Patent Abstract:
A prosthesis and kit for replacing an ankle joint, and methods of applying the devices or systems. The prosthesis is an intramedullary device directed towards replacement of either of the tibia or fibula bone, wherein the prosthesis is a replacement for the lateral malleolus or the medial malleolus, respectively.

Full Description:
RELATED APPLICATIONS 
     The present application claims the benefit of U.S. Provisional Application Ser. No. 61/362,122, filed on 7 Jul. 2010. 
    
    
     BACKGROUND OF THE INVENTION 
     The invention relates to ankle replacement prostheses and systems, as well as associated surgical instruments and procedures. The present invention is more specifically towards intramedullary ankle joint replacements. 
     Until the early to mid 1970&#39;s, patients with injured or diseased ankle joints commonly resulting from rheumatism, or degenerative or traumatic arthritis, had few options when their ankle joints failed. The most common procedure to help these patients regain some use of their ankle was obliteration of the joint by fusion, a procedure that is still commonly used today. Fusion, however, rendered the ankle stiff and generally immobile relative to the lower leg, resulting in limited use and additional stresses on the knee and hip joints. 
     Probably the first reported use of total ankle prosthesis was by Buckholz in 1969. The medical community recognized that such ankle replacement led to largely increased use of the ankle joint because the replacement permitted ankle ranges of motion which generally attempted to mimic the natural human joint. Since that time, ankle replacement prostheses have become increasingly common in use and improved in design. 
     Ankle fractures are particularly common in people having bone disease, such as osteoporosis. Geriatrics, particularly woman, are very susceptible to ankle fractures, and the prognosis after fracture is generally poor, even with the use of a prosthesis. In general, currently used prostheses do not afford the necessary flexibility required for an ankle joint and recovery can be slow and arduous. The fusing together of bones or bone segments required and carried out with prior prostheses limits the ability of the ankle joint to completely heal properly, particularly with those who may have limited mobility prior to the ankle fracture. 
     Stability and weight bearing are other issues that are more important when replacing an ankle joint as opposed to other joints. For example, hip, shoulder, or knee joints are not required to bear the load that is required from an ankle joint. Consequently the use of replacement devices for these other joints does not necessarily translate to possible joints for an ankle joint. 
     SUMMARY OF THE INVENTION 
     The present invention is directed towards a prosthesis and kit for replacing an ankle joint, and methods of applying the devices or systems. The prosthesis is an intramedullary device directed towards replacement of either of the tibia or fibula bone, wherein the prosthesis is a replacement for the lateral malleolus or the medial malleolus, respectively. 
     The device has a first end that is inserted into the intramedullary canal of either the fibula or tibia. A second end of the device is shaped and configured to assimilate the shape of the lateral or medial malleolus, respectively. The device will be secured to the respective tibia or fibula. Likewise, a system could comprise two devices, wherein one is directed towards each of the tibia and fibula. 
     The invention also contemplates methods of installing or inserting the device, wherein the particular malleolus is resected, sufficiently or completely so that the device will replicated the contours of the bone once inserted. The first end of the device is inserted into the intramedullary canal and secured to the bone. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an ankle joint. 
         FIG. 2  is a perspective view of the ankle joint of  FIG. 1 , with a break being shown in the fibula bone. 
         FIG. 3A  is a perspective view of an ankle replacement device according to the present invention. 
         FIG. 3B  is a second perspective view of the device of  FIG. 3A . 
         FIG. 4  is a side view of the device of  FIG. 3A . 
         FIG. 5  is a view of the ankle of  FIG. 2  showing an incision being made in the skin for eventual insertion of a prosthesis as shown in  FIG. 3A . 
         FIG. 6  demonstrates a prosthesis being inserted into the incision of  FIG. 5  to determine a properly sized prosthesis. 
         FIG. 7  demonstrates the ankle of  FIG. 2  being resected to prepare the ankle for placement of the device of  FIG. 3A  within the ankle. 
         FIG. 8  depict the device of  FIG. 3A  being inserted into the fibula. 
         FIG. 9  depicts the device of  FIG. 3A  being affixed to the ankle. 
         FIG. 10  is a perspective view of the ankle of  FIG. 1 , with a break being shown in the tibia bone. 
         FIG. 11A  is a perspective view of a second ankle replacement device according to the present invention. 
         FIG. 11B  is second perspective view of the device of  FIG. 11A . 
         FIG. 12  is a side view of the device of  FIG. 11A . 
         FIG. 13  is a view of the ankle of  FIG. 10  showing an incision being made in the skin for eventual insertion of a prosthesis as shown in  FIG. 11A . 
         FIG. 14  demonstrates a prosthesis being inserted into the incision of  FIG. 13  to determine a properly sized prosthesis. 
