Abstract:
A method prepares an ankle joint of a patient for replacement. The patient includes a tibia ( 20 ) having a medial portion ( 22 ), a talus ( 40 ), and an ankle ( 10 ) having a medial portion. The method employs a cutting alignment apparatus ( 50 ) including a first portion external to the patient and a second portion, and surgically prepares and exposes the medial portion of the ankle for replacement. The second portion of the cutting alignment apparatus is coupled to the tibia, and a cutting guide ( 90 ) is disposed with respect to the cutting alignment apparatus. The medial portion of the tibia is detached, a portion of the tibia proximate the talus is cut, and a portion of the talus proximate the tibia is cut. An ankle prosthesis ( 100 ) is installed to the ankle, and the medial portion of the tibia is reattached.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Pat. Appl. Ser. No. 60/761,007, filed Jan. 20, 2006; and of U.S. Provisional Pat. Appl. Ser. No. 60/781,634, filed Mar. 13, 2006. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates to a method of preparing an ankle joint for replacement, and more particularly to an ankle prosthesis and a method of preparing the ankle joint for replacement implementing such ankle prosthesis and an alignment apparatus that enables such replacement to be performed from a medial position on the ankle. 
         [0004]    2. Background Information 
         [0005]    Ankle prostheses and ankle replacement methods have been implemented for the past few decades producing numerous prostheses and approaches to the treatment of diseased, injured or otherwise compromised ankle joints. Many types of total ankle prostheses have been developed including a cylindrical-type ankle replacement, the spherical-type ankle replacement, the sliding cylindrical-type ankle replacement, the Buechel-Pappas Total Ankle Replacement System, the Scandinavian Total Ankle Replacement system, or STAR system, Hintegra ankle system, ESKA implant, and the Agility™ Total Ankle System. Generally two broad categories exist in ankle replacement prostheses, fixed-bearing ankle implants having fixed components and mobile-bearing implants having mobile components. The fixed-bearing ankle implants are generally semi-constrained, although some are fully constrained, to have a single articulation capability between a tibial and a talar component with some allowance for rotation. The mobile-bearing implants have minimal constraints due to the articulation permitted by a meniscus positioned between tibial and talar components. 
         [0006]    Many ankle prostheses in the United States are the fixed-bearing ankle implant type, such as the Agility™ Total Ankle System, due to its FDA approval status. In these types of semi-constrained fixed bearing devices, the tibial prosthesis component and the talar prosthesis component have a plastic insert slidingly positioned within the tibial component between the two components. In these fixed-bearing ankle implants, the two components generally work directly with each other in various fashions and all require incisions and installation from an anterior position on the ankle, save certain methods published for the ESKA ankle replacement. 
         [0007]    Most of the known prostheses further require significant amounts of bone to be resected from the tibia and talus in order to install the traditionally bulky components into the ankle joint. As is well known in the art, the more bone that is removed, or resealed, the more likely the failure of the component as the bone typically is its hardest at its outside surface. Thus, many devices fail for reasons of subsidence of the component wherein the significant bone resection and the implanting of a component will cause the component to crush into the cancellous bone over time under pressure. 
         [0008]    Another ankle replacement that has been developed is the ESKA implant which differs from the other ankle implants in that it requires incision and installation from a lateral position on the ankle. However, this preparation requires the devascularization of the fibula, release of the syndesmotic ligaments and significant bone resection. 
         [0009]    No known prosthesis disclosed is designed, configured and installed from a medial position on the ankle. 
         [0010]    Some of the most common problems encountered with prior art ankle prostheses are loosening of the components, instability, loss of bone support, subsidence, inadequate motion and noticeable scaring on the most visible parts of the ankle. Further, and more importantly, ankle replacement is more challenging than other procedures such as hip or knee replacement due to the limited soft tissue envelope that is sparse at the ankle and has minimal flexibility. Thus, ankle replacement is associated with a high complication rate. This complication rate is exacerbated by the dense intersection of tendons and nerves in the anterior (or front) and lateral sides of the ankle. 
         [0011]    Accordingly, wound problems are not uncommon due to the present techniques and prostheses known in the art. 
       SUMMARY OF THE INVENTION 
       [0012]    The present invention is directed to a method and apparatus for ankle replacement. A cutting alignment apparatus may be provided for assisting in performing an arthroplasty procedure. The cutting alignment apparatus may include a first positioner having first rods extending therefrom in a first direction and first alignment extensions extending from the first positioner in a second direction. The first positioner may further have securing apertures extending through the first positioner in a second direction. A second positioner may have second rods extending therefrom in the second direction. The second positioner may further have second apertures extending therethrough in the first direction and may be in communication with the first positioner via the first rods, which are positioned within the second apertures. A third positioner may have third apertures extending therethrough in the second direction wherein the third positioner is in communication with the second positioner via the second rods positioned within the third apertures. The third positioner may further have a fourth aperture extending therethrough in a third direction. 
