Abstract:
Disclosed is a navigation-training model comprises a base, a holding device for securing a surgical practice model bone to the base in a predetermined position, and a support for fixing a patient tracker onto the base at a predetermined orientation. With the fixed relative positions of the support and the holding device, constant orientation of the patient tracker and the surgical practice model bone is achieved each time they are placed on the navigation-training model. A navigation-training apparatus having the navigation-training model is also disclosed, which includes a navigation system and a surgical tool with a tool tracker. Fluoroscopic images of the surgical practice model bone are captured once and uploaded into a computer of the navigation system. The practice of the fluoroscopic images-guided orthopedic surgery can thus be carried out with the fluoroscopic images loaded onto the navigation system without the need for further fluoroscopy. This eliminates X-ray exposure and standardizes the procedures of navigation-training.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a navigation-training device for the surgery, particularly to a navigation-training model for the fluoroscopic images-guided orthopedic surgery and apparatus having the model as well as a method for using the same.  
         [0003]     2. Description of the Related Art  
         [0004]     Computer-assisted surgery has significantly redefined the way that surgical operations are performed. By combining computer software with trackers, the surgical navigation apparatus holds great promise for minimally invasive surgery. During image-guided orthopedic surgery, trackers are used to track the position of the patient&#39;s surgical anatomy (called patient tracker) and the surgeon&#39;s tools (called tool tracker) in real time with reference to the pre-acquired images. A typical fluoroscopically-based surgical navigation system employs a patient tracker for insertion into the patient&#39;s body. It tracks the surgical site of interest of a patient. X-ray images are then taken utilizing a fluoroscopic imager which is also tracked by the navigation system. The surgeon then positions and guides the tracked surgical tool to the preoperatively planned locations with the aid of the quantitative and qualitative navigational information after calibration of the tracked surgical tool in the same 3D coordinate system as the fluoroscopic images and the patient tracker. This relatively new technology will be increasingly used in the coming years due to its advantages. Like in all new surgical procedures, pre-surgery training is vital for the success in surgery to guarantee quality treatment, to avoid complications and to ensure good clinical results. This is of special importance where new computer technologies are combined with surgical procedures.  
         [0005]     DiGioia A M III et al., (1998) Computer Assisted Orthopedic Surgery: Image Guided and Robotic Assistive Technologies.  Clin. Orthop.,  1(354), 8-16, and Kahler D. (2004) Image Guidance: Fluoroscopic navigation,  Clin. Orthop.,  1(421), 70-76, disclose information on image-guided surgical navigation, which are incorporated herein as references.  
         [0006]     However, without standardized procedures and designated training models, surgeons may experience significant difficulty during training on using the surgical navigation apparatus. During in vitro surgical navigation training, the surgical practice model bone is difficult to be orientated in the same position before and after fluoroscopically imaging and in the same position relative to the patient tracker. It often requires a great deal of adjustments before the correct location can be identified. Repeated fluoroscopy therefore has to be done before each training practice. It is cumbersome while providing less than satisfactory system for training. For practice in human and animals, while the problem with the change in relative positions between the patient tracker and the tool tracker cannot be totally solved and hence fluoroscopic images still have to be taken to determine the position during the training, these practical sessions are expensive and time-consuming as well as presenting an ethical issue.  
         [0007]     At present, there is no satisfactory means for obtaining extensive, inexpensive, non-operative experience in using the surgical navigation system.  
       SUMMARY OF THE INVENTION  
       [0008]     An object of the present invention is to provide a navigation-training model for fluoroscopic images-guided orthopedic surgery, by which constant orientation and relative positions of the patient tracker and the surgical practice model bone can be achieved each time they are placed on the navigation-training model. No repeated fluoroscopy has to be taken and this reduces the X-ray exposure of the trainer. The navigation-training model is portable and can be used for training on any navigation-training system. It provides effective, inexpensive and extensive training on surgical navigation procedures.  
         [0009]     The navigation-training model for orthopedic surgery according to the invention comprises a base, a holding device for fixing a surgical practice model bone to the base in a predetermined position, and a support mounted to the base for securing a patient tracker in a predetermined orientation.  
