Abstract:
Disclosed is a femoral resection guide for measuring and guiding resection of anterior portion and posterior portion of a femur and method thereof. The femoral resection guide comprises a front block, a rear block, a reference gauge means and a locking means. A main scale marked portion is provided corresponding to the front scale member and the rear scale member in order to obtain a size of a patient&#39;s femur. The front block and the rear block are respectively provided with a resection guide surface for guiding a cutting tool to cut the femur. Moreover, the positions of the front resection guide surface and the rear resection guide surface in relation to the distal section of the femur can be adjusted, so that the problem of over or insufficient resection can be avoided, and the purchase cost and the storage space of the femoral resection instruments can be significantly reduced.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to Taiwanese Patent Application No. 103216989, filed Sep. 25, 2014, which is hereby incorporated by reference. 
       FIELD OF THE INVENTION 
       [0002]    The present invention relates to a femoral resection, and more particularly, to a femoral resection guide for measuring various sizes of femurs and for guiding resection of various sizes of femurs and a method thereof. 
       BACKGROUND OF THE INVENTION 
       [0003]    In the femoral replacement surgery, a surgeon uses a measurement gauge to measure a size of a patient&#39;s femur so as to select an implant with suitable size and an implanting position according to the size obtained by the measurement gauge. Thereafter, a resection block corresponding to the size of implant is used to guide a cutting tool for the femoral resection. 
         [0004]    The surgeon selects, according to the condition of patient&#39;s femur, one of the measurement gauge from different measurement gauges, each measurement gauge having different reference datum. One of the measurement gauge uses an anterior cortex as the reference datum to fix a front resection position of the femur, and thereafter a rear resection position of the femur is adjusted according to the size of the implant. Another one of the measurement gauge uses a posterior condyle as the reference datum to fix a rear resection position of the femur, and thereafter a front resection position of the femur is adjusted according to the size of the implant. However, when the patient&#39;s femur happens to be with size just between two implanting implants, the selection of either one of the measurement gauges will cause a problem that there will always be with over or insufficient resection of the anterior portion or the posterior portion to thus adversely affect the mobility of the patient&#39;s knee after the surgery. 
         [0005]    In order to enhance the accuracy of the femoral resection, which can therefore achieve a perfect match between the implant and the patient&#39;s femur, the surgeon have to prepare different measurement gauges, each with different reference datum, and plural cutting blocks, each corresponding to every different size of implant. Therefore, the quantity of the femoral resection instruments becomes increased to cause a higher purchase cost and a larger storage space of the femoral resection instruments. 
       SUMMARY OF THE INVENTION 
       [0006]    In view of the above, the present invention provides a femoral resection guide which can be used to adjustably position on the distal section of the femur to thus avoid the problem of having over or insufficient resection of the anterior portion or the posterior portion in such as way that the purchase cost and the storage space of the femoral resection instruments can be decreased. 
         [0007]    The present invention utilizing a femoral resection guide for measuring and guiding resection of anterior portion and posterior portion of a femur, comprising: 
         [0008]    a front block provided with a front datum member and a front scale member, wherein the front datum member is provided with a stylus for contacting an anterior cortex of the femur and has a front resection guide surface for guiding a cutting tool to resect the anterior portion of the femur, the front scale member is provided extending backwardly from the front datum member along a extending direction and is formed with a plurality of adjustably fixed portions arranged along the extending direction, and the front block has a front fixed hole by which the front block is enabled to fix on a distal section of the femur; 
         [0009]    a rear block provided with a rear datum member and a rear scale member, wherein the rear datum member is provided with a rear resection guide surface for guiding a cutting tool to cut the posterior portion of the femur, the rear scale member is provided extending forwardly from the rear datum member along the extending direction and is slidingly engaged with the front scale member, and the rear block has a rear fixed hole by which the rear block is enabled to fix on the distal section of the femur; 
         [0010]    a reference gauge means provided with a reference member, wherein the reference member is provided with a longitudinal portion extended along a length adjustment direction and a feet portion connected with the longitudinal portion, the longitudinal portion is provided on the rear block in an adjustment position along the length adjustment direction, the feet portion and the rear resection guide surface are provided therebetween with a spacing distance corresponding to a resection amount of the posterior portion of the femur, the feet portion is used to contact the posterior condyle of the femur; and 
         [0011]    a locking means provided between the front scale member and the rear scale member for locking them in a locked state or provided between the rear scale member and the reference gauge means for locking them in a locked state, 
         [0012]    wherein a main scale marked portion is provided corresponding to both the front scale member and the rear scale member, and a measurement is performed by sliding the rear scale member and the front scale member relative to each other along the extending direction to an adjusted position defined by a selected one of the adjustably fixed portions. 
