The present invention relates to prosthetic systems for the replacement of limbs or portions thereof. More particularly, the invention concerns a modular system that can be used in the extremities that have experienced bone loss or significant, irreparable bone trauma.
Artificial or prosthetic joints of the extremities are well-known. Many of prosthetic joints are modular, meaning that they include a selection of different components to account for differences in patient anatomy or surgical procedures. For example, U.S. Pat. No. 5,314,479, owned by the assignee of the present invention, discloses a modular shoulder prosthesis that includes an array of selectable stems, bodies, collars and head members. The modular prosthesis of the '479 patent allows the orthopaedic surgeon to assemble a custom prosthetic joint by selecting different sizes, shapes and orientations of the individual joint components.
Certain orthopedic prosthetic devices include implants or stems configured to reside within the intramedullary canal of a long bone. For instance, the modular prosthesis of the '479 patent mentioned above includes a stem sized to be received within the humerus and held in place with bone cement. Two differently sized stems are provided, each having different lengths and diameters to accommodate differently sized bones. In lieu of a kit with differently sized stems, other systems utilize variable length stems. One such adjustable length implant includes threaded telescoping portions, such as the implant shown in U.S. Pat. No. 5,358,524. This particular device is intended for adjustment over time as the limb grows. An adjustable artificial femoral diaphysis is disclosed in U.S. Pat. No. 4,384,373 that employs a similar threaded telescoping arrangement to accommodate any length femur.
These modular or adjustable devices all require a certain amount of viable bone, and are not suited for limb preservation when a significant portion of a long bone has been lost due to tumor, end-stage revision or severe trauma. In cases involving significant bone loss, very little is presently available to preserve the damaged limb and the opportunity for mobility of the patient.
Consequently, there is a need for a system that allows preservation of a badly damaged limb, and more importantly for protecting patient mobility in the wake of severe damage to a limb. There is a further need for a system that can accommodate differences in patient anatomy, as well as differences in the traumatized limb to be repaired.
In order to address these needs, the present invention provides a comprehensive modular implant system designed to meet the challenges of limb-sparing surgery. In one embodiment, the comprehensive modular orthopaedic implant system comprises at least three components, with at least one component configured for replacement of a portion of the bone of a limb of a patient, and at least another component configured for implantation within a remaining portion of the bone. The implant system further includes a male-female engagement between adjacent ones of the components. In a preferred embodiment, the male-female engagement is a press-fit engagement, and most preferably a Morse taper engagement.
In one feature of the invention, at least one component includes a joint component configured to form part of a skeletal joint. For instance, the modular implant system contemplates a proximal femoral replacement for use with a hip joint prosthesis, as well as a distal femoral replacement and a proximal tibial replacement for a knee joint prosthesis.
In a further feature of the invention, the comprehensive modular orthopaedic implant system includes a stem configured for implantation within the intramedullary canal of the remaining bone. This stem can be used to replace a severely damaged portion of the long bone adjacent a particular joint being replaced. This modular stem component provides the orthopaedic surgeon with the ability to assess how much bone needs to be replaced and then assemble a modular construct meeting that need.
As an attribute of the overall modularity of the inventive system, a series of modular components can be combined to replace an entire long bone, such as a femur. The modular system thus include an array of segmental components that can act as spacers to fill the length of removed bone. These segmental component can be selected from a plurality of segmental components having different lengths. A given construct may include multiple segmental component selected from the plurality of segmental components having different lengths.
In one inventive feature, the plurality of segmental components can include a first group of segmental components having lengths of 25 mm, 30 mm, 35 mm, 40 mm and 45 mm. In another feature, a second group of segmental components can be provided having lengths of 65 mm, 85 mm, 105 mm and 125 mm. In a particular modular construct, a segmental component selected from the first group can be combined with a segmental component selected from either the first group or the second group to produce a combined length from 50 mm to 170 mm in 5 mm increments.
