WO2015134626A2

WO2015134626A2 - Shoulder prosthesis

Info

Publication number: WO2015134626A2
Application number: PCT/US2015/018755
Authority: WO
Inventors: Thomas F. HOLOVACS
Original assignee: General Hospital Corp
Current assignee: General Hospital Corp
Priority date: 2014-03-04
Filing date: 2015-03-04
Publication date: 2015-09-11
Anticipated expiration: 2016-09-04
Also published as: WO2015134626A3

Abstract

A shoulder prosthesis includes a humeral component and a glenoid component. The humeral component has a convex head, and the glenoid component includes a body having a concave articulating surface dimensioned for engaging the head of the humeral component. In another embodiment, the humeral component includes a concave socket, and the glenoid component includes a head having a concave articulating surface. The articulating surface of the glenoid head is dimensioned for articulating in the socket of the humeral component. The head or socket of the humeral component can comprise a polymeric material such as a polyolefin. The body or head of the glenoid component can comprise a metallic material such as stainless steel, a cobalt-chromium alloy, titanium, a titanium alloy, tantalum, or a tantalum alloy.

Description

Shoulder Prosthesis

CROSS-REFERENCES TO RELATED APPLICATIONS

[0001] This application claims priority from U .S. Patent Application No. 61 /947,657 filed March 4, 2014.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

[0002] Not Applicable.

BACKGROUND OF THE INVENTION

1 . Field of the Invention

[0003] This invention relates to a shoulder prosthesis having a humeral

component and a glenoid component.

2. Description of the Related Art

[0004] Total shoulder replacement is a well-accepted treatment option for patients with osteoarthritis of the shoulder (glenohumeral joint). This procedure involves replacement of both the humeral head and the glenoid. The humeral head can be replaced/resurfaced with either a stemmed implant which is secured, in part, in the canal of the humerus or a stemless implant which is secured with the humeral head itself. The glenoid is a pear-shaped bone which is part of the scapula. It is the "socket" of the shoulder. The bony geometry of the glenoid is such that there is a shallow concavity which comprises the socket. The glenoid is small (approximately 3 cm. x 4 cm. dimension). Glenoid replacement/resurfacing is accomplished by initially preparing the glenoid by performing a circumferential reaming of a constant diameter. The reaming prepares the glenoid by removing any remaining cartilage and bone such that the subchondral bone is exposed. The cortical bone of the glenoid, which outlines the peripheral shape of the glenoid is reamed along with the rest of the glenoid surface. Once reaming and preparation of the glenoid is accomplished, a glenoid-shaped component is cemented onto the glenoid to serve as the bearing surface for the humeral articulation with the glenoid.

[0005] The majority of unsatisfactory results after total shoulder arthroplasty are caused by the failure of a polyethylene glenoid component. For example,

glenohumeral translation can cause edge loading and flattening of the rim of a polyethylene glenoid component which results in a decrease in the stability provided by the glenoid component. Edge loading can also cause a rocking-horse loosening mechanism in which loading of one edge of the glenoid component causes the opposite edge to lift off of the glenoid bone. Wear of a polyethylene glenoid component can also create polyethylene particles that may lead to progressive resorption of bone and consequently to prosthetic failure.

[0006] Therefore, there is a need for an improved shoulder prosthesis that minimizes the risk of glenoid component failure.

SUMMARY OF THE INVENTION

[0007] In one aspect, the invention provides a shoulder prosthesis having a humeral component and a glenoid component. The humeral component includes a convex head; and the glenoid component includes a body having a concave articulating surface and a second surface opposite the articulating surface wherein the articulating surface is dimensioned for engaging the head of the humeral component and the second surface is dimensioned for being secured to a scapula. The glenoid component further includes a fixation member extending away from the second surface. The humeral head of the humeral component comprises a polymeric material such as a polyolefin or a polyamide. The glenoid component comprises a metallic material such as stainless steel, a cobalt-chromium alloy, titanium, a titanium alloy, tantalum, or a tantalum alloy.

[0008] In another aspect, the invention provides a shoulder prosthesis having a humeral component and a glenoid component. The humeral component includes a concave socket; and the glenoid component includes a head having a concave articulating surface and having a second surface opposite the articulating surface. The articulating surface of the glenoid head is dimensioned for articulating in the socket of the humeral component, and the second surface of the glenoid head is dimensioned for being secured to a scapula. The glenoid component further includes a fixation member extending away from the second surface. The socket of the humeral component comprises a polymeric material such as a polyolefin or a polyamide. The head of the glenoid component comprises a metallic material such as stainless steel, a cobalt-chromium alloy, titanium, a titanium alloy, tantalum, or a tantalum alloy. [0009] In another aspect, the invention provides a method of using a shoulder prosthesis. The method includes attaching humeral component to a glenoid surface of a scapula. The humeral component includes a convex head. The method further includes attaching a glenoid component to a humerus, and the glenoid component includes a body having a concave articulating surface and a second surface opposite the articulating surface wherein the articulating surface is dimensioned for engaging the head of the humeral component and the second surface is dimensioned for being secured to a scapula. The glenoid component further includes a fixation member extending away from the second surface. The humeral head of the humeral component comprises a polymeric material such as a polyolefin or a polyamide. The glenoid component comprises a metallic material such as stainless steel, a cobalt- chromium alloy, titanium, a titanium alloy, tantalum, or a tantalum alloy.

