The authors have no acknowledgments.

The study was approved by the ethics committee of our institution (reference 2020-277-1). Patients signed the CT scan informed consent.
1. Downloading the CT images
<ol>
	<li>Gain access to a picture archiving and communication system (PACS). 
	NOTE: Each software package has a different way of accessing a PACS, but all of them have a way to download a study in the DICOM format. If there is a question regarding how this is done, ask the system administrator of the center or the radiologists of the center.</li>
	<li>Download the full CT scan in the DICOM format while maintaining patient anonymity.</li>
</ol>
2. Obtaining the 3D biomodel (Supplementary File 1-Figure S1)
<ol>
	<li>Download the software 3D Slicer (see the Table of Materials). Install the program on the computer.</li>
	<li>Import the CT images in the DICOM format.
	<ol>
		<li>Click on the DCM icon on the top-left corner of the screen.</li>
		<li>Click on Import DICOM Files on the left side of the screen, and wait for a window to open that makes it possible to choose the folder where the CT study is saved in the DICOM format.</li>
		<li>Click on &#34;DummyPatName!&#34; on the top right of the screen. If the folder has more than one CT study, click on the series &#34;DummySeriesDesc!&#34; with the most images at the bottom of the screen.</li>
		<li>Click on Load on the lower-right margin.</li>
	</ol>
	</li>
	<li>Create the 3D biomodel.
	<ol>
		<li>Click the menu bar at the top of the screen, and wait for the DICOM to appear.</li>
		<li>In the dropdown menu, choose the Legacy | Editor option. Press ok on the message that appears (Supplementary File 1-Figure S2).</li>
		<li>Wait for a new menu to appear on the left side of the screen. Click on the Threshold Effect icon.</li>
		<li>Move the bar in the lower box until only the bone is painted in the images on the right. In this way, select the value of the Hounsfield units to be included in the model.</li>
		<li>Once the desired paint level is achieved, click on Apply. The selection is marked with the color green (Supplementary File 1-Figure S3).</li>
		<li>Select the option Make Model Effect from the side menu (the same as the previous one). Select Apply (Supplementary File 1-Figure S4).</li>
		<li>In the upper-right window, the 3D model is generated. Click on the golden frame, Center the 3D view on the scene, to center the image in the center of the window (Supplementary File 1-Figure S4).</li>
	</ol>
	</li>
	<li>Save the biomodel (Supplementary File 1-Figure S5).
	<ol>
		<li>Click on Save in the upper-left margin.</li>
		<li>In the box that appears, only select the file &#34;tissue&#34; (Supplementary File 1-Figure S5).</li>
		<li>In the second column, in the dropdown menu, select STL.</li>
		<li>In the third column, in the dropdown menu, choose where to save ithe STL file. Click on Save. This is the file that will be used in the following steps.</li>
	</ol>
	</li>
</ol>
3. Preparation of the biomodel
<ol>
	<li>Download the MeshMixer software (see the Table of Materials). Install the program on the computer.
	<ol>
		<li>Import the STL image by selecting the Import option in the center of the screen (Supplementary File 1-Figure S6).</li>
	</ol>
	</li>
	<li>Select the biomodel.
	<ol>
		<li>Look for the Select option in the menu on the left side. Use any of the following main methods to select.</li>
		<li>Use the Select tool, select the thickness of the brush, and double-click on the femur (Supplementary File 1-Figure S7). If it is not possible to separate only the femur, it means that it has direct contact with other bone structures or soft parts; in that case, select Edit | Generate face Groups from the menu (Supplementary File 1-Figure S7). Use the Angle Threshold option and move the bar until the different structures have a different color, indicating that the pieces have been recognized as separate (Supplementary File 1-Figure S8).
		<ol>