         [0013]    The method of ankle replacement may comprise the steps of employing an external fixator apparatus to position an ankle, surgically preparing and exposing a medial portion of the ankle for replacement, forming at least one alignment aperture in a medial portion of the tibia and performing an osteotomy of the medial portion of the tibia, applying a cutting alignment apparatus such that a cutting guide of the cutting alignment apparatus is positioned in a desired orientation, cutting a portion of a tibia and a talus of the ankle, installing an ankle prosthesis and reattaching the medial portion of the tibia. 
         [0014]    In accordance with one aspect of the invention, a joint prosthesis comprises: a first joint component having a first locking feature; a second joint component; and a meniscus insert disposed between the first joint component and the second joint component, wherein the meniscus insert has a second locking feature, which is structured to lock to the first locking feature of the first joint component, and wherein the first and second locking features are both structured to permit the meniscus insert to pivot with respect to the first joint component. 
         [0015]    As another aspect of the invention, a method prepares an ankle joint of a patient for replacement. The patient includes a tibia having a medial portion, a talus, and an ankle having a medial portion. The method comprises: employing a cutting alignment apparatus including a first portion external to the patient and a second portion; surgically preparing and exposing the medial portion of the ankle for replacement; coupling the second portion of the cutting alignment apparatus to the tibia; disposing a cutting guide with respect to the cutting alignment apparatus; detaching the medial portion of the tibia; cutting a portion of the tibia proximate the talus; and cutting a portion of the talus proximate the tibia. 
         [0016]    As another aspect of the invention, a cutting alignment apparatus is for use in performing an arthroplasty procedure of a patient including a tibia having a medial portion, a talus, and an ankle. The cutting alignment apparatus comprises: a first positioner comprising first rods extending therefrom in a first direction and first alignment extensions extending from the first positioner in a second direction, the first positioner being structured to be secured to the tibia; a second positioner comprising second rods extending therefrom in the second direction, and second apertures extending therethrough in the first direction, the first rods of the first positioner being positioned within the second apertures; a third positioner comprising third apertures extending therethrough in the second direction, a fourth aperture extending therethrough in a third direction, and a third rod extending from the fourth aperture, the second rods of the second positioner being positioned within the third apertures; and a cutting guide positioned from the third rod and being structured to face the medial portion of the tibia and the talus. 
         [0017]    These and other features and characteristics of the present invention, as well as the methods of operation and functions of the related elements of structures and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended to unduly limit the present invention. As used in the specification and the claims, the singular form of “a”, “an” and “the” include plural referents unless the context clearly dictates otherwise. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1  is a perspective view of an embodiment of a cutting alignment apparatus in accordance with the present invention; 
           [0019]      FIG. 2  shows a perspective view of an embodiment of a first positioner in accordance with the present invention; 
           [0020]      FIG. 3  is a perspective view of an embodiment of a second positioner in accordance with the present invention; 
           [0021]      FIG. 4  is a perspective view of an embodiment of a third positioner having a cutting guide positioned thereon in accordance with the present invention; 
           [0022]      FIG. 5  shows a front elevational view of an embodiment of a preparation step for the medial portion of the tibia in accordance with the present invention; 
           [0023]      FIG. 6  illustrates a lateral view of an ankle that has undergone an embodiment of a preparation step for the medial portion of the tibia in accordance with the present invention; 
           [0024]      FIG. 6   a  illustrates a lateral view of an ankle that has undergone an embodiment of a preparation step for the medial portion of the tibia in accordance with the present invention; 
           [0025]      FIG. 6   b  illustrates a lateral view of an ankle that has undergone an embodiment of a preparation step for the medial portion of the tibia in accordance with the present invention; 
           [0026]      FIG. 7  is a lateral elevational view of an embodiment of a first positioner, having an alignment rod positioned therethrough, as it may be secured to the tibia in accordance with the present invention; 
           [0027]      FIG. 8  is a front elevational view of an embodiment of a second and third positioner, having an alignment rod positioned therethrough, as they may be positioned in accordance with the present invention; 
           [0028]      FIG. 9  shows a front elevational view of an embodiment of a preparation step for the tibia and talus in accordance with the present invention; 
           [0029]      FIG. 10  is a perspective view of a saw as it may be used with an embodiment of a cutting guide in accordance with the present invention; 
           [0030]      FIG. 11  is a front elevational view of an embodiment of a preparation step for the tibia and the talus in accordance with the present invention; 
           [0031]      FIG. 12  is a plan view of an embodiment of a measuring implement in accordance with the present invention; 
           [0032]      FIG. 13  illustrates a front elevational view of an embodiment of a preparation step utilizing the measuring implement in accordance with the present invention; 
           [0033]      FIG. 14  shows a perspective view of an embodiment of a tibial component of an ankle replacement as it may be positioned in accordance with the present invention; 
           [0034]      FIG. 14   a  is a perspective view of an embodiment of a tibial component of an ankle replacement in accordance with the present invention; 