[0010] In yet another aspect, the invention provides a method of using a shoulder prosthesis. The method includes attaching a humeral component to a humerus. The humeral component includes a concave socket. The method further includes attaching a glenoid component to a glenoid surface of a scapula. The glenoid component includes a head having a concave articulating surface and having a second surface opposite the articulating surface. The articulating surface of the glenoid head is dimensioned for articulating in the socket of the humeral component, and the second surface of the glenoid head is dimensioned for being secured to a scapula. The glenoid component further includes a fixation member extending away from the second surface. The socket of the humeral component comprises a polymeric material such as a polyolefin or a polyamide. The head of the glenoid component comprises a metallic material such as stainless steel, a cobalt-chromium alloy, titanium, a titanium alloy, tantalum, or a tantalum alloy.

[0011] The glenoid component can be modular or monoblock. The humeral component can be modular or monoblock. In one form, the body of the glenoid component is pear-shaped. In one form, the body of the glenoid component is dimensioned such that the glenoid component is flush with native peripheral glenoid bone when the glenoid component is secured to the scapula. [0012] The fixation member of the glenoid component may include a stem connected to and extending away from the body of the glenoid component. A Morse taper may be used to connect the stem to the body of the glenoid component. The fixation member of the glenoid component may comprise a generally oblong keel connected to and extending away from the body of the glenoid component. The keel may be comprised of the metallic material, and a Morse taper may be used to connect the keel to the body of the glenoid component. Further, the fixation member of the glenoid component may include one or more pegs connected to and extending away from the body of the glenoid component, and each peg may be comprised of the metallic material. Each peg may be connected to a mounting plate of the fixation member and a Morse taper may be used to connect the mounting plate to the body of the glenoid component.

[0013] The head of the humeral component includes an average thickness of the polymeric material in the range of 5 millimeters to 30 millimeters. In other

embodiments, the head of the humeral component includes an average thickness of the polymeric material in the range of 10 millimeters to 30 millimeters. In yet another embodiment, the head of the humeral component includes an average thickness of the polymeric material in the range of 20 millimeters to 30 millimeters. The thickness is measured along a reference line from a bearing surface of the head to a center point of the head.

[0014] The polymeric material of the head can be selected from the group consisting of low-density polyethylenes, high-density polyethylenes, linear low- density polyethylenes, ultra-high molecular weight polyethylenes, and mixtures thereof. The metallic material of the body may be selected from the group consisting of stainless steel, cobalt-chromium alloys, titanium, titanium alloys, tantalum, and tantalum alloys.

[0015] The humeral component may further include a stem connected to and extending away from the convex head. The stem may be dimensioned for insertion into an intramedullary canal of a humerus. The humeral component may further include a generally oblong keel connected to and extending away from the convex head. The keel may be comprised of the polymeric material. The humeral component may further include one or more pegs connected to and extending away from the convex head. Each peg may be comprised of the polymeric material.

[0016] The fixation member of the glenoid component may include a stem connected to and extending away from the head of the glenoid component. A Morse taper may be used to connect the stem to the head of the glenoid component. The fixation member of the glenoid component may comprise a generally oblong keel connected to and extending away from the head of the glenoid component. The keel may be comprised of the metallic material, and a Morse taper may be used to connect the keel to the head of the glenoid component. Further, the fixation member of the glenoid component may include one or more pegs connected to and extending away from the head of the glenoid component, and each peg may be comprised of the metallic material. Each peg may be connected to a mounting plate of the fixation member and a Morse taper may be used to connect the mounting plate to the head of the glenoid component.

[0017] The socket of the humeral component includes an average thickness of the polymeric material in the range of 5 millimeters to 30 millimeters. The thickness is measured from a bearing surface of the socket to a center point of the socket.

[0018] The polymeric material of the socket can be selected from the group consisting of low-density polyethylenes, high-density polyethylenes, linear low- density polyethylenes, ultra-high molecular weight polyethylenes, and mixtures thereof. The metallic material of the head may be selected from the group consisting of stainless steel, cobalt-chromium alloys, titanium, titanium alloys, tantalum, and tantalum alloys.

[0019] The humeral component may further include a stem connected to and extending away from the socket. The stem may be dimensioned for insertion into an intramedullary canal of a humerus. The humeral component may further include a generally oblong keel connected to and extending away from the socket. The keel may be comprised of the polymeric material. The humeral component may further include one or more pegs connected to and extending away from the socket. Each peg may be comprised of the polymeric material. In some embodiments, the socket of the humeral component comprises a base layer and a liner layer. A first thickness of the base layer may be measured along a radial reference line from a tangent point T on a periphery of the socket to the concave articulating surface. The first thickness may be in the range of 5 millimeters to 1 5 millimeters. A second thickness of the liner layer may be measured along the radial reference line from the tangent point T on the periphery of the socket to the concave articulating surface. The second thickness may be in the range of 5 millimeters to 15 millimeters.

[0020] It is one advantage of the invention to provide a shoulder prosthesis that decreases the flattening of the rim of a glenoid component when edge loading of the glenoid component occurs.

[0021] It is another advantage of the invention to provide a shoulder prosthesis that decreases or eliminates the rocking-horse loosening mechanism in which loading of one edge of the glenoid component causes the opposite edge to lift off of the glenoid bone.

[0022] It is yet another advantage of the invention to provide a shoulder prosthesis that in which the amount of particles produced by wear of the articulating humeral and/or glenoid components is decreased.

[0023] These and other features, aspects, and advantages of the present invention will become better understood upon consideration of the following detailed description, drawings and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 shows an anterior view of a right shoulder prosthesis according to the invention.

