CN116650144A - Method for monitoring back inclination angle of tibial plateau in tibial high-level osteotomy in real time - Google Patents

Method for monitoring back inclination angle of tibial plateau in tibial high-level osteotomy in real time Download PDF

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CN116650144A
CN116650144A CN202310671143.4A CN202310671143A CN116650144A CN 116650144 A CN116650144 A CN 116650144A CN 202310671143 A CN202310671143 A CN 202310671143A CN 116650144 A CN116650144 A CN 116650144A
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tibia
tibial
tibial plateau
reference array
plateau
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周再望
黄志俊
刘金勇
钱坤
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Lancet Robotics Co Ltd
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Abstract

The invention discloses a method for monitoring the back inclination angle of a tibial plateau in a tibial high-level osteotomy in real time, which comprises the following steps: s1, shooting CT images before operation, and establishing a tibial plateau normal phasor and a tibial axis direction vector; s2, intraoperatively installing a tibia reference array; s3, positioning the reference array by using a positioning camera respectively; s4, shooting a CBCT image in the operation, and performing conversion of a space transformation matrix by using a tibia reference array in a virtual space coordinate system and a camera space coordinate system; s5, obtaining the expression of the tibial plateau normal phasor and the tibial axis vector under the same coordinate system; s6, acquiring reference array positioning in real time through an optical camera in operation, and acquiring a tibia PTS; the invention realizes real-time monitoring of PTS in operation by utilizing optical navigation data, reduces the times of X-ray and CBCT shooting in operation, and reduces the radiation exposure of patients and doctors.

Description

Method for monitoring back inclination angle of tibial plateau in tibial high-level osteotomy in real time
Technical Field
The invention relates to the technical field of tibial plateau back rake measurement, in particular to a method for monitoring the back rake of a tibial plateau in a tibial high-level osteotomy.
Background
Tibial plateau back tilt (posterior tibial slope, PTS) is one indicator that requires significant attention in tibial plateau osteotomies (high tibial osteotomy, HTO). The value of PTS is changed by the HTO gap-opening operation, and proper PTS can help to increase the stability of knee joint, otherwise, the risk of ligament tear of patient is increased: for patients with anterior cruciate ligament insufficiency, the PTS should be reduced; for patients with posterior cruciate ligament insufficiency, the PTS should be increased.
PTS is defined broadly as the angle between the perpendicular to the axis of the tibia and the tibial plateau, but there is no academic unification of the provision for measuring:
one type of PTS measurement is performed on a two-dimensional X-ray diagram, as shown in FIG. 9, which is a lateral X-ray diagram of a patient's leg, line 1 is a tangent to the anterior cortical bone of the tibia, which is taken as the tibial axis; straight line 2 is the perpendicular to straight line 1; line 3 is a tangent to the tibial plateau; the included angle between the straight lines 2 and 3 is PTS; also, there are other ways to define the axis of tibia by measuring PTS on a two-dimensional X-ray chart, and as shown in FIG. 10, a tangent to the posterior cortical bone (PTC) of tibia or the proximal anatomical axis of Tibia (TPAA) is used as the axis of tibia.
Because the two-dimensional X-ray image is difficult to ensure alignment of the tibia (different axis projections can be obtained by shooting at different angles) when shooting, and because the shielding of other tissues of the tibia platform is possibly unclear, the accuracy of the PTS measured by the method is problematic. On the other hand, by using three-dimensional data of tibia, such as CT and MRI, PTS can be obtained by calculating the geometric relationship of feature points of the three-dimensional image of tibia or adjusting the cross section of the three-dimensional image to a proper position, and accuracy of PTS measurement can be significantly improved.
For the actual application scene of HTO, the existing two-dimensional and three-dimensional PTS measurement means cannot support accurate intraoperative real-time monitoring of PTS. In HTO surgery, if a doctor needs to know the PTS value of a patient at a certain time, an X-ray image must be taken or a CBCT scan must be performed on an operating table, which not only complicates the operation, but also increases the radiation exposure of the doctor and the patient.
Disclosure of Invention
The invention aims at solving the problems existing in the prior art and provides a method for monitoring the back inclination angle of a tibial plateau in a tibial high-level osteotomy in real time; the PTS is monitored in real time during operation by utilizing the optical navigation data, so that the times of X-ray and CBCT shooting during operation are reduced, and the radiation exposure of patients and doctors is reduced.