         [0010]     The surgical practice model bone used in the invention is a model bone such as, but not limited to, a plastic pelvic bone, a plastic proximal femur bone, and a plastic femur bone covered with or without insulating material and inserted with a stainless steel rod.  
         [0011]     In an embodiment of the navigation-training model, the surgical practice model bone is a plastic pelvic bone, the support is a pin tilted in a first predetermined angle with the surface of the base, the holding device includes two parted stainless steel poles and two parted stainless steel screws in two parallel rows and the base which maintains constant orientation and relative positions of the patient tracker and the plastic pelvic bone for the training.  
         [0012]     In another embodiment of the navigation-training model, the surgical practice model bone is a plastic proximal femur bone, the base is in a rectangular shape, the support is a patient tracker pin fixed to the base so as to form a second predetermined angle with the base and a third predetermined angle between the projecting line of the patient tracker pin onto the base and the elongated side of the base.  
         [0013]     The holding device in this embodiment includes two parted metal poles and a holding block mounted therebetween along the elongated side of the base. The holding block has a lower portion disposed on the base and an upper portion removable from the lower portion, two windows are provided symmetrically at the joint between the upper portion and the lower portion, and a tunnel is provided extended along the elongated direction of the base between the two windows to hold the plastic proximal femur bone.  
         [0014]     The base in this embodiment maintains constant orientation and relative positions of the patient tracker and the plastic proximal femur bone for the training.  
         [0015]     In still another embodiment of the navigation-training model, the surgical practice model bone is a plastic femur bone, covered with insulating materials and inserted with a stainless steel rod with two parallel holes at the distal end thereof.  
         [0016]     The holding device in this embodiment includes a first and a second holding blocks mounted on the base, the first holding block secures a support which is a patient tracker pin tilted in a predetermined direction and secures the stainless steel rod horizontally extended towards the second holding block, and the second holding block has two windows and a tunnel is provided extended along the elongated direction of the base between the two windows to hold the plastic femur bone.  
         [0017]     The base in this embodiment maintains constant orientation and relative positions of the patient tracker and the plastic femur covered with insulating materials for the training.  
         [0018]     Another object of the present invention is to provide a navigation-training apparatus for fluoroscopic images-guided orthopedic surgery, which is designed to permit a surgeon to practice a fluoroscopic images-guided orthopedic surgery in a simulated environment.  
         [0019]     According to the invention, the navigation-training apparatus for fluoroscopic images-guided orthopedic surgery comprises: 
        a navigation-training model including: a base, a holding device for fixing a surgical practice model bone to the base in a predetermined position, and a support mounted on the base for securing a patient tracker in a predetermined orientation;     a navigation system having a computer that stores a plurality of fluoroscopic images of the surgical practice model bone; and     at least one surgical tool attached with a tool tracker communicated with the navigation system.        
 
         [0023]     In the apparatus of the present invention, the navigation system can track the location of the surgical tool on a display thereof with respect to the fluoroscopic images and the patient tracker in a 3D coordinate system, when a navigation training is performed.  
         [0024]     Still another object of the present invention is to provide a navigation-training method for fluoroscopic images-guided orthopedic surgery, by which constant orientation and relative positions of the patient tracker and the surgical practice model bone are maintained. A surgeon can practice surgical procedures using a surgical tool attached with a tool tracker without repeated fluoroscopy and the result can be observed on a display of the navigation system in real-time.  
         [0025]     According to the invention, the navigation-training method for fluoroscopic images-guided orthopedic surgery comprises: 
        1) providing a navigation-training model, which includes: a base; a holding device for fixing a surgical practice model bone to the base in a predetermined position; and a support mounted to the base for securing a patient tracker in a predetermined orientation;     2) providing fluoroscopic images of the model bone and uploading the same in the navigation system;     3) loading the fluoroscopic images on a display of the navigation system; and     4) performing a navigation training with a surgical tool attached with a tool tracker communicating with the navigation system tracking the location of the surgical tool on the display with respect to the fluoroscopic images and the patient tracker in a 3D coordinate system.        
 
         [0030]     By utilizing the navigation-training apparatus and the training method for fluoroscopic images-guided orthopedic surgery of the present invention, the fluoroscopic images of the model bone are captured once. There is no need to take further fluoroscopic images and no need to adjust the relative positions of the patient tracker and the surgical practice plastic bone during training. X-ray exposure to the training personnel is therefore eliminated. The fluoroscopic image sets and the navigation-training models are portable and can be used for training on any navigation system.  