[0025] Figure 2 shows an exploded anterior view of an example embodiment of a left shoulder prosthesis according to the invention.

[0026] Figure 3 shows an exploded anterior view of another example embodiment of a left shoulder prosthesis according to the invention.

[0027] Figure 3A is a cross-sectional view of an example embodiment of a humeral component dimensioned for use with a shoulder prosthesis according to the invention.

[0028] Figure 4 shows an exploded anterior view of an example embodiment of a right shoulder prosthesis according to the invention. [0029] Figure 5 shows an exploded anterior view of an example embodiment of another right shoulder prosthesis according to the invention.

[0030] Figure 5A is a cross-sectional view of an example embodiment of another humeral component dimensioned for use with a shoulder prosthesis according to the invention.

[0031 ] Figure 6 shows an exploded anterior view of yet another example embodiment of a right shoulder prosthesis according to the invention.

[0032] Like reference numerals will be used to refer to like parts from Figure to Figure in the following description of the drawings.

DETAILED DESCRIPTION OF THE INVENTION

[0033] Figure 1 shows an anterior view of a right shoulder replacement 10. A glenoid component 12 is positioned in a resected portion of the glenoid cavity 13 of the scapula 14. The glenoid cavity 13 is located on the head of the scapula 14 between an external border 15 and an upper border 16, and between the acromion process 17 and the coracoid process 18. The clavicle 19 is positioned above the glenoid component 12. A humeral component 21 is attached to a proximal end of the humerus 22. A spherical head 23 of the humeral component 21 articulates with the glenoid component 12 which extends outward from the natural bearing surface of the glenoid cavity 13.

[0034] The glenoid component 12 comprises, or may consist essentially of, a metallic material such as stainless steel, a cobalt-chromium alloy, titanium, a titanium alloy, tantalum, or a tantalum alloy. The humeral component 21 comprises, or may consist essentially of, a polymeric material such as a polyolefin or a polyamide.

Preferably, the spherical head 23 of the humeral component 21 comprises a polymeric material such as a low-density polyethylene, a high-density polyethylene, a linear low-density polyethylene, an ultra-high molecular weight polyethylene, or mixtures thereof. Most preferably, the spherical head 23 of the humeral component 21 comprises an ultra-high molecular weight polyethylene which refers to linear non- branched chains of ethylene having molecular weights in excess of about 500,000 daltons, preferably above about 1 ,000,000 daltons, and more preferably above about 2,000,000 daltons. [0035] A non-limiting example of a left shoulder prosthesis 210 according to the invention is shown in Figure 2. The shoulder prosthesis 210 can be provided as a kit for use with the method of the invention. An appropriate size of glenoid component 212 and humeral component 221 are selected for use in the shoulder prosthesis 210, and a marking tool, such as a cauterizer, is used indicate the position of one or more holes to be drilled in the glenoid surface 26 of the glenoid cavity 13 of the scapula 14 for receiving the glenoid component 212. In the example shown in Figure 2, holes 240, 242, 244 are drilled in the glenoid surface 26 in the locations marked in the previous step. The glenoid component 212 includes pegs 250, 252, 254 extending from a bottom surface 256 of a body 257 of the glenoid component 212. The pegs 250, 252, 254 are dimensioned to fit in the holes 240, 242, 244, respectively. While three pegs 250, 252, 254 and three corresponding holes 240, 242, 244 are depicted in Figure 2, it is contemplated that fewer or more pegs and corresponding holes may be provided on the bottom surface 256 of the glenoid component 212 and the glenoid surface 26, respectively, so long as rotation and/or movement of the glenoid component 212 once received by the glenoid cavity 13 is limited. Following the successful dry-fit of the pegged glenoid component 212 of the proper size, the glenoid component 212 can be secured in place in the glenoid cavity 13 using a press-fit or bone cement such as polymethyl methacrylate (PMMA). The glenoid component 212 (body 257 and pegs 250, 252, 254) comprises a metallic material such as stainless steel, a cobalt-chromium alloy, titanium, a titanium alloy, tantalum, or a tantalum alloy.

[0036] The humeral component 221 includes a humeral head 223 and a stem 262, which may be provided as separate components for assembly or as an integral component. When the humeral head 223 and the stem 262 are provided as separate components, the humeral component 221 may be implanted in the humerus 22 as follows. First, the head of the humerus 22 is resected and the intramedullary canal 24 of the humerus 22 is inspected. Tools, such as a reamer, may be used to clean material out of the intramedullary canal 24. Once the intramedullary canal 24 in the humerus 22 has been prepared, the surgeon can then "press-fit" the stem 262 (which is tapered for ease of insertion) into the intramedullary canal 24 of the humerus 22. Optionally, the stem 262 can be cemented in the intramedullary canal 24, and/or bone screws can be used to further secure the stem 262 in the

intramedullary canal 24 of the humerus 22. Next, the humeral head 223 of the humeral component 221 is secured to the stem 262 using a press fit, such as a Morse taper, or a fastener, such as one or more screws. Optionally, the humeral head 223 can be secured to the stem 262 before inserting the stem 262 into the intramedullary canal 24 of the humerus 22. In the case of an integral humeral head 223 and stem 262, the step of securing the humeral head 223 to the stem 262 is not necessary.