           [0035]      FIG. 14   b  is a perspective view of an embodiment of a tibial component of an ankle replacement in accordance with the present invention; 
           [0036]      FIG. 14   c  is a perspective view of an embodiment of a tibial component of an ankle replacement in accordance with the present invention; 
           [0037]      FIG. 15  illustrates a perspective view of an embodiment of a talar component of an ankle replacement as it may be positioned in accordance with the present invention; 
           [0038]      FIG. 16  is a perspective view of an embodiment of a meniscus insert of an ankle replacement in accordance with the present invention; 
           [0039]      FIG. 16   a  is a perspective view of an embodiment of a meniscus insert of an ankle replacement in accordance with the present invention; 
           [0040]      FIG. 16   b  is a perspective view of an embodiment of a meniscus insert of an ankle replacement in accordance with the present invention; 
           [0041]      FIG. 17  is a front elevational view illustrating an embodiment of an inserted ankle replacement and a preparation step for the medial portion of the tibia in accordance with the present invention; 
           [0042]      FIG. 18  is a perspective view of an embodiment of a cutting guide in accordance with the present invention; 
           [0043]      FIG. 19  illustrates a perspective view of an embodiment of a talar component of an ankle replacement as it may be positioned in accordance with the present invention; 
           [0044]      FIG. 20  is a perspective view of an embodiment of a cutting guide in accordance with the present invention; and 
           [0045]      FIG. 21  is illustrates a perspective view of an embodiment of a talar component of an ankle replacement as it may be positioned in accordance with the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0046]    For purposes of the description hereinafter, the terms “upper”, “lower”, “right”, “left”, “vertical”, “horizontal”, “top”, “bottom”, “lateral”, “longitudinal” and derivatives thereof shall relate to the invention as it may be oriented in the drawing figures. However, it is to be understood that the invention may assume various alternative variations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the invention. Hence, specific dimensions and other physical characteristics related to the embodiments disclosed herein are not to be considered as unduly limiting. For example, certain portions of the invention are shown as oblong blocks having circular holes positioned therethrough, which could be configured in a number of shapes and manners as various embodiments of the invention described herein. 
         [0047]    As employed herein, the term “osteotomy” is employed in accordance with its traditional meaning to refer to the cutting or otherwise suitable removal or severing of bone. 
         [0048]    As employed herein, the terms “cut” and “cutting” refer to the process of slicing, chiseling, or otherwise suitably removing or severing bone. 
         [0049]    As employed herein, the terms “drill” and “drilling” refer to the process of creating a hole, bore or aperture in bone. 
         [0050]    As employed herein, the term “cutting device” refers to any known or suitable tool or mechanism suitable for “cutting” bone. 
         [0051]    As employed herein, the term “drilling device” or “drill” refers to any known or suitable tool (e.g., without limitation, drill bit) or mechanism for “drilling” bone. 
         [0052]    As employed herein, the term “bone” refers to any known or suitable human, animal or artificial structure suitable for use in the body as a component of the skeleton. 
         [0053]    As employed herein, the term “guide” refers to any known or suitable mechanism, apparatus or fixture (e.g., without limitation, jig), or suitable combination thereof, for establishing a predetermined desired relationship (e.g., suitably precise alignment) between two or more components in order to perform a procedure (e.g., without limitation, an osteotomy) in a suitably precise and accurate manner, which can be substantially replicated or reproduced. 
         [0054]    As employed herein, the terms “fastener” and “fastening mechanism” refer to any known or suitable connecting, securing or tightening material, structure or device and expressly include, but are not limited to, suitable protrusions for securing one component to another, as well as receptacles (e.g., without limitation, recesses; slots; sockets; grooves), combinations of interlocking protrusions and receptacles, welds, and devices such as pins, rivets, screws, bolts and any suitable combination of bolts, nuts (e.g., without limitation, lock nuts) and/or washers. 
         [0055]    As employed herein, the statement that two or more parts are “coupled” together shall mean that the parts are joined together either directly or joined through one or more intermediate parts. 
         [0056]    As employed herein, the term “number” refers to the quantity one or an integer greater than one (i.e., a plurality). 
         [0057]    As employed herein, the term “patient” shall mean human beings and other members of the animal kingdom. 
         [0058]    As employed herein, the term “meniscus” shall mean any mobile bearing structure or surface between two other structures or surfaces, such as, for example, a meniscus insert between first and second joint components. 
         [0059]    The present invention is directed to an ankle prosthesis, a method of preparing the ankle joint for replacement implementing such ankle prosthesis and an alignment apparatus that enables such replacement to be performed from a medial position on the ankle, as illustrated in various embodiments in  FIGS. 1-21 . In general, an ankle prosthesis  100  of the present invention is adapted for use in connection with the method of preparing the ankle joint for replacement, which may also implement a cutting alignment apparatus  50 . As discussed hereinafter, the components of the ankle prosthesis  100  and the cutting alignment apparatus  50  provide a configurable and modifiable ankle replacement system and alignment therefore, allowing a patient receiving such method of ankle replacement to more effectively overcome the symptoms for which the arthroplasty procedure was performed. 