         [0031]     During the training for a specific fluoroscopic images-guided orthopedic surgery, the surgeon just puts the patient tracker and a surgical practice model bone in the fixed position of the navigation-training model, so that constant orientation and relative positions of the patient tracker and the surgical practice model bone are achieved. Then specific fluoroscopic images are recalled from the computer of the navigation system. The surgeon can thus practice the procedures with a surgical tool with a tool tracker attached, and the result can be observed on the display of the navigation system in real-time.  
         [0032]     Therefore, the present invention provides a simple, low cost, efficient and safe training model, apparatus and method that allow a surgeon to practice fluoroscopic images-guided orthopedic surgery without the need for assistance, complicated surgical set-ups, adjustments of relative positions of the patient tracker and the model bone, and the exposure to X-ray.  
         [0033]     Other objects and advantages of the present invention will become apparent from the following detailed description when read in conjunction with the accompanying drawings.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0034]      FIG. 1  shows a pelvic fracture fixation navigation-training model and a plastic pelvis model bone placed next to the navigation-training model;  
         [0035]      FIG. 2  shows a plastic pelvis model bone fixed onto the pelvic fracture fixation navigation-training model in  FIG. 1 ;  
         [0036]      FIG. 3  shows a fluoroscopic image of the outlet view of the plastic pelvis model bone secured on the pelvic fracture fixation navigation-training model as shown in  FIG. 1 ;  
         [0037]      FIG. 4  shows a fluoroscopic image of the inlet view of the plastic pelvis model bone secured on the pelvic fracture fixation navigation-training model as shown in  FIG. 1 ;  
         [0038]      FIG. 5  shows a fluoroscopic image of the frontal view of the plastic pelvis model bone secured on the pelvic fracture fixation navigation-training model as shown in  FIG. 1 ;  
         [0039]      FIG. 6  shows a fluoroscopic image of the true sagittal view of the plastic pelvis model bone secured on the pelvic fracture fixation navigation-training model as shown in  FIG. 1 ;  
         [0040]      FIG. 7  shows loading of fluoroscopic images of the frontal, true sagittal, inlet and outlet views of the plastic pelvis secured on the pelvic fracture fixation navigation-training model from the system during training;  
         [0041]      FIG. 8  shows a navigation-training model for hip screw/intramedullary fixation of trochanteric fractures and a plastic proximal femur model bone placed next to the navigation-training model;  
         [0042]      FIG. 9  shows the plastic proximal femur model bone placed onto the navigation-training model for hip screw/intramedullary fixation of trochanteric fractures as shown in  FIG. 8 ;  
         [0043]      FIG. 9   a  shows a top view of the navigation-training model for hip screw/intramedullary fixation of trochanteric fractures in  FIG. 9 ;  
         [0044]      FIG. 9   b  shows a side view of the navigation-training model for hip screw/intramedullary fixation of trochanteric fractures in  FIG. 9 ;  
         [0045]      FIG. 10  shows a fluoroscopic image of the frontal view of the plastic proximal femur model bone secured on the navigation-training model for hip screw/intramedullary fixation of trochanteric fractures;  
         [0046]      FIG. 11  shows a fluoroscopic image of the true sagittal view of the plastic proximal femur model bone secured on the navigation-training model for hip screw/intramedullary fixation of trochanteric fractures;  
         [0047]      FIG. 12  shows a distal locking navigation-training model and a section of the plastic proximal femur model bone covered with insulating materials;  
         [0048]      FIG. 13  shows a section of the plastic proximal femur model bone covered with insulating materials placed onto the distal locking navigation-training model;  
         [0049]      FIG. 13   a  shows a top sectional view of the distal locking navigation-training model;  
         [0050]      FIG. 13   b  shows a view taken along the line A-A shown in  FIG. 13 ;  
         [0051]      FIG. 14  shows a fluoroscopic image of the frontal view of the plastic femur model bone inserted with an intramedullary nail with two interlocking holes and secured on the distal locking navigation-training model; and  
         [0052]      FIG. 15  shows a fluoroscopic image of the true sagittal view of the plastic femur model bone inserted with an intramedullary nail with two interlocking holes and secured on the distal locking navigation-training model. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0053]     The present invention will be further described below with reference to the drawings.  