[0037] The humeral head 223 articulates with a concave surface 259 of the glenoid component 212 in the shoulder prosthesis 210. The humeral head 223 of the humeral component 221 can comprise, or may consist essentially of, a polymeric material such as a polyolefin or a polyamide. Preferably, the humeral head 223 of the humeral component 221 comprises a polymeric material such as a low-density polyethylene, a high-density polyethylene, a linear low-density polyethylene, an ultrahigh molecular weight polyethylene, or mixtures thereof. Most preferably, the humeral head 223 of the humeral component 221 comprises an ultra-high molecular weight polyethylene.

[0038] A non-limiting example of a left shoulder prosthesis 310 according to the invention is shown in Figure 3. The shoulder prosthesis 310 can be provided as a kit for use with the method of the invention. An appropriate size of glenoid component 312 and humeral component 321 are selected for use in the shoulder prosthesis 310, and a marking tool, such as a cauterizer, is used indicate the position of two holes to be drilled in the glenoid surface 26 of the glenoid cavity 13 of the scapula 14 for receiving the glenoid component 312. In the example shown in Figure 3, spaced apart holes are drilled in the glenoid surface 26 in the locations marked in the previous step. The material between the holes is removed thereby creating an oblong slot 340 in the glenoid surface 26. The glenoid component 312 includes a generally oblong keel 350 extending from a bottom surface 356 of a body 357 of the glenoid component 212. The oblong keel 350 fits in the oblong slot 340. Following the successful dry-fit of the keeled glenoid component 312 of the proper size, the glenoid component 312 can be secured in place in the glenoid cavity 13 using a press-fit or bone cement such as polymethyl methacrylate. The glenoid component 312 (body 357 and keel 350) comprises a metallic material such as stainless steel, a cobalt-chromium alloy, titanium, a titanium alloy, tantalum, or a tantalum alloy.

[0039] Still looking at Figure 3, the humeral component 321 includes a humeral head 323. The humeral component 321 may be implanted in the humerus 22 as follows. First, the head of the humerus 22 is resected. The surgeon can then attach the humeral component 321 to the humerus 22. The humeral component 321 may comprise a stemless humeral head 323, or the humeral head 323 may include a stem. The humeral head 323 articulates with a concave surface 359 of the glenoid component 312 in the shoulder prosthesis. The humeral head 323 of the humeral component 321 can comprise, or may consist essentially of, a polymeric material such as a polyolefin or a polyamide. Preferably, the humeral head 323 of the humeral component 321 comprises a polymeric material such as a low-density polyethylene, a high-density polyethylene, a linear low-density polyethylene, an ultrahigh molecular weight polyethylene, or mixtures thereof. Most preferably, the humeral head 323 of the humeral component 321 comprises an ultra-high molecular weight polyethylene.

[0040] Turning now to Figure 3A, the shoulder prosthesis 310 may comprise another humeral component 321 a that includes a humeral head 323a and a stem

362a, which may be provided as separate components for assembly or as an integral component. When the humeral head 323a and the stem 362a are provided as separate components, the humeral component 321 a may be implanted in the humerus 22 as follows. First, the head of the humerus 22 is resected and the intramedullary canal 24 of the humerus 22 is inspected. Tools, such as a reamer, may be used to clean material out of the intramedullary canal 24. Once the intramedullary canal 24 in the humerus 22 has been prepared, the surgeon can then "press-fit" the stem 362a (which is tapered for ease of insertion) into the

intramedullary canal 24 of the humerus 22. Optionally, the stem 362a can be cemented in the intramedullary canal 24, and/or bone screws can be used to further secure the stem 362a in the intramedullary canal 24 of the humerus 22. Next, the humeral head 323a of the humeral component 321 a is secured to the stem 362a using a press fit, such as by way of a Morse taper 367a. Optionally, the humeral head 323a can be secured to the stem 362a before inserting the stem 362a into the intramedullary canal 24 of the humerus 22. In the case of an integral humeral head 323a and stem 362a, the step of securing the humeral head 323a to the stem 362a is not necessary. The humeral head 323a articulates with a concave surface 359 (see Figure 3) of the glenoid component 312 in the shoulder prosthesis 310.

[0041] The humeral head 323a of the humeral component 321 a can comprise, or may consist essentially of, a polymeric material such as a polyolefin or a polyamide. Preferably, the humeral head 323a of the humeral component 321 a comprises a polymeric material such as a low-density polyethylene, a high-density polyethylene, a linear low-density polyethylene, an ultra-high molecular weight polyethylene, or mixtures thereof. Most preferably, the humeral head 323a of the humeral component 321 a comprises an ultra-high molecular weight polyethylene. The stem 362a, including the Morse taper 367a, can comprise a metallic material such as stainless steel, a cobalt-chromium alloy, titanium, a titanium alloy, tantalum, or a tantalum alloy. Alternatively, the stem 362a, including the Morse taper 367a, can comprise the same materials as the humeral head 323a of the humeral component 321 a.

[0042] Still looking at Figure 3A, the humeral head 323a is generally

hemispherical with a radius R. A portion of the humeral head 323a near the center point C of the humeral head 323a is removed to matingly engage with the Morse taper 367a section of the stem 362a. Preferably, the Morse taper 367a section of the stem 362a is sized to create as thick of a humeral head 323a as possible. For example, the Morse taper 367a section of the stem 362a can be sized such that an average thickness T of the polymeric material for the humeral head 323a of the humeral component 321 a is in the range of 5 millimeters to 30 millimeters with the thickness being measured from a concave bearing surface 359a along line R of Figure 3A that runs from the center point C to the concave bearing surface 359a of the humeral head 323a of the humeral component 321 a. Average thicknesses for the polymeric material for the humeral head 323a of the humeral component 321 a can be in the range of 10 millimeters to 30 millimeters, or 20 millimeters to 30 millimeters. In a non-limiting example wherein the humeral component 321 a comprises a hemispherical humeral head 323a and integral stem 362a, and the humeral component 321 a consists essentially of a polymeric material, the average thickness T for the polymeric material of the humeral head 323a of the humeral component 321 a will be equal to the radius R (e.g., 20 to 30 millimeters) in Figure 3A.