         [0013]    Another object of the present invention is to provide a femoral resection guide, wherein the front datum member is provided with a front guiding slot having the front resection guide surface. 
         [0014]    Another object of the present invention is to provide a femoral resection guide, wherein the rear datum member is provided with a rear guiding slot having the rear resection guide surface. 
         [0015]    Another object of the present invention is to provide a femoral resection guide, wherein a wing portion is formed extending from the front block or the rear block, and the wing portion has a positioning hole to allow a femoral cutting block to be installed. 
         [0016]    Another object of the present invention is to provide a femoral resection guide, wherein the stylus is provided removable from the front datum member. 
         [0017]    Another object of the present invention is to provide a femoral resection guide, wherein the rear scale member includes a connecting base in which the longitudinal portion is slidingly socketed. 
         [0018]    Another object of the present invention is to provide a femoral resection guide, wherein a secondary scale marked portion is provided corresponding to the connecting base and the longitudinal portion to display the spacing distance between the feet portion and the rear resection guide surface. 
         [0019]    Another object of the present invention is to provide a femoral resection guide, wherein a secondary scale marked portion is provided corresponding to the connecting base and the rear scale member to display the spacing distance between the feet portion and the rear resection guide surface. 
         [0020]    Another object of the present invention is to provide a femoral resection guide, wherein the connecting base is pivotally disposed on the rear scale member in such a manner that the feet portion pivots on the connecting base, the reference gauge means includes a rotatable circular base and an eccentric rotor, the rotatable circular base is disposed on the rear scale member, the eccentric rotor is disposed on the rotatable circular base by being deviated from a rotation axis of the rotatable circular base, and the longitudinal portion is slidingly connected with the eccentric rotor. 
         [0021]    Another object of the present invention is to provide a femoral resection guide, wherein an external rotation scale marked portion is provided corresponding to the rear block and the rotatable circular base to display the rotation angle of the feet portion. 
         [0022]    Another object of the present invention is to provide a femoral resection guide, wherein the reference member has a fixed hole by which the reference member is allowed to fix on the distal section of the femur. 
         [0023]    The present invention utilizing a method for using the femoral resection guide to cut femur at anterior portion and posterior portion, comprising steps of: 
         [0024]    (a) obtaining the size of the femur by positioning the femoral resection guide on the distal section of the femur, and sliding the front block and the rear block relative to each other to lean the feet portion of the reference gauge means against a posterior condyle of the femur and make the stylus be in contact with the anterior cortex of the femur; 
         [0025]    (b) adjusting a spacing distance between the front resection guide surface of the front block and the rear resection guide surface of the rear block, the spacing distance being corresponding to a size of an implant which is adapted to the femur; 
         [0026]    (c) directing the front resection guide surface and the rear resection guide surface to a position corresponding to a portion to be cut on the distal section of the femur by adjusting the longitudinal portion of the reference gauge means in a direction along the length adjustment direction to a selected adjustably fixed portion and shifting the front block and the rear block relative to the reference gauge means; 
         [0027]    (d) fixing the front block and the rear block on the distal section of the femur by passing a fixed nail through the fixed hole; and 
         [0028]    (e) cutting the portion to be cut of the femur by taking the front resection guide surface of the front block and/or the rear resection guide surface of the rear block as a reference resection plane. 