In order to achieve the above purpose, the invention adopts the following technical scheme:
a method for monitoring the back tilt angle of a tibial plateau in a tibial plateau osteotomy in real time, which comprises the following steps:
s1, shooting and intercepting CT images of a tibia part before operation, reconstructing tibia surface grid data, and establishing an inner tibia plateau method phasorLateral tibial plateau phasor>And tibial axis direction vector->
S2, mounting a tibia proximal reference array at a proximal position of tibia in operation, and mounting a tibia handle reference array at a bone handle position of tibia, wherein the tibia proximal reference array comprises a plurality of reflecting balls and a plurality of metal balls, and the tibia handle reference array comprises a plurality of reflecting balls;
s3, respectively positioning the reflective balls of the two reference arrays by using a positioning camera to obtain a tibia near-end reference array coordinate system F rf1 And tibial stem reference array coordinate system F rf2 And a camera coordinate system F camera Respectively to F rf1 And F is equal to rf2 Is calculated and converted to obtain F rf1 And F is equal to rf2 A space transformation matrix T between rf1torf2 ；
S4, shooting an intraoperative CBCT image with a tibia proximal end and a tibia proximal end reference array, and obtaining a virtual space coordinate system F imagespace Next, overlapping the preoperative CBCT image with the proximal tibia of the intraoperative CBCT image; in the coordinate system F by metal balls in the proximal tibial reference array imagespace And at F rf1 The point set below, build F imagespace To F rf1 Is a spatial transformation matrix T of (2) imagespacetorf1 Then combine the transformation matrix T rf1torf2 Obtaining F imagespace To F rf2 Is a spatial transformation matrix T of (2) imagespacetorf2 ；
S5, obtaining the normal vector of the medial tibial plateau by calculation through conversion of a space transformation matrixAt F rf1 Expressed below asLateral tibial plateau normal vector->At F rf1 The lower expression is->Tibial axis direction vector->At F rf2 The lower expression is->
S6, acquiring F from positioning camera in real time in operation camera To F rf1 And F is equal to rf2 Is calculated to obtain F rf1 To F rf2 Real-time transformation matrix T of (2) rf1torf2_tmp Combining the axis direction vector of tibiaAt F rf2 Expression of->Obtaining a tibial axis direction vector +.>At F rf1 Expression of->Same coordinate axis F rf1 And obtaining the PTS of the inner tibia and the outer tibia according to the angle between the normal phasors of the inner tibia platform and the outer tibia platform and the axial direction vector of the tibia.
The step S1 specifically comprises the following steps:
fitting a space plane on the medial tibial plateau, and obtaining the normal vector pointing from the proximal end to the distal end of the tibia, namely the normal vector of the medial tibial plateauFitting a space plane on the lateral tibial plateau, and obtaining the normal vector pointing from the proximal end to the distal end of the tibia, namely the normal vector of the medial tibial plateau +.>
PCA principal component analysis is carried out on all vertexes of the surface of the tibia grid, and feature vectors from the proximal end to the distal end of the tibia corresponding to the maximum feature value are marked asThe geometric centers of all points of the medial tibia plateau and the lateral tibia plateau are marked as C, and from the C point, the geometric centers are marked as +.>Establishing a plurality of planes for the normal direction, calculating the geometric centers of the closed surrounding rings obtained by intersecting the planes with the tibia, fitting a straight line to the geometric centers by using a least square method, and recording the direction vector of the straight line from the proximal end to the distal end of the tibia as the tibiaBone axis direction vector->
The step S3 specifically comprises the following steps:
the positioning system presets the arrangement mode of the reflective balls in each reference array, and the spherical center coordinates of each reflective ball are captured in real time by the positioning camera, so that the positioning camera coordinate system F can be obtained by calculation camera Respectively to a coordinate system F rf1 And F is equal to rf2 Is a spatial transformation matrix T of (2) cameratorf1 And T is cameratorf2 Thereby learning the space pose of each reference array and obtaining F by conversion rf1 And F is equal to rf2 Space transformation matrix between
T rf1torf2 ＝(T cameratorf1 ) -1 ·T cameratorf2 ；