[0043] Another non-limiting example of a right shoulder reverse prosthesis 410 according to the invention is shown in Figure 4. By "reverse", it is meant that the glenoid component has a convex articulation surface and the humeral component has a concave articulation surface. The shoulder prosthesis 410 can be provided as a kit for use with the method of the invention. An appropriate size of glenoid component 412 and humeral component 421 are selected for use in the shoulder prosthesis 410, and a marking tool, such as a cauterizer, is used indicate the position of two holes to be drilled in the glenoid surface 26 of the glenoid cavity 13 of the scapula 14 for receiving the glenoid component 412. In the example shown in Figure 4, spaced apart holes are drilled in the glenoid surface 26 in the locations marked in the previous step. The material between the holes is removed thereby creating an oblong slot (similar to slot 340 in Figure 3) in the glenoid surface 26. The glenoid component 412 includes a generally oblong keel 450 extending from a bottom surface 456 of a mounting body 457 of the glenoid component 412. The keel 450 fits in the oblong slot created in the glenoid. Following the successful dry-fit of the keeled mounting body 457 of the proper size, a glenoid head 459 of the glenoid component 412 can be secured to the mounting body 457 using a press fit (such as a Morse taper), or fasteners (e.g., screws), or cement. The glenoid component 412 (keeled mounting body 457 and head 459) comprises a metallic material such as stainless steel, a cobalt-chromium alloy, titanium, a titanium alloy, tantalum, or a tantalum alloy.

[0044] Still referring to Figure 4, the shoulder prosthesis 410 comprises a humeral component 421 including a humeral socket 423 having a concave surface 424. The humeral component 421 may be implanted in the humerus 22 as follows. First, the head of the humerus 22 is resected and the intramedullary canal 24 of the humerus 22 is inspected and tools (such as a reamer) may be used to clean material out of the intramedullary canal 24. Once the intramedullary canal 24 in the humerus 22 has been prepared, the surgeon can then "press-fit" the stem 462 (which is tapered for ease of insertion) into the intramedullary canal 24 of the humerus 22. Optionally, the stem 462 can be cemented in the intramedullary canal 24, and/or bone screws can be used to further secure the stem 462 in the intramedullary canal 24 of the humerus 22. Next, the humeral socket 423 of the humeral component 421 is secured to the stem 462 using a press fit, such as a Morse taper, or a fastener, such as one or more screws. Optionally, the humeral socket 423 can be secured to the stem 462 before inserting the stem 462 into the intramedullary canal 24 of the humerus 22. The concave surface 424 of the humeral socket 423 articulates with the convex glenoid head 459 of the glenoid component 412 in the shoulder prosthesis 410. The humeral socket 423 of the humeral component 421 comprises, or may consist essentially of, a polymeric material such as a polyolefin or a polyamide. Preferably, the humeral socket 423 of the humeral component 421 comprises a polymeric material such as a low-density polyethylene, a high-density polyethylene, a linear low-density

polyethylene, an ultra-high molecular weight polyethylene, or mixtures thereof. Most preferably, the humeral socket 423 of the humeral component 421 comprises an ultra-high molecular weight polyethylene.

[0045] Yet another non-limiting example of a right shoulder reverse prosthesis 510 according to the invention is shown in Figure 5. The shoulder prosthesis 510 can be provided as a kit for use with the method of the invention. By "reverse", it is meant that the glenoid component has a convex articulation surface and the humeral component has a concave articulation surface. An appropriate size of glenoid component 512 and humeral component 521 are selected for use in the shoulder prosthesis 510, and a marking tool, such as a cauterizer, is used indicate the position of two holes to be drilled in the glenoid surface 26 of the glenoid cavity 13 of the scapula 14 for receiving the glenoid component 512. In the example shown in Figure 5, spaced apart holes (similar to holes 240, 244 in Figure 2) are drilled in the glenoid surface 26 in the locations marked in the previous step. The glenoid component 512 includes pegs 540, 544 extending from a bottom surface 556 of a mounting body 557 of the glenoid component 512. The pegs 540, 544 fit in the holes created in the glenoid surface 26. Following the successful dry-fit of the pegged mounting body 557 of the proper size, a glenoid head 559 of the glenoid component 512 can be secured to the mounting body 557 using a press fit (such as a Morse taper), or fasteners (e.g., screws), or cement. The glenoid component 512 (keeled mounting body 557 and head 559) comprises a metallic material such as stainless steel, a cobalt-chromium alloy, titanium, a titanium alloy, tantalum, or a tantalum alloy.

[0046] Still referring to Figure 5, the shoulder prosthesis 510 comprises a humeral component 521 including a humeral socket 523 having a concave surface 524. The humeral component 521 may be implanted in the humerus 22 as follows. First, a marking tool, such as a cauterizer, is used indicate the position of two holes to be drilled in the humerus 22 for receiving the humeral socket 523. In the example shown in Figure 5, spaced apart holes (similar to holes 240, 244 in Figure 2) are drilled in the humerus 22 in the locations marked in the previous step. The humeral socket 523 includes pegs 560, 564 extending from a bottom surface 566 of the humeral socket 523. The pegs 560, 564 fit in the holes created in the humerus 22.

