Patent Application
20110166661
The present invention relates to an inverted or an anatomical shoulder prosthesis including a graft to lateralize a glenoid component of the shoulder prosthesis.
Total shoulder prostheses, are commonly said to be inverted when they comprise, on the one hand, a glenoid part integral with the glenoid surface of a scapula of a patient's shoulder and delimiting a convex articular surface and, on the other hand, a humeral part integral with the humerus of the shoulder and delimiting a concave articular surface, the cooperation of these articular surfaces allowing an articulated connection to be reproduced at the shoulder. With this type of prosthesis, it is common, during adduction movement of the shoulder, for the lower portion of the humeral prosthetic part to strike the pillar of the scapula, i.e. the lower portion of the bone glenoid surface located, when the patient stands upright, just below the glenoid prosthetic part. This interference between the humeral prosthetic part and the scapula limits the range of the adduction movement and may cause pain to the patient or even lead to the prosthesis becoming dislodged, in particular by osteolysis of the scapula.
Various aspects of the invention relate to surgical methods and corresponding surgical instruments for reducing risk of interference between the scapula and the humeral part of an inverted or an anatomical shoulder prosthesis. All references to a “shoulder prosthesis” should be interpreted to include a total shoulder prosthesis with a humeral component and a glenoid component (including anatomical, inverted, or interpositional configurations), or a partial shoulder prosthesis with a glenoid component with an anatomical or resurface humeral head.
Some embodiments relate to a surgical method for fitting an inverted shoulder prosthesis, the prosthesis including a glenoid component having a convex articular surface and an opposing face, this fitting method including successive preoperative steps in which a graft is provided, the graft is placed on the previously prepared glenoid surface of a scapula of a patient's shoulder, and the glenoid component is implanted so as to cover the graft positioned on the glenoid surface with the opposing face of the glenoid component and to anchor the glenoid component in the glenoid surface through the graft. In some embodiments, a geometric center of articulation of the glenoid component is situated at the bone face in the glenoid surface, where a radius of curvature of a convex articular surface of the glenoid component is selected so a center of rotation of the glenoid component is in or behind a plane comprising a distal surface of the graft.
In some embodiments, the method includes “lateralizing” the glenoid component relative to the patient's scapula, withdrawing the glenoid component from the patient's scapula in a plane frontal to the patient, by interposing the graft between this glenoid component and the glenoid surface. In other words, the graft forms an outer lateral extension of the glenoid surface, extending the scapula, whereas the combination of the graft and the prosthetic glenoid component forms a composite prosthetic unit. The glenoid component is optionally implanted so as to cover a side of the graft opposing the glenoid surface, where the component includes a bone anchoring structure or anchor portion, such as a central tail, sufficiently elongate to pass through the graft and in the bone of the scapula delimiting the glenoid surface. According to some embodiments, once the graft has fused with the glenoid surface, a distal surface of the graft becomes the effective glenoid surface. References to glenoid surface should be interpreted to include a prepared or an unprepared exposed surface of a glenoid cavity.
In some embodiments, an articular face of the glenoid component occupies, relative to the scapula, a position laterally more remote than a position the articular face would occupy were the graft omitted. Removing the glenoid component laterally helps reduce risk of interference between the pillar of the scapula and the lower portion of the humeral prosthetic part cooperating with the glenoid articular face. The lateralization of the prosthetic glenoid component also helps increase tension in the rotator muscles of the shoulder and the co-adaptation vector of the deltoid muscle, which helps stabilize the prosthetic glenoid and humeral components and promote better mobility in relative rotation with a lower risk of shoulder dislocation. Furthermore, compared to typical inverted shoulder prostheses, which can be described as a medialized prostheses, lateralized prostheses according to various embodiments help restore some of the curved surface of the patient's shoulder, giving the shoulder a more pleasing appearance than the “coat hanger” appearance conferred by medialized prostheses.
Some embodiments relate to glenoid components that include adjustable length tails, or anchoring structures for use with grafts having a variety of thicknesses, according to embodiments of the present invention. For example, in some embodiments, a surgeon or other user selects a desired bone graft thickness and adjusts the overall length of an anchoring portion of the glenoid component for use with that graft thickness. By adjusting the overall length of the anchoring structures, the glenoid components are better able to facilitate lateralization of the center of rotation of the glenoid component with a secure affixation into the boney structure forming the glenoid, for example, as well as additional or alternative advantages.
According to various embodiments, complete exposure of the glenoid surface is not required and is optionally limited to positioning of the graft, promoting efficiency and reproducibility. The graft is optionally taken from the patient, although allografts, xenografts, metals, natural or synthetic materials are employed as desired. In some embodiments, the graft is taken from the upper epiphysis of the humerus of the patient's shoulder, such that the graft originates from the patient, thereby helping to limit risk of rejection, poor biological compatibility, and transmission of disease or infection, for example. Moreover, efficiencies are realized in that often times in order to implant a corresponding humeral component, the epiphysis of the patient's humerus is to be prepared by withdrawing a substantial amount of cancellous bone matter from this epiphysis which can then be used to provide the graft rather than, for example, simply discarding such bone matter. Accordingly, in some embodiments, the method includes a shaping step in which the bone matter forming the upper humeral epiphysis is shaped into a one-piece volume extending in length about an axis inclined relative to the longitudinal direction of the humerus, and a cutting step in which the volume of bone matter is removed from the humerus by cutting the humeral epiphysis transversely to the axis of this volume, the volume of bone matter thus removed forming the graft.