         FIG. 15  demonstrates the ankle of  FIG. 10  being resected to prepare the ankle for placement of the device of  FIG. 11A  within the ankle. 
         FIG. 16  depicts the device of  FIG. 11A  being inserted into the ankle. 
         FIG. 17  depicts the device of  FIG. 11A  being affixed to the ankle. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention which may be embodied in other specific structures. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims. 
       FIG. 1  depicts a normal ankle joint, free of fracture. The ankle generally consists of the distal ends of the fibula and tibia bones, which are connected to the talus bone. The fibula bone comprises the lateral malleolus, which is connected to the talus by way of the lateral ligament. The tibia bone comprises the medial malleolus, which is connected to the talus by way of the deltoid ligament. The tibia and fibula are connected two one another by way of the syndesmotic ligament. 
     If undue stress is put on the ankle joint, the joint may fracture, with either the fibula or tibia fracturing, or possibly both. Often a fracture will form at the proximal end of respective malleolus, e.g. the lateral or medial malleolus. Such a fracture of the lateral malleolus is shown in  FIG. 2 , wherein the fracture is shown on the fibula at the proximal end of the lateral malleolus. 
       FIGS. 3A-4  depicts a prosthesis  100  according to the present invention to address a fracture as shown in  FIG. 2 . The prosthesis  100  generally comprises a proximal portion  102  and a distal portion  104 . The proximal portion  102  comprises an insert  106  that will be positioned within the intramedullary canal of the fibula. The proximal portion  102  preferably has a smaller diameter than the distal portion  104 , so that when the insert  106  is inserted into the intramedullary canal, there is a definite distance that the prosthesis  100  may be inserted into the intramedullary canal. The insert  106  can be of any shape, e.g. a post or wedge or multiple posts or wedges, that will allow the insert  106  to be properly inserted and affixed within the intramedullary canal. The insert  106  has at least one hole  108  and preferably a plurality of holes  108  that will allow screws  110  (see  FIG. 7 ) to attach the prosthesis  100  to the fibula. A plurality of holes  108  is preferable, in that it allows for the insert  106 , and the prosthesis  100  in general, to be attached at varying angles and elevations, depending on a particular fracture or on other characteristics, such as the age or gender of the patient. 
     Still referring to  FIGS. 3A-4 , the distal portion  104  generally forms a body  112  that is shaped and sized to follow the contours of the lateral malleolus. The body  112  also has an opening  114 , and preferably a plurality of openings  114 . The openings  114  are generally used during the implantation of the prosthesis as an insertion guide when positioning the prosthesis. The openings  114  may also receive screws  110  so that the distal portion  104  may also be attached to the joint by way of screws  110  (see  FIG. 7 ). As with the insert  106 , it is preferable for the body  112  to have a plurality of openings  114  so that the prosthesis  100  can be positioned at varying angles and elevations. A through bore  116  may also be located on the body, which can receive a pin for syndesmotic fixation, if necessary. 
     The prosthesis  100  is also designed to provide protection for the ankle and surrounding tendons once the prosthesis  100  is inserted. For example, a groove  118  is located in the body  112 , which is intended to protect the peroneal tendon once the prosthesis is properly positioned. The peroneal tendon will rest within the groove  118 , thereby allowing the groove to act as a shield for the tendon. The body  112  may have a groove  118  on either the right side or the left side of the body  112 , or both sides of the body  112 , which will allow the prosthesis to be used for a right or left ankle repair. 
       FIGS. 5-9  depict the prosthesis  100  being secured to the fibula bone. Initially, a doctor, surgeon, or radiologist will take a radiograph or X-ray of the ankle to assist with making a template for the ankle and to assist in properly sizing a prosthesis to be used in the ankle repair. 
       FIG. 5  shows a doctor or surgeon preparing the fractured ankle of  FIG. 2  for insertion of the prosthesis  100 . An incision over the lateral malleolus will be cut into the skin of the ankle to thereby expose the malleolus. The tendons, e.g. the peroneal tendon, will be mobilized by the surgeon. 
       FIG. 6  show a prosthesis  100  being inserted into the incision. The prosthesis  100  is used as a trial implant to determine the appropriate size for a prosthesis  100  that will eventually be inserted into the incision. The use of a trial implant will also assist in determining the necessary level of bone resection that will be required for the fractured/comminuted bone. 
       FIG. 7  demonstrates the bone being resected for insertion of the prosthesis  100 . An oscillating saw is used to cut the bone at the levels of the trial implant (see  FIG. 6 ). The bone is resected so that once the prosthesis  100  is positioned, it will follow the contours of the native lateral malleolus. Similarly, the intramedullary canal will be resected so that it will be shaped to receive the proximal portion  102  of the prosthesis. The resected bone fragments will detached from the ligamentous and tendon attachments so that the properly sized and configured cavity will remain within the ankle joint. The relevant canal, e.g. the endosteal canal, will be enlarged with reamers on the lateral malleolus to insure proper alignment within the cavity. The amount of bone material that will be resected will depend on the size and severity of the fracture. 