Following the successful dry-fit of the pegged humeral socket 523 of the proper size, the humeral socket 523 can be secured in place in the humerus 22 using a bone cement such as polymethyl methacrylate. The concave surface 524 of the humeral socket 523 articulates with the convex glenoid head 559 of the glenoid component 512 in the shoulder prosthesis 510. The humeral socket 523 of the humeral component 521 comprises, or may consist essentially of, a polymeric material such as a polyolefin or a polyamide. Preferably, the humeral socket 523 of the humeral component 521 comprises a polymeric material such as a low-density polyethylene, a high-density polyethylene, a linear low-density polyethylene, an ultra-high molecular weight polyethylene, or mixtures thereof. Most preferably, the humeral socket 523 of the humeral component 521 comprises an ultra-high molecular weight polyethylene.

[0047] Turning now to Figure 5A, the shoulder prosthesis 510 may comprise another humeral component 521 a that includes a humeral socket 523a having a concave articulation surface 524a. Using pegs 560a, 564a, the humeral component 521 a may be implanted in the humerus 22 in the same manner as humeral component 521 . The humeral socket 523a may include a base layer 575a and a liner layer 577a which serves as the concave articulation surface 524a. Non-limiting example humeral socket diameters D, as shown in Figure 5A, are 40 to 60

millimeters.

[0048] In one non-limiting version of the humeral component 521 a, the base layer 575a comprises a polymeric material such as a polyolefin or a polyamide.

Preferably, the base layer 575a of the humeral component 521 comprises a polymeric material such as a low-density polyethylene, a high-density polyethylene, a linear low-density polyethylene, an ultra-high molecular weight polyethylene, or mixtures thereof. Most preferably, the base layer 575a of the humeral component 521 comprises an ultra-high molecular weight polyethylene. The liner layer 577a can comprise a polymeric material such as a polyolefin or a polyamide. Preferably, the liner layer 577a of the humeral component 521 comprises a polymeric material such as a low-density polyethylene, a high-density polyethylene, a linear low-density polyethylene, an ultra-high molecular weight polyethylene, or mixtures thereof. Most preferably, the liner layer 577a of the humeral component 521 comprises an ultrahigh molecular weight polyethylene. The base layer 575a and the liner layer 577a can comprise the same or different materials.

[0049] In another non-limiting version of the humeral component 521 a, the base layer 575a comprises a metallic material such as stainless steel, a cobalt-chromium alloy, titanium, a titanium alloy, tantalum, or a tantalum alloy; and the liner layer 577a can comprise a polymeric material such as a polyolefin or a polyamide. Preferably, the liner layer 577a of the humeral component 521 comprises a polymeric material such as a low-density polyethylene, a high-density polyethylene, a linear low-density polyethylene, an ultra-high molecular weight polyethylene, or mixtures thereof. Most preferably, the liner layer 577a of the humeral component 521 comprises an ultrahigh molecular weight polyethylene.

[0050] In another non-limiting version of the humeral component 521 a, the liner layer 577a is omitted and the base layer 575a serves as the concave articulation surface 524a. The base layer 575a can comprise, or may consist essentially of, a polymeric material such as a polyolefin or a polyamide. Preferably, the base layer 575a of the humeral component 521 comprises a polymeric material such as a low- density polyethylene, a high-density polyethylene, a linear low-density polyethylene, an ultra-high molecular weight polyethylene, or mixtures thereof. Most preferably, the base layer 575a of the humeral component 521 comprises an ultra-high molecular weight polyethylene.

[0051] In any of the embodiments of Figure 5A, the radial thickness of the base layer 575a as measured along radial reference line R2 from tangent point T to the concave articulation surface 524a (see Figure 5A) may be in the range of 5

millimeters to 15 millimeters, and the radial thickness of the liner layer 577a as measured along radial reference line R2 from tangent point T to the concave articulation surface 524a (see Figure 5A) may be in the range of 5 millimeters to 15 millimeters.

[0052] Still another non-limiting example of a right shoulder reverse prosthesis 610 according to the invention is shown in Figure 6. The shoulder prosthesis 610 can be provided as a kit for use with the method of the invention. An appropriate size of glenoid component 612 and humeral component 621 are selected for use in the shoulder prosthesis 610, and a marking tool, such as a cauterizer, is used indicate the position of a hole to be drilled in the glenoid surface 26 of the glenoid cavity 13 of the scapula 14 for receiving the glenoid component 412. In the example shown in Figure 6, a hole (similar to hole 240 in Figure 2) is drilled in the glenoid surface 26 in the location marked in the previous step. The glenoid component 612 includes a stem 640 extending from a bottom surface 656 of the glenoid component 612. The stem 640 fits in the hole created in the glenoid. Following the successful dry-fit of the stemmed glenoid component 612 of the proper size, the glenoid component 612 including a convex glenoid head 659 can be secured to the glenoid surface 26 using a press fit or cement. The glenoid component 612 (stem 640 and head 659) comprises a metallic material such as stainless steel, a cobalt-chromium alloy, titanium, a titanium alloy, tantalum, or a tantalum alloy.