         [0060]    Generally in arthroplasty procedures, an external fixator apparatus (not shown) may be applied to the area of interest to assist in normalizing and distracting the joint that is intended to undergo the medical procedure. More specifically, the external fixator apparatus is employed to distract the bones concerned with the ankle joints for positioning the ankle joint into proper alignment. In a preferred embodiment, the method of preparing the ankle joint includes applying the external fixator apparatus to the lateral side of the lower leg of the patient. 
         [0061]    As is common in the art of arthroplasty procedures, pins, nails or screws may be placed into the tibia  20 , the talus  40  and the calcaneus  36 . The external fixator apparatus may be actuated to separate the tibia  20  from the talus  40  a sufficient distance such that the proper alignment is achieved in order to perform the remaining steps of the method of preparation of the present invention. However, the final separation will be determined by the medical professional implementing such external fixator apparatus based upon the symptoms of the patient and the diagnosis of the medical professional that will best accomplish a successful arthroplasty procedure. After the arthroplasty procedure is completed, the external fixator may be distracted slowly until the ankle joint is in the proper alignment and pain is relieved. When the medical professional is satisfied that distraction is no longer necessary, the external fixator may be removed. 
         [0062]    As can be seen in  FIG. 5 , the method of preparation includes the forming of alignment apertures  21  into the medial portion  22  of the tibia  20 . The forming of the alignment apertures  21  may be accomplished in a number of ways including, but not limited to, drilling, boring, etc. with a tool  23 . In a preferred embodiment, at least two alignment apertures  21  may be formed in the medial portion  22  of the tibia  20  as illustrated in  FIG. 6 . However, due to varied circumstances it may only be necessary in certain instances to form one alignment aperture  21  in an appropriate location such as, for example, in the vicinity of the valley of the chevron osteotomy discussed in greater detail below. 
         [0063]    The method further includes an osteotomy of the medial portion  22  of the tibia  20 . In a preferred embodiment, the osteotomy is performed forming tibial chevron section  25  where the medial portion  22  of the tibia  20  is removed as shown in  FIG. 6 . In order to perform such osteotomy, the posterior tibial tendon retinaculum and superficial deltoid may be taken down such that the medial portion  22  of the tibia  20  may be removed as illustrated in  FIGS. 6-6   b.    
         [0064]    Further, as can be seen in  FIGS. 6   a  and  6   b , more than one type of osteotomy may be performed on the medial portion  22  of the tibia  20  in accordance with the invention. For example, as shown in FIG.,  6   a , a crescentic section  25   a  may be removed by using a crescentic saw blade to perform the osteotomy. Similarly, as also generally shown in  FIG. 6   a , a circular section  25   a  may be removed by using a biradial saw blade. A further example of the osteotomy that may be performed, as determined by the medical professional implementing such method of preparation according to the present invention, is a valley section  25   b  as illustrated in  FIG. 6   b . Accordingly, any number of osteotomies may be performed, as may be determined by the medical professional based upon the composure and integrity of the medial portion  22  of the tibia  20  specific to the patient undergoing such method of preparation may be used in accordance with the present invention. 
         [0065]    Next, a lateral incision (not shown) may be made over a distal portion  32  of the fibula  30  which is shown in  FIG. 8 . The incision may be made such that the syndesmosis located in this area of the ankle may be exposed. A dissection may then be performed such that at least the inferior aspect of the syndesmosis may be taken down. This may further expose the distal portion  32  of the fibula  30  to assist in performing the arthroplasty procedure and preventing unnecessary damage to the distal portion  32  of the fibula  30 . For example, exposing this area visually enables prevention of damage from over cutting, as will be described in greater detail below, and may also provide access to the lateral side of the ankle for assisting in positioning the ankle prosthesis  100  as can be seen in  FIGS. 11 ,  13  and  17 . 
         [0066]    The cutting alignment apparatus  50 , and components thereof, is illustrated generally in  FIGS. 1-4  and  7 - 11  for assisting in performing an arthroplasty procedure as will be discussed in greater detail below. The main components of the cutting alignment apparatus  50  include a first positioner  60 , a second positioner  70  and a third positioner  80 . As can be seen in the drawings, a cutting guide  90  may also be attached in order to perform embodiments of the ankle preparation method described herein. Although the cutting alignment apparatus  50  is separable for convenience in sterilizing the cutting alignment apparatus  50 , in accordance with the present invention, the cutting alignment apparatus  50  may also be unitary provided it allows for the same functionality. Accordingly, when component portions of the cutting alignment apparatus  50  are discussed, it is herein understood that other portions of the cutting alignment apparatus  50  may also be physically attached during these steps. 
         [0067]    For purposes of describing the cutting alignment apparatus  50 , several components of the cutting alignment apparatus  50  will be described based upon their interspatial relations with other components. Accordingly, a first direction  61 , a second direction  71  and a third direction  81  will be used to describe these interrelated components. As viewed in  FIG. 1 , the first direction  61  is indicated with an arrow and corresponds with the indicated direction with reference to the X axis generally. Likewise, the second direction  71  is also indicated with an arrow and corresponds with the direction indicated by the arrow in reference to the Y axis generally. The third direction  81  is also indicated with an arrow and corresponds with the direction indicated with reference to the Z axis generally. Again, these dimensional descriptions related to the embodiments disclosed herein are not to be considered as unduly limiting but are merely used for the purpose of describing embodiments of the general interspatial relations of the components of the present invention. 