       FIG. 8  shows the proximal portion  102  of the prosthesis  100  being inserted into the intramedullary canal so that it may be affixed to the fibula. The prosthesis  100  will be inserted so that it is properly affixed to the fibula, but also to protect the peroneal tendon with the use of the posterior groove  118  The tendon will sit within the groove  118 , thereby allowing the groove  118  to protect the tendon. Similarly, as shown in  FIG. 8 , enough of the lateral malleolus remains around the prosthesis  100  so that the prosthesis  100  is retained properly, which will prevent the prosthesis from unnecessarily moving from side to side once positioned in the ankle. 
     Once properly inserted, the prosthesis will mimic the shape and contour of the fibula, particularly the lateral malleolus, as shown in  FIG. 9 . The prosthesis  100  than can be secured to the ankle joint using screws  110 . Preferably, the prosthesis  100  is locked in place by securing one or more, e.g. two, screws  110  laterally through fibula, the syndesmosis, and locking the screws to the tibia. Alignment guides may be used to assist insertion of the screws. Screws  110  will also be used to secure the distal portion  104  properly within the lateral malleolus. The resultant arrangement allows for a repaired ankle that will closely resemble the fibula bone prior to fracture, thereby decreasing the amount of time needed for recovery and increasing the chance that the patient will recover mobility and stability of the ankle. 
     As noted above, a fracture may also occur in the tibia, as opposed to the fibula. Such a fracture is depicted in  FIG. 10 . Such a fracture typically happens at the proximal end of the medial malleolus.  FIGS. 11A-12  show a prosthesis  200  according to the present invention for addressing fractures as shown in  FIG. 10 . The prosthesis  200  is similar to the prosthesis  100  described above in  FIG. 3A-4 , except that the prosthesis  200  is directed towards a fracture of the tibia as opposed to the fibula. That is, the prosthesis  200  is designed to be shaped according to the contours of the medial malleolus as opposed to the lateral malleolus. 
     Still referring to  FIGS. 11A-12 , the prosthesis comprises a proximal portion  202  and a distal portion  204 . The proximal portion comprises an insert  206  that will be inserted into the intramedullary canal of the tibia. As with the prosthesis  100 , the proximal portion  202  preferably has a smaller diameter than the distal portion  204 , so that when the insert  206  is inserted into the intramedullary canal, there is a definite distance that the prosthesis  200  may be inserted into the intramedullary canal. The insert  206  can be of any shape, e.g. a post or wedge or multiple posts or wedges, that will allow the insert  206  to be properly inserted and affixed within the intramedullary canal. The insert  206  has a hole  208  or plurality of holes  208  for attachment to the tibia by way of screws  210  (see  FIG. 13 ). A plurality of holes  208  is preferable, in that it allows for the insert  206 , and the prosthesis  200  in general, to be attached at varying angles and elevations, depending on a particular fracture or on other characteristics, such as the age or gender of the patient. 
     Still referring to  FIGS. 9A-10 , the distal portion  204  of the prosthesis  200  generally forms a body  212  that is shaped and sized to follow the contours of the medial malleolus. The body  212  also has an opening  214 , and preferably a plurality of openings  214 . The openings  214  are generally used during the implantation of the prosthesis as an insertion guide when positioning the prosthesis. The openings  214  may also receive screws  210  so that the distal portion  204  of the prosthesis  200  may also be attached to the ankle joint by way of screws  210  (see  FIG. 7 ). As with the insert  206 , it is preferable for the body  212  to have a plurality of openings  214  so that the prosthesis  100  can be positioned at varying angles and elevations. A through bore  216  may also be located on the body, which can receive a pin for syndesmotic fixation, if necessary. 
     The prosthesis  200  is also designed to provide protection for the ankle and surrounding tendons, e.g. posterior tibial tendon, once the prosthesis  200  is inserted. For example, a groove  218  is located on the body  212 , which is intended to protect the posterior tibial tendon once the prosthesis is properly positioned. The posterior tibial tendon will rest within the groove  218 , thereby allowing the groove to act as a shield for the tendon. The body  112  may have a groove  218  on either the right side or the left side of the body  212 , or both sides of the body  212 , which will allow the prosthesis to be used for a right or left ankle repair. 
       FIGS. 13-17  depict the prosthesis  200  being secured to the tibia bone. Initially, a doctor, surgeon, or radiologist will take a radiograph or X-ray of the ankle to assist with making a template for the ankle and to assist in properly sizing a prosthesis to be used in the ankle repair. 