			<li>With the Select tool, hold down the left mouse button while painting the part of the biomodel of interest.</li>
			<li>With the Select tool, click on a point outside the model, and hold down the left mouse button while painting a circle that includes the part that is of interest.</li>
		</ol>
		</li>
		<li>Use the Select tool to select the part of interest. Look for the option Select | Modify | Invert in the side menu, and press Delete&#160;(Supplementary File 1-Figure S9) to delete the unselected parts. At this juncture, the biomodel of the clean femur is obtained (Supplementary File 1-Figure S9).</li>
		<li>Make the model solid (Supplementary File 1-Figure S10).</li>
		<li>Navigate to Edit | Make Solid | Solid Type| Accurate.</li>
		<li>Maximize the Solid Accuracy and Mesh Density values.</li>
	</ol>
	</li>
	<li>Save the biomodel. Select the Export option from the side menu. Select the STL format and the folder to which the biomodel is exported.</li>
</ol>
4. Calculation of the proximal femoral anteversion
<ol>
	<li>Download the 3D Builder software (see the Table of Materials). Install the program on the computer. 
	NOTE: The program can only be downloaded if the operating system of the computer is Windows.</li>
	<li>Click on the Insert icon at the top of the screen (Supplementary File 1-Figure S11). Click on Add to import the biomodel to the scene (Supplementary File 1-Figure S12). 
	NOTE: The left mouse button makes it possible to rotate the object to see it in a 360&#176; view. With the right button, it is possible to scroll along the object. The central wheel of the mouse allows for zooming in.</li>
	<li>Click on Object | Settle to fix the object to the work plane so that it rests on the femoral condyles and the trochanter mayor. 
	NOTE: It is advisable to put the object vertically parallel to the y-axis and perpendicular to the x-axis marked on the working plane (Supplementary File 1-Figure S13).</li>
	<li>Perform the femoral osteotomy.
	<ol>
		<li>Click on Edit | Split from the top menu . When a rectangular cut plane appears, select Keep Both (Supplementary File 1-Figure S14).
		<ol>
			<li>Use the Move Mode button on the bar in the lower margin of the screen to move the cutting plane horizontally and vertically.</li>
		</ol>
		</li>
		<li>Use the Rotate Mode button on the bar in the lower margin of the screen to rotate the plane around the femur (Roll: 90&#176;, Pitch: 0&#176;, Yaw: 0&#176;) (Supplementary File 1-Figure S14).</li>
		<li>Put the cutting plane parallel to the x-axis and perpendicular to the y-axis. Click on Split. In this case, perform the osteotomy above the trochanter minor (intertrochanteric) (Supplementary File 1-Figure S15).</li>
	</ol>
	</li>
	<li>Calculate the femoral anteversion.
	<ol>
		<li>Insert the guides, which help to establish the reference points to measure the femoral anteversion in the image in the 3D environment of the program according to Murphy&#39;s method (Supplementary File 1-Figure S16A,B). To insert the guides, click on Insert | Add, and choose the 3mf Supplementary File 2. 
		NOTE: These guides were designed in-house, and the 3mf file Supplementary File 2 is accessible as a supplementary material provided in this article. The Murphy 3D method was implemented by establishing three measurement points in the same way as in the conventional method11 but in a 3D environment. The usual circumference at the level of the femoral head was replaced by a sphere, and the measurement was established by a circumference at the level of the trochanter minor. As a distal reference, the posterior intercondylar line was taken, as defined in the original Murphy method.</li>
		<li>Select only the proximal part of the femur on the right side of the screen and click on CTRL + X to cut the selection. This is how the femoral diaphysis appears (Supplementary File 1-Figure S17).</li>
		<li>Select the red circular guide and the purple circular guide (doing this means that they will be together) on the right side of the screen. Use the commands in the bottom margin panel to move the guides. 