         [0054]     In the present invention, the term “a patient tracker” is a common tracker used in this field, provided that it can be used to track the relative position of the surgical site relative to the fluoroscopic images. The term of “a tool tracker” may be the same type of tracker as the patient tracker or any of those used in the art, provided that it can be used to track the position of the tool relative to the fluoroscopic images and the patient tracker. Trackers that can be used in the present invention may be from different companies using different tracking technologies like optical, ultrasound and electromagnetic. Example of the tracking system used in the invention include, but not to be limited, optical tracking system using Infrared cameras and LED trackers (optical type) commercially obtained from Stryker Corp (Corporate headquarters, Michigan USA).  
         [0055]     The fluoroscopic images of the model are live X-ray images captured by a mobile C-arm fluoroscope. During actual surgical procedure, a patient tracker is inserted into the patient&#39;s body and it tracks the surgical site of interest of a patient. X-ray images are then taken by a C-arm fluoroscope which is also tracked by the navigation system. Therefore, their relative positions are known. The fluoroscopic images are displayed on the computer of the navigation system. A surgical tool is attached with a tool tracker and both are calibrated and validated in the calibration station which communicates with the IR camera of the navigation system. This serves to calibrate the surgical tool and the tool tracker in the same 3D coordinate system as the patient tracker and the fluoroscopic images. The tracked tool is shown as crosshairs on the fluoroscopic images displayed on the computer screen. The surgeon can then use the tracked surgical tool for surgical planning and surgical operation.  
         [0056]     In a first embodiment of the present invention, a pelvic navigation-training apparatus is provided for training on computer-assisted fluoroscopic images-guided surgery to fix pelvic fractures with screw insertion. The pelvic navigation-training apparatus comprises a pelvic navigation-training model and a navigation system having a computer that stores a plurality of fluoroscopic images of the plastic pelvic model bone mounted on the navigation-training model.  
         [0057]     Referring to  FIGS. 1 and 2 , the pelvic navigation-training model used in this pelvic navigation-training apparatus includes: a base  1 , a holding device for fixing a plastic pelvic model bone  3  on the base  1  in a precise position for training of the specific orthopedic surgical procedure, and a patient tracker pin  6  mounted on the base  1  and set in a predetermined orientation for securing a patient tracker  61 .  
         [0058]     In this embodiment of the invention, the base  1  used in this pelvic navigation-training model is made of acrylic, and formed in a rectangular shape with a size of 355 mm (L)×255 mm (W)×15 mm (H).  
         [0059]     The holding device includes two parted stainless steel poles  2  and two parted stainless steel screws  4 , which are in two rows and parallel. For example, the two stainless steel poles  2  which are of a size of 6 mm in diameter and 100 mm in height are fixed on the base  1  to maintain the precise position of the plastic pelvic model bone  3 , and are 65 mm apart from each other. Two stainless steel screws  4  of 5 mm in diameter are attached to the base  1  for passing through the sacral foramina of the sacrum of the plastic pelvic model bone  3  and are 35 mm apart from each other. The plastic pelvic model bone  3  is then further secured on the base with nuts  5 . The stainless steel poles  2  and screws  4  are fitted accurately to two brands of plastic model bones.  
         [0060]     The patient tracker pin  6  is fixed on the base and tilted 70° from the surface of the base  1  for fitting the patient tracker  61  in this embodiment, which visualizes the plastic pelvic model bone  3  for the training of screw fixation of pelvic fractures.  
         [0061]     With the plastic pelvic model bone  3  being fixed to the pelvic navigation-training model, fluoroscopic images of the plastic pelvic model bone  3  are taken by a C-arm fluoroscope (not shown) and stored in a computer of a navigation system.  FIGS. 3 through 6  respectively show outlet, inlet, frontal, and true sagittal views of these fluoroscopic images of the plastic pelvic model bone  3 . The fluoroscopic images stored in the computer can be retrieved for surgically training.  