         [0068]    The first positioner  60  may be utilized for accomplishing several attributes of alignment with regards to the expected positioning of components that comprise the ankle joint. In particular, referring to  FIGS. 1 ,  2  and  7 , the first positioner  60  may have an apparatus alignment rod  68  positioned within an alignment rod aperture  67 . The alignment rod aperture  67  may be positioned through the first positioner  60  generally vertically or in a direction with reference to the Z axis. Accordingly, the alignment rod  68  may be retained within the alignment rod aperture  67  to assist in alignment of the ankle  10  with respect to various alignment orientations such as, for example, varus/valgus alignment. 
         [0069]    Once alignment of the first positioner  60  is determined, first alignment extensions  66  of the first positioner  60  may be used to locate the tibia  20 . First alignment extensions  66  extend from the first positioner  60  in the second direction  71  generally. The first positioner  60  may also have securing member apertures  65  extending through the first positioner  60  in the second direction  71  as well. The securing member apertures  65  preferably do not intersect with the first alignment extensions  66 , although it is possible provided that alignment extensions  66  do not interfere with elements positioned within securing member apertures  65  such as, for example, where alignment extensions  66  are removable or repositionable to prevent interference. Alternatively, securing member apertures  65  may not be necessary and thus would not be present in the first positioner  60 , as will be discussed in greater detail below. 
         [0070]    While first alignment extensions  66  are resting on the tibia  20  with the first positioner  60  in the desired aligned orientation, securing members  63  may be inserted into the tibia  20  through securing member apertures  65  as illustrated in  FIGS. 7 and 8 . Securing members  63  may generally comprise pins, nails or screws that may be secured into the tibia  20 , thus securing the first positioner  60  in place. However, as mentioned above, securing apertures  65  may not be necessary as alternative securing means (not shown) may be implemented in place of securing members  63 . For example, a medical professional may determine to perform the method of preparation implementing bone clamps (not shown) or securing straps (not shown) to secure the first positioner  60  in place. 
         [0071]    The first positioner  60  has first rods  64  extending from the first positioner  60  in the first direction  61 . The first rods  64  may be used to connect the first positioner  60  to the second positioner  70 , unless second positioner  70  is already connected in a unitary embodiment. The first positioner  60 , first rods  64  and first alignment extensions  66  may be constructed of any suitable materials able to undergo the sterilization processes required for surgical instrumentation. Further, first rods  64  and first alignment extensions  66  may or may not be detachable from the first positioner  60  depending upon the desired orientation of the cutting alignment apparatus  50  and restrictions of the required sterilization processes and equipment. 
         [0072]    The second positioner  70  has second rods  74  extending in the second direction  71  from the second positioner  70 . The second positioner  70  also has second apertures  72  extending through the second positioner  70  in the first direction  61 . Thus, the first rods  64  may be positioned within the second apertures  72  to connect the second positioner  70  to the first positioner  60 . The second positioner  70  may then be in communication with the first positioner  60  accordingly. In a preferred embodiment, the second positioner  70  will be adjustably engaged with the first positioner  60  such that the second positioner  70  may be translated along first rods  64  to be positioned appropriately for the overall alignment of the cutting alignment apparatus  50 . For example, the second positioner  70  may slide along first rods  64  to allow adjustability. The second rods  74  and second positioner  70  may likewise be constructed of any suitable materials able to undergo the sterilization processes required for surgical instrumentation and may or may not be detachable from one another. 
         [0073]    The third positioner  80  has third apertures  82  extending through the third positioner  80  in the second direction  71 . The second rods  74  may be positioned within the third apertures  82 . Again, the positioning of the second rods  74  within the third apertures  82  may form the connection between the second and third positioners  70 ,  80  in the separable embodiment of the invention or otherwise may already be thus positioned in the unitary embodiment. Thus, the third positioner  80  may be in communication with the second positioner  70  via the second rods  74  positioned within the third apertures  82 . In a preferred embodiment, the third positioner  80  may also be adjustably engaged with the second positioner  70  in a similar manner as the connection between the first and second positioners  60 ,  70  providing translation of the third positioner  80  in order to properly position the third positioner  80  for the overall alignment of the cutting alignment apparatus  50 . 
         [0074]    The third positioner  80  also has a fourth aperture  86  extending through the third positioner  80  in the third direction  81 . A third rod  84  may be positioned within the fourth aperture  86  that may be removable or merely adjustable within the fourth aperture  86  as in the unitary embodiment. At the end of the third rod  84 , the cutting guide  90  may be positioned. Accordingly, the cutting guide  90  may be in communication with the third positioner  80  such that the cutting guide  90  may be adjusted, or translated, along at least the Z axis with reference to the third direction  81 . In order to assist in maintaining the desired position of the cutting guide  90 , at least one adjustor  85  may be employed. Adjustor  85  may be a fine screw to allow for fine adjustments along the Z axis or may otherwise be a course position holder used to secure third rod  84  in a desired position. The cutting guide  90  may also be permitted to rotate about the Z axis in order to permit further adjustment if necessary. 