		NOTE: The red guide represents the rotational axis of the osteotomy, while the violet guide represents the rotational axis of the femur.</li>
		<li>Put the guides in the center of the femoral diaphysis, and use the commands of the inferior margin panel to adjust the size. Ensure that all the edges touch the cortex of the bone (Supplementary File 1-Figure S18). 
		NOTE: When the two guides, the red circumference and the purple circumference, are used for the first time, they are selected together so that they move as a block, as if they were one guide, to measure the FAV, and they are placed in the femoral diaphysis just above the lesser trochanter at the osteotomy line.</li>
		<li>Click on CTRL + V to paste the proximal femur again (Supplementary File 1-Figure S19).</li>
		<li>Select only the sphere on the right side of the screen. Use the commands in the bottom margin panel to move the sphere and place it on top of the femoral head. Adjust the size, including all the edges touching the bone cortex (Supplementary File 1-Figure S20).</li>
		<li>Select the proximal femur on the right side, and cut it (CTRL + X).</li>
		<li>Select only the red plane on the right side of the screen (Supplementary File 1-Figure S21).</li>
		<li>Use the commands in the lower margin panel to move the red plane, and place it so that it passes through the center of the sphere and through the center of the circular guides. 
		NOTE: The grades marked by the panel in the lower margin correspond to the pathological femoral anteversion calculated on the CT using Murphy&#39;s method.</li>
		<li>Press CTRL + V to paste the proximal femur again (Supplementary File 1-Figure S22 A,B) .</li>
	</ol>
	</li>
	<li>Perform the rotational osteotomy of the proximal femur.
	<ol>
		<li>Select the proximal femur + the red circumference (only the red) + the sphere on the right side.</li>
		<li>Make an internal derotational proximal femoral osteotomy of 20&#176; (use the commands on the panel of the lower margin; add 20 on Pitch) (Supplementary File 1-Figure S23).</li>
		<li>Measure the new femoral anteversion (Supplementary File 1-Figure S24). 
		NOTE: The two guides are used again to perform the osteotomy. In this case, only the red guide is selected together with the proximal femur (so that when the proximal femur rotates, the red guide also rotates; step 4.6.1), while the violet guide is not selected (Supplementary File 1-Figure S25). In this way, the violet guide remains in the femoral diaphysis and does not participate in the rotation of the proximal femur.
		<ol>
			<li>Select the proximal femur + the red circumference, and press CTRL + X to cut these two elements.</li>
			<li>Select only the red plane, and place it so that it passes through the center of the sphere and through the center of the purple circular guide. 
			NOTE: A 1:1 relationship between the magnitude of the osteotomy and the correction of the deformity is not achieved because the derotation of the proximal femur does not follow the anatomical axis of the femur.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Perform the adjustment of the rotational osteotomy.
	<ol>
		<li>Select the femoral diaphysis + the red plane. Press CTRL + X to cut (Figure 27). (Supplementary File 1-Figure S25).</li>
		<li>Select the proximal femur + the sphere + the red circumference.</li>
		<li>Move the three elements en bloc so that the center of the red circumference matches the center of the purple circumference&#160;(Supplementary File 1-Figure S26).</li>
		<li>Recalculate the new femoral anteversion with the adjustment made (Supplementary File 1-Figure S27). 
		NOTE: Through this 3D method, it is shown that the rotation axis of the femur and the rotation axis of the osteotomy do not coincide. For this reason, it is necessary to make an adjustment that involves realigning the two guides so that the original femoral axis and the osteotomy axis coincide.</li>
	</ol>
	</li>
</ol>