         [0029]    Another object of the present invention is to provide a method, wherein the reference member of the reference gauge means is provided to rotate with respect to the rear block as the axis of rotation, and the method further includes, before the step (a), a step of rotating the front block and the rear block until to a rotation angle relative to the feet portion of the reference gauge means according to an external rotation angle of the femur. 
         [0030]    Another object of the present invention is to provide a method, wherein in the step (b), the position of the rear resection guide surface of the rear block is adjusted by sliding the rear block relative to the front block. 
         [0031]    Another object of the present invention is to provide a method, wherein in the step (b), the position of the front resection guide surface of the front block is adjusted by sliding the front block relative to the rear block and the feet portion. 
         [0032]    Another object of the present invention is to provide a method, further comprising, before the step (b), a step of removing the stylus. 
         [0033]    Another object of the present invention is to provide a method, further comprising, between the step (b) and the step (c), a step (b1) of fixing the front block on the distal section of the femur by passing a fixed nail through the fixed hole of the front block. 
         [0034]    Another object of the present invention is to provide a method, further comprising, between the step (b1) and the step (c), a step (b2) of removing the fixed nail. 
         [0035]    Another object of the present invention is to provide a method, further comprising, before the step (c), a step of fixing the reference gauge means on the distal section of the femur by passing a fixed nail through the fixed hole of the reference gauge means. 
         [0036]    In view of the characteristic features as above, the femoral resection guide of the present invention can be used to measure the size of the femur and to guide the cutting tool for the resection of the anterior cortex and the posterior condyle of the femur by means of the resection guide surfaces, in such as way that the measurement gauge and the cutting block are being integrated. Further, in the present invention, the spacing distance between the front resection guide surface and the rear resection guide surface can be adjusted by sliding front block and the rear block in relation to each other, it does not need to purchase various cutting blocks that respectively corresponds to various sizes of implants. Therefore, the purchase cost and the storage space of the femoral resection instruments can be significantly reduced, and the operation of femoral resection guide becomes more convenient at the same time. In addition, the positions of the front resection guide surface and the rear resection guide surface in relation to the distal section of the femur can be adjusted according to the adjustment position, so that the problem of over or insufficient resection of the anterior cortex or the posterior condyle can be avoided by use of the femoral resection guide of the present invention when the size of the patient&#39;s femur happens to be between two most suitable implants. Accordingly, the mobility of the patient&#39;s knee is more improved after surgery. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0037]    The structure and the technical means adopted by the present invention to achieve the above and other objectives can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings. 
           [0038]      FIG. 1  is a stereogram illustrating a femoral resection guide according to an embodiment of the present invention; 
           [0039]      FIG. 2  is a schematic view illustrating the femoral resection guide when a front block and a rear block are relatively sliding according to the embodiment of the present invention; 
           [0040]      FIG. 3  is a schematic view illustrating the femoral resection guide when the rear block and a reference member are relatively sliding according to the embodiment of the present invention; 
           [0041]      FIG. 4  is a schematic view illustrating the femoral resection guide when the rear block and a reference member are relatively rotating according to the embodiment of the present invention; 
           [0042]      FIG. 5  is a schematic view of a femur of the present invention; 
           [0043]      FIG. 6A  is a back view of a femoral resection guide according to another embodiment of the present invention; 
           [0044]      FIG. 6B  is a front view of the femoral resection guide according to the another embodiment of the present invention; 
           [0045]      FIG. 7  is a flowchart of a method for using the femoral resection guide to measure and to cut the femur according to an embodiment of the present invention; 
           [0046]      FIGS. 8A ,  8 B,  10  to  13 ,  15 ,  17  and  18  are schematic views illustrating the processes of the method of the present invention; 
           [0047]      FIG. 9  is a detailed flowchart of a step  21  of the method of the present invention; 
           [0048]      FIG. 14  is a detailed flowchart of a step  261  of the method of the present invention; and 
           [0049]      FIG. 16  is a flowchart detailing a step  264  of the method. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0050]    Embodiments are described in detail below with reference to the  FIGS. 1 to 18 , and the description is used for explaining the embodiments of the present invention only, but is not intended to limit the described embodiments of the present invention. 
