Patent Publication Number: US-2023132821-A1

Title: Total knee joint prosthesis for revision after a unicompartmental knee arthroplasty

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is based on and claims the priority benefits of China application No. 202111283975.6, filed on Nov. 1, 2021. The entirety of China application No. 202111283975.6 is hereby incorporated by reference herein and made a part of this specification. 
     TECHNICAL FIELD 
     The present application relates to the technical field of biomaterials for implant or intervention, and particularly to a total knee joint prosthesis for revision after a unicompartmental knee arthroplasty. 
     BACKGROUND ART 
     A single condylar knee joint prosthesis is a surgical implant for replacing a knee joint and applied to a unicompartmental knee arthroplasty. An upper portion of the tibia and lower portion of the femur of human body need to be removed a half during the unicompartmental knee arthroplasty, and the half is used to accommodate the single condyle knee joint prosthesis. 
     However, when the single condylar knee joint is revised and replaced with a total knee joint replacement, the other half of the upper portion of the tibia and lower portion of the femur of human body need to be removed, and a tibia plateau after this removal and a tibia plateau after unicompartmental knee arthroplasty needs to be flush. Currently, a method of keeping flush between a tibia plateau after this removal and a tibia plateau after unicompartmental knee arthroplasty is that: a patch is increased at the tibia plateau after unicompartmental knee arthroplasty, then the patch is fixed on the top end of the human tibia through a locking nail, and the total knee joint prosthesis is mounted on the tibia plateau after this removal and the patch. 
     However, when the patch is fixed on the human tibia through the locking nail, it will additionally increase the pain of patient and results in a long operation time. 
     SUMMARY 
     In order to reduce the pain of patient for revision after the unicompartmental knee arthroplasty and shorten the operation time, the present application provides a total knee joint prosthesis for revision after a unicompartmental knee arthroplasty. 
     The total knee joint prosthesis for revision after a unicompartmental knee arthroplasty in the present application adopts the following technical solution: 
     a total knee joint prosthesis for revision after a unicompartmental knee arthroplasty includes a tibial plateau and a tibial pad mounted on the tibial plateau, in which the tibial plateau includes an installation platform and an installation column fixedly connect to a side of the installation platform; a filling block is provided on a side of the installation platform towards the installation column; and the filling block is configured to be placed at a side of the human tibia where a unicompartmental knee arthroplasty is performed. 
     In the above technical solution, when the single condylar knee joint for revision is replaced by a total knee joint, an upper side of the tibia and a lower side of the femur of the human body may be directly treated according to requirement of surgery; then the tibial plateau is mounted on an upper side of the human tibia. Because the filling block is directly provided on the installation platform, a patch is not needed to be mounted through surgery on the side of the human tibia where the previous unicompartmental knee arthroplasty is performed, and the installation column is directly mounted on the upper side of the human tibia. At this time, the filling block is attached to the side of the human tibia where a unicompartmental knee arthroplasty is performed, which may reduce an additional pain of patient due to mounting the patch, and reduce operation steps of mounting the patch, and shorten the operation time. 
     In some embodiments, two limiting bosses are fixedly connected to a side of the installation platform away from the installation column; the two limiting bosses are separately located at two opposite sides of the installation platform; each of the two limiting bosses has an inclined side wall at a side facing with each other; each of the two limiting boss has a width configured to be gradually increased from a side close to the installation platform to a side away from the installation platform; and two chutes are formed on the tibial pad for the two limiting bosses to slide into. 
     In the above technical solution, the position of the tibial pad in the width direction of the limiting boss may be fixed by the cooperation of the two limiting bosses, avoiding the tibial pad from sliding along the width direction of the limiting bosses. Meanwhile, because each of the two limiting bosses has an inclined side wall at a side facing with each other, the position of the tibial pad in the axial direction may be limited. 
     In some embodiments, a front boss is fixedly connected to the installation platform, and a triangular structure is spatially formed by the front boss and the two limiting bosses. 
     In the above technical solution, the position of the tibial pad in the length direction of the limiting boss may be fixed by the front boss, avoiding the tibial pad from sliding on the installation platform under external force. 