<ol>
	<li>Teitge, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Does+lower+limb+torsion+matter.">Does lower limb torsion matter.</a> Techniques in Knee Surgery. 11 (3), 137-146 (2012).</li><li>Teitge, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+power+of+transverse+plane+limb+mal-alignment+in+the+genesis+of+anterior+knee+pain-Clinical+relevance.">The power of transverse plane limb mal-alignment in the genesis of anterior knee pain-Clinical relevance.</a> Annals of Joint. 3, 70 (2018).</li><li>Delgado, E. D., Schoenecker, P. L., Rich, M. M., Capelli, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Treatment+of+severe+torsional+malalignment+syndrome.">Treatment of severe torsional malalignment syndrome.</a> Journal of Pediatric Orthopedics. 16 (4), 484-488 (1996).</li><li>Bruce, W. D., Stevens, P. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surgical+correction+of+miserable+malalignment+syndrome.">Surgical correction of miserable malalignment syndrome.</a> Journal of Pediatric Orthopedics. 24 (4), 392-396 (2004).</li><li>Teitge, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Patellofemoral+syndrome+a+paradigm+for+current+surgical+strategies.">Patellofemoral syndrome a paradigm for current surgical strategies.</a> The Orthopedic Clinics of North America. 39 (3), 287-311 (2008).</li><li>Leonardi, F., Rivera, F., Zorzan, A., Ali, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bilateral+double+osteotomy+in+severe+torsional+malalignment+syndrome:+16+years+follow-up.">Bilateral double osteotomy in severe torsional malalignment syndrome: 16 years follow-up.</a> Journal of Orthopaedics and Traumatology. 15 (2), 131-136 (2014).</li><li>Stevens, P. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Success+of+torsional+correction+surgery+after+failed+surgeries+for+patellofemoral+pain+and+instability.">Success of torsional correction surgery after failed surgeries for patellofemoral pain and instability.</a> Strategies in Trauma and Limb Reconstruction. 9 (1), 5-12 (2014).</li><li>Dickschas, J., Harrer, J., Reuter, B., Schwitulla, J., Strecker, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Torsional+osteotomies+of+the+femur.">Torsional osteotomies of the femur.</a> Journal of Orthopaedic Research. 33 (3), 318-324 (2015).</li><li>Naqvi, G., Stohr, K., Rehm, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Proximal+femoral+derotation+osteotomy+for+idiopathic+excessive+femoral+anteversion+and+intoeing+gait.">Proximal femoral derotation osteotomy for idiopathic excessive femoral anteversion and intoeing gait.</a> SICOT-J. 3, (2017).</li><li>Iobst, C. A., Ansari, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Femoral+derotational+osteotomy+using+a+modified+intramedullary+nail+technique.">Femoral derotational osteotomy using a modified intramedullary nail technique.</a> Techniques in Orthopaedics. 33 (4), 267-270 (2018).</li><li>Stambough, J. B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Knee+pain+and+activity+outcomes+after+femoral+derotation+osteotomy+for+excessive+femoral+anteversion.">Knee pain and activity outcomes after femoral derotation osteotomy for excessive femoral anteversion.</a> Journal of Pediatric Orthopedics. 38 (10), 503-509 (2018).</li><li>Murphy, S. B., Simon, S. R., Kijewski, P. K., Wilkinson, R. H., Griscom, N. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Femoral+anteversion.">Femoral anteversion.</a> Journal of Bone and Joint Surgery. American Volume. 69 (8), 1169-1176 (1987).</li><li>Gracia-Costa, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Análisis por elementos finitos de las presiones femoropatelares previas y posteriores a osteotomía desrrotadora. , (2019).</li><li>Ferr&#224;s-Tarrag&#243;, J., Sanchis-Alfonso, V., Ram&#237;rez-Fuentes, C., Rosell&#243;-A&#241;&#243;n, A., Baixauli-Garc&#237;a, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+3D-CT+Analysis+of+femoral+symmetry-Surgical+implications.">A 3D-CT Analysis of femoral symmetry-Surgical implications.</a> Journal of Clinical Medicine. 9 (11), 3546 (2020).</li><li>Chen, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Treatment+of+die-punch+fractures+with+3D+printing+technology.">Treatment of die-punch fractures with 3D printing technology.</a> Journal of Investigative Surgery. 31 (5), 385-392 (2017).</li><li>Wells, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Femoral+morphology+in+the+dysplastic+hip:+Three-dimensional+characterizations+with+CT.">Femoral morphology in the dysplastic hip: Three-dimensional characterizations with CT.