[0053] Still referring to Figure 6, the shoulder prosthesis 610 comprises a humeral component 621 including a humeral socket 623 having a concave surface 624. The humeral component 621 may be implanted in the humerus 22 as follows. First, a marking tool, such as a cauterizer, is used indicate the position of two holes to be drilled in the humerus 22 for receiving the humeral socket 623. In the example shown in Figure 6, spaced apart holes (similar to holes 240, 244 in Figure 2) are drilled in the humerus 22 in the locations marked in the previous step. The material between the holes is removed thereby creating an oblong slot (similar to slot 340 in Figure 3) in the glenoid surface 26. The humeral socket 623 includes an oblong keel 660 extending from a bottom surface 666 of the humeral socket 623. The oblong keel 660 fits in the slot created in the humerus 22. Following the successful dry-fit of the keeled humeral socket 623 of the proper size, the humeral socket 623 can be secured in place in the humerus 22 using a bone cement such as polymethyl methacrylate. The concave surface 624 of the humeral socket 623 articulates with the convex glenoid head 659 of the glenoid component 612 in the shoulder prosthesis 610. The humeral socket 623 of the humeral component 621 comprises, or may consist essentially of, a polymeric material such as a polyolefin or a polyamide. Preferably, the humeral socket 623 of the humeral component 621 comprises a polymeric material such as a low-density polyethylene, a high-density polyethylene, a linear low-density polyethylene, an ultra-high molecular weight polyethylene, or mixtures thereof. Most preferably, the humeral socket 623 of the humeral component 621 comprises an ultra-high molecular weight polyethylene.

[0054] Thus, the invention provides an improved shoulder prosthesis that minimizes the risk of glenoid component failure.

[0055] Although the invention has been described in considerable detail with reference to certain embodiments, one skilled in the art will appreciate that the present invention can be practiced by other than the described embodiments, which have been presented for purposes of illustration and not of limitation. Therefore, the scope of the appended claims should not be limited to the description of the embodiments contained herein.

Claims

CLAIMS What Is Claimed Is:

1 . A shoulder prosthesis comprising:

a humeral component including a convex head; and

a glenoid component including a body having a concave articulating surface and a second surface opposite the articulating surface, the articulating surface being dimensioned for engaging the head of the humeral component, the second surface being dimensioned for being secured to a scapula, the glenoid component further including a fixation member extending away from the second surface,

wherein the head of the humeral component comprises a polymeric material, and

wherein the body of the glenoid component comprises a metallic material.

2. The shoulder prosthesis of claim 1 wherein:

the head of the humeral component consists essentially of the polymeric material, and

the body of the glenoid component consists essentially of the metallic material.

3. The shoulder prosthesis of claim 1 wherein:

the head of the humeral component includes an average thickness of the polymeric material in the range of 5 millimeters to 30 millimeters, the thickness being measured along a reference line from a bearing surface of the head to a center point of the head.

4. The shoulder prosthesis of claim 1 wherein:

the head of the humeral component includes an average thickness of the polymeric material in the range of 10 millimeters to 30 millimeters, the thickness being measured along a reference line from a bearing surface of the head to a center point of the head.

5. The shoulder prosthesis of claim 1 wherein:

the head of the humeral component includes an average thickness of the polymeric material in the range of 20 millimeters to 30 millimeters, the thickness being measured along a reference line from a bearing surface of the head to a center point of the head.

6. The shoulder prosthesis of claims 1 or 2 wherein:

the polymeric material is selected from the group consisting of polyolefins and polyamides.

7. The shoulder prosthesis of claims 1 or 2 wherein:

the polymeric material is selected from the group consisting of low-density polyethylenes, high-density polyethylenes, linear low-density polyethylenes, ultrahigh molecular weight polyethylenes, and mixtures thereof.

8. The shoulder prosthesis of claims 1 or 2 wherein:

the metallic material is selected from the group consisting of stainless steel, cobalt-chromium alloys, titanium, titanium alloys, tantalum, and tantalum alloys.

9. The shoulder prosthesis of claims 1 or 2 wherein:

the humeral component further includes a stem connected to and extending away from the convex head, the stem being dimensioned for insertion into an intramedullary canal of a humerus.

10. The shoulder prosthesis of claims 1 or 2 wherein:

the humeral component further includes a generally oblong keel connected to and extending away from the convex head, the keel comprising the polymeric material.

1 1 . The shoulder prosthesis of claims 1 or 2 wherein:

the humeral component further includes at least one peg connected to and extending away from the convex head, each peg comprising the polymeric material.

12. The shoulder prosthesis of claims 1 or 2 wherein:

the fixation member of the glenoid component comprises a stem connected to and extending away from the body of the glenoid component.

13. The shoulder prosthesis of claim 12 wherein:

a Morse taper is used to connect the stem to the body of the glenoid component.

14. The shoulder prosthesis of claims 1 or 2 wherein:

the fixation member of the glenoid component comprises a generally oblong keel connected to and extending away from the body of the glenoid component, the keel comprising the metallic material.

15. The shoulder prosthesis of claim 14 wherein:

a Morse taper is used to connect the keel to the body of the glenoid

component.

16. The shoulder prosthesis of claims 1 or 2 wherein:

the fixation member of the glenoid component comprises at least one peg connected to and extending away from the body of the glenoid component, each peg comprising the metallic material.

17. The shoulder prosthesis of claim 16 wherein:

each peg is connected to a mounting plate of the fixation member and a Morse taper is used to connect the mounting plate to the body of the glenoid component.