         [0062]     A surgical tool attached with a tool tracker is communicated with a navigation system. The navigation system provides the calibration and display of the relative positions of the patient tracker, the fluoroscopic images and the tracked surgical tool in a common 3D coordinate system.  
         [0063]     During the training, the plastic pelvis model bone  3  and the patient tracker  61  are placed on the navigation-training model. The fluoroscopic images of different views of the plastic pelvis model bone  3  as shown in  FIG. 7  are loaded onto the computer of the navigation system. A tool tracker is fixed on the surgical tool and both are calibrated with the navigation system. Crosshairs show the relative locations of the surgical tool to the fluoroscopic images and the patient tracker in different views on a display of the navigation system. The trainee can thus practice computer-assisted images-guided screw insertion using the navigation-training model with the surgical tool. The procedures can be followed exactly and the result can be observed on the display in real-time.  
         [0064]     In a second embodiment of the present invention, a hip screw/intramedullary fixation of trochanteric fractures navigation-training apparatus is provided for training on fluoroscopic images-guided cannulated hip screws and Gamma nail insertion and lag screw positioning. This fluoroscopic images-guided navigation-training apparatus comprises a corresponding navigation-training model, and a navigation system having a computer that stores a plurality of fluoroscopic images of the plastic proximal femur model bone mounted on the navigation-training model.  
         [0065]     Referring to  FIGS. 8 and 9 , the navigation-training model used in this hip screw/intramedullary fixation of trochanteric fractures navigation-training apparatus includes: a base  1 , a holding device for fixing a plastic proximal femur model bone  9  on the base  1  in a precise position for the training of the specific orthopedic surgical procedure, and a patient tracker pin  6  mounted on the base  1  and set in a predetermined orientation for securing a patient tracker  61 .  
         [0066]     In this embodiment, the base  1  is made of acrylic, and is shaped in a rectangle with the size of 333 mm (L)×163 mm (W)×15 mm (H).  
         [0067]     The holding device of this navigation-training model includes two parted aluminum poles  8  and a holding block  10  mounted therebetween along the elongated side of base  1 . The holding block  10  has a lower portion  101  disposed on the base and an upper portion  102  removable from the lower portion. Two windows  112  are provided symmetrically at the joint between the upper portion and the lower portion, and a cylindrical tunnel  103  is provided extended along the elongated direction of the base between the two windows to hold the plastic proximal femur bone.  
         [0068]     The two aluminum poles  8 , for example, can be of 12.5 mm in diameter and of different heights (66 mm and 88 mm), and fixed 233 mm apart from each other on the base  1 . The two aluminum poles  8  serve to maintain the plastic proximal femur model bone  9  fixed in the accurate position. The holding block  10  can be made of epoxy, with dimension of 80 mm (L)×62 mm (W)×62 mm (H) and has two openings  112  at both sides for distal locking and lag screw insertion.  
         [0069]     Referring to  FIGS. 9   a  and  9   b , the patient tracker pin  6  is fixed on the base  1  at 45° from the surface of the base  1 , and 25° between the projecting line of the patient tracker pin  6  onto the base  1  and the elongated side of the base  1 . It visualizes the plastic proximal femur model bone  9  for training on fluoroscopic images-guided cannulated hip screws and Gamma nail insertion and lag screw positioning.  
         [0070]     During computer-assisted images-guided surgical training, the plastic proximal femur model bone  9  is secured by two aluminum poles  8  and the epoxy holding block  10 , and the patient tracker  61  is attached to the patient tracker pin  6 . Fluoroscopic images of the plastic proximal femur model bone  9  are taken by a C-arm fluoroscope as indicated above.  FIGS. 10 and 11  show the fluoroscopic images of the plastic proximal femur model bone  9  which are frontal and true sagittal views. The fluoroscopic images of different views of the plastic proximal femur model bone  9  are loaded onto the computer of the navigation system.  
         [0071]     A tool tracker is then fixed to the surgical tool and both are calibrated with the navigation system. Crosshairs show the relative locations of the tool to the fluoroscopic images and the patient tracker in different views on the display of the navigation system. The trainee can then practice computer-assisted images-guided cannulated hip screws and Gamma nail insertion and lag screw positioning with the tracked surgical tool. The procedures can be followed exactly and the result can be observed on the display in real-time.  