The step S4 specifically comprises the following steps:
creating a spatial transformation matrix T of a pre-operative CBCT image and an intra-operative CBCT image 1 Will T 1 The method comprises the steps of using an intraoperative CBCT image to enable a tibia proximal end of the intraoperative CBCT image to move to a position close to an overlapping position with a tibia proximal end of a preoperative CBCT image, and using an ITK image registration frame to enable matching degree of the tibia proximal end and the tibia proximal end to be optimal;
the center point of the metal ball is concentrated at F imagespace The following description is the point set I, the metal sphere center point set F rf1 The method is described as a point set II, wherein the point set I is used as a source point set, the point set II is used as a target point set, and a space rigidity transformation matrix is calculated, and the matrix is F imagespace To F rf1 Is denoted as T imagespacetorf1 The method comprises the steps of carrying out a first treatment on the surface of the Then
T imagespacetorf2 ＝T imagespacetorf1 ·T rf1torf2 。
The step S5 specifically comprises the following steps:
t-shaped memory imagespacetorf1 The upper right corner 3X3 rotation matrix is R 1 The normal vector of the medial tibial plateau is F rf1 Expression belowNormal vector to lateral tibial plateau at F rf1 Expression of->It can be calculated as:
t-shaped memory imagespacetorf2 The upper right corner 3X3 rotation matrix is R 1 Then the tibial axis direction vector is at F rf2 Expression belowIt can be calculated as: />
The step S6 specifically comprises the following steps:
intraoperative acquisition of F from a positioning camera in real time camera To F rf1 And F is equal to rf2 The transformation matrices are denoted T respectively cameratorf1_tmp And T is cameratorf2_tmp Calculate F at this time rf1 To F rf2 Real-time conversion matrix of (a)
T rf1torf2_tmp ＝(T cameratorf1_tmp ) -1 ·T cameratorf2_tmp ；
T-shaped memory rf1torf2_tmp The upper right corner 3X3 rotation matrix is R tmp At this time, the tibial axis direction vector is F rf1 Expression belowIt can be calculated as:
the medial tibial PTS can be calculated as:
the lateral tibial PTS can be calculated as:
compared with the prior art, the invention has the beneficial effects that:
1. the real-time monitoring of PTS in operation is realized by utilizing the optical navigation data, and no extra PTS measurement step is needed in operation;
2. the acquired PTS value is based on three-dimensional CT data, so that the accuracy is high;
3. the patient only needs to shoot 1 CT before the operation, and shoot 1 CBCT in the operation, can accomplish the required image registration of PTS real-time supervision, carries out X-ray perspective for many times in order to acquire PTS for the art, has reduced patient and doctor's radiation exposure.
Drawings
FIG. 1 is a schematic view of the present invention in a proximal tibial endpoint selection set;
FIG. 2 is a schematic view of the present invention for creating a tibial axis direction vector at the proximal end of the tibia;
FIG. 3 is a schematic representation of the coordinate system conversion of the positioning camera of the present invention with the proximal tibial reference array, the tibial stem reference array, and;
FIG. 4 is a schematic view of the mounting locations of the proximal tibial reference array, the tibial stem reference array, and the tibia of the present invention;
FIG. 5 is a schematic representation of the range of intraoperative CBCT shots of a tibia in accordance with the present invention;
FIG. 6 is a schematic illustration of the registration process of the intra-operative CBCT image and the pre-operative CBCT image according to the present invention;
FIG. 7 is a schematic diagram showing the completion of registration of an intraoperative CBCT image with a preoperative CBCT image in accordance with the present invention;
FIG. 8 is a schematic diagram of coordinate system conversion of a virtual image space and a camera space according to the present invention;
fig. 9 is a schematic diagram of a prior art measurement PTS of the present invention;
FIG. 10 is a schematic view of a tibial axis of the prior art of the present invention;
fig. 11 is an overall flow chart of the method of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made more apparent and fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. All other embodiments, which can be made by one of ordinary skill in the art without undue burden on the person of ordinary skill in the art based on embodiments of the present invention, are within the scope of the present invention.