     In some embodiments, a clamping slot is formed on a side of the front boss towards the limiting boss, and a clamping block configured to be snapped into the clamping slot is fixedly connected to a side of the tibial pad. 
     In the above technical solution, when the tibial pad is mounted on the installation platform, the clamping block on the tibial pad is exactly snapped into the clamping slot, so that a circumferential position of the tibial pad may be fixed, and the tibial pad may be fixed more firmly. 
     In some embodiments, the clamping block includes a fixing block fixedly connected to the tibial pad and an abutting block vertically and fixedly connected to the fixing block. 
     In the above technical solution, the position of the abutting block on the tibial pad may be fixed by the fixing block, and the abutting block may be directly snapped into the clamping slot, so that the front boss may be fixed with the tibial pad. 
     In some embodiments, a side of the abutting block away from the tibial pad is provided with a guiding surface. 
     In the above technical solution, the guiding surface can make the abutting block smoothly slide into the clamping slot, so that the front boss may be fixed with the tibial pad. 
     In some embodiments, a reinforcing rib is fixedly connected between the installation column and the installation platform. 
     In the above technical solution, the reinforcing rib can increase a connection strength between the installation platform and the installation column and reduce a possibility of fracture caused by the force between the two. 
     In some embodiments, a plurality of the reinforcing ribs are provided around a axis of the installation column at intervals. 
     In the above technical solution, the structural strength between the installation platform and the installation column is higher. 
     In some embodiments, a cement tank is formed on a side of the installation platform towards the installation column. 
     In the above technical solution, the cement tank may be filled with bone cement, the tibial plateau can not only be fixed on the human tibia through the installation column, but also through the bone cement, thereby increasing the contact area between the tibial plateau and the human tibia, so that the tibial plateau is fixed more firmly. 
     In summary, the present application has at least one of the following beneficial technical effects: 
     1. in the present application, a filling block is provided on a side of the installation platform towards the installation column; and the filling block is configured to be placed at a side of the human tibia where a unicompartmental knee arthroplasty is performed. Because the filling block is directly provided on the installation platform, a patch is not needed to be mounted through surgery on the side of the human tibia where the previous unicompartmental knee arthroplasty is performed, and the installation column is directly mounted on the upper side of the human tibia. At this time, the filling block is attached to the side of the human tibia where a unicompartmental knee arthroplasty is performed, which may reduce an additional pain of patient due to mounting the patch, and reduce operation steps of mounting the patch, and shorten the operation time; 
     2. a gradually changing width of the limiting boss may fix the position of the tibial pad in radial and axial direction at the same, and reduce the probability of the tibial pad sliding out from the holding chamber; and 
     3. the cement tank may increase the mounting area of the installation platform and the human tibia, so the tibial plateau is mounted more firmly, and the mounting stability is better. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    shows an overall structure diagram of the present application. 
         FIG.  2    shows a structure diagram of another perspective of the present application. 
         FIG.  3    shows a diagram illustrating a structure of the tibial plateau. 
         FIG.  4    shows a diagram illustrating a structure of the tibial pad. 
     
    
    
     DETAILED DESCRIPTION 
     The present application is further described in detail below in combination with  FIGS.  1 - 4   . 
     An embodiment of the present application discloses a total knee joint prosthesis for revision after a unicompartmental knee arthroplasty. Referring to  FIG.  1   , the total knee joint prosthesis includes a tibial plateau  1  and a tibial pad  2  mounted on the tibial plateau  1 , in which, the tibial plateau  1  includes an installation platform  11  and an installation column  12  fixedly connected to a side of the installation platform  11 ; a filling block  13  for increasing a thickness of the installation platform  11  is provided on a side of the installation platform  11  towards the installation column  12 ; the filling block  13  is configured to be placed at a side of a human tibia where a unicompartmental knee arthroplasty is performed; and the tibial pad is positioned at a side of the installation platform  11  away from the installation column  12 . When the single condyle knee joint prosthesis is revised after a unicompartmental knee arthroplasty, the removed human tibia is more during a unicompartmental knee arthroplasty. Therefore, when the tibial plateau  1  is mounted during a total knee joint replacement surgery, the filling block  13  can be placed towards the side of the human tibia where a unicompartmental knee arthroplasty is performed; then the tibial plateau  1  is mounted on the human tibia; and the filling block  13  can be attached to the human tibia after unicompartmental knee arthroplasty. Therefore, the tibial plateau  1  may be mounted without adding a patch, and further the mounted tibial plateau  1  can be attached to the human tibia well. The operation time and operation steps for mounting a patch can be omitted; the pain of the patient caused by mounting a patch may be avoided; the operation steps may be simplified; and a whole operation time may be shortened. 