         [0072]     In a third embodiment of the present invention, the distal locking navigation-training apparatus is provided for training on computer-assisted fluoroscopic images-guided distal locking. This navigation training apparatus comprises a distal locking navigation training model and a navigation system having a computer that stores a plurality of fluoroscopic images of the plastic femur model bone mounted on the navigation-training model.  
         [0073]     Referring to  FIGS. 12 and 13 , the distal locking navigation-training model used in this distal locking navigation-training apparatus includes: a base  1 , a holding device for fixing a plastic femur model bone  18  onto the base  1  in a precise position for training of specific orthopedic surgical procedure, and a patient tracker pin  6  set in a predetermined orientation for securing a patient tracker  61 .  
         [0074]     The plastic femur model bone  18  is covered with insulating materials  19  and inserted with a stainless steel rod  14 . The stainless steel rod  14  has two parted parallel holes  16  at the distal end thereof.  
         [0075]     In this embodiment, the base  1  used in this distal locking navigation-training model is made of acrylic, in a rectangular shape, with a size of 325 mm (L)×195 mm (W)×15 mm (H).  
         [0076]     The holding device used in this distal locking navigation-training model includes a first holding block  13  and a second holding block  17  mounted to the base  1 . For example, the first holding block  13  has a size of 100 mm (L)×75 mm (W)×128 mm (H). The first holding block  13  and the second holding block  17  can be made of acrylic. The first holding block  13  secures a patient tracker pin  6  in a predetermined direction and secures the stainless steel rod  14  horizontally extended toward the second holding block  17 .  
         [0077]     The stainless steel rod  14 , for example, having a length of 210 mm, a thread length of 62 mm, and a diameter of 12 mm, which simulates an interlocking nail, is mounted horizontally to the first holding block  13  at a height of 80 mm. Referring to  FIGS. 12 and 13 , a set screw  15  on the threaded insert is used to maintain the correct orientation of the stainless steel rod  14 . Two screw holes  16  of 6.28 mm in diameter and 25.4 mm apart from each other are drilled on the stainless steel rod  14  passing through the medullary canal of the plastic bone  18  to simulate the distal locking holes of the interlocking nail.  
         [0078]     The second holding block  17  has two windows  171  and a cylindrical tunnel  172  is provided extended along the elongated direction of the base between the two windows  171  to hold the plastic femur bone  18 . Since the plastic femur model bone  18  is covered with insulating materials  19 , the distal locking holes  16  of the stainless steel rod  14  are not exposed.  
         [0079]     The patient tracker pin  6  is tilted 45° with the surface of the base  1 , referring to  FIG. 13   a , the projecting line of the patient tracker pin  6  onto the base  1  is parallel with the elongated side of the base  1  which visualizes the plastic femur model bone  18  covered with insulating materials  19  for training on fluoroscopic images-guided distal locking.  
         [0080]     With the plastic femur model bone  18  being fixed on the distal locking navigation-training model, fluoroscopic images of the plastic femur model bone  18  mounted on the distal locking navigation-training model are captured by the C-arm fluoroscope. Referring to  FIGS. 14 and 15 , the fluoroscopic images of the plastic femur model bone  18  used in the embodiment are frontal and true sagittal views. They are stored in the computer of the navigation system and can be retrieved for surgical training.  
         [0081]     During computer-assisted images-guided surgical training, the plastic femur model bone  18  is secured to the base  1  and the patient tracker  61  is attached to the patient tracker pin  6 . The fluoroscopic images of different views of the plastic femur model bone  18  inserted with the stainless steel rod  14  having distal locking holes  16  as shown in  FIGS. 14 and 15  are loaded onto the computer of the navigation system. A tool tracker is fixed to the surgical tool and both are calibrated with a common 3D coordinate system, and crosshairs show the relative locations of the surgical tool to the fluoroscopic images and the patient tracker in different views on the display of the navigation system. The trainee can thus practice computer-assisted images-guided distal locking with the surgical tool. The procedures can be followed exactly and the result can be observed on the display in real-time.  
         [0082]     It should be understood that the above description and embodiments of the invention are merely intended to be illustrative, and equivalents to the invention may be apparent to those skilled in the art without departing from the spirit of the invention.