A method for monitoring the back tilt angle of a tibial plateau in a tibial plateau osteotomy in real time, which comprises the following steps:
s1, shooting and intercepting CT images of a tibia part before operation, reconstructing tibia surface grid data, and establishing an inner tibia plateau method phasorLateral tibial plateau phasor>And tibial axis direction vector->
S2, mounting a tibia proximal reference array at a proximal position of tibia in operation, and mounting a tibia handle reference array at a bone handle position of tibia, wherein the tibia proximal reference array comprises a plurality of reflecting balls and a plurality of metal balls, and the tibia handle reference array comprises a plurality of reflecting balls;
s3, respectively positioning the reflective balls of the two reference arrays by using a positioning camera to obtain a tibia near-end reference array coordinate system F rf1 And tibial stem reference array coordinate system F rf2 And a camera coordinate system F camera Respectively to F rf1 And F is equal to rf2 Is calculated and converted to obtain F rf1 And F is equal to rf2 A space transformation matrix T between rf1torf2 ；
S4, shooting an intraoperative CBCT image with a tibia proximal end and a tibia proximal end reference array, and obtaining a virtual space coordinate system F imagespace Next, overlapping the preoperative CBCT image with the proximal tibia of the intraoperative CBCT image; in the coordinate system F by metal balls in the proximal tibial reference array imagespace And at F rf1 The point set below, build F imagespace To F rf1 Is a spatial transformation matrix T of (2) imagespacetorf1 Then combine the transformation matrix T rf1torf2 Obtaining F imagespace To F rf2 Is a spatial transformation matrix T of (2) imagespacetorf2 ；
S5, obtaining the normal vector of the medial tibial plateau by calculation through conversion of a space transformation matrixAt F rf1 Expressed below asLateral tibial plateau normal vector->At F rf1 The lower expression is->Tibial axis direction vector->At F rf2 The lower expression is->
S6, acquiring F from positioning camera in real time in operation camera To F rf1 And F is equal to rf2 Is calculated to obtain F rf1 To F rf2 Real-time transformation matrix T of (2) rf1torf2_tmp Combining the axis direction vector of tibiaAt F rf2 Expression of->Obtaining a tibial axis direction vector +.>At F rf1 Expression of->Same coordinate axis F rf1 And obtaining the PTS of the inner tibia and the outer tibia according to the angle between the normal phasors of the inner tibia platform and the outer tibia platform and the axial direction vector of the tibia.
The step S1 specifically comprises the following steps:
the patient performs CT shooting including complete operation side tibia before operation, cuts out a three-dimensional image of a tibia part, marks as image_pre, reconstructs tibia surface grid data on the basis of the image_pre, and marks as tibia_surface. As shown in the following diagram, the image_pre and the tibia_surface are used as the input of the subsequent operation, wherein the data format of the image_pre is vtkImageData, and the data format of the tibia_surface is vtkPolyData;
as shown in fig. 1, at least 3 points are clicked on the medial tibial plateau of the tibia_surface to form a point set pset_medium;
at least 3 points are clicked on the lateral tibia platform of the tibia_surface to form a point set Pset_surface;
clicking 1 Point at the most protruding position of the tibia_surface tibial tubercle, and marking as Point_cycle;
calculating the geometric center of Pset_media and P1 and P2; the ordered Point set formed by P1, P2 and Point_cycle is marked as Pset_landmark_target;
fitting a space plane to the point set Pset_medium by using a least square method, and obtaining a normal vector pointing from the proximal tibia to the distal tibia, namely a medial tibial plateau normal vector
Fitting a space plane to the point set Pset_planar by using a least square method, and obtaining a normal vector pointing from the proximal tibia to the distal tibia, namely a medial tibial plateau normal vector
PCA principal component analysis is carried out on all vertexes of the surface of the tibia_surface grid, and the feature vector corresponding to the maximum feature value is recorded asAdjust->To ensure +.>From the proximal tibia to the distal end;
as shown in FIG. 2, the geometric centers of all points Pset_medium and Pset_temporal are noted as C, starting from point C, to6 planes are established for the normal direction, the distance between the point C and the first plane is 40mm, and the distance between the adjacent planes is 20mm; calculating the geometric center of the closed enclosure ring obtained by intersecting the planes with the tibia_surface, and fitting a straight line to the 6 centers by using a least square method, wherein the direction vector of the straight line from the proximal end to the distal end of the tibia is the tibia axis direction vector->
The step S2 specifically comprises the following steps:
as shown in fig. 3, a plurality of reflective balls (white balls in the figure) which can be identified by the optical positioning camera are respectively attached to the proximal tibia reference array and the proximal tibia reference array (the number is more than or equal to 3), and the reflective balls are not developed in the CBCT image; the reflective spheres of the two reference arrays are arranged differently. The reflective sphere centers of the reference array may form a spatial coordinate system (the formation mode is not unique, for example, one sphere center is the origin of the coordinate system, the connection line direction of two sphere centers is the x-axis direction of the coordinate system, the x-axis direction is multiplied by the direction vector of the connection line of the other two sphere centers to obtain the z-axis direction, and the z-axis direction is multiplied by the x-axis direction to obtain the y-axis direction).