       FIG. 13  shows a doctor or surgeon preparing the fractured ankle of  FIG. 10  for insertion of the prosthesis  200 . An incision over the lateral malleolus will be cut into the skin of the ankle to thereby expose the malleolus. The tendons, e.g. the posterior tibial tendon, will be mobilized by the surgeon. 
       FIG. 14  show a prosthesis  200  being inserted into the incision. The prosthesis  200  is used as a trial implant to determine the appropriate size for a prosthesis  200  that will eventually be inserted into the incision. The use of a trial implant will also assist in determining the necessary level of bone resection that will be required for the fractured/comminuted bone. 
     Referring to  FIG. 15 , the tibia bone is resected so that once the prosthesis  200  is positioned within the intramedullary canal, it will follow the contours of the native lateral malleolus. An oscillating saw is used to cut the bone at the levels of the trial implant (see  FIG. 14 ). In the same fashion, the intramedullary canal will be resected so that it will be shaped to properly receive the proximal portion  202  of the prosthesis. The resected bone fragments will detached from the ligamentous and tendon attachments so that the properly sized and configured cavity will remain within the ankle joint. The relevant canal, e.g. the endosteal canal, will be enlarged with reamers on the medial malleolus to insure proper alignment within the cavity. The amount of bone material that will be resected will depend on the size and severity of the fracture. 
       FIG. 16  shows the proximal portion  202  of the prosthesis  200  being inserted into the intramedullary canal so that it may be affixed to the tibia. Once properly inserted, the prosthesis  200  will mimic the shape and contour of the tibia, particularly the medial malleolus, as shown in  FIG. 17 . The prosthesis  200  than can be secured to the ankle joint using screws  210 . One or more screws  210 , e.g. three screws  210 , preferably with the screws  210  being in the form of offset screws, will pass through the medial mallelolar cortex, through the intramedullary canal, and ending in the distal side of the tibia, e.g. the tibial metaphysic. The arrangement helps to promote boney in-growth into the prosthesis, thereby increasing the recovery and stability of the repaired ankle. The resultant arrangement allows for a repaired ankle that will closely resemble the fibula bone prior to fracture, thereby decreasing the amount of time needed for recovery and increasing the chance that the patient will recover mobility and stability of the ankle. 
     The prosthesis  200  will be inserted so that it is properly affixed to the fibula, but also to protect the posterior tibial tendon with the use of the posterior groove  218  (see  FIG. 12 ). The tendon will sit within the groove  218 , thereby allowing the groove  218  to protect the tendon and also to prevent the prosthesis from unnecessarily moving from side to side once positioned in the ankle. 
     As such, the present invention is directed towards a prosthesis generally comprising a proximal portion that will be inserted into the intramedullary canal of a specific bone of the ankle joint, and a distal portion that is shaped and designed to replicate the malleolus section of the particular bone that the prosthesis is used in connection with. By using the prostheses to replicate the shape and form of the bone prior to fracture, these prostheses increase the stability of the ankle joint and also decrease the recovery time, as the ankle joint is capable of bearing weight sooner than prior art devices. Similarly, the intramedullary design also promotes healing and recovery, in that it fosters grafting of the prosthesis to the bone. 
     The prostheses of the present invention may be made of any suitable biocompatible material. Preferably the prostheses are made of a material that will help with in bone growth. A porous material, e.g. sintered titanium, is one preferred material. For example, the prosthesis  100 ,  200  may have a titanium porous coating, which assists in bone growth. 
     It should also be understood that, if necessary, the present invention contemplates a kit that will include both a prosthesis  100  for use with the fibula and a prosthesis  200  for use with the tibia. However, one of the advantages of the present invention over the prior art is that it is not necessary that both the fibula and tibia be resected if one of the bones is not fractured. The prostheses are inserted and attached independently from one another, which also provides for a more efficient reconstruction process for the ankle joint, since alignment of separate prostheses for the fibula and tibia during surgery is not necessary. Likewise, it should be understood that the use of screws  110 ,  210  refers generally to attachment means for the ankle, e.g. pins, bolts, screws, clamps, etc., that are commonly used in surgical procedures. It is also understood that the length of the screws  210 ,  110  is determinative on the needs of a particular fracture, including such factors as age of the person requiring the prosthesis. For example, a screw may be sufficiently long so that the screw will intersect syndesmotic ligament, or it may be determined that a shorter screw will be sufficient. Any length of screw  210  or other fastening device will be fall within the scope of the present invention. 
     The foregoing is considered as illustrative only of the principles of the invention. Furthermore, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims.

Technology Classification (CPC): 0