     In particular, a thickness of the filling block  13  can be designed according to actual situation. When the unicompartmental knee arthroplasty is operated, the severity of the illness of each patient is different, so the sizes of removed tibias are different. Therefore, a suitable thickness of the filling block  13  can be chosen according to the sizes of removed tibias of different patients in actual application. Moreover, the position of the filling block  13  also need be determined according to the position of the previous unicompartmental knee arthroplasty of the patient, such that the filling block  13  can be positioned at the side of the human tibia where a unicompartmental knee arthroplasty is preformed, that is, the filling block  13  will be positioned at the side where a patch is to be mounted. In the present application, the filling block  13  is fixedly connected to the installation platform  11 , in which the operation is more convenient, the hurt to human body is reduced and the operation time is shortened, compared with the current operation of mounting a patch on the human tibia through a locking nail. 
     Meanwhile, the filling block  13  is fixedly connected to the installation platform  11 . On one hand, such arrangement avoids the hurt to the human body caused by directly mounting the patch on the human tibia and shortens the operation time. On the other hand, a stepped surface is formed between a side of the filling block  13  towards the installation column  12  and the installation platform  11 , which makes the installation platform  11  be attached to the human tibia better; plays a circumferential limiting role to the installation platform  11 ; and improves the stability of the installation platform  11  after installation. 
     In particular, in order to increase the connection strength between the installation platform  11  and installation column  12 , a reinforcing rib  14  is fixedly connected between the installation platform  11  and the installation column  12 ; a plurality of the reinforcing ribs  14  are provided around the axis of the installation column  12  at equal intervals; and four reinforcing ribs  14  are adopted in the present application as an example. 
     Referring to  FIG.  2   , when the tibial plateau  1  is mounted on the human tibia, the installation of the tibial plateau  1  may be achieved by fixedly connecting the installation column  12  to the human tibia. In particular, in order to increase the installation strength of the tibial plateau  1 , a cement tank  111  is formed on a side of the installation platform  11  towards the installation column  12 , and the cement tank  111  may be filled with bone cement. The tibial plateau  1  can be fixedly connected to the human tibia not only through the installation column  12 , but also through the bone cement filled into the cement tank  111 , so that the installation strength of the tibial plateau  1  can be more firmly. 
     Referring to  FIGS.  1  and  3   , the tibial pad  2  is detachedly connected to a side of installation platform  11  away from the installation column  12 . Specifically, two limiting bosses  15  are fixedly connected to a side of the installation platform  11  away from the installation column  12 ; the two limiting bosses  15  are separately positioned at two opposite sides of the installation platform  11 . Each of the two limiting bosses  15  has an inclined side wall. Specifically, each of the two limiting boss  15  has a width configured to be gradually increased from a side close to the installation platform  11  to a side away from the installation platform  11 . In particular, each of the two limiting bosses  15  has an inclined side wall which may be arranged at a side close to each other or a side away from each other. Referring to  FIG.  4   , two chutes  21  are formed on the tibial pad  2  to be embedded by the two limiting bosses  15 . The tibial pad  2  may be fixed on the installation platform  11  through sliding the limiting boss  15  from a side of the tibial pad  2  to the chute  21 , which may avoid the tibial pad  2  from sliding in the width direction of the limiting boss  15  and in a direction away from the installation platform  11 . 