As shown in fig. 4, the proximal tibial reference array is mounted in a proximal tibial position and the tibial stem reference array is mounted in a tibial stem position in a rigid manner, such as by means of bone screw fixation, it being noted that the reference array or its fixation means cannot interfere with the cutting plane.
The step S3 specifically comprises the following steps:
the positioning system presets the arrangement mode of the reflective balls in each reference array, and the spherical center coordinates of each reflective ball are captured in real time by the positioning camera, so that the positioning camera coordinate system F can be obtained by calculation camera Respectively to a coordinate system F rf1 And F is equal to rf2 Is a spatial transformation matrix T of (2) cameratorf1 And T is cameratorf2 Thereby learning the space pose of each reference array and obtaining F by conversion rf1 And F is equal to rf2 Space transformation matrix between
T rf1torf2 ＝(T cameratorf1 ) -1 ，T cameratorf2 ；
It should be noted that, in addition to the reflective spheres, a plurality of (number greater than or equal to 3) metal spheres (black spheres in fig. 2 and 3) capable of being developed in CBCT are embedded in the proximal tibial reference array, and the proximal tibial reference array coordinate system F rf1 Under the condition, the sphere centers (sphere centers 1, 2, 3 and 4) of the metal spheres form an ordered point set Pset_design, and the coordinate value of the point set is a tool design value known in advance; the tibial stem reference array lacks a metal ball.
Because the positioning camera can output the pose of the reference array under the coordinate system of the positioning camera in real time, the spatial positioning of the tibia can be realized as long as the relative pose relation (image registration) of the tibia and the reference array is additionally known, so that the real-time PTS is solved.
The step S4 specifically comprises the following steps:
performing tibia CBCT shooting by using an O arm or a three-dimensional C arm, and ensuring that a dotted line frame area in the figure 5 falls within a scanning range, namely the obtained three-dimensional image needs to comprise a tibia near end and a tibia near end reference array; the obtained intra-operative CBCT image is recorded as image-intra, and is imported into a virtual image space as shown in FIG. 6, and the coordinate system of the virtual image space is F imagespace 。
Sequentially clicking a medial tibial plateau center point (point a in fig. 6), a lateral tibial plateau center point (point b in fig. 6) and a tibial nodule most protruding point (point c in fig. 6) on image_intra, wherein the three points form a point set Pset_landmark_src;
then, importing an image_pre and a Pset_landmark_target into the virtual image space;
using the vtkLandmarkTransform function, a spatial rigid transformation matrix is calculated with pset_landmark_src as the source point set and pset_landmark_target as the target point set, thereby creating a spatial transformation matrix T1 of the pre-operative CBCT image (image_pre) and the intra-operative CBCT image (image_intra).
As shown in fig. 7, T is 1 For image_intra, the image_intra is moved to a near overlapping position near image_pre, but because Pset_landmark_src and Pset_landmark_target are both manually clicked, there is always an error in the positions of the two on the bone surface, so the overlapping degree of the image_intra and the image_pre is not high enough
Using the ITK image registration framework, a rigid registration matrix T of image_pre (as fix image) and image_intra (as moving image) is calculated 2 : the scale calculation mode (metric) selects the image mutual information value scale MattesMutualInformationImageToImageMetric; the interpolator (interpolator) is a linear interpolator imagefunction;
will T 2 The matching degree of the image_intra and the image_pre is optimal when the matching degree is applied to the image_intra.