         [0051]    Referring to  FIGS. 1 to 4 , it is a femoral resection guide  100  for measuring and guiding resection of an anterior portion A and a posterior portion P of a femur F (as shown in  FIG. 5 ) according to one embodiment of the present invention. The femoral resection guide  100  includes a front block  1 , a rear block  2 , a reference gauge means  3  and a locking means  4 . 
         [0052]    Referring to  FIGS. 1 ,  2  and  5 , the front block  1  is provided with a front datum member  11  and two front scale members  12  parallel to each other. The front datum member  11  is provided with a stylus  111  for contacting the anterior cortex C 1  of the femur F. Preferably, the stylus  111  is provided removable from the front datum member  11 . The front datum member  11  has a front resection guide surface  112  for guiding a cutting tool (not shown) to resect the anterior portion A of the femur F. In this embodiment, the front datum member  11  is provided with a front guiding slot  113  having the front resection guide surface  112 . However, the invention is not limited to this. The front resection guide surface  112  may be disposed on an upper surface of the front datum member  11 . 
         [0053]    Referring to  FIGS. 1 ,  2  and  5 , the front scale members  12  are provided extending backwardly from the front datum member  11  along an extending direction D 1 , and the front scale members  12  are formed with a plurality of adjustably fixed portions  121  arranged along the extending direction D 1 . The front block  1  has a front fixed hole  13  by which the front block  1  is enabled to be fixed on a distal section D of the femur F. Specifically, the front datum member  11  is formed with an extending portion  114  which is provided with the front fixed hole  13 . 
         [0054]    Referring to  FIGS. 1 ,  2  and  5 , the rear block  2  is provided with a rear datum member  21  and a rear scale member  22 . The rear datum member  21  is provided with a rear resection guide surface  211  for guiding a cutting tool to cut the posterior portion P of the femur F. In this embodiment, the rear datum member  21  is provided with a rear guiding slot  212  having the rear resection guide surface  211 . However, the invention is not limited to this. The rear resection guide surface  211  may be disposed on an upper surface of the rear datum member  21 . The rear scale member  22  is provided extending forwardly from the rear datum member  21  along the extending direction D 1 , and the rear scale member  22  is slidden and engaged with the front scale members  12 . Preferably, the rear block  2  has a rear fixed hole  23  and a connecting base  24 . The rear fixed hole  23  is used to fix the rear block  2  on the distal section D of the femur F. Specifically, the rear datum member  21  is formed with an extending portion  213  which is provided with the rear fixed hole  23 . Preferably, the connecting base  24  is pivotally disposed on the rear scale member  22 . 
         [0055]    Referring to  FIGS. 1 ,  2  and  5 , the front scale members  12  and the rear scale member  22  are provided with a main size-marking portion. The main size-marking portion includes a main size-indicating portion  122  provided on the front scale members  12  and a main size-reading portion  221  provided on the rear scale member  22 . The main size-reading portion  221  is moved a related position of the main size-indicating portion  122  by sliding the front block  1  and the rear block  2  in relation to each other. It is noted that a spacing distance between the front resection guide surface  112  of the front block  1  and the rear resection guide surface  211  of the rear block  2  is read as a size of an implant when the main size-reading portion  221  marks on an integer index of the main size-indicating portion  122 . 
         [0056]    Referring to  FIGS. 1 and 3 , the reference gauge means  3  is provided with a reference member  31 , a rotatable circular base  32  and an eccentric rotor  33 . The reference member  31  is provided with a longitudinal portion  311  extending along a length adjustment direction D 2  and a feet portion  312  connected with the longitudinal portion  311 . The longitudinal portion  311  is slidden and socketed in the connecting base  24  of the rear scale member  22  in an adjustment position along the length adjustment direction D 2 . The connecting base  24  and the longitudinal portion  311  are integral to provide with a secondary scale marked portion to display the spacing distance between the feet portion  312  and the rear resection guide surface  211 . Referring to  FIGS. 1 ,  4  and  5 , the feet portion  312  pivots on the connecting base  24  by the longitudinal portion  311 . Referring to  FIG. 6A , the reference member  31  is provided with a fixed hole  314  by which the reference member  31  is allowed to be fixed on the distal section D of the femur F. The rotatable circular base  32  is provided on the rear scale member  22 . The eccentric rotor  33  is disposed in the rotatable circular base  32  by being deviated from a rotation axis of the rotatable circular base  32 . The longitudinal portion  311  is slidden and connected with the eccentric rotor  33 . 