18. The shoulder prosthesis of claims 1 or 2 wherein:

the glenoid component is modular.

19. The shoulder prosthesis of claims 1 or 2 wherein:

the glenoid component is monoblock.

20. The shoulder prosthesis of claims 1 or 2 wherein:

the humeral component is modular.

21 . The shoulder prosthesis of claims 1 or 2 wherein:

the humeral component is monoblock.

22. The shoulder prosthesis of claims 1 or 2 wherein:

the body of the glenoid component is pear-shaped.

23. The shoulder prosthesis of claims 1 or 2 wherein:

the body of the glenoid component is dimensioned such that the glenoid component is flush with native peripheral glenoid bone when the glenoid component is secured to the scapula.

24. A shoulder prosthesis comprising:

a humeral component including a concave socket; and

a glenoid component including a head having a concave articulating surface and having a second surface opposite the articulating surface, the articulating surface being dimensioned for articulating in the socket of the humeral component, the second surface being dimensioned for being secured to a scapula, the glenoid component further including a fixation member extending away from the second surface,

wherein the socket of the humeral component comprises a polymeric material, and

wherein the head of the glenoid component comprises a metallic material.

25. The shoulder prosthesis of claim 24 wherein:

the socket of the humeral component consists essentially of the polymeric material, and

the head of the glenoid component consists essentially of the metallic material.

26. The shoulder prosthesis of claims 24 or 25 wherein:

the socket of the humeral component includes an average thickness of the polymeric material in the range of 5 millimeters to 20 millimeters, the thickness being measured from a bearing surface of the socket to a center point of the socket.

27. The shoulder prosthesis of claims 24 or 25 wherein:

28. The shoulder prosthesis of claims 24 or 25 wherein:

29. The shoulder prosthesis of claims 24 or 25 wherein:

30. The shoulder prosthesis of claims 24 or 25 wherein:

the humeral component further includes a stem connected to and extending away from the socket, the stem being dimensioned for insertion into an

intramedullary canal of a humerus.

31 . The shoulder prosthesis of claims 24 or 25 wherein:

the humeral component further includes a generally oblong keel connected to and extending away from the socket, the keel comprising the polymeric material.

32. The shoulder prosthesis of claims 24 or 25 wherein:

the humeral component further includes at least one peg connected to and extending away from the socket, each peg comprising the polymeric material.

33. The shoulder prosthesis of claims 24 or 25 wherein:

the fixation member of the glenoid component comprises a stem connected to and extending away from the head of the glenoid component.

34. The shoulder prosthesis of claim 33 wherein:

a Morse taper is used to connect the stem to the head of the glenoid component.

35. The shoulder prosthesis of claims 24 or 25 wherein:

the fixation member of the glenoid component comprises a generally oblong keel connected to and extending away from the head of the glenoid component, the keel comprising the metallic material.

36. The shoulder prosthesis of claim 35 wherein:

a Morse taper is used to connect the keel to the head of the glenoid

component.

37. The shoulder prosthesis claims 24 or 25 wherein:

the fixation member of the glenoid component comprises at least one peg connected to and extending away from the head of the glenoid component, each peg comprising the metallic material.

38. The shoulder prosthesis of claim 37 wherein:

each peg is connected to a mounting plate of the fixation member and a Morse taper is used to connect the mounting plate to the head of the glenoid component.

39. The shoulder prosthesis claims 24 or 25 wherein:

the socket of the humeral component comprises a base layer and a liner layer, and

a first thickness of the base layer as measured along a radial reference line from a tangent point T on a periphery of the socket to the concave articulating surface is in the range of 5 millimeters to 15 millimeters, and

a second thickness of the liner layer as measured along the radial reference line from the tangent point T on the periphery of the socket to the concave

articulating surface is in the range of 5 millimeters to 15 millimeters.

40. A method for using a shoulder prosthesis, the method comprising:

attaching a humeral component to a humerus, the humeral component including a concave socket; and

attaching a glenoid component to a glenoid surface of a scapula, the glenoid component including a head having a concave articulating surface and having a second surface opposite the articulating surface, the articulating surface being dimensioned for articulating in the socket of the humeral component, the second surface being dimensioned for being secured to a scapula, the glenoid component further including a fixation member extending away from the second surface,

wherein the socket of the humeral component comprises a polymeric material, and

wherein the head of the glenoid component comprises a metallic material.

41 . The method of claim 40 wherein:

42. The method of claim 40 wherein:

43. The method of claim 40 wherein:

44. The method of claim 40 wherein:

45. The method of claim 44 wherein:

a Morse taper is used to connect the stem to the body of the glenoid component.

46. The method of claim 40 wherein:

47. The method of claim 46 wherein:

a Morse taper is used to connect the keel to the body of the glenoid

component.

48. The method of claim 40 wherein:

49. The method of claim 48 wherein:

50. A method for using a shoulder prosthesis, the method comprising:

wherein the socket of the humeral component comprises a polymeric material, and

wherein the head of the glenoid component comprises a metallic material.

51 . The method of claim 50 wherein:

intramedullary canal of a humerus.

52. The method of claim 50 wherein:

53. The method of claim 50 wherein:

54. The method of claim 50 wherein:

55. The method of claim 54 wherein: a Morse taper is used to connect the stem to the head of the glenoid component.

56. The method of claim 50 wherein:

57. The method of claim 56 wherein:

a Morse taper is used to connect the keel to the head of the glenoid

component.

58. The method claim 50 wherein:

59. The method of claim 58 wherein: