Knee Navi AR App
Total knee arthroplasty (TKA) is a very successful procedure and implant survival now approaches 95% at 15 years . The success of this procedure as measured by pain relief, improved function, greater patient satisfaction, and implant longevity is predicated on a number of factors. These include prosthetic factors such as implant size, tribology, geometry, alignment, and position; patient factors including size, weight, activity, the existence of medical comorbidities, psychological, and physiological response to joint surgery; and surgical factors including surgical skill and experience, duration of surgery, appropriate preparation, and implantation of the prosthesis. Recently, there has been greater focus on surgical technique and its relationship to implant performance and survival. In addition, greater attention is being paid to reducing surgical trauma through less invasive surgery and better implant positioning through computer-assisted surgery (CAS) . The relationship between implant malalignment and longevity is strictly connected. For example, deviations in coronal alignment greater than 3° of varus have been correlated with poorer implant survival. Shifts in the mechanical axis away from the neutral position are associated with patterns of femoro tibial tracking that is associated with abnormal stresses at the bearing surface that can lead to accelerated wear. A number of studies have reported that even in major arthroplasty centers the incidence of unacceptable implant alignment may exceed 25%, thus potentially exposing a large number of patients to reduced implant longevity . Varus or valgus malalignment of the mechanical axis of more than 3° is thought to be associated with poor outcome and reduced life expectancy. Conventional TKA techniques usually rely on intra-medullary rods or extramedullary guides to establish implant orientation. Both these alignment tools have inherent limitations in detecting malalignment and poor component positioning. While intramedullary systems typically fail in deformed femora and tibiae and may be associated with a higher rate of fat embolism, extramedullary guides are associated particularly with uncertainties and technical difficulties in obese patients. Moreover, traditional intraoperative techniques used to determine femuro-tibial alignment are relatively subjective and provide only single instance data points
In contrast, computer navigation systems can provide continuous real-time measurements of limb alignment and implant orientation
Achieving a near neutral mechanical axis is one of a number of aims of CAS. Centers that advocate the use of this technique have reported an increase in the numbers of patients whose postoperative knee alignment is within 3° of the mechanical axis as compared to conventional techniques. To date, the clinical relevance of CAS in terms of improving function and patient quality of life, however, would seem paramount to the adoption of this technique and, yet, this has not been the subject of much investigation and what has been reported to date remains inconclusive .
Use of App may be proven in pending studies compare the alignments achieved by the use of computer navigation and conventional methods that is better. The most important advantage using CAS and robotic technology is the understanding of the mistakes that we face during surgery and also
But cons are costs,l earning curve ,more materials to be sterilized and longer time for the surgeon in performing joint replacement, increasing time of surgery and increasing hospital costs, each company dedicated the CAS technology to their own prosthetic devices.
One of the most important results for many surgeons using CAS and robotics has been to perform less soft tissue releases to correctly balance the knee. Digital surgery that will allow the surgeon to use less bulky instrumentation, to be less invasive, decrease tissue morbidity, and reach higher implant technique accuracy
The App offers a knee navigation system .
Information such as optimal resection planes and targeted limb alignment is displayed to the surgeon during the operation before performing bone preparation, also according to a surgeon’s specific preference (posterior slope, femur flexion, bone resections, varus/valgus, joint line, etc.). The main workstation is the Iphone unit with the computing power, a monitor for control,Variables controlled osteotomy cuts ,soft tissue balancing ,lower limb Alignmnet
Navigation for Total knee replacement TKR has been reported to provide better results than conventional surgical technique, but is expensive.
App offers an aid to surgeon to navigate during Total knee arthroplasty procedure in augmented reality AR by allowing to:
to estimate rotational alignment -white side line is to be seen, tibia posterior slope by presenting joint line planes, varus/valgus stability in real time, eliminating the need for additional soft tissue releases during surgery, and providing more precise estimation of component placement in coronal, sagittal according to a surgeon’s specific preference
present joint line planes in AR position is helpful during revision sursery
Calculate tibia torsion, and measure of bone resections in mm.
assist with soft tissue balance.
- calculate in real time the mechanical axis deviation (in mm) MAD, anatomical and mechanical femoral axes angle (aMFA), mechanical lateral proximal femoral angle (mLPFA), mechanical lateral distal femoral angle(mLDFA), joint line convergence angle (JLCA), mechanical medial proximal tibial angle (mMPTA), mechanical lateral distal tibial angle (mLDTA), Hip Knee Ankle line (HKA) and Mid joint line (MJL) orientation that gives the surgeon valuable objective intraoperatively informations.
- estimate kinematic alignment of the knee (KAO) and relevant values are presented and avoiding residual joint obliquity or malalignment.
- have a navigating guidance of saw bone blade. Surgeon is able to monitor the position and orientation of saw blade in Augmented Reality minimizing the risk of intraoperative technical pitfalls and achieve a safe and accurate osteotomy.
-data to be reported on the screen, and the surgeon can recalculate the deformity with numbers and then determine how much can be corrected.
-not require advanced preoperative imaging, such as CT scanning; planning can be done exclusively intraoperative by registering bony and cartilage landmarks .
-the surgeon to expedite the procedure effortlessly-based on patient’s anatomy allow prediction, by visualising all necessary anatomical axes in AR before actual bone resection of tibia and femur during total knee arthroplasty, and foresee what effect could bring a modification of one parameter to the rest.
Disclaimer
Before you use the software. The software should be used only for educational purpose namely training Orthopaedic Residents etch. Never use in real Surgery regarding its plausibility, validation is pending. The app is for educational use. Clinical judgment and experience are required to properly use the software.These instructions alone do not replace in depth training in planning for osteotomies. It only serves as a general guideline. All information received from the software output must be reviewed before any actual attempt at lab i.e. cutting saw bone for training purpose! The App indicated for assisting during training the Operator. Judgment and experience are required to properly use the App. The software is not for primary image interpretation. Any influence to the operators in making decisions remains Surgeons own responsibility and experience. App does not dispense medical advice.
How it works
Before app use instruments should be 3D-printed before using the app after downloading the appropriate 3D files from developers side (www.orthopractis.com). Each instrument is recognised by separate dedicated attached QR-code images. Dedicated QR-code images should be exported from the app by pressing the export button. All related QR-code images are exported in photo library. After printing them in a colour printer in adhesive paper they should to be attached separately to each dedicated instrument accordingly. Each printed QR-code image work as unique dedicated tracker for femur, upper tibia distal tibia, pointer respectively and should be in the visual field of iPhone’s camera. In details, each time the QR-code image is recognised, a different colour sphere appears for each instrument namely red for femur, magenta for pointer, blue for distal tibia, green for upper tibia white for femur head centre of rotation. These appear at the center of the rectangular image over the surface respectively, for each dedicated QR-code. The QR-code images are recognised continuously and tracked in real time by the App, as along as the top centred button is on (highlighted). The tracking system is the iPhone’s camera.
A.Passive Markers.
Two Passive markers F for femur, and T for tibia carrying the respective QR-code images must are firmly mounted on distal femur F and over proximal tibia T respectively. The position is guided by corresponding colour of the sphere which appears over the QR-code image during recognition of the app namely red and white and for Femoral marker( -same tool is carrying two QR-code images, Fw-white, Fr- red), and blue for proximal tibia P.
The QR-code image attached over the front femur marker F (red) surface act as a dynamic reference base attached to the system. In case the leg is placed in different position during surgery, the attached Fr change position and move as a whole array. Accidental intra-operatively changing position is common, and there is no need to re-registering the points. The App updates the position of registered points in AR according to their new position.
B.Pointer Tool (PT).
A device dedicated for surface registration - should be 3D-printed. The other side of the rod is the side that acts as mechanical pointer tip locator.
The QR-code image (magenta) dedicated for the PT should also exported from the app by pressing the export button and printed in a common colour printer preferably as an adhesive label, and attached firmly to dedicated rectangular surface plane of pointer tool. The QR-code image marker is captured and recognised continuously in real time by the App and a magenta sphere appears over the center of the QR-code image. Once the QR-code image is recognised in Augmented reality view, a cylinder appears with two spheres at the edges: one proximal (magenta) appear over the center of the attached QR-code image over the dedicated rectangular surface, and second distally a red sphere appears over the tip of rod at the pointer tip in augmented reality (AR). Distal sphere should coincide with the tip and this should be corrected before registration by calibration.
Calibration is achieved by simply pressing the directions buttons (+,-) over the screen, thus the position (XYZ) of magenta tip sphere and the attached grey cylinder in augmented reality [magenta and red sphere are the edge of cylinder] are adjusted as whole construction accordingly. The user aim the pointer tip sphere in AR to be aligned in all dimensions and coincide over the mechanical pointer tip location of the rod of the PPT tool.
More specifically:
- By pressing the + or - button in the upper row, the (z) distance is adjusted respectively. It is recommended first to measure manually the distance from tip-pointer to case (by default this is 20 cm), and calibrate first the Z distance, which is the real distance from the magenta sphere on the center of the QR-image surface to tip of the pointer. The following x and y calibration procedure are in two dimension over the screens phone (x,y), aiming to bring the presented red sphere to coincide optically with actual pointer tip.
- In the intermediate row the + or - button adjust the (x) distance of magenta sphere.
- In the last row by pressing the + or - button the (y) distance magenta sphere is adjusted likewise.
C. Saw Adaptor (SA)
The SA helps to navigate the saw blade accurately. SA can be 3D-printed and inserted as an accessory to real saw blade. A QR-code image dedicated for the saw adaptor should be recognized by the App and is continuously tracked. Saw adaptor can be adapted over conventional saw orthopaedic blade and calibration is unnecessary as long as the distance between QR-code image and cutting edge saw is 26mm (Z axis).
The SA helps to determine the exact spatial orientation of saw blade aiding the accuracy of the oscillating Bone saw blade. Two perpendicular crossed rectangular planes appear (one blue horizontal, one vertical green) in AR. The crossing point of the planes is passing to the center of the saw blade. a hit sound is played confirming that direction of saw blades is the right according to planed.
D.Validator tool
Estimation of extension and flexion space is achieved by using the spacer which allow to assess the gap parallelism manually.The tool is a spacer, to measure the gap between the femur and the tibia in flexion and extension but carry a dedicated QR-code image (black). Once is recoconized a orange cylinder appears over the ridges of the tool perpendicular to the tool axis. The angle between transepicondylar line (blue) and the above mention orange cylinder allow to estimate the φ angle and likewise between the Femoral flexion axis (green) the BA angle - Balance angle.
During gap acquisition, the femur and the tibia assume a position that depend exclusively on ligament constraints by enabling the surgeon, together with the information provided by the software φ angle, to perform a navigated ligament balancing. Varus and valgus stress is applied near full extension and around 90 degrees of flexion to assess stability. Measured φ angle between tool and epicondylar axis in saggital plane depicts the laxity of knee if φ> 2 degrees then knee is lax.
E. Joint Liner tool
Useful for joint line registration and posterior condyles registration and looks like butterfly with tail where a qr code image is attached and a green there appears .
Operative set up working with app.
The patient pelvis is in decubitus position or in supine position. In case you place the patient in lateral decubitus only first three registration points should be chosen in sagittal plane instead by <<touching>> three points preferably at the surface of two back post of the patient.
Bicortical, partially threaded pins screws for the passive markers are inserted through a tiny (<1 cm) skin incision percutaneously into distal femur and the epiphysis of the proximal tibia both 10 cm away from the joint line. On the femur, the pins are placed starting approximately 5 cm superior to the patella. All Passive markers should firmly attached to the body of mini external fixator in the predetermined location respectively namely red , white and for Femoral -same tool is carrying two QR-code images one in front and one in the back surface of tool, and blue for proximal tibia.
Prerequiside is visual contact through i-Phone’s camera of QR-code image over Passive Markers. Initially the Femoral Passive Markers (FPS) is to be recognised by starting the app before any registration attempt. Powerful undo feature gives the user the freedom to make corrections without resetting. Simply by clicking the undo button the measurement returns to last chosen point and you are ready to choose the same point again, without reseting and starting again from the beginning. Red recognized QR-code Image attached over Passive Sensor must recognized first in order to trigger functionality of the app this Qr code image acts as a dynamic reference base, by accidental change position intra-operatively the app updates the position of registered points in AR according to the new position of patient pelvis respectively without to reregister position of all future register points are updated continuously while the QR-code images acts as a dynamic reference guide marker.
Landmark Registration
Once the QR-code image is recognised over the PT tool, and this is confirmed by appearing a magenta sphere over the middle or dedicated QR-code, a grey cylinder appears in AR overlaid on the actual PT tool. PT tool is ready to be used for registering points over a surface. Coloured spheres in augmented reality appear at the tip of PT after touching any point over the iPhone’s screen, or by pressing the volume-up button (with volume-down button the undo command is executed). Calibration of the pointer should be done before registration.
XYZ-planes registration
The surgeon selects sequentially three different points (P1,P2,P3) over the surgical bed in the same plane. Through the selected points the coronal plane is defined and a red hazy transparent plane is depicted (coronal) passing through the green spheres constantly in augmented reality.
With the same manner during the registration phase certain stable epicutaneous, pre-defined, pelvic anatomical landmarks-obtained through the drapes, have to be registered. The points that should be acquired are first the Anterior Superior Iliac Spine (ASIS) (P4) and second - the second Anterior Superior Iliac Spine (ASIS)(P5) across. By registering both points a green transparent plane (transverse plane) passing through the green spheres, perpendicular to previous transparent red plane (coronal) is depicted in augmented reality. By repeating the same procedure and registering at last the symphysis pubis (P6), a transparent blue plane appears (sagittal plane) passing through the sphere, perpendicular to previously planes. For every three points of registration - three green spheres appear and in the centroid position between these points in space a light blue sphere appears which represents the final registration point of interest.
Femoral registration
A. Registration of Femoral Head center.
Passive Marker F is fixed in distal side of the femur. The F tool is carrying two different QR-code images over two different surface one in left (Fr- red) and one in right side of the tool (Fw-white). By seeing with iPhone camera view the back side QR- code image- Fw a white sphere appear and two perpendicular cylinders, dedicated for registration of femoral head center. The distal vertical cylinder ending at white sphere should be directed at femur centre. A red sphere over the respective QR code marker at front and is a reference for any movement of the femur part (please see tutorial video).
By moving the whole leg in four random different positions, preferably- north, south, east, west each time - and touching over iPhone screen each time, four positions in space are registered.Yellow spheres each time a point are registered and at the end one point is calculated as the centre of femoral head and finally a magenta sphere appears. Femoral head center is being calculated and presented at last in AR as a magenta sphere inside the femoral head, depicting the center of femoral head, and the center of rotation of femoral head.
B. Femur shaft and condyles regisration.
With Pointer Tool (PT) a surface registration of anatomical landmarks should be done. For every three points of registration a centroid point appears and by the following order user should select the following anatomical points sequentially in certain clock-wise fashion starting in following order.
Trochanter major raw femur head estimation.
More accurate Registration follow by selecting another two points one at the tip of one in trochanter major T and one over patient skin by raw estimation over femoral head Hc.
Femoral shaft landmarks Registration.
By circumferential manner registration of three points around the distal part of femoral thigh, a dark brown sphere appears -Anterior Femoral cortex point-AFC. In distal femur with previous reported technique likewise. After registration a certain colourful points appear respectively:
Anterior Femoral cortex - purple -FAC
Medullary canal entry point - centroid - red- MCEP
medial epicondyle - centroid - dark blue- MEPI
Medial condyle anterior - centroid - cyan-MCA1
Medial condyle anterior - centroid - cyan- MCA2
Medial condyle middle - centroid - magenta-MCM1
Medial condyle middle - centroid - magenta- MCM2
lateral epicondyle, - centroid - dark blue- LEPI
Lateral condyle anterior - centroid - cyan- LCA
Lateral condyle middle - centroid - magenta-LCM
Posterior condyles and joint line registration.
Recovering initial joint line is important to mark in space after inserting the joint Liner tool (that uses the Green QR-code green for recognition) after moving forward or backward till that no more room left to enter meaning that the posterior elements are going also to be registered adequately. By pressing the i-phone’s screen, acting as an insert button a yelow plane appear depicting native joint line and three points in posterior condyles are registered automatically
Medial condyle posterior - centroid - orange- MCP1
Medial condyle posterior - centroid - orange- MCP2
Lateral condyle posterior - centroid - orange- LCP
The joint line is also registered and automatically appears as yellow plane over native joint line.
Whiteside Line AP (purple), Femoral Mechanical Axis (red), Transepicondylar line (blue) Femoral flexion axis (green) and posterior femur condylar line (brown)
are being calculated and appear as cylinders over femur condyles.
Tibial landmarks Registration
Proximal tibia registration
With the same manner, once the blue QR-code image is recognised, the user can register the tibial anatomical landmarks by selecting three points as follows:
Tibia - medial tibial plateaux - magenta spheres
medial tibial Anterior plateaux -MTA
medial tibial Middle plateaux -MTM
medial tibial Posterior plateaux -ΜΤP
Tibia - lateral tibial plateaux - white spheres
Lateral tibial Anterior plateaux -LTA
Lateral tibial Middle plateaux- LTM
Lateral tibial Posterior plateaux-LΤP
Distal Tibial landmarks Registration
The most prominent points on the medial and lateral malleoli are registered with pointer tool, likewise after three points registration the following anatomical landmarks should be selected.
MM medial malleolus, magenta spheres
medial malleolus posterior-MMPS
medial malleolus anterior -MMAN
AM Anterior surface distal tibia - anterior malleus - dark blue spheres
LM lateral malleolus white spheres]
lateral malleolus anterior - LMAN
lateral malleolus posterior- LMPS
Presentation of Axis.
The depicted orange line represent the current mechanical axis of the leg. We can measure the mechanical axis deviation (MAD) -orange line- in millimetres, that is the perpendicular distance from the center of the knee joint to the mechanical leg axis, to the knee joint center. This line physiologically runs on average 4 (±2) mm medial to the center of the knee joint. If the mechanical axis runs lateral by > 10 mm or > 15 mm medial to this point, this indicates either a valgus or a varus deformity, respectively.
In addition by measuring Hip Knee Ankle line (HKA) and Mid Joint Line (MJL) orientation, App allows to evaluate in real time the success of intended osteotomy by evaluating the kinematic alignment of the knee (KAO), avoiding residual joint obliquity or malalignment.
Elevator technique in proximal tibia and distal femur.
Neutral mechanical alignment is currently considered the “gold standard” and primary aim of every total knee replacement (TKR). In order to cut perpendicular to mechanical axis and add the preferred metal implant an elevator plane module is added in order to help surgeon calculate precisely the exact location in mm of distal femoral and tibia.
Tibia side
By indenting to proceed to bone resection in tibia a red plane appears perpendicular to tibia mechanical axis by pressing + or - button the preferred size of bone resection is adjusted and the amount of resection can be seen in real time in augmented reality over real tibia in mm prior actual resection. The technique works like an elevator and red plane goes up or down always perpendicular to axis by presenting in mm the size of resection. Once the preferred resection plane is decided the bone saw cut navigation device is attached to bone saw.. Real time estimation is given by measuring the distance in mm between two planes, from tibia joint line to the current desired level of bone resection, increasing or reducing the amount of resection by pressing + or - button the respective distance is depicted on screen reading real time, for medial side as MCM and LCM for lateral side. Accurate cutting of the tibia’s is followed by the technique presented below in bone saw cut navigation.
Femur side
By pressing the next button the osteotomy red plane appears perpendicular over femurs mechanical axis. Likewise by pressing the + or - the red osteotomy elevates or descends as previously reported. According to surgeon preference the value of intended osteotomy in mm is also presented. Real time estimation is given by measuring the distance in mm between two planes from femoral joint line plane to the current desired level of bone resection plane . Iincreasing or reducing it by pressing + or - button distance is depicted on screen reading real time for medial side as MCM and LCM for lateral side respectively. Technique of accurate cutting of the femur is presented below.
Bone Saw cut navigation
The Saw Adaptor (SA) helps to navigate the saw blade accurately. A QR-code image dedicated for the saw adaptor and should be recognized and continuously tracked by the App. Position of the osteotomy planes of resection are defined and a red hazy transparent osteotomy plane is depicted passing through the tibia constantly in augmented reality. Once the dedicated QR-code image for the saw adaptor is recognised, two perpendicular planes around the saw blade appear with different hazy transparent colours (green-sagittal, coronal-blue,) in augmented reality over the center of tip of the bone saw blade, extending also over the blade span. The coronal plane -blue hazy transparent plane- is depicted passing through two blue spheres constantly in augmented reality which are extending at the edges of the blade. A green transparent plane (sagittal) is passing through the green spheres, perpendicular to previous transparent blue plane (coronal).
Over the screen in real time two angles corresponding to the direction of saw blade are depicted. For reasons of simplicity every colour of a plane corresponds certain direction. More specifically:
The row with green tile by red tile represents the angle subtended by sagittal plane (green) of the blade saw and the sagittal osteotomy plane (blue). Also ω’ angle is printed which is calculated in real time and is the difference of current direction of saw blade during osteotomy with the previous planed direction of osteotomy plane (ω angle). When ω’ angle and ω angle are zero, then the current position of saw plate in sagittal plane meet the planed position of direction of osteotomy.
The row with blue tile by red tile represents the angle subtended by the coronal plane of the blade saw (red) and coronal osteotomy plane (red). The angle formed by navigated saw blade and the osteotomy plane in coronal plane should be zero, indicating that the navigated saw blade is parallel to planned osteotomy plane.
The following two conditions during bone cut by the navigated saw blade should be full-filled in order to hear an audible hit sound, an indication that we are at right plane according to planed osteotomy in space:
a. The difference between ω’ angle and ω angle to be 0°±3°
b. The angle formed by navigated saw blade and the osteotomy plane in coronal plane is 0°±3°
Both values separately turn green whenever the 0°±3° criterion is meet according to current position, otherwise return red.
Manipulating the Oscillating Bone Saw Cutting Machine Orthopedic Power Tool in real time the surgeon, values of all above mentioned angles change respectively, obtaining positional information and direction with accuracy in real time in augmented reality by observing the screen.
Screen readings:
Arrows pointing up above normal arrow pointing down below normal.
mLPFA = mechanical lateral proximal femoral angle, normal value 90°±5°, yellow
mLDFA = mechanical lateral distal femoral angle, normal value 87°±3°, orange
aLDFA = anatomical lateral distal femoral angle, normal value 81°± 2°, green
aMFA = anatomical mechanical femoral axes angle, normal value 6°±1°.
JLCA = joint line convergence angle, normal value 0°-2°, light blue.
d = distance in mm between femoral joint center and tibia joint centre normal values <=6mm, subluxation due to ligament laxity.
Ant - femoral anteversion approximately.
mMPTA = mechanical medial proximal tibial angle, normal value 87°±3°, brown.
mLDTA = mechanical lateral distal tibial angle 89°±3°, blue.
aFTA = anatomical femorotibial angle, standard value 173°-175°.
MAD = mechanical axis deviation in mm.
Type of deformity
normal no message,
femoral (mLDFA ≥ 87°±3°) varus otherwise valgus, deviation or deformity,
Tibia (mMPTA ≥ 87°±3°) valgus otherwise varus, deviation or deformity,
differentiate between a femoral and a tibial cause of malalignment
Genu varum, Anatomical femorotibial angle (aFTA) > 173–175° and
Genu valgum, Anatomical femorotibial angle (aFTA) < 173–175°
HKA = Hip Knee Ankle line, normal range 180 ° ± 3° otherwise knee <177° varus (valgus >184).
MJL = Mid joint line orientation (normal 87° - 94°, varus<86° , valgus>94° .
KAO = Kinematical Aligned Osteotomy, normal if HKA and MJL are normal, otherwise abnormal.
JLa = correction angle adjusted by taking into account ligament laxity measured by joint line convergence angle (JLCA) JLa = a - (JLCA-2)/2 , when JLCA>2.
MCM dista= distance in mm from current desired resection plane level to medial side of tibia joint line plane.
LCM dista = distance in mm from current desired resection plane level to lateral side of tibia joint line plane.
BA = Knee ligament balane angle calculated from validator tool at perpendicular orange cylinder and flexion knee axis.
φ= Knee ligament balane angle calculated from validator tool at perpendicular orange cylinder and epicondylar axis.
tS =Torsion angle of tibia
In quick review
-QR code recognition first red . Unlock app - qr code assign image to red sphere
-three points should always be selected by the tip of pointer tool in order the centroid of these to be registered as anatomical landmark.
Surgical bed
1.three point selected over the over an imaginary triangular place at surgical bed - red transparent plane appear -coronal plane is depicted in AR
Pelvic landmarks Registration.
Right Anterior Superior Iliac Spine (ASIS) -(three points)
Left Anterior Superior Iliac Spine (ASIS)- (three point
symphysis pubis (three point)
transparent blue plane appears (saggital plane) perpendicular to all planes perpendicular to previous transparent red plane (coronal) and transverse in augmented reality.
Femoral head landmarks
Femur QR white ->while move leg ->A4,A3,A2,A1 at press screen yellow points magenta at femur head
tip of trochanter major T
Femur head centre, three points over skin- HC
Anterior Femoral cortex - purple -FAC
Medullary canal entry point - centroid - red- MCEP
medial epicondyle - centroid - dark blue- MEPI
Medial condyle anterior - centroid - cyan-MCA1
Medial condyle anterior - centroid - cyan- MCA2
Medial condyle middle - centroid - magenta-MCM1
Medial condyle middle - centroid - magenta- MCM2
lateral epicondyle, - centroid - dark blue- LEPI
Lateral condyle anterior - centroid - cyan- LCA
Lateral condyle middle - centroid - magenta-LCM
Insert Joint line tool
Three points are registered automatically
Medial condyle posterior - centroid - orange- MCP1
Medial condyle posterior - centroid - orange- MCP2
Lateral condyle posterior - centroid - orange- LCP
Whiteside Line AP (purple), Femoral Mechanical Axis (red), Transepicondylar line (blue) Femoral flexion axis (green) and posterior femur condylar line (brown)
are being calculated and appear as cylinders over femur condyles.
Tibial landmarks Registration after blue qr recognition is unlocked
Proximal tibia registration
Tibia - medial tibial plateaux - magenta spheres
medial tibial Anterior plateaux -MTA
medial tibial Middle plateaux -MTM
medial tibial Posterior plateaux -ΜΤP
Tibia - lateral tibial plateaux - white spheres
Lateral tibial Anterior plateaux -LTA
Lateral tibial Middle plateaux- LTM
Lateral tibial Posterior plateaux-LΤP
Distal Tibial landmarks Registration
MM medial malleolus, magenta spheres
medial malleolus posterior-MMPS
medial malleolus anterior -MMAN
AM Anterior surface distal tibia - anterior malleus - dark blue spheres
LM lateral malleolus white spheres]
lateral malleolus anterior - LMAN
lateral malleolus posterior- LMPS