         [0057]    Specifically, referring to  FIG. 3 , the secondary scale marked portion includes a secondary size-indicating portion  241  provided on the connecting base  24  and a secondary size-reading portion  313  provided on the longitudinal portion  311 . The spacing distance between the feet portion  312  and the rear resection guide surface  211  is adjusted by sliding the reference gauge means  3  and the rear block  2  in relation to each other, and the spacing distance between the feet portion  312  and the rear resection guide surface  211  is obtain by reading the scale of the secondary size-reading portion  313  which is pointed by the secondary size-indicating portion  241 . The spacing distance between the feet portion  312  and the rear resection guide surface  211  corresponds to a resection amount of the posterior portion P of the femur F when the feet portion  312  is allocated as leaning against the posterior condyle C 2  of the femur F. However, the present invention is not limited to this. Referring to  FIG. 6B , according to another embodiment of the present invention, the secondary scale marked portion is provided on the connecting base  24  and the rear scale member  22 . Specifically, the secondary size-indicating portion  241   a  is provided on the connecting base  24 , and the secondary size-reading portion  313   a  is provided on the rear scale member  22 . 
         [0058]    Preferably, referring to  FIG. 4 , the rear scale member  22  and the rotatable circular base  32  is integral to provide an external rotation scale marking portion for displaying the rotation angle of the feet portion  312 . Specifically, the external rotation scale marked portion includes an external rotation-indicating portion  222  provided on the rear scale member  22  and an external rotation-reading portion  321  provided on the rotatable circular base  32 . When the feet portion  312  is being rotated, a eccentric rotor  33  is rotating along with the rotation of the longitudinal portion  311  in the rotatable circular base  32  by being deviated from a rotation axis of the rotatable circular base  32 , so as to enable the external rotation-reading portion  321  to display the rotation angle of the feet portion  312  on the external rotation-indicating portion  222 . 
         [0059]    The locking means  4  includes a first locking member  41  and a second locking member  42 . The first locking member  41  is provided between the front scale member  12  and the rear scale member  22  for locking them in a locked state. The second locking member  42  is provided between the rear scale member  22  and the reference gauge means  3  for locking them in a locked state. As an alternative, the locking means  4  may only include either the first locking member  41  or the second locking member  42 . 
         [0060]    Preferably, each front scale member  12  is extended outwardly to form a wing portion  123 . The wing portions  123  are provided with two positioning holes H respectively for positioning a cutting block (not shown). Alternatively, the wing portions  123  having the wing portions  123  may be formed by extending from the rear scale member  22 . 
         [0061]    Referring to  FIG. 7 , a method that uses the femoral resection guide  100  for cutting the femur F at the anterior portion A and the posterior portion P comprises steps of: first, obtaining the size of the femur F by positioning the femoral resection guide  100  on the distal section D of the femur F, and sliding the front block  1  and the rear block  2  relative to each other to lean the feet portion  312  of the reference gauge means  3  against a posterior condyle C 2  of the femur F and make the stylus  111  be in contact with the anterior cortex C 1  of the femur F (step  14 ). Then, adjusting a spacing distance between the front resection guide surface  112  of the front block  1  and the rear resection guide surface  211  of the rear block  2 , the spacing distance being corresponding to a size of an implant which is adapted to the femur F (step  20 ). After that, directing the front resection guide surface  112  and the rear resection guide surface  211  to a position corresponding to a portion to be cut on the distal section D of the femur F by adjusting the longitudinal portion  311  of the reference gauge means  3  in a direction along the length adjustment direction D 2  to a selected adjustably fixed portion and shifting the front block  1  and the rear block  2  relative to the reference gauge means  3  (step  30 ). Afterwards, fixing the front block  1  and the rear block  2  on the distal section D of the femur F by passing a fixed nail N through the fixed hole (step  40 ). Finally, cutting the portion to be cut of the femur F by taking the front resection guide surface  112  of the front block  1  and/or the rear resection guide surface  211  of the rear block  2  as a reference resection plane (step  50 ). 
