachment zones 624, 626 and 628 have been described in the context of a joint sparing endoprothesis 600 for use in an thoracic limb of a dog, similar structures are usable in any orthopaedic implant for replacing bone tissues to which a muscle was attached, which include a body shaped to replace the bone tissues and provided with one or more muscles attachment zone configured and sized for reattaching one or more muscles thereto after the bone tissues are removed and the orthopaedic implant is implanted. Also, the texture of the muscle attachment zone is usable in other implants in which integration with muscle tissue is desired, even if the implant is not intended to replace a bone. Finally, the proposed texture is also usable in implants intended for osteointegration of colonization by tendon tissues, among other uses.

[00148] In use, muscle tissues are compressed against the muscle attachment zones 624, 626 and 628 and then colonized by the muscles to attach the muscles to the endoprosthesis 600 to allow the patient to move the latter, thereby restoring function to the member in which the endoprosthesis 600 is implanted. [00149] Although the present invention has been described hereinabove by way of exemplary embodiments thereof, it will be readily appreciated that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, the scope of the claims should not be limited by the exemplary embodiments, but should be given the broadest interpretation consistent with the description as a whole. The present invention can thus be modified without departing from the spirit and nature of the subject invention as defined in the appended claims.

Claims

WHAT IS CLAIMED IS:

1. An orthopaedic implant for replacing bone tissues to which a muscle was attached, comprising: a body shaped to replace the bone tissues, the body being provided with a muscle attachment zone configured and sized for reattaching the muscle thereto after the bone tissues are removed and the orthopaedic implant is implanted.

2. The orthopaedic implant as defined in claim 1 , wherein the muscle attachment zone includes a tridimensional porous structure including interconnected pores configured to be colonized by the muscle after the muscle is reattached to the muscle attachment zone.

3. The orthopaedic implant as defined in claim 2, wherein the tridimensional porous structure extends from an underlying continuous bulk surface of the body.

4. The orthopaedic implant as defined in claim 3, wherein the tridimensional porous structure includes zigzagging struts interconnected to each other at nodes.

5. The orthopaedic implant as defined in claim 4, wherein the nodes form a tridimensional orthogonal grid.

6. The orthopaedic implant as defined in claim 5, wherein the tridimensional porous structure has a porosity of between about 30% and about 80%.

7. The orthopaedic implant as defined in claim 5 or 6, wherein the nodes are spaced apart centre-to centre from each other in a plane of the orthogonal grid by a distance of from about .25 to about 2.5 mm, an wherein the struts have a transversal cross-sectional area of from about .05 to about 1 mm².

8. The orthopaedic implant as defined in any one of claims 2 to 7, wherein the implant is further provided with suture apertures extending through the body for receiving a suture usable to secure the muscles to the orthopaedic implant until the tridimensional porous structure is colonized.

9. The orthopaedic implant as defined in claim wherein the implant has a substantially smooth surface outside of the muscle attachment zones.

10. The orthopaedic implant as defined in any one of claims 1 to 9, wherein the implant is metallic.

11. The orthopaedic implant as defined in any one of claims 1 to 10, wherein the implant is articulated.

12. The orthopaedic implant as defined in any one of claims 1 to 10, wherein the implant is an endoprosthesis for replacing an excised proximal portion of a humerus to which muscles were attached, the humerus defining a medullary cavity, the endoprosthesis being securable to both a remaining portion of the humerus and a scapula, the scapula defining a scapular spine defining two side surfaces and terminated by an acromion, the endoprosthesis including:

-a scapular fixation securable to the scapula;

- a humeral fixation insertable in the medullary cavity; and

- a joint replica extending therebetween for replacing the excised proximal portion, the muscle attachment zone being provided in the joint replica.

13. The orthopaedic implant as defined in claim 12, wherein the joint replica includes a replica scapular portion and a replica humeral portion articulated to each other, the muscle attachment zone being provided in the humeral portion.

14. The orthopaedic implant as defined in claim 13, wherein the replica scapular portion is formed integrally with the scapular fixation and the replica humeral portion is formed integrally with the humeral fixation.

15. The orthopaedic implant as defined in claim 13 or 14, wherein the replica scapular portion and the replica humeral portion are articulated to each other through a ball-and-socket joint allowing rotation in all planes.

16. The orthopaedic implant as defined in any one of claims 12 to 15, wherein the scapular fixation includes a pair of arms securable to the scapula.

17. The orthopaedic implant as defined in claim 16, wherein the arms define an acromion receiving recess.

18. The orthopaedic implant as defined in any one of claims 1 to 17, wherein growth factors are provided at the muscle attachment zone

19. The orthopaedic implant as defined in claim 18, wherein the growth factors include a collagen matrix.

20. An endoprosthesis usable in a patient for replacing an excised proximal portion of a humerus to which muscles were attached, the humerus defining a medullary cavity, the endoprosthesis being securable to both a remaining portion of the humerus and a scapula, the scapula defining a scapular spine defining two side surfaces and terminated by an acromion, the endoprosthesis comprising:

-a scapular fixation securable to the scapula;

-a humeral fixation insertable in the medullary cavity; and a joint replica extending therebetween for replacing the excised proximal portion.

21. The endoprosthesis as defined in claim 20, wherein the scapular fixation is securable adjacent to or directly to the scapular spine.

22. The endoprosthesis as defined in claim 21 , wherein the scapular fixation includes two arms extending from the joint replica, the arms each defining an arm bone facing surface configured and sized to abut against and conform to a respective one of the side surfaces.

23. The endoprosthesis as defined in claim 22, wherein an acromion recess is defined at an origin of the two arms, the acromion recess being configured and sized for receiving the acromion thereinto.

24. The endoprosthesis as defined in claim 22 or 23, wherein the arms are substantially parallel to each other.

25. The endoprosthesis as defined in claim 24, wherein the arms each define mounting apertures extending therethrough for receiving fasteners thereinto to fasten the arms to the scapula.

26. The endoprosthesis as defined in claim 25, wherein each arm include from 4 to 12 mounting apertures.

27. The endoprosthesis as defined in claim 25 or 26, wherein the mounting apertures are substantially perpendicular to the arm bone facing surface.

28. The endoprosthesis as defined in any one of claims 22 to 27, wherein the bone facing surfaces of each arm are substantially perpendicular to each other.

29. The endoprosthesis as defined in any one of claims 22 to 28, wherein the arms define chamfered free ends.

30. The endoprosthesis as defined in any one of claims 20 to 29, wherein the joint replica is substantially elongated and the humeral fixation includes a stem extending coaxially with the joint replica.

31. The endoprosthesis as defined in claim 30, wherein the stem is provided with stem apertures extending laterally therethrough.

32. The endoprosthesis as defined in any one of claims claim 20 to 31 , wherein the joint replica defines a muscle attachment zone configured and sized for reattaching thereto at least one of the muscles.

33. The endoprosthesis as defined in claim 32, wherein the muscle attachment zones is provided with suture apertures through which a suture may be inserted to secure the at least one of the muscles to the endoprosthesis.

34. The endoprosthesis as defined in claim 32 or 33, wherein the muscle attachment zone is as defined in any one of claims 1 to 19.

35. The endoprosthesis as defined in claim 32, 33 or 34, wherein, when the endoprosthesis is in use, the muscle attachment zone is located at a position substantially similar or adjacent to an insertion of the at least one of the muscles muscle prior to excision.

36. The endoprosthesis as defined in any one of claims 32 to 35, wherein the muscle attachment zone is configured and located for attaching thereto a deep pectoral.

37. The endoprosthesis as defined in claim 36, wherein the muscle attachment zone is provided substantially opposed to the arms on the joint replica, with part of the muscle attachment zone being generally in axial alignment with the arms, so that once the prosthesis is implanted in the patient, the muscle attachment zone faces laterally outwardly relative to the patient.

38. The endoprosthesis as defined in any one of claims 32 to 35, wherein the muscle attachment zone is configured and located for attaching thereto at least one of a superficial pectoral and a medial triceps.

39. The endoprosthesis as defined in claim 38, wherein the muscle attachment zone is configured and located for attaching thereto the superficial pectoral and the medial triceps.

40. The endoprosthesis as defined in claim 39, wherein the muscle attachment zone is provided adjacent the humeral fixation, so that once the prosthesis is implanted in the patient, the muscle attachment zone faces laterally outwardly relative to a patient.

41. The endoprosthesis as defined in any one of claims 32 to 35, wherein the muscle attachment zone is configured and located for attaching thereto at least one of a brachialis, a triceps accessory and a lateral triceps.

42. The endoprosthesis as defined in claim 41 , wherein the muscle attachment zone is configured and located for attaching thereto the brachialis, the triceps accessory and the lateral triceps.