</a> Clinical and Orthopaedics and Related Research. 475 (4), 1045-1054 (2016).</li><li>Liang, H., Ji, T., Zhang, Y., Wang, Y., Guo, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reconstruction+with+3D-printed+pelvic+endoprostheses+after+resection+of+a+pelvic+tumour.">Reconstruction with 3D-printed pelvic endoprostheses after resection of a pelvic tumour.</a> The Bone and Joint Journal. 99-B (2), 267-275 (2017).</li><li>Wang, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Computer-aided+designed,+three+dimensional-printed+hemipelvic+prosthesis+for+peri-acetabular+malignant+bone+tumour.">Computer-aided designed, three dimensional-printed hemipelvic prosthesis for peri-acetabular malignant bone tumour.</a> International Orthopaedics. 42 (3), 687-694 (2018).</li><li>Wong, K. C., Kumta, S., Geel, N. V., Demol, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=One-step+reconstruction+with+a+3D-printed,+biomechanically+evaluated+custom+implant+after+complex+pelvic+tumor+resection.">One-step reconstruction with a 3D-printed, biomechanically evaluated custom implant after complex pelvic tumor resection.</a> Computed Aided Surgery. 20 (1), 14-23 (2015).</li><li>Fang, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surgical+applications+of+three-dimensional+printing+in+the+pelvis+and+acetabulum:+From+models+and+tools+to+implants.">Surgical applications of three-dimensional printing in the pelvis and acetabulum: From models and tools to implants.</a> Der Unfallchirurg. 122 (4), 278-285 (2019).</li><li>Upex, P., Jouffroy, P., Riouallon, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Application+of+3D+printing+for+treating+fractures+of+both+columns+of+the+acetabulum:+Benefit+of+pre-contouring+plates+on+the+mirrored+healthy+pelvis.">Application of 3D printing for treating fractures of both columns of the acetabulum: Benefit of pre-contouring plates on the mirrored healthy pelvis.</a> Orthopaedics &amp; Traumatology, Surgery &amp; Research. 103 (3), 331-334 (2017).</li><li>Xie, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Three-dimensional+printing+assisted+ORIF+versus+conventional+ORIF+for+tibial+plateau+fractures:+A+systematic+review+and+meta-analysis.">Three-dimensional printing assisted ORIF versus conventional ORIF for tibial plateau fractures: A systematic review and meta-analysis.</a> International Journal of Surgery. 57, 35-44 (2018).</li><li>Scorcelletti, M., Reeves, N. D., Rittweger, J., Ireland, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Femoral+anteversion:+Significance+and+measurement.">Femoral anteversion: Significance and measurement.</a> Journal of Anatomy. 237 (5), 811-826 (2020).</li><li>Seitlinger, G., Moroder, P., Scheurecker, G., Hofmann, S., Grelsamer, R. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+contribution+of+different+femur+segments+to+overall+femoral+torsion.">The contribution of different femur segments to overall femoral torsion.</a> The American Journal of Sports Medicine. 44 (7), 1796-1800 (2016).</li><li>Kaiser, P., Attal, R., Kammerer, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Significant+differences+in+femoral+torsion+values+depending+on+the+CT+measurement+technique.">Significant differences in femoral torsion values depending on the CT measurement technique.</a> Archives of Orthopaedic and Trauma Surgery. 136 (9), 1259-1264 (2016).</li><li>Schmaranzer, F., Lerch, T. D., Siebenrock, K. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differences+in+femoral+torsion+among+various+measurement+methods+increase+in+hips+with+excessive+femoral+torsion.">Differences in femoral torsion among various measurement methods increase in hips with excessive femoral torsion.</a> Clinical Orthopaedics and Related Research. 477 (5), 1073-1083 (2019).</li><li>Sanchis-Alfonso, V., Domenech-Fernandez, J., Ferras-Tarrago, J., Rosello-A&#241;on, A., Teitge, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+incidence+of+complications+after+derotational+femoral+and/or+tibial+osteotomies+in+patellofemoral+disorders+in+adolescents+and+active+young+patients:+A+systematic+review+with+meta-analysis.">The incidence of complications after derotational femoral and/or tibial osteotomies in patellofemoral disorders in adolescents and active young patients: A systematic review with meta-analysis.</a> Knee Surgery, Sports Traumatology, Arthroscopy. 30 (10), 3515-3525 (2022).</li></ol>