         [0075]    The third positioner  80  may be utilized for accomplishing several attributes of alignment with regards to the desired positioning of the cutting guide  90  and the position of the lower leg and ankle joint generally. In particular, referring to  FIGS. 1 ,  4  and  8 , the third positioner  80  may have a cutter alignment rod  88  positioned within a cutter alignment rod aperture  87 . The cutter alignment rod apciture  87  may be positioned through the third positioner  80  generally vertically or in a direction with reference to the Z axis. The cutter alignment rod  88  may thus be retained within the cutter alignment rod aperture  87  to assess the alignment of the ankle  10  and lower leg with respect to various alignment orientations such as, for example, procurvation/recurvation alignment. Once the alignment of the ankle  10  and lower leg is diagnosed through the use of the cutter alignment rod  88 , the cutting guide  90  may be positioned more accurately to the desired orientation. 
         [0076]    The third positioner  80 , third rod  84 , cutter alignment rod  88 , adjustor  85  and cutting guide  90  may all be constructed of any suitable materials able to undergo the sterilization processes required for surgical instrumentation and may or may not be detachable from one another. 
         [0077]    As shown in  FIGS. 9-11 ,  14  and  15  in a preferred embodiment, the cutting guide  90  is specifically configured to be implemented with the particular mounting portions  112 , 122  of the ankle prosthesis  100 . Accordingly, the cutting guide  90  is provided with mount cut apertures  91  that correspond with mounting portions  112 , 122  of the ankle prosthesis  100 . Other mounting configurations may require differing mount cut apertures depending upon the configuration of alternate mounting portions in accordance with the present invention. For example, alternate embodiments may include triangular mounting portions  112   b , cross mounting portions  112   c , etc. as opposed to cylindrical mounting portions  112 , 122  as will be discussed in greater detail below. 
         [0078]    As can be seen in  FIGS. 1 ,  4  and  9 - 11 , the cutting guide  90  has cutting slots  92  positioned therethrough. Cutting slots  92 , in the preferred embodiment, are of a sufficient length to permit adequate cutting of the section of bone to be removed. In addition, the cutting slots  92  have a sufficient height to permit a blade  142  of a saw  140  to pass therethrough while guiding the blade  142  along the desired orientation of the cutting guide  90 . Accordingly, the cutting slots  92  are positioned to ensure the proper cut once the cutting guide  90  is aligned. 
         [0079]    Before the cutting step begins, the cutting guide  90  may be secured to the tibia  20  to ensure the cutting guide  90  is properly positioned. Thus, cutting guide  90  may be provided with cutting securing member apertures  95  positioned therethrough. Accordingly, cutting securing members  93  may affix the cutting guide  90  to the ankle  10  to ensure a proper cutting location insertion into the bone of the ankle  10 . Securing members  93  may comprise nails, screws, pins etc. Again, as with the first positioner  60 , cutting guide  90  may be secured to ensure proper cutting orientation in other fashions in accordance with the present invention. For example, a medical professional may determine to perform the method of preparation implementing bone clamps (not shown) or securing straps (not shown) to secure the cutting guide  90  in place. 
         [0080]    The method may further include the use of retractors (not shown) before the cutting step. Retractors are generally known in the surgical arts and may be implemented to hold back the edges of the surgical incision made on the medial area of the ankle  10 . 
         [0081]    As suggested above, protectors (not shown) may be inserted into the area exposed near the distal portion  32  of the fibula  30  to prevent unnecessary damage that may occur from over cutting. In addition, a stop  144  may be implemented on the blade  142  of the saw  140  to prevent over cutting. 
         [0082]    Referring to  FIGS. 9-11  and  13 , the preparation of the tibia  20  and talus  40  of ankle  10  to receive the ankle prosthesis  100  is shown. As can be seen in  FIG. 9 , a tool such as, for example, a drill  97  may be used with the cutting guide  90  to form a tibial mounting recess  26  in the tibia  20 . The drill  97  is positioned within the mount cut aperture  91  and inserted into the tibia  20  a desired depth. Various methods to control the depth may be implemented including, but not limited to, a stop (not shown) on the drill, a mark on the drill  97  indicating the desired depth, etc. As can be seen in  FIG. 14 , the tibial mounting recesses  26  will provide a configuration to which the ankle prosthesis  100  may be secured. Likewise, the drill  97  may also be inserted into the lower mount cut apertures  91  a desired depth to form a talar mounting recess  44  in the talar dome  42  as shown in  FIGS. 9 and 15 . 
         [0083]    As discussed above, alternate embodiments may include triangular mounting portions  112   b , cross mounting portion  112   c , etc., as opposed to cylindrical mounting portions  112 , 122  and illustrated in  FIGS. 14   b - 14   c . Likewise, triangular mounting portions and, cross mounting portions (similar to portions  112   b , 112   c ) may also be implemented in a similar fashion with other mounting components of the ankle prosthesis  100  (i.e., talar mounting component  120  discussed below). Accordingly, other tools may be used to form mounting recesses that conform to the mounting portions of the ankle prosthesis  100  selected by the medical professional. In addition, the cutting guide will also be provided with mount cut apertures that correspond with the desired shape of mounting recesses in accordance with present invention. 
         [0084]    With the cutting guide  90  secured to the ankle  10 , and the mounting recesses  26 , 44  formed, the osteotomy of the tibia  20  and talar dome  42  may be performed using the saw  140  positioned through the cutting slots  92 . Although in the preferred embodiment the mounting recesses  26 , 44  are formed before the osteotomy of the tibia  20  and talar dome  42 , these steps may be reversed as preferred by the medical professional implementing such method of preparation according to the present invention. 
         [0085]      FIGS. 10 and 11  illustrate the saw blade  142  as it may be utilized to make a generally straight cut to form tibial section  28  and a talar section  46 . In the preferred embodiment, the tibial section  28  will intersect the tibial mounting recess  26  and the talar section  46  will intersect the talar mounting recess  44 . Such intersection will better prepare the ankle  10  to receive the ankle prosthesis  100 . 
         [0086]    A measuring device  150  may be employed to determine the appropriate size of the ankle prosthesis  100 . As can be seen in  FIG. 13 , the measuring device  150  is used to measure the dimensions of the tibial section  28  as well as the talar section  46 . The measuring device  150  may be made of any suitable materials as are consistent with the requirements of the sterilization processes required. Further, the measuring device  150  may use any scale, as indicated by the shading in  FIG. 12 , necessary to best correlate that measurement with the appropriate sized ankle prosthesis  100 . 
         [0087]    As shown in  FIGS. 14 ,  14   a ,  15 ,  16  and  17 , the ankle prosthesis  100  may include a tibial component  110 , a talar component  120  and a meniscus insert  130 . When positioned together in the preparation of an ankle replacement, they function to serve the patient as an artificial ankle. The tibial component  110  is impacted into tibial mounting recesses  26 , as shown in  FIG. 14 , using conventional methods known in the art. For example, as will vary by medical professional and standards set by the FDA, the tibial component insert  110  may be cemented into the tibia  20  or otherwise secured as required by regulation. Likewise, as can be seen in  FIG. 15 , the talar component  120  may be impacted into the talar mounting recesses  44 . 
         [0088]    The tibial component  110  of the ankle prosthesis.  100  is generally formed out of a plate  114  having the tibial mounting portions  112  formed in the top of the plate  114 . The plate  114  may be treated or otherwise texturized to better assist in the acceptance of the ankle prosthesis with the bone. On the opposing side of the plate  114  from the tibial mounting portions  112  is formed a recess  116  having inner walls  115  and a recessed surface  117 . Recess  116  is provided to receive the meniscus insert  130  shown in  FIG. 16 . Within the recess  116  and extending toward the tibial mounting portions  112  into the plate  114 , is formed an attachment recess  118  in the recessed surface  117 . The tibial component  110  may be made of suitable materials capable of sterilization requirements and biomedical requirements for use with resected bone material. Several alloy metal materials are contemplated such as, for example, cobalt-chromium alloy, in the preferred embodiment having a surface treatment to ensure their smooth yet hard surface. However, any suitable material may be used as required for the given application and factors taken into consideration for the receiving patient. 
         [0089]    The meniscus insert  130 , as illustrated in  FIG. 16 , has an attachment protrusion  138  that may take the form of a knob, a sphere, a cone having its circular cross section position on a post, etc. The attachment protrusion  138  in the preferred embodiment includes a disk-like shape positioned on a post. The meniscus insert  130  thus attaches to the tibial component  110  by inserting the attachment protrusion  138  into the attachment recess  118  of the tibial component  110 . Once attached, the meniscus insert  130  should not be able to be removed from the tibial component  110  in the preferred embodiment. Further, in many preparation methods implemented according to the present invention, it may be preferable to attach the meniscus insert  130  to the tibial component  110  before impaction of the tibial component  110 . In the preferred embodiment, ultra-high molecular-weight polyethylene (UHMWPE) may be used to form the meniscus insert  130  although other suitable materials may be implemented. 
         [0090]    Multiple shapes may be used to accomplish the securing of a meniscus insert  130  to the tibial component  110  that are contemplated within the scope of the present invention. For example, as shown in  FIG. 16   a , the attachment protrusion  138   a  may consist of a ridge that engages an attachment recess  118   a  of the tibial component  110 . See  FIG. 14   b . In this embodiment, the ridge  138   a  may fit within the attachment recess  118   a  to secure the meniscus insert  130   a  to the tibial component  110 . Further, in certain installations, the meniscus insert may not require any attachment protrusion as the compression of the weight upon the ankle prosthesis  100  and the manner in which the installation is performed by the medical professional may allow the ankle prosthesis  100  assembly to hold the meniscus insert in place. 