The invention contemplates various combinations of modular components for addressing different orthopaedic surgical needs. For instance, in one embodiment, the construct includes only a pair of stems configured for implantation within proximal and distal portions of the bone, and a spacer disposed between the pair of stems. Another construct utilizes a first joint component configured to form part of a skeletal joint at the proximal end of the limb, a second joint component configured to form part of a skeletal joint at the distal end of the limb, and at least two intermediate segmental components spanning the length of the limb between said first and second joint components, all incorporating a male-female engagement between adjacent one of the components.
For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and described in the following written specification. It is understood that no limitation to the scope of the invention is thereby intended. It is further understood that the present invention includes any alterations and modifications to the illustrated embodiments and includes further applications of the principles of the invention as would normally occur to one skilled in the art to which this invention pertains.
The present invention contemplates a limb preservation system that includes a comprehensive set of modular implants capable of addressing a wide range of orthopaedic conditions. Components of the system can be combined in a variety of ways to account for variations in patient anatomy and differences in bone or limb trauma. For instance, the comprehensive modular implant system of the present invention can be employed as a replacement for the proximal or distal femur, total femur, proximal tibia or a long bone mid-shaft. The particular modular components can be selected after consideration of the limb trauma, and more specifically in view of the degree and type of bone loss involved, such as might occur due to tumor, end-stage revision or trauma.
Referring to
On the other hand, a distal replacement can be fashioned from the components of the present comprehensive modular implant system. For instance, a distal femoral replacement 12, illustrated in
The modular system can be configured for total long bone replacement. In one embodiment, as shown in
Referring to
In some cases, the proximal and distal ends of the limb are intact, but the mid-shaft portion of the long bone is damaged beyond repair. In these instances, the modular implant system of the present invention provides a mid-shaft replacement 18 that can include opposite stems 26 joined by a female-female segmental component 42. The segmental component 42 can essentially operate as a spacer between the two stems 26 to span a space left by a removed portion of bone.
As best seen in the exploded diagrams of
The arrangement of the male and female elements for each connection shown in
Referring now to
In accordance with the present invention, the conventional proximal femoral component is modified to include a male-female connection element, such as a Morse taper bore 57 at the distal end of the component 20. In addition, the component includes a number of anti-rotation tabs 55 projecting from the distal end. The bore 57 and tabs 55 mate with complementary elements, as described herein.
With reference to the total femoral replacement 14 shown in
In order to accommodate the mating of the Morse taper components, the bore 57 of the proximal femoral component 20 communicates with a bore 58, as shown in
Referring again to
As shown in
Since the segmental component 22 incorporates a Morse taper fit, the taper bore 65 is provided with a vent bore 66, as shown in
In accordance with the present invention, the male-female segmental components 22 contribute to one aspect of the modularity of the present system. As illustrated in
In one aspect of the invention, the array of segmental components 22 is provided in 5 mm increments of increasing length. Thus, in a specific embodiment, the array includes male-female segmental components having lengths of 25, 30, 25, 40, and 45 mm. In the first instance, these lengths permit replacement of varying lengths of the long bone adjacent the proximal or distal ends. For instance, the segmental component 22 is used in the proximal femoral replacement 10, so the length of the component can be selected based on the amount of bone removed at the proximal end of the limb.
In a second instance, the lengths can be combined for a total long bone replacement, such as the total femoral replacement 14. In addition to the aforementioned lengths, the array can include longer components 22 having lengths of 65, 85, 105 and 125 mm. It can be appreciated that this selection of segmental component lengths permits combined lengths increasing in 5 mm increments from the 45 mm component to the 125 mm component. For instance, a 50 mm length can be achieved with two 25 mm components, while a 110 mm length uses an 85 mm and a 25 mm segmental component. Virtually any length of long bone can be accommodated by combining only two of the segmental components from the array of sizes just described. Viewed from another angle, a kit containing the components of the comprehensive modular implant system of the present invention only needs to include one of each of the sizes mentioned above to replace the bone virtually any limb.