The authors have no conflicts of interest to disclose.

The most important finding of this study is that 3D technology allows the planning of proximal external derotational femoral osteotomy. This technology can simulate the surgery that is to be performed on a specific patient on the computer. It is a simple, reproducible, and free technique that uses software adaptable to most computers. The only technical problem may be that the 3D builder software works only with the Windows operating system. The major limitation is the learning curve. This protocol is still in the prelim...

Anterior knee pain (AKP) is a common clinical issue among adolescents and young adults. There is a growing body of evidence that increased femoral anteversion (FAV) plays an important role in the genesis of AKP1,2,3,4,5,6,7,8,9,10,11. In addition, this same evidence suggests that a derotational femoral osteotomy is beneficial for these patients, as good clinical results have been reported1,2,3,4,5,6,7,8,9,10,11. However, this type of surgery is not widely used in daily clinical practice among orthopedic surgeons, especially in the cases of adolescents and young active patients with anterior knee pain27, because the many controversial aspects generate uncertainty. For example, it has been observed that sometimes the correction obtained after the osteotomy is not what was previously planned. That is, there is not always a 1:1 ratio between the amount of rotation planned when performing the osteotomy and the amount of FAV corrected. This finding has not been studied to date. Therefore, it is the subject of the present paper. To explain the discrepancy between the magnitude of the rotation performed with the osteotomy and the magnitude of the correction of FAV, it was hypothesized that the axis of rotation of the osteotomy and the axis of rotation of the femur may not coincide.
One of the main problems to be addressed is accurately locating the femoral axis of rotation and the axis of rotation of the osteotomy. The first femoral axis is the femoral axis measured on the CT scan at the time of the patient&#39;s diagnosis, while the second femoral axis is the femoral axis measured after performing the osteotomy. Over the last decade, 3D technology has become increasingly important in preoperative planning, especially in orthopedic surgery and traumatology, for simplifying and optimizing surgical techniques15,16. The development of 3D technology has supported the creation of anatomical biomodels based on 3D imaging tests such as CT, in which customized prosthetic implants can be adapted17,18,19 and osteosynthesis plates can be molded in the case of fractures20,21,22. Additionally, 3D planning has already been used in previous studies to analyze the origin of the deformity in unilateral torsional alterations of the femur14. Currently, there are several software programs that are completely free and adaptable to most computers and 3D printers on the market, making this technology easily accessible to most surgeons in the world. This 3D planning allows for the accurate calculation of the initial axis of rotation of the femur and the axis of rotation of the femur after the intertrochanteric osteotomy has been performed. The main purpose of this study is to demonstrate that the axis of rotation of the femoral intertrochanteric osteotomy and the axis of rotation of the femur do not coincide. This 3D technology makes it possible to visualize this discrepancy between the axes and correct it through an adjustment of the osteotomy. The ultimate goal is to stimulate greater interest from orthopedic surgeons in this type of surgery.
This protocol with a 3D methodology is conducted in four fundamental steps. First, CT images are downloaded, and the 3D biomodel is created from the DICOM (Digital Imaging and Communication in Medicine) files of the CT scan. Higher-quality CT scans allow for better biomodels but mean the patient receives more ionizing radiation. For surgical planning with biomodels, the quality of conventional CT is sufficient. The DICOM image of a CT scan consists of a folder with many different files, with one file for each CT cut made. Each of these files contains not only the CT cut&#39;s graphical information but also the metadata (data associated with the image). To open the image, it is essential to have a folder with all the files of the series (the CT). The biomodel is extracted from the totality of the files.
Second, to obtain the 3D biomodel, it is necessary to download the 3D Slicer computer program, an open-source program with many utilities. Furthermore, this is the most widely used computer software in international 3D laboratories and has the advantage of being completely free of cost and downloadable from its main page. As this software is an X-ray image viewer, the DICOM image must be imported into the program.
Third, the first biomodel obtained with 3D Slicer will not match with the definitive one, because there will be regions such as the CT table or bones and soft parts nearby that are of no interest. The biomodel is &#34;cleaned&#34; almost automatically with the 3D design software, MeshMixer, which can also be downloaded directly from its official website for free. Finally, femoral anteversion is calculated, and the osteotomy is simulated using another free software from the Windows Store, 3D Builder.