According to some methods, a surgical joint repair includes adjusting a length of the graft along an axis of a volume of bone matter and shaping respective longitudinal end faces of the graft to be substantially complementary to an opposing face of the glenoid component and the glenoid surface previously prepared. During the shaping step, the shaped volume of bone matter is chosen from a cylinder and a frustum of a cone, for example, centered on the axis of the shaped volume of bone matter. Before or during the shaping step, the end of the upper humeral epiphysis is resected as desired, for example, over a first plane. During the cutting step, the humeral epiphysis is optionally cut over a second plane, the first and second planes being transverse to the axis of the shaped volume of bone matter. A relative inclination of the first and second planes is adjusted as desired. During or after the shaping step, a recess is optionally formed that is centered on the axis of the volume of bone matter in the humeral epiphysis. In some embodiments, the glenoid component is anchored in the glenoid surface through the recess and, before carrying out the shaping step, a marker pin is inserted into the humeral epiphysis, thereby allowing, during the shaping step, positioning of the axis of the volume of bone matter relative to the humerus.
According to some other embodiments, rather than taking the graft from the patient's humeral epiphysis, the graft is taken from a bone region in the patient other than the upper humeral epiphysis, such as the patient's ilium, or the graft is formed as an allograft, a graft of synthetic origin, a graft of metallic origin, combinations thereof, or other material. For example, in some embodiments a protection layer is attached to at least a part of the graft that is not in contact with the glenoid surface and at least a part of the opposing face of the glenoid component is supported on the protection layer. In some embodiments, some or all of the surfaces on the glenoid component that engage with the graft are covered with hydroxyapatite or materials having a functionally similar surface state, such as a honeycomb surface state, allowing bone adhesion and rehabilitation to be improved. Selected surfaces of the glenoid component may be constructed of materials that facilitate fusion with bone, such as those disclosed in U.S. Pat. No. 7,250,550.
According to still other embodiments, the graft includes a purée of bone substance (e.g, originating from the patient, in such as from the upper epiphysis of the humerus, or from another, source, such as a synthetic or metallic source). In some embodiments, the purée of bone substance is advantageously used with a protective structure, such as a lattice shaped into a cage that is filled with the purée. The lattice cage optionally facilitates good exchange of biological flows between the purée forming the graft and the surrounding tissues of the shoulder.
The invention also relates to a set of surgical instruments for fitting a shoulder prosthesis. The set includes a shaping ancillary instrument that shapes the bone matter forming the upper humeral epiphysis of a humerus into a one-piece volume extending in length about an axis inclined relative to the longitudinal direction of the humerus, and a cutting ancillary instrument that cuts the humeral epiphysis shaped by the shaping ancillary instrument, for cutting the volume of bone matter transversely to the axis of this volume. The cutting ancillary instrument is optionally used to remove the volume of bone matter from the humerus that is formed into a graft.
The set of instruments according to the invention allows implementation of the fitting method defined hereinbefore, the shaping and cutting steps of which are respectively carried out by the shaping and cutting ancillary instrument. The volume of bone matter removed from the humerus using the cutting ancillary instrument can thus be used as the bone graft for carrying out the general fitting method defined hereinbefore in order laterally to offset the convex articular surface of a glenoid component of the prosthesis relative to the scapula of the patient's shoulder, during implantation of this glenoid component.
According to advantageous features of this set of instruments, taken in isolation or in any technically feasible combination:
the set comprises a resecting instrument for resecting the end of the humeral epiphysis, which resecting instrument is either carried by a specific resection ancillary instrument, distinct from the other ancillary instrument of the set or integrated in the shaping ancillary instrument;
the resecting instrument comprises a planar reamer so as to resect the humeral epiphysis over a first plane transverse to the axis of the volume of bone matter;
the set comprises a humeral epiphysis drilling instrument which is adapted to form a recess, centered on the axis of the volume of bone matter, in the humeral epiphysis and which is either integrated in the shaping ancillary instrument, or the resection ancillary instrument, or is carried by a specific drilling ancillary instrument distinct from the other ancillary instrument of the set;
the set comprises a marker pin or a similar marker instrument capable of being inserted into the humeral epiphysis and suitable for guiding the shaping ancillary instrument and optionally at least one of the other ancillary instrument of the set;
the set comprises an inserting ancillary instrument for inserting the marker pin into the humeral epiphysis, which inserting instrument is suitable for adjusting the direction of insertion of this pin relative to the humerus;
the inserting ancillary instrument comprises, on the one hand, a rounded bell-shaped body configured internally to cover the upper humeral epiphysis in the manner of a cap and, on the other hand, a guide for applying the marker pin, which guide opens into the body;
the shaping ancillary instrument comprises a bell-shaped saw which is suitable for cutting the bone matter forming the humeral epiphysis by shaping it into the volume of bone matter;
the saw has an optionally perforated cylindrical or frustoconical inner face so as to provide the volume of bone matter with the overall shape of a cylinder or frustum of a cone, centered on the axis of this volume;
the cutting ancillary instrument comprises a tubular block suitable for being slipped about the volume of bone mass shaped by the shaping ancillary instrument, this block delimiting, at its longitudinal end turned during operation toward the humerus, an incision zone in the humeral epiphysis, in order to cut the volume of bone matter transversely to the axis thereof;
the incision zone forms a transverse slot for the passage of a saw blade or the like, in order to cut the volume of bone matter over a second plane transverse to the axis of this volume; and
the cutting ancillary instrument comprises an annular body adapted to be mounted around the humeral epiphysis while surrounding at least the volume of bone matter shaped by the shaping ancillary instrument, this body delimiting a guide surface for a cutting instrument to cut at least the volume of bone matter transversely to its axis.