In view of the “mix and match” aspect of the array of segmental components 22, the need for the male-male segmental component 36 can be appreciated. Specifically, since any of the segmental components 22 can be combined and then mated with other replacement components, it is important that the components 22 include a male and a female connection element. If it is desirable to include only female Morse taper bores in the proximal or distal femoral/tibial components, then it is inevitable that a like Morse element will be juxtaposed when a replacement stack is created. Thus, the male-male segmental component 36 can be interposed to provide a connection for juxtaposed female elements.
Returning to
The distal femoral component 28 mates with a tibial insert bearing 30, shown in detail in
As with the other components, the knee joint elements represented by the components 28, 30 and 32 can all be formed substantially as any known knee joint. For instance, the components can be part of the S-ROM® knee implant provided by DePuy Orthopaedics, Inc. The revision tray 32 can be the M.B.T. tray, also from DePuy Orthopaedics. As shown in
The modular implant system of the present invention is capable of certain of the replacement configurations that utilize elongated stems for fixation within the intramedullary canal of the associated long bone. Thus, a kit for this modular system can include femoral stems 26 and 26′ as illustrated in
It can be appreciated that any of the stems or stem extensions can have an exterior surface prepared for cementing within an existing bone. Thus, the stems or extension can include channels or openings for receiving bone cement and providing a firm fixation to the surrounding bone. These same components can be porous coated using known technology. On the other hand, components that are not intended for fixation to surrounding tissue, such as the segmental components, are preferably treated to have a very smooth, non-adherent surface, such as through bead-blasting and polishing.
The comprehensive nature of the modular implant system of the present invention contemplates a kit that can be used for proximal tibial replacement as part of a prosthetic knee joint. Thus, as shown in
A further feature of the modularity of the present invention is the ability to replace only a segment of a long bone, while leaving the proximal and distal ends intact. Such a replacement might occur where a limb has suffered a severe trauma at the mid-section of the bone, requiring replacement of that section. In order to address this trauma indication, the present invention provides a mid-shaft replacement 18, shown in
The heart of this mid-shaft replacement 18 is the female-female segmental component 42. In accordance with convention established above, this component 42 includes a female connection element, such as Morse taper bore 97, and anti-rotation tabs 99 at each end of the component. Due to the nature of mid-shaft bone replacement, it is preferable to offer the segmental component 42 in a single length. Most preferably, the component 42 has a length of 55 mm, which is believed to be optimum for most mid-shaft replacement procedures. Any greater damage to the bone would usually require replacement of the entire bone, using the replacement assembly shown in
The components of the modular implant system of the present invention can be formed of conventional bio-compatible metals or suitably strong materials. For instance, the proximal femoral and proximal tibial components 20 and 38, respectively, can be formed of a titanium alloy. The distal femoral component 28 and the stems and extensions can be formed of a cobalt-chromium alloy. Most preferably, the segmental components 22, 36 and 42 are formed of a titanium alloy.
The stem and extensions can be cemented or porous coated and can be straight or bowed depending upon the preferred application. These components can be offered in conventional lengths and diameters, with femoral straight stems in 100 mm and 125 mm length and curved stems in 150 mm and 200 mm lengths. The diameters can range from 9 mm to 18.5 mm. Tibial stems can have a conventional diameter of 13 mm and lengths of 30 mm or 60 mm. In addition, appropriately modified fluted tibial rods can be provided of lengths between 75 mm and 150 mm and diameters between 10 mm and 24 mm.
In one preferred embodiment, the comprehensive modular implant system is provided to the orthopaedic surgeon in a kit. The kit can include all of the components necessary to perform any of the replacement surgeries described above. The components can be assembled in the operating room, if necessary.
While the invention has been illustrated and described in detail in the drawings and foregoing description, the same should be considered as illustrative and not restrictive in character. It is understood that only the preferred embodiments have been presented and that all changes, modifications and further applications that come within the spirit of the invention are desired to be protected.
This application is a continuation of co-pending application Ser. No. 10/135,791, filed on Apr. 30, 2002, the disclosure of which is hereby totally incorporated by reference in its entirety.
Number | Date | Country | |
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Parent | 10135791 | Apr 2002 | US |
Child | 11241461 | Sep 2005 | US |