<table><tbody><tr><td>3D Builder</td><td>Microsoft Corporation, Washington, USA</td><td></td><td>open-source program; https://apps.microsoft.com/store/detail/3d-builder/9WZDNCRFJ3T6?hl=en-us&amp;amp;gl=us</td></tr><tr><td>3D Slicer</td><td>3D Slicer Harvard Medical School, Massachusetts, USA</td><td></td><td>open-source program; https://download.slicer.org</td></tr><tr><td>MeshMixer&amp;nbsp;</td><td>Autodesk Inc&amp;nbsp;</td><td></td><td>open-source program; https://meshmixer.com/download.html</td></tr></tbody></table>

three-dimensional preoperative virtual planning in derotational proximal femoral osteotomy

Anterior knee pain (AKP) is a common pathology among adolescents and adults. Increased femoral anteversion (FAV) has many clinical manifestations, including AKP. There is growing evidence that increased FAV plays a major role in the genesis of AKP. Furthermore, this same evidence suggests that derotational femoral osteotomy is beneficial for these patients, as good clinical results have been reported. However, this type of surgery is not widely used among orthopedic surgeons.
The first step in attracting orthopedic surgeons to the field of rotational osteotomy is to give them a methodology that simplifies preoperative surgical planning and allows for the previsualization of the results of surgical interventions on computers. To that end, our working group uses 3D technology. The imaging dataset used for surgical planning is based on a CT scan of the patient. This 3D method is open access (OA), meaning it is accessible to any orthopedic surgeon at no economic cost. Furthermore, it not only allows for the quantification of femoral torsion but also for carrying out virtual surgical planning. Interestingly, this 3D technology shows that the magnitude of the intertrochanteric rotational femoral osteotomy does not present a 1:1 relationship with the correction of the deformity. Additionally, this technology allows for the adjustment of the osteotomy so that the relationship between the magnitude of the osteotomy and the correction of the deformity is 1:1. This paper outlines this 3D protocol.

Femoral anteversion can be measured by different methods. Some of them focus on the femoral neck, using the line passing through the center of the neck and one passing through the femoral condyles as references. Others add a third reference point at the lesser trochanter23. Murphy&#39;s method, which is the most reliable in clinical practice because it has the best clinical-radiological relationship, is one such method using a third reference point25,<sup class="...

Watch this Scientific Journal Video about Three-Dimensional Preoperative Virtual Planning in Derotational Proximal Femoral Osteotomy at JoVE.com

Three-Dimensional Preoperative Virtual Planning in Derotational Proximal Femoral Osteotomy

This work presents a detailed surgical planning protocol using 3D technology with free open-source software. This protocol can be used to correctly quantify femoral anteversion and simulate derotational proximal femoral osteotomy for the treatment of anterior knee pain.

Anterior knee pain (AKP) is a common pathology among adolescents and adults. Increased femoral anteversion (FAV) has many clinical manifestations, ...

three-dimensional-preoperative-virtual-planning-derotational-proximal

Research

JoVE Journal

Medicine

915 Views.  Hospital Arnau de Vilanova. This work presents a detailed surgical planning protocol using 3D technology with free open-source software. This protocol can be used to correctly quantify femoral anteversion and simulate derotational proximal femoral osteotomy for the treatment of anterior knee pain.

Video: Three-Dimensional Preoperative Virtual Planning in Derotational Proximal Femoral Osteotomy

Individualized Stem-positioning in Calcar-guided Short-stem Total Hip