The invention also relates to an inverted shoulder prosthesis comprising a glenoid component having a convex articular surface and an opposing face, wherein the prosthesis comprises a protection layer for protecting a graft interposed, when the prosthesis is fitted, between said opposing face and the glenoid surface of a scapula of a patient's shoulder, this protection layer being suitable for both covering at least a part of the graft that is not in contact with the glenoid surface and forming a support for at least a part of said opposing face.
The graft protected by the protection layer of the prosthesis according to the invention can be taken from the upper humeral epiphysis using the set of instruments defined hereinbefore, or else be chosen from a graft taken from a bone region in the patient other than the upper humeral epiphysis, in particular from the patient's ilium, an allograft and a graft of synthetic or metallic origin. In practice, this prosthesis is fitted in accordance with the general method defined hereinbefore.
According to advantageous features of this prosthesis, the prosthesis optionally includes a protection layer, such as for example, a layer of hydroxyapatite or other material that has a functionally similar surface state, such as a honeycomb surface state, allowing bone adhesion and rehabilitation to be improved. In another embodiment, the protection layer includes a shape of a ring suitable for surrounding, in a close-fitting manner, the portion of the bone graft not in contact with the glenoid surface, it being appreciated that, in practice, this ring is used for a one-piece graft obtained, in particular, by the set of instruments as defined hereinbefore. The protection layer may also be a lattice shaped as a cage adapted to be filled with a purée of bone matter forming the graft.
A better understanding of the invention will be facilitated on reading the following description given merely by way of example and with reference to the drawings, in which:
The glenoid component 10 comprises a head 11, also described as a head structure, which has, on the side opposing the glenoid surface G of the scapula S, a convex articular surface 11A, also described as a face, of generally hemispherical shape and, on the side turned toward the glenoid surface, an opposing face 11B. In the example considered in the figures, this face 11B is generally planar but, in non-illustrated variations, this face 11B can have a more elaborate geometry, being, for example, substantially concave or convex.
The glenoid component 10 also comprises an anchoring tail 12, also described as an anchor portion, which extends transversely so as to protrude from the face 11B, in the direction opposing the face 11A, and the free end part of which is securely anchored in the glenoid surface G, thus joining the glenoid component to the scapula S. In practice, in a manner not shown, the anchoring tail 12 can be provided, at its end turned toward the head 11, with a base accommodated inside the head 11, being securely joined thereto. In other words, more generally, the connection between the tail 12 and the head 11 can assume a broad range of forms, such as material continuity, respective wedging surfaces, attached mechanical assembly structures, etc. Also by way of non-illustrated variation, the tail 12 can be externally threaded or, generally, have a surface state promoting the anchoring thereof.
Between the face 11B of the glenoid head 11 and the glenoid surface G of the scapula S there is interposed a graft 2 having a substantially cylindrical outer shape with a circular base, the external diameter of which is substantially equal to that of the head 11. The outer lateral face 2A of the graft 2 thus extends substantially in the extension of the hemispherical face 11A. The graft 2 has, on its side opposing the glenoid surface G, a longitudinal end face or distal surface 2B covered by the face 11B of the head 11 and, on its side directed toward the glenoid surface, a longitudinal end face or medial surface 2C resting against the glenoid surface G. Once the graft 2 fuses with the glenoid surface G, the effective glenoid surface G is displaced laterally outward to the distal surface 2B of the graft 2.
In the example considered in the figures, the longitudinal end faces 2B and 2C are planar; this has proven to be an embodiment that is simple to handle and easy to obtain, as will be referred to hereinafter. However, in practice, these faces 2B and 2C can have more elaborate geometries: on one side, the face 2B is provided to be covered in a substantially complementary manner with the face 11B of the head 11, including in this face 11B the zones or the structure for connecting to the tail 12, it being understood that, as indicated hereinbefore, this face 11B can be generally concave, convex or planar; on the opposing side, the face 2C is provided to embrace the surface of the glenoid surface G, which has been previously prepared for this purpose, so that the face 2C and the glenoid surface G are substantially complementary and can equally well be planar or curved.
The graft 2 can be a one-piece bone graft, a plurality of random or pre-formed bone pieces, one or more layers of bone material, a purée of bone substance, or combinations thereof. In addition to the patient's bone, the graft 2 can also be formed from an allograft, a xenograft, a synthetic material, a porous metal or a combination thereof. The graft 2 can optionally be resorbable. The graft 2 may be used alone or in combination with bone replacements, bone fillers, bone cements and/or bone adhesives. Various bone replacements, bone fillers, bone cements and bone adhesives are disclosed in U.S. Pat. No. 6,692,563 (Zimmerman), which is hereby incorporated by reference. Various additives can be included in the graft 2, such as for example, bone growth agents or pain inhibitors. In one embodiment, reinforcing fibers are added to the purée of bone substance.
In some embodiments, the graft is formed of materials into which native bone will grow to create a structure with properties comparable to native bone, such as for example, a three-dimensional porous matrix or scaffold. Examples of a porous matrix or scaffold include a reticulated bioceramic framework, structured porous tantalum, synthetic fiber mesh, and the like. Various porous matrices and scaffoldings are disclosed in U.S. Pat. Nos. 4,479,271; 6,511,511; 6,605,117; 6,797,006; 6,902,584; and 7,250,550, which are hereby incorporated by reference.
The graft 2 can be made from a variety of synthetic compounds, such as for example, polyglycolide, polylactides, polycaprolactones, polytrimethylenecarbonates, polyhydroxybutyrates, polyhydroxyvalerates, polydioxanones, polyorthoesters, polycarbonates, polytyrosinecarbonates, polyorthocarbonates, polyalkylene oxalates, polyalkylene succinates, poly(malic acid), poly(maleic anhydride), polypeptides, polydepsipeptides, polyvinylalcohol, polyesteramides, polyamides, polyanhydrides, polyurethanes, polyphosphazenes, polycyanoacrylates, polyfumarates, poly(amino acids), modified polysaccharides (e.g., cellulose, starch, dextran, chitin, chitosan, etc.), modified proteins (e.g., collagen, casein, fibrin, etc.) and their copolymers, or combinations thereof. Other polymers include polyglycolide, poly(L-lactide-co-glycolide), poly(D,L-lactide-co-glycolide), poly(L-lactide), poly(D,L-lactide), poly(L-lactide-co-D,L-lactide), polycaprolactone, poly(L-lactide-co-caprolactone), poly(D,L-lactide-co-caprolactone) polytrimethylenecarbonate, poly(L-lactide-co-trimethylenecarbonate), poly(D,L-lactide-co-trimethylen-ecarbonate), polydioxanone and copolymers, and polymer blends thereof. Various methods of manufacturing the bone graft from a synthetic compound can be found in U.S. Pat. Nos. 6,767,928; 6,730,252; 6,541,022; 6,454,811, which are hereby incorporated by reference. Optionally, before or during the surgical procedure the graft 2 can be secured to the glenoid component 10 using additional methods known in the art, such as for example biocompatible adhesives, mechanical fasteners, or combinations thereof.
The graft 2 can be made from a variety of metallic solutions, such as for example, a highly porous metal having interconnecting pores. In one embodiment, the porous metal is about 80% porous. The metal has a porosity giving it a mechanical and physical structure similar to that of bone such that bone ingrowth is promoted. The highly porous metal used to form the graft 2 has a high strength-to-weight ratio and low stiffness and is capable of withstanding physiologic loading and minimizing stress. The porous metal may have, for example, a trabecular configuration. In one embodiment, the porous metal may include growth factors to further stimulate bone ingrowth. An example of a suitable graft is one formed from tantalum and vapour deposition techniquies. An example of a suitable commercially available porous metal includes but is not limited to, “TRABECULAR METAL,” available from Zimmer Technology, Warsaw, Ind.
In some embodiments, the tail 12 passes straight through the graft 2, in the longitudinal direction thereof. In other words, the length of the tail 12 is much greater than that of the graft 2, so that at least a substantial part of the tail 12 is anchored securely in the native layer of the glenoid surface G. As described in greater detail, in some embodiments the overall length of the tail 12 is adjustable to accommodate a variety of thicknesses of the graft 2 and/or geometry of the glenoid surface G.
In optional embodiments (not shown), the securing of the graft 2 to the glenoid surface G can be reinforced by fasteners additional to the tail 12, such as screws distributed around the tail 12 and passing through the graft 2 over at least part of the length thereof.
The humeral component 20 comprises a tail 21 for anchoring in the medullary cavity M of the humerus H. At its upper end, the tail 21 is provided with a head 22, also described as a humeral head, having, on its side opposing the tail 21, a concave articular face 22A in the form of a portion of a sphere, the radius of which is substantially equal to that of the face 11A. References to a humeral head should be interpreted to include a prepared or an unprepared natural humeral head as well as synthetic, or prosthetic humeral heads. When the prosthesis 1 is implanted, as shown in
Given the presence of the graft 2, the face 11A is remote from the resected surface of the glenoid surface G in the sense that, if the graft 2 were omitted, the face 11A would be directly juxtaposed with the resected surface of the glenoid surface. Thus, on account of the graft 2, the glenoid articular face 11A and, accordingly, the humeral articular face 22A are laterally remote from the glenoid surface G, limiting the risk of the lower portion of the head 22 interfering with the bottom of the glenoid surface G, (e.g., with the pillar P of the scapula S). Thus, lateralization of the prosthesis 1 can be adjusted and modified based on the thickness of the graft 2. As the thickness of the graft 2 increases, the amount of lateralization also increases. In addition, it will be understood that, as a consequence resulting from this lateralization desired within the scope of the invention, the graft 2 acts as bone matter to make good any bone deficit in the glenoid surface.
In practice, the glenoid component 10 can be of a broad range of sizes, to which the graft 2 is adapted. Typically, the head 11 is available in at least two different sizes, namely with an external diameter of about 36 mm or about 42 mm, it being understood that other sizes are conceivable. Similarly, the length l of the graft 2 can have a broad range of values, distributed in practice in a uniform sequence, in a manner adapted to the morphology and/or to the pathology of the patient. The graft 2 can thus have lengths of about 3, 6, 8 or 10 mm, whereas the tail 12 has a length of between about 15 and about 25 mm, possibly greater.
A surgical method seeking to implant the shoulder prosthesis 1 of
In its common part, the shaft 31 is secured, in particular detachably, to a body 32 in the shape of an upwardly rounded bell. The body 32 is generally arranged transversely to the shaft 31, extending in length about a central geometrical axis 33. Projected in a plane mediolateral to the patient and containing the longitudinal axis of the shaft 31, as shown in
The body 32 has on its inside a concave surface 34, of which the main center of curvature and the peak pertain substantially to the central geometrical axis 33. The concave surface 34 is provided to reproduce approximately the surface features of the upper epiphysis of a normal anatomical humerus, it being understood that, in practice, the surgeon has a range of a plurality of homothetic ancillary instruments 30, the bodies 32 of which have respective dimensions associated with the size and the state of the patient's bones. On its outer face, the body 32 is provided with a protruding tube 35 centered on the central geometrical axis 33 and opening into the interior of the body 32, on its inner surface 34.
The shaft 31 is inserted into the medullary cavity M of the humerus H until contact is established between the inner surface 34 and the humeral epiphysis E, the body 32 then covering the epiphysis E in the manner of a cap. Then, advantageously, the shaft 31 is driven in rotation about itself, over a short course, in order to allow for the retroversion of the humerus H. In a manner known to those of skill in the art, the shaft 31 is provided, in its proximal end part, with diametral through-orifices 36 angularly offset from one another about the longitudinal axis of the shaft 31 and, as a function of the retroversion of the patient determined by the surgeon, an elongate rod (not shown) is introduced into one of these orifices in order effectively to display the retained direction of retroversion, so that the shaft 31 is rotated on itself until this retroversion rod is aligned with the patient's forearm.
A guide pin 40, at the pointed distal end 41, is then introduced into the tube 35, from the free end thereof, and is inserted into the humeral epiphysis E over a substantial depth, as indicated by arrow 42 in
Once the guide pin 40 has reached an insertion depth in, or even through, the humerus H sufficient securely to anchor it, the ancillary instrument 30 is withdrawn, without removing the guide pin 40. The humerus H is then in the state illustrated by solid lines in
In a variation, when carrying out the first stage of the operation, the guide pin 40 is inserted in the humerus H without being guided, i.e. without using the ancillary instrument 30.
In a second stage, the surgeon will resect the end of the humeral epiphysis E using an ancillary instrument 50 illustrated in
The surgeon threads the ancillary instrument 50 around the guide pin 40 by introducing it by the terminal drill 53 thereof, as indicated by arrow 54 in
In a third stage, once the ancillary instrument 50 has been removed from the guide pin 40, the surgeon will cut the humeral epiphysis E in a manner centered on the guide pin 40, i.e. he will shape the bone matter forming this epiphysis E into a cylinder E3 having a center axis EX-X corresponding to the axis 33, as illustrated in
The rod 61 of the ancillary instrument 60 is slipped around the guide pin 40, which is left in place in the humeral epiphysis E, until its distal end is received in a complementary manner in the recess E1. In doing this, the saw 62 gradually cuts out the bone matter from the epiphysis E so as to obtain the bone cylinder E3, it being noted that a corresponding part of the recess E1 passes through the entire length of said bone cylinder. The length of the cylinder E3 thus obtained, i.e. its dimension along its axis EX-X, is determined by the depth of action of the saw 62, wherein this depth can easily be marked along the rod 61, in particular by markings.
Once the ancillary instrument 60 has been removed, the humerus H is in the state illustrated in
In a fourth stage, the surgeon will remove the cylinder of bone matter E3 from the humerus H using a cutting ancillary instrument 70 illustrated in
After having removed the guide pin 40, the ancillary instrument 70 is slipped around the humeral cylinder E3, as indicated by arrow 76 in
Once the ancillary instrument 70 has been removed, the surgeon recovers the cylinder of bone matter E3 thus separated from the humerus H.
In a non-illustrated variation, the slot 73 can be provided so as to be inclined relative to the longitudinal direction of the block 71 so that, in contrast to the cylinder E3 described hereinbefore, the bone cylinder thus obtained has longitudinal end faces inclined relative to one another. The graft 2 is thus able to make good the wear to a peripheral portion of the glenoid surface G, it being noted that the inclination of the slot 73 is advantageously adjustable as a function of the wear noted by the surgeon during the operation.
Before describing the following stage of the operation, namely the fifth stage,
Thus,
The ancillary instrument 130 allows the guide pin 40 to be inserted in the humeral epiphysis E so as to be close-fitted relative to the humerus H, as indicated by the arrow 142 in
As a variation of both the ancillary instrument 50 and the ancillary instrument 60 shown in
Hence, when the ancillary instrument 160 is slipped round the guide pin 40, the teeth 163 of the saw 162 gradually cut out the bone matter of the humeral epiphysis E so as to obtain the bone cylinder E3. Once the entire height of the saw 162 has thus been introduced into the epiphysis, the reamer 166 begins to cut the upper end of this epiphysis and thus progressively resects this end until the cutting plane E2 is obtained.
Once the ancillary instrument 160 has been released, the humerus H is in the state shown in
The surgeon then uses a drilling ancillary instrument 167 comprising a bored shaft 168 of which the distal end is provided with a drill 153. By slipping the shaft 168 around the guide pin 40, as indicated by the arrow 169 in
In practice, the drilling ancillary instrument 167 can also be used after a variation of the ancillary instrument 50, depleted of the drill 53, has been used and/or after a variation of the ancillary instrument 60, of which the rod 61 does not project on the distal side of the base wall of the saw 62 has been used.
As a variation of the ancillary instrument 70 shown in
Hence, by manipulating the shaft 176, the surgeon positions the annular body 171 around the humeral epiphysis E so as to position the guide surface 173 in a suitable manner relative to the cylinder of bone matter E3. The surgeon then applies the cutting instrument against this surface 173 in a guided manner in order to cut the base of the cylinder E3 over the cutting plane E4 and release this cylinder from the humerus H.
Advantageously, the guide surface 173 forms an angle of approximately 155 degrees with the longitudinal direction of the shaft 176, and this allows the ancillary instrument 170 also to be used to prepare the implantation of the humeral component 20 at a later stage, by positioning the shaft 176 in such a way that its longitudinal direction is substantially aligned with the longitudinal direction of the humerus H, as illustrated in
In a fifth stage, the cylinder of bone matter E3 is used to form the graft 2 described hereinbefore. In order to do this, this cylinder is fitted on the glenoid surface G. The glenoid surface G is previously prepared for this purpose, being opened up and, if necessary, resected. The glenoid component 10 is then implanted in the configuration described hereinbefore with reference to
If the longitudinal end faces of the bone cylinder have been formed so as to be inclined relative to each other, it will be understood that the interposing of this cylinder, as the graft, between the glenoid component 10 and the glenoid surface G allows inclination, in particular downward inclination, of the glenoid articular face 11A.
More generally, it will be understood that the dimensions desired by the surgeon for the graft 2, in particular as a function of the size of the glenoid component 10, determine the dimensions of the ancillary instruments 50, 60 and 70 or the ancillary instruments 160, 168 and 170 used to take the bone cylinder E3 from the humeral epiphysis E. In particular, the internal diameter of the saw 62 or 162 determines the external diameter of the graft 2. Similarly, the depth of action of this saw determines the length/of the graft while at the same time allowing for any adjustment in length resulting from the positioning of the sawing slot 73 or the guide surface 173.
Furthermore, the geometry desired for the longitudinal end faces 2B and 2C of the graft 2 directly conditions the embodiment of the resection ancillary instrument 50 and cutting ancillary instrument 70 or the ancillary instrument 160 and 170, in the sense that the parts of these ancillary instruments that determine the incision profile of the bone are shaped to form an appropriate incision in the humeral epiphysis. Optionally, these ancillary instruments 50 and 70 can be associated with one or more ancillary instrument for resurfacing the longitudinal end faces of the removed cylinder E3.
In practice, the surgeon also takes account of the state of the cancellous bone matter forming the epiphysis E in order, if necessary, to remove the graft with as healthy a constitution as possible. For this purpose ancillary instrument for gripping and storing the graft 2 after it has been released from the humerus H can optionally be provided, in order to limit the risks of damaging the graft.
Furthermore, in non-illustrated variations, the graft 2 can have volume forms other than a cylinder as in the figures, provided that the volume of bone matter forming the graft 2 has a shape generally centered about a longitudinal axis of the type of the axis EX-X, while at the same time defining a lateral face and longitudinal end faces of the type of the faces 2A, 2B and 2C. For example, the graft 2 can thus be truncated in shape, having a longitudinal axis EX-X; in this case, the inner surface of the crown saw 62 or 162 is, for example, provided so as to be truncated.
Optionally, the graft 2 can be protected laterally by a reinforcing structure, such as for example ring 80 shown in
If the ring 80 is implanted in conjunction with the graft 2, it protects the lateral face 2A of the graft 2 and forms a support for at least a part of the face 11B of the glenoid component 10, thus limiting the stresses applied to the graft 2. Advantageously, the ring 80 is covered with hydroxyapatite or, more generally, has a porous or honeycomb surface state allowing improved bone adhesion and rehabilitation of the ring 80 to the graft 2 and to the resected surface part of the glenoid surface G that is not covered by the graft 2. In one embodiment, the ring 80 is attached to the glenoid component 10.
In practice, it will be understood that the inner surface of the ring 80 is advantageously complementary with the face 2A of the graft 2, whereas its outer face can have advantageous optional configurations. The outer surface can thus be provided so as to be truncated and diverged toward the glenoid surface G, so holes passing through the ring 80 in respective directions substantially perpendicular to the outer surface thereof are able to receive screws or the like in order to reinforce the securing of the graft 2 to the glenoid surface G. Similarly, the bottom portion of the ring 80 can be provided so as to be less thick than the remainder of the ring so as not subsequently to disturb the humeral component 20 during adduction movements on the part of the patient.
In a variation of the fitting method, rather than delivering a one-piece bone volume such as the cylinder E3, in the upper humeral epiphysis E, the graft 2 can consist of a purée of bone substance. This substance is taken from the spongy bone zones of the humeral epiphysis, in particular when preparing the humerus H for the fitting of the humeral implant. In practice, in order to contain this purée of bone substance during implantation of the glenoid component 10, a reinforcing structure, such as for example a lattice 90 shaped as a cage 92 for receiving this purée will advantageously be used, as shown in
The lattice 90 forming the cage 92 allows exchanges of biological fluids between the purée of bone substance with which the cage is filled and the surrounding tissues of the patient. The cage 92 thus prevents necrosis of the purée of bone substance while mechanically protecting it. In particular the cage 92 absorbs a proportion, or even the majority, of the stresses applied to the graft 2 consisting of the purée of bone substances by forming, in the region of its lateral end walls 92A and 92B, supports for the face 11B of the glenoid component 10 and the previously prepared surface of the glenoid surface G respectively. The bone substance preferably chemically bonds with the glenoid surface G through the lattice 90. In effect, the glenoid surface G is extended laterally outward to engage with the face 11B of the glenoid component 10.
In another embodiment, the cage 92 is constructed from a porous matrix or scaffold, without the purée of bone substance. The cage 92 can be, for example, reticulated bioceramic framework, structured porous tantalum, synthetic fiber mesh, and the like. The native bone of the glenoid surface G grows into the porous matrix or scaffold to create a graft with structure properties comparable to native bone. The cage 92 is alternately made of a slow-absorbing, biologically benign material, such as Poly-4-hydroxybutyrate (a.k.a. Tephaflex™), poly(urethane urea) (Artelon™), surgical silk, or other materials, known to the art, having similar characteristics, such as disclosed in U.S. Patent Publication No. 2007/0198087, entitled Method and Device for Rotator Cuff Repair, filed Feb. 5, 2007 and U.S. Patent Publication No. 2007/0276509, entitled Tissue Scaffold, filed Aug. 9, 2007, the entire disclosures of which are incorporated by reference. Other less preferred embodiments employ non-absorbable materials such as PTFE, Polypropylene, Nylon, or other biocompatible, inert materials known to the art.
Before or after implanting of the glenoid component 10, the humeral component 20 is implanted in the humerus H, advantageously using ancillary instrument (not shown), the handling of which is marked by the end part of the recess E1 remaining in the humeral epiphysis E after removal of the bone volume such as the cylinder E3. If the surgical actions applied to the humerus H for implanting the component 20 by way of the recess E1 are dispensed with and these actions are therefore generally independent of those applied to the humerus for taking the graft 2, the ancillary instrument 30 can be simplified, as it is in this case no longer necessary to take account of the retroversion of the patient's forearm in order to insert the guide pin 40. The shaft 31 may in this case assume the form of an intramedullary humeral rod.
According to a variation of the fitting method, the graft 2, whether in the form of a one-piece bone volume or of a purée of bone substance, is not taken from the humeral epiphysis E but rather is taken from another of the patient's bones, in particular from his ilium, or consists of an allograft, a graft of synthetic origin or a graft of metallic origin, it being understood that the dimensions of this synthetic graft are provided so as to be appropriate for the glenoid component 10 to be implanted, as stated hereinbefore for the removed cylinder E3 or cone frustum. Obviously, the protection ring 80 and the cage 92 described hereinbefore can be used in conjunction with a graft of this type of alternative origin.
The glenoid component 220 includes a recess 230 that engages with distal surface 232 of the reinforcing structure 222. An anchor 234 optionally extends through the reinforcing structure 222 and graft 224 to further secure the glenoid component 220 to the scapula S. In the illustrated embodiment, the anchor 234 includes a pointed tip 236 to facilitate insertion into the glenoid surface G. The radius of curvature 228 of convex articular surface 235 is preferably selected such that the center of rotation 233 of the glenoid component 220 is preferably either in or behind plane 237 comprising a distal surface 239 of the graft 224. Once the graft 224 has fused with the glenoid surface G, the distal surface 239 of the graft 224 becomes the effective glenoid surface.
The adjustable anchor portion also includes an opposite reinforcing structure 308 that extends over the reinforcing structure 302 and bone graft 310 and restricts lateral movement of the bone graft 310. Thus, the adjustable anchor portion is formed of two, opposing portions—the first and second reinforcing structures 304, 308. In the illustrated embodiment, the opposite reinforcing structure 308 telescopically engages with the reinforcing structure 302 to adjust an overall length of the reinforcing structure 308. The bone graft 310 has a distal face 312 and a medial face 313 and defines a thickness between the distal and medial faces 312, 313. The bone graft 310 can be a one-piece bone volume, a purée of bone substance, or any of the other materials previously described. The opposite reinforcing structure 308 optionally includes a plurality of holes 307 to facilitate bone in-growth.
In some embodiments, the glenoid component 300 includes an articulation surface 315A and an engagement surface 315B that is attached to distal surface 312 of the opposing reinforcing structure 308. In the illustrated embodiment, the glenoid component 300 is mounted to the opposing reinforcing structure 308 off-center. The opposing reinforcing structure 308 preferably has a plurality of mounting features that permit the surgeon to locate the glenoid component 300 in a variety of locations. The radius of curvature of convex articular surface 314 is preferably selected so the center of rotation 319 is in or behind plane 316 comprising distal surface 318 of the bone graft 310. In another embodiment, the center of rotation is close to the plane 316.
As shown, the glenoid component 300A also includes an anchoring tail 304A, also described as an anchoring portion or anchoring structure, that extends transversely from the engagement face 303A and is adapted to be anchored in the glenoid surface G (
As shown, the anchoring tail 304A defines an overall length and includes a first portion 305A having an inner lumen 306A, a second portion 307A, and a lock member 308A. The first portion 305A optionally has a substantially circular cross-section, although non-circular cross-sections (e.g., hexagonal or square), are contemplated. As described, the tail 304A is configured such that a user is able to telescope the second portion 307A in and out of the first portion 305A in order to adjust the overall length of the anchoring tail 304A. In some embodiments, the second portion 307A includes a conical threadform or a buttress threadform.
The inner lumen 306A of the first portion 305A optionally includes female threading (not shown). The second portion 307A is adapted to telescopically fit within the inner lumen 306A of the first portion 305A, the second portion 306A having male threading 309A according to some embodiments. The second portion 307A is optionally substantially cylindrical with a circular transverse cross-section, although other cross sections (e.g., hexagonal or square) are contemplated. The lock member 308A is optionally formed similar to a nut, with flats or other surface features. The overall length of the tail 304A is adjusted by rotating the second member within the first member to the desired overall length. The overall length is optionally locked by tightening the lock member 308 to help ensure the anchoring tail 304A remains at the desired length and does not back or forward rotate to a different overall length.
In some embodiments, a bone graft (not shown) such as those previously described, is received by the tail 304A, the bone graft optionally including a central aperture or other feature that fits over the tail that restricts lateral movement of the bone graft and secures the bone graft to the tail 304A, where the tail 304A receives the bone graft with a medial surface of the bone graft engaged with the engagement face 303A. In some embodiments, the bone graft is first received against the engagement face 303A and then the tail 304A is secured to the head 301A thereby securing the bone graft to the head 301A. In some embodiments, the bone graft is received over the first portion 305A of the tail 304A and then the second portion 306A is secured to the first portion 305A of the tail 304A.
As shown, the glenoid component 300B also includes an anchoring tail 304B that extends transversely from the face 302B and is adapted to be anchored in the glenoid surface G (
As shown, the anchoring tail 304B defines an overall length and includes a first portion 305B having an inner lumen 306B and a second portion 307B. The second portion 307B is optionally interchanged with a similar component having a substantially different configuration, such as a different length. For example, a third portion 308B is shown which may be substituted for the second portion 307B. Additional components, of different lengths, widths, cross-sections, or other alternate configurations that are adapted to be secured to the first portion 305B are also available according to some embodiments.
The first portion 305B optionally has a substantially circular cross-section, although non-circular cross-sections (e.g., hexagonal or square), are contemplated. As alluded to in the foregoing description, the tail 304B is configured such that a user is able to select between a plurality of extensions (e.g., between second and third portions 307B, 308B) in order to adjust the overall length of the anchoring tail 304B. The inner lumen 306B of the first portion 305B optionally includes female threading (not shown). In some other embodiments, the first portion 305B includes male threading for mating with female threading on the second portion 307B and/or third portion 307C.
In some embodiments, the second portion 307B has a narrowed region 309B with male threading adapted to form a complementary fit with the female threading of the first portion 305B. The second portion 307B is optionally substantially cylindrical with a circular transverse cross-section, although other cross sections (e.g., hexagonal or square) are contemplated. As shown, the second portion 307B has a length that is substantially longer than that of the third portion 308B. Thus, a user desiring to adjust the overall length of the anchoring tail 304B is able to not attach any additional component to the first portion 305B (i.e., utilize the non-extended length of the anchoring tail 304B), or select between securing one of a plurality of additional components of different lengths (e.g., the second and third portions 307B, 308B) to the first portion 305B to extend the overall length of the anchoring tail 304B.
In some embodiments, a bone graft 309B such as those previously described, is received by the tail 304B, the bone graft optionally including a central aperture or other feature that fits over the tail that restricts lateral movement of the bone graft and secures the bone graft to the tail 304B. As shown in
In some embodiments, the bone graft 309B is first received against the engagement face 303B and then the tail 304B is secured to the head 301B thereby securing the bone graft to the head 301B. In some embodiments, the bone graft 309B is received over the first portion 305B of the tail 304B and then the second portion 306B is secured to the first portion 305B of the tail 304B.
In the illustrated embodiment, the glenoid component 340 is secured to glenoid surface G using a plurality of fasteners 352. Although distal surface 354 of the glenoid component 340 is illustrated as planar it can be configured for with either a convex or concave articular surface, depending on the application.
The bone graft 426 can be a one-piece volume, a plurality of pieces, purée of bone substance, or a combination thereof. In one embodiment, a plurality of pre-formed bone grafts of known shape are available to the surgeon during the procedure. The surgeon removes material from the exposed surface 422 of the glenoid surface G corresponding to the shape of one of the pre-formed bone grafts. The surgeon then places the pre-formed bone graft into the corresponding recess formed in the glenoid surface G.
In the illustrated embodiment, anchor 446 of the base plate 444 and/or the glenoid component 440 are located off-set from the center axis 448 of the glenoid surface G. Lower portion 450 of the convex articular surface 452 extends beyond the pillar of the scapula S to minimize interference with the humeral prosthetic portion. The radius of curvature of convex articular surface 452 is preferably selected so the center of rotation around the glenoid component 440 is preferably in a plane 454 comprising a distal surface 456 of the bone graft 458 or between the plane 454 and the glenoid surface G.
In the illustrated embodiment, the exposed surface 460 of the glenoid surface G includes one or more defects 462. These defects 462 are preferably repaired with a one-piece bone graft, a plurality of pieces, purée of bone substance, or a combination thereof 464. After the repair, the exposed surface 460 of the glenoid surface G is preferably generally planar and well suited to receive the bone graft 458.
The curvilinear surface C of the humeral epiphysis E is located on base 502, as illustrated in
In one embodiment, the resulting bone graft 500 is an annular ring with a planar surface 512 and a curvilinear surface 514 as illustrated in
Various modifications and additions can be made to the exemplary embodiments discussed without departing from the scope of the present invention. For example, the distal surfaces of the glenoid components disclosed herein can be used with an interpositional implant, such as disclosed in U.S. Pat. Nos. 6,436,146; 5,723,018; 4,846,840; 4,206,517; and U.S. Provisional Application Ser. No. 61/015,042, entitled INTRA-ARTICULAR JOINT REPLACEMENT, the complete disclosures of which are hereby incorporated by reference. While the embodiments described above refer to particular features, the scope of this invention also includes embodiments having different combinations of features and embodiments that do not include all of the described features. Accordingly, the scope of the present invention is intended to embrace all such alternatives, modifications, and variations as fall within the scope of the claims, together with all equivalents thereof.
| Number | Date | Country | Kind |
|---|---|---|---|
| 0700622 | Jan 2007 | FR | national |
The present application is a continuation-in-part application of U.S. patent application Ser. No. 12/020,913 filed Jan. 28, 2008, entitled “Method and Apparatus for Fitting a Shoulder Prosthesis,” which claims priority to French Application No. 0700622, entitled “Méthode et ensemble d'instrumentation chirurgicale pour poser une prothèse totale d'épaule inversée, et prothèse correspondante,” filed Jan. 30, 2007 and also claims the benefit of U.S. Provisional Application Ser. Nos. 60/888,437 filed Feb. 6, 2007, 60/971,762 filed Sep. 12, 2007 (both entitled “Method and Apparatus for Fitting an Inverted Shoulder Prosthesis”) and U.S. Provisional Application Ser. No. 61/015,042, entitled “Intra-Articular Joint Replacement,” filed Dec. 19, 2007, the complete disclosures of each of which are hereby incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60888437 | Feb 2007 | US | |
| 60971762 | Sep 2007 | US | |
| 61015042 | Dec 2007 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12020913 | Jan 2008 | US |
| Child | 13007355 | US |