         [0091]    Additional embodiments include meniscus insert  130   b  having lips  139   a  extending forward and rearward of a concave recess  139  of meniscus insert  130   b . Lips  139   a  are beneficial where sublexation, or anterior/posterior migration, of the ankle prosthesis  100  may occur. Thus, as the ankle joint may be thrust in a forward or rearward direction parallel to the surface of the ground once installed, lips  139   a  will assist the ankle prosthesis  100  from slipping out of position, which would potentially cause the ankle prosthesis  100  to become dislodged. However, it will be understood that lips  139   a  will further be shaped so as to prevent unwanted impingement of the user of the ankle prosthesis  100  while the ankle joint is undergoing plantar flexion and/or dorsiflexion. 
         [0092]    As can be seen in  FIG. 15 , the talar component  120  generally forms a mound surface  129  having a generally convex shape. On the underside of the mound  129  is formed talar mounting portions  122  projecting away from a flat surface  124 . Further, the mound surface  129 , flat surface  124  and talar mounting portions  122  are intersected by sidewalls  125  of the talar component  120 . Preferably, talar component  120  is provided with a wide base that approximates the shape of the talar section  46  of the talus  40  such that subsidence of the talar component  120  will be minimized. 
         [0093]    Further, other embodiments may provide additional beneficial methods of preparation and talar components  120   a , 120   b  to further prevent subsidence of the component wherein significant bone resection and implanting of the component will not cause the component to crush into the cancellous bone over time under pressure. As can be seen in  FIGS. 18-21 , differing talar sections  46   a , 46   b  may be implemented in accordance with the present invention for use with talar components  120   a , 120   b  having surfaces  124   a , 124   b , respectively. Likewise, matching cutting guides  90   a , 90   b  may be implemented to assist in the shaping of talar sections  46   a , 46   b , respectively. More specifically, cutting slots  92   a , 92   b  having mount cut apertures  91  on cutting guides  90   a , 90   b  will assist in the shaping of the talar dome  42 . 
         [0094]      FIG. 17  illustrates ankle prosthesis  100  as it may be permanently positioned and prepared. As can be seen in  FIGS. 14-17 , the talar component  110  is attached to the meniscus insert  130  and rests on the talar component  120 . More specifically, an upper surface  137  of the meniscus insert  130  interfaces with the recessed surface  117  as the meniscus insert  130  rotates within the inner walls  115 . Further, the mound surface  129  of the talar component  120  interfaces with a concave recess  139  of the meniscus component  130 . The interface between the talar component  120  and the meniscus insert  130  is further partially constrained to a rocking motion by the interface of recessed walls  135  of the meniscus insert  130  and the sidewalls  125  of the talar component  120 . Accordingly, the interface between the tibial component  110  and the meniscus insert  130  permits the ankle prosthesis  100  limited rotational movement while the interface of the talar component  120  and the meniscus insert  130  provides limited front-to-back rocking motion for the patient receiving the ankle prosthesis  100 . 
         [0095]    The final steps in the method of preparation according to the present invention include replacing the medial portion  22  of the tibia  20  with at least one screw  29 . Thus, the tibial chevron section  25  is resecured to the medial portion  22  of the tibia  20 . The incision is then closed after the posterior tibial tendon retinaculum and superficial deltoid are repositioned or otherwise treated, thus completing the method for preparing the ankle for replacement according to the present invention. 
         [0096]    Although the cutting alignment apparatus  50  may be employed at any time before the cutting step in the method of preparation described herein, it may be convenient to apply the cutting alignment apparatus  50  just before the cutting step implementing the cutting guide  90 . However, other arrangements of the order of steps are contemplated to accomplish the method of preparation of the present invention. For example, it may be found convenient to apply the cutting alignment apparatus  50  to achieve greater confidence in alignment for certain medical professionals if implemented earlier in the process immediately before the cutting step implementing the cutting guide  90 . 
         [0097]    In addition, the present invention is applied from a medial approach that endures to the benefit of the medical professional in the ease of preparation of the ankle and the user of the ankle replacement for healing purposes and overall stability of the ankle joint after surgery. Further, because of the very common front to back rocking motion of the ankle (plantar flexion/dorsiflexion), the ability of the tibial and talar components to be mounted transversely, i.e., with mounting portions transverse to the motion/force applied to the ankle prosthesis, the ankle prosthesis is thus provided with immediate rigid fixation and further optimizes bony ingrowth of the ankle prosthesis. 
         [0098]    Although the invention has been described in detail for the purpose of illustration based on what is currently considered to be the most practical and preferred embodiments, it is to be understood that such detail is solely for that purpose and that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover modifications and equivalent arrangements that are within the spirit and scope of the appended claims. For example, it is to be understood that the present invention contemplates that, to the extent possible, one or more features of any embodiment can be combined with one or more features of any other embodiment.