43. The endoprosthesis as defined in claim 42, wherein the muscle attachment zone is adjacent the arms, opposed to a region of the joint replica substantially longitudinally opposed to the arms on the joint replica, so that once the prosthesis is implanted in the patient, the muscle attachment zone faces laterally inwardly relative to a patient.

44. The endoprosthesis as defined in any one of claims 32 to 35, wherein the muscle attachment zone is configured and located for attaching thereto a supraspinatus.

45. The endoprosthesis as defined in claim 44, wherein the muscle attachment zone is adjacent the arms, substantially parallel thereto.

46. The endoprosthesis as defined in any one of claims 20 to 45, wherein the endoprosthesis is made of a single integrally extending piece of material.

47. The endoprosthesis as defined in any one of claims 20 to 45, wherein the joint replica is articulated.

48. The endoprosthesis as defined in claim 47, wherein the joint replica includes a replica scapular portion and a replica humeral portion articulated to each other.

49. The endoprosthesis as defined in claim 48, wherein the replica scapular portion is formed integrally with the scapular fixation and the replica humeral portion is formed integrally with the humeral fixation.

50. The endoprosthesis as defined in claim 48 or 49, wherein the replica scapular portion and the replica humeral portion are articulated to each other through a ball- and-socket joint allowing rotation in all planes.

51. The endoprosthesis as defined in claim 50, wherein

- the replica scapular portion defines a scapular end surface opposed to the scapular fixation in which a sphere cap shaped scapular recess is formed;

- the replica humeral portion defines a humeral end surface opposed to the medullar fixation;

- a stem terminated by a head extends from the humeral end surface, the head defining a head distal surface shaped like a portion of an outer surface of a sphere and having a radius of curvature substantially similar that of the scapular recess; -the head abuts against the scapular recess and is rotatable relative thereto.

52. The endoprosthesis as defined in claim 51 , wherein the head has a larger diameter than a transversal section of the stem.

53. The endoprosthesis as defined in claim 52, further comprising a pair of retaining cap positioned between the humeral end surface and the scapular end surface and shaped so to conform to the shape of the humeral and scapular end surfaces, the retaining caps defining a stem receiving aperture receiving the stem thereinto so that the stem is movable in the stem receiving aperture to articulate the joint replica, the stem receiving aperture defining a neck of a diameter smaller than a diameter of the head adjacent the head.

54. The endoprosthesis as defined in claim 53, further comprising a polymer insert between the retaining caps and the humeral end surface.

55. The endoprosthesis as defined in claim 53, further comprising a polymer insert between the scapular recess and the head.

56. The endoprosthesis as defined in claim 53, 54 or 55, wherein the retaining caps are secured to the humeral end surface.

57. A kit for implanting an endoprosthesis to replace an excised proximal portion of a humerus having a medullary cavity, comprising:

-an endoprosthesis as defined in any one of claims 20 to 56;

-a cutting guide to guide a cut made to excise the proximal portion of the humerus; -a reaming guide to guide reaming of the medullary cavity after excision of the proximal portion of the humerus;

-a drilling guide to guide drilling of lateral apertures through a remaining distal portion of the humerus.

58. A method of using an orthopaedic implant to replace excised bone tissues in a patient, the bone tissues having one or more muscles attached thereto prior to excision, the orthopaedic implant including one or more muscle attachment zones provided with a porous textured surface, the method comprising:

-sectioning the one or more muscles;

-excising the excised bone tissues;

-positioning the orthopaedic implant at a position substantially similar to the position of the excised bone tissues prior to excision; and

-securing at least some of the one or more muscles to the one or more muscle attachment zones so that the muscles are in register with the porous textured surface.

59. The method as defined in claim 58, further comprising colonizing the porous textured surface with the muscles.

60. The method as defined in claim 58 or 59 further comprising providing muscle growth factors at the textured porous surface.

61. The method as defined in claim 59, wherein the muscles are secured with a suture to secure the muscles prior to completion of colonization. A prosthesis, comprising: a scapular fixation for attaching to the scapula, a humeral fixation insertable in the medullary cavity of a distal portion of the humerus after the proximal portion thereof has been excised, and a joint replica extending therebetween.

62. An implant usable adjacent muscle tissues, comprising: a body, the body being provided with a muscle attachment zone configured and sized for attaching the muscle tissues thereto, the muscle attachment zone including a tridimensional porous structure including interconnected pores configured to be colonized by the muscle tissues after the muscle tissues are abutted thereagainst.