         [0062]    All steps in this method will be described in detail below. It will be appreciated that the specification may have presented the method of the present invention with a particular sequence of steps. However, the method does not rely on the particular sequence of steps set forth herein, and under reasonable circumstances, other sequences of steps may be possible. Therefore, the particular sequence of the steps set forth in the specification should not be construed as limitations on the claims. 
         [0063]    Referring to  FIG. 7  in conjunction with  FIG. 4 , selectively, the front block  1  and the rear block  2  are being rotated until to a rotation angle relative to the feet portion  312  of the reference gauge means  3  according to an external rotation angle of the femur (step  10 ), and the rear block  2  and the reference gauge means  3  are locked by the second locking member  42  (step  12 ). In the embodiment, the rotation angle of the front block  1  in relation to the rear block  2  is 5 degrees. Selectively, a method for using the femoral resection guide  100   a  further includes, before the step  12 , a step of fixing the reference gauge means  3  on the distal section D of the femur F by passing a fixed nail N through the fixed hole  314  of the reference gauge means  3 . 
         [0064]    Referring to  FIGS. 7 ,  8 A,  8 B, the size of the femur F is obtained by reading a scale of main size-indicating portion  122  which is pointed by the rear resection guide surface  211  in a state that the feet portion  312  is leaning against a posterior condyle C 2  of the femur F and the stylus  111  is therefore in contact with the anterior cortex C 1  of the femur F (step  14 ). In the present embodiment, the main size-reading portion  221  points at a position of the indicia mark of 3.5 on the main size-indicating portion  122 . A surgeon can either choose a scale mark of 3 (i.e. downward size) or a scale mark of 4 (i.e. upward size) by sliding the front block  1  and the rear block  2  in relation to each other, so as to select an implant corresponding to the scale a mark of 3 or an implant corresponding to the scale mark of 4. 
         [0065]    Referring to  FIG. 7 , in the step  20 , the portion to be cut of the femur F is cut by taking the rear resection guide surface  211  of the rear block  2  as a reference resection plane (step  21 ) or cutting the portion to be cut of the femur F by taking the front resection guide surface  112  of the front block  1  as a reference resection plane (step  26 ). 
         [0066]    Specifically, referring to  FIGS. 9 and 10 , in step S 21 , the front block  1  is fixed on the distal section D of the femur F by passing a fixed nail N through the fixed hole  13  of the front block  1  (step  211 ). Referring to  FIGS. 9 and 11 , the position of the rear resection guide surface  211  is forwardly adjusted in a manner that utilizes the main size-reading portion  221  to point to the scale mark of 3 on the main size-indicating portion  122  by sliding the rear block  2  forwardly when the second locking member  42  is unlocked (step  212 ). It will be appreciated that in the step  212 , the reference member  31  is kept leaning against a posterior condyle C 2  of the femur F, and the spacing distance between the feet portion  312  and the rear resection guide surface  211  is increased when the rear block  2  is sliding forwardly. After the position of the rear resection guide surface  211  is adjusted, the second locking member  42  returns to the locked state. The position of the rear resection guide surface  211  is determined as being suitable or not (step  213 ). 
         [0067]    In case that the position of the rear resection guide surface  211  is suitable, referring to  FIGS. 9 and 12 , the femoral resection guide  100  is fixed on the distal section of the femur F by passing plurality of fixed nails through the fixed hole  13 , the fixed hole  23  and the positioning hole H (step  40 ). Thereafter, the anterior portion A of the femur F is cut along the front resection guide surface  112  of the front block  1  and the posterior portion P of the femur F along the rear resection guide surface  211  of the rear block  2  by the cutting tool (step  50 ). 