As shown in fig. 7, the image_intra is manually marked with the center points of the metal ball images in the order of pset_design to form a point set pset_extracted;
as shown in fig. 8, at F imagespace Hereinafter, the set of metal sphere center points is described as point set one (pset_extracted), while the set of metal sphere center points is in the proximal tibial reference array coordinate system F rf1 The following description is set of points two (pset_design), using the vtkLandmarkTransform function, calculating a spatially rigid transformation matrix with pset_design as the source set and pset_extracted as the target set, which is F at this time imagespace To F rf1 Is denoted as T imagespacetorf1 The method comprises the steps of carrying out a first treatment on the surface of the Then
T imagespacetorf2 ＝T imagespacetorf1 ·T rf1torf2 。
The step S5 specifically comprises the following steps:
t-shaped memory imagespacetorf1 The upper right corner 3X3 rotation matrix is R 1 The normal vector of the medial tibial plateau is F rf1 Expression belowNormal vector to lateral tibial plateau at F rf1 Expression of->It can be calculated as:
t-shaped memory imagespacet o rf2 The upper right corner 3X3 rotation matrix is R 1 Then the tibial axis direction vector is at F rf2 Expression belowIt can be calculated as: />
The step S6 specifically comprises the following steps:
intraoperative acquisition of F from a positioning camera in real time camera To F rf1 And F is equal to rf2 The transformation matrices are denoted T respectively camerat orf1_ tmp And T is camerat orf2_ tmp Calculate F at this time rf1 To F rf2 Real-time conversion matrix of (a)
T rf1torf2_tmp ＝(T cameratorf1_tmp ) -1 ·T cameratorf2_tmp ；
T-shaped memory rf1torf2_tmp The upper right corner 3X3 rotation matrix is R tmp At this time, the tibial axis direction vector is F rf1 Expression belowIt can be calculated as:
the medial tibial PTS can be calculated as:
the lateral tibial PTS can be calculated as:
although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims (6)

1. A method for monitoring the back tilt angle of a tibial plateau in a tibial plateau osteotomy in real time, which is characterized by comprising the following steps:
s1, shooting and intercepting CT images of a tibia part before operation, reconstructing tibia surface grid data, and establishing an inner tibia plateau method phasorLateral tibial plateau phasor>And tibial axis direction vector->
S2, mounting a tibia proximal reference array at a proximal position of tibia in operation, and mounting a tibia handle reference array at a bone handle position of tibia, wherein the tibia proximal reference array comprises a plurality of reflecting balls and a plurality of metal balls, and the tibia handle reference array comprises a plurality of reflecting balls;
s3, respectively positioning the reflective balls of the two reference arrays by using a positioning camera to obtain a tibia near-end reference array coordinate system F rf1 And tibial stem reference array coordinate system F rf2 Calculating a camera coordinate system F camera Respectively to F rf1 And F is equal to rf2 Is converted to F rf1 And F is equal to rf2 A space transformation matrix T between rf1torf2 ；
S4, shooting an intraoperative CBCT image with a tibia proximal end and the tibia proximal end reference array, and obtaining a virtual space coordinate system F imagespace Next, overlapping the preoperative CBCT image with the proximal tibia of the intraoperative CBCT image; in a coordinate system F by the metal balls in the proximal tibial reference array imagespace And at F rf1 The point set below, build F imagespace To F rf1 Is a spatial transformation matrix T of (2) imagespacetorf1 Then combine the transformation matrix T rf1torf2 Obtaining F imagespace To F rf2 Is a spatial transformation matrix T of (2) imagespacetorf2 ；
S5, obtaining the normal vector of the medial tibial plateau by means of calculation through conversion of a space transformation matrixAt F rf1 The lower expression is->The lateral tibial plateau normal vector +.>At F rf1 The lower expression is->Said tibial axis direction vector->At F rf2 The lower expression is->
S6, acquiring F from positioning camera in real time in operation camera To F rf1 And F is equal to rf2 Is calculated to obtain F rf1 To F rf2 Real-time transformation matrix T of (2) rf1torf2_tmp Combining the axis direction vector of tibiaAt F rf2 Expression of->Obtaining a tibial axis direction vector +.>At F rf1 Expression of->Then according to the same coordinate axis F rf1 And obtaining the PTS of the medial tibia and the lateral tibia by the angle between the normal phasor of the inferior medial tibial plateau and the lateral tibial plateau and the axial vector of the tibia.