     Referring to  FIGS.  3 - 4   , in order to avoid the tibial pad  2  from sliding along a length direction of the limiting boss  15  at the installation platform  11  after the tibial pad  2  is mounted on the installation platform  11 , a front boss  16  is fixedly connected to the installation platform  11 , and the tibial pad  2  is formed with a holding groove  22  for embedding the front boss  16  to be embedded. A triangular structure is spatially formed by the front boss  16  and the two limiting bosses  15 . And a holding chamber  17  for holding the tibial pad  2  is formed between the front boss  16  and the two limiting bosses  15 . The tibial pad  2  is directly placed on the installation platform  11  from the holding chamber  17  during installation, then the tibial pad  2  is operated to slide towards the limiting bosses  15 , such that the limiting bosses  15  is cooperated with the chute  21 . The tibial pad  2  may be fixed in a radial direction and axial direction by the cooperation of the limiting bosses  15  and front boss  16 . Therefore, the probabilities of the tibial pad  2  sliding on the tibial plateau  1  and the tibial pad  2  falling off the installation platform  11  can be reduced. 
     The position of the tibial pad  2  may be firmly fixed on the installation platform  11  when the tibial pad  2  is mounted on the installation platform  11  due to the arrangement of the chute  21  and holding groove  22 . And the limiting boss  15  and the front boss  16  would not be exposed to the outside to affect the normal operation. 
     Referring to  FIGS.  3 - 4   , meanwhile, in order to limit a circumferential position of the tibial pad  2  and reduce the turning of the tibial pad  2  under an external force after being mounted on the installation platform  11 , a clamping slot  161  is formed at a side of the front boss  16  towards the limiting bosses  15 , and a clamping block  23  configured to be snapped into the clamping slot  161  is fixedly connected to the tibial pad  2  and also fixedly connected to a sidewall of the holding groove  22 . The clamping block  23  includes a fixing block  231  fixedly connected to the tibial pad  2  and a abutting block  232  vertically and fixedly connected to a side of the fixing block  231 . The abutting block  232  and the fixing block  231  are integrally formed, so that the abutting block  232  and the fixing block  231  can form an elastic part. When the tibial pad  2  is slid from the holding chamber  17  to the limiting bosses  15 , the two limiting bosses  15  can cooperate with the chute  21 ; then the tibial pad  2  is directly pressed down; the abutting block  232  will abut against a sidewall of the front boss  16  and is elastically moved relative to the tibial pad  2  under the counterforce of the front boss  16  until the abutting block  232  slides into the clamping slot  161 , thereby the circumferential position of the tibial pad  2  is fixed. Further, in order to facilitate the sliding of the holding groove  22  into the clamping slot  161 , a guiding surface  2321  is provided at a side of the abutting block  232  abutted against the front boss  16 , which is positioned at a side of the abutting block  232  away from the fixing block  231 . When the tibial pad  2  is placed on the installation platform  11  from the holding chamber  17 , the two limiting bosses  15  will cooperate with the chute  21 ; then the tibial pad  2  is pressed; the guiding surface  2321  of the abutting block  232  will abut against the front boss  16  and smoothly slide into the clamping slot  161 ; and then the circumferential position of the tibial pad  2  is fixed. 
     An implementation principle of a total knee joint prosthesis for revision after a unicompartmental knee arthroplasty in an embodiment of the present application is that: when the single condylar knee joint prosthesis is replaced by a total knee joint replacement, the filling block  13  may be arranged according to the position and size of the patch needed to be added, and the filling block  13  may be fixedly connected to the installation platform  11 . During the operation, the doctor may directly insert the installation column  12  into a position of the human tibia to be mounted, therefore a stepped surface of the installation platform  11  towards a side of the installation column  12  is cooperated with a stepped surface of the top end of the human tibia cut in the unicompartmental knee arthroplasty. The doctor can directly operate the total knee joint replacement surgery, and need not to mount the patch on the human tibia through the locking nail, thereby reducing the pain of the patient during revision, reducing the operation step and shortening the operation time. During the operation, the installation column  12  can be directly fixed on the human tibia by the bone cement, and the installation platform  11  can be fixed on the human tibia through bone cement filled into the cement tank  111 . Then, the tibial pad  2  is mounted on the installation platform  11 , so the tibial pad  2  may be fixed on the tibial plateau  1 . 
     The above are the preferred embodiments of the present application, which are not intended to limit the protection scope of the present application. Therefore, all equivalent changes made according to the structure, shape and principle of the present application should be covered within the protection scope of the present application.