         [0068]    Referring to  FIG. 9 , in case that the position of the rear resection guide surface  211  is not suitable, the front block  1  and the rear block  2  are locked by the first locking member  41  (step  214 ). Referring to  FIGS. 9 and 13 , the fixed nails passed on the fixed hole  13  of the front block  1  (step  215 ) and the stylus  111  is removed (step  216 ). Referring to  FIGS. 9 and 13 , the positions of the front resection guide surface  112  of the front block  1  and the rear resection guide surface  211  of the rear block  2  are backwardly adjusted in such a manner that the spacing distance between the feet portion  312  and the rear resection guide surface  211  is reduced by backwardly sliding the front block  1  and the rear block  2  in relation to the reference member  31  (step  217 ). The position of the front resection guide surface  112  is determined as being suitable or not (step  218 ). The step  40  is executed when the position of the front resection guide surface  112  is suitable. The step  207  is repeatedly executed until the position of the front resection guide surface  112  becomes suitable if the front resection guide surface  112  is not being suitable. 
         [0069]    Referring to  FIG. 6 , in the step  26 , either the scale mark of 4, i.e. upward size, (step  261 ) or the scale mark of 3, i.e. downward size (step  264 ), on the main size-indicating portion  122  pointed by the main size-reading portion  221  can be chosen. 
         [0070]    The step  261  includes the steps of: referring to the  FIGS. 14 and 15 , enabling the main size-reading portion  221  to point to the position of the indicia mark of 4 on the main size-indicating portion  122  by forwardly sliding the front block  1  in relation to the rear block  2  and the feet portion  312  to forwardly adjust the position of the front resection guide surface  112  (step  262 ). Then, determining the position of the front resection guide surface  112  is being suitable or not (step  263 ). Executing the step  40  when the position of the front resection guide surface  112  is suitable. Repeatedly executing the step  264  when the front resection guide surface  112  is unsuitable. 
         [0071]    The step  264  includes the steps of: referring to the  FIGS. 16 and 17 , the stylus  111  is removed (step  265 ), and the main size-reading portion  221  is enabled to point at the position of the indicia mark of 3 on the main size-indicating portion  122  by backwardly sliding the front block  1  relative to the rear block  2  and the feet portion  312  to backwardly adjust the position of the front resection guide surface  112  (step  266 ). Determining the position of the front resection guide surface  112  is being suitable or not (step  267 ). Executing the step  40  when the position of the front resection guide surface  112  is suitable. 
         [0072]    Referring to the  FIG. 16 , the front scale member  12  and the rear scale member  22  is locked by the first locking member  41  when the front resection guide surface  112  is unsuitable (step  268 ). Referring to the  FIG. 18 , the positions of the front resection guide surface  112  of the front block  1  and the rear resection guide surface  211  of the rear block  2  is forwardly adjusted in a manner that forwardly adjusting the front block  1  and the rear block  2  to increase the spacing distance between the feet portion  312  and the rear resection guide surface  211  (step  269 ). Then, determining the positions of the front resection guide surface  112  and the rear resection guide surface  211  are being suitable are not (step  270 ). 
         [0073]    It is noted that, according to this embodiment, the step of adjusting the spacing distance between the front resection guide surface  112  and the rear resection guide surface  211  by sliding the front block  1  and the rear block  2  relative to each other is performed firstly, and then the step of adjusting the position of the femoral resection guide  100  which is positioned on the femur F and adjusting the resection amount of the posterior portion P of the femur F by adjusting the reference member  31  is secondly performed. Selectively, the step of adjusting the position of the femoral resection guide  100  which is positioned on the femur F and adjusting the resection amount of the posterior portion P of the femur F by adjusting the reference member  31  can be executed firstly, and then the step of adjusting the spacing distance between the front resection guide surface  112  and the rear resection guide surface  211  by sliding the front block  1  and the rear block  2  in relation to each other can be then secondly executed. 
         [0074]    The above describes the preferred embodiments of the present invention. The above description is not intended to limit the scope of the present invention, so the equivalent structural changes according to the above specification and the accompanied claims of the present invention are considered to be included within the scope of the present invention.