2. The method for real-time monitoring of tibial plateau back rake in high tibial osteotomy as in claim 1, wherein step S1 comprises:
fitting a space plane on the medial tibial plateau, and obtaining the normal vector pointing from the proximal end to the distal end of the tibia, namely the normal vector of the medial tibial plateauFitting a space plane on the lateral tibial plateau, and obtaining the normal vector pointing from the proximal end to the distal end of the tibia, namely the normal vector of the medial tibial plateau +.>
PCA principal component analysis is carried out on all vertexes of the surface of the tibia grid, and feature vectors from the proximal end to the distal end of the tibia corresponding to the maximum feature value are marked asThe geometric centers of all points of the medial tibia plateau and the lateral tibia plateau are marked as C, and from the C point, the geometric centers are marked as +.>For normal direction, a plurality of planes are established, the geometric centers of the closed surrounding rings obtained by intersecting the planes with the tibia are calculated, a least square method is used for fitting a straight line to the geometric centers, and the direction vector of the straight line pointing to the far end from the proximal end of the tibia is recorded as the axis direction vector of the tibia>
3. The method for real-time monitoring of tibial plateau back rake in high tibial osteotomy as in claim 1, wherein step S3 comprises:
the positioning system presets the arrangement mode of the reflective balls in each reference array, and captures each reflective ball in real time through the positioning cameraThe center coordinates of the ball can be calculated to obtain a positioning camera coordinate system F camera Respectively to a coordinate system F rf1 And F is equal to rf2 Is a spatial transformation matrix T of (2) cameratorf1 And T is cameratorf2 Thereby learning the space pose of each reference array and obtaining F by conversion rf1 And F is equal to rf2 Space transformation matrix between
T rf1torf2 ＝(T cameratorf1 ) -1 ·T cameratorf2。
4. The method for real-time monitoring of tibial plateau back rake in high tibial osteotomy as in claim 1, wherein step S4 comprises:
creating a spatial transformation matrix T of a pre-operative CBCT image and an intra-operative CBCT image 1 Will T 1 The method comprises the steps of using an intraoperative CBCT image to enable a tibia proximal end of the intraoperative CBCT image to move to a position close to an overlapping position with a tibia proximal end of a preoperative CBCT image, and using an ITK image registration frame to enable matching degree of the tibia proximal end and the tibia proximal end to be optimal;
the center point of the metal ball is concentrated at F imagespace The following description is the point set I, the metal sphere center point set F rf1 The method is described as a point set II, wherein the point set I is used as a source point set, the point set II is used as a target point set, and a space rigidity transformation matrix is calculated, and the matrix is F imagespace To F rf1 Is denoted as T imagespacetorf1 The method comprises the steps of carrying out a first treatment on the surface of the Then
T imagespacetorf2 ＝T imagespacetorf1 ·T rf1torf2 。
5. The method for real-time monitoring of tibial plateau back rake in high tibial osteotomy as in claim 1, wherein step S5 comprises:
t-shaped memory imagespacetorf1 The upper right corner 3X3 rotation matrix is R 1 The normal vector of the medial tibial plateau is F rf1 Expression belowAnd outside are connected withNormal vector of lateral tibial plateau at F rf1 Expression of->It can be calculated as:
t-shaped memory imagespacetorf2 The upper right corner 3X3 rotation matrix is R 1 Then the tibial axis direction vector is at F rf2 Expression belowIt can be calculated as: />
6. The method for real-time monitoring of tibial plateau back rake in high tibial osteotomy as in claim 1, wherein step S6 comprises:
intraoperative acquisition of F from a positioning camera in real time camera To F rf1 And F is equal to rf2 The transformation matrices are denoted T respectively cameratorf1_tmp And T is cameratorf2_tmp Calculate F at this time rf1 To F rf2 Real-time conversion matrix of (a)
T rf1torf2_tmp ＝(T cameratorf1_tmp ) -1 ·T cameratorf2_tmp ；
T-shaped memory rf1torf2_tmp The upper right corner 3X3 rotation matrix is R tmp At this time, the tibial axis direction vector is F rf1 Expression belowIt can be calculated as:
the medial tibial PTS can be calculated as:
the lateral tibial PTS can be calculated as:
CN202310671143.4A 2023-06-07 2023-06-07 Method for monitoring back inclination angle of tibial plateau in tibial high-level osteotomy in real time Pending CN116650144A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117084787B (en) * 2023-10-18 2024-01-05 杭州键嘉医疗科技股份有限公司 Method and related equipment for checking internal and external rotation angles of tibial prosthesis installation

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117084787B (en) * 2023-10-18 2024-01-05 杭州键嘉医疗科技股份有限公司 Method and related equipment for checking internal and external rotation angles of tibial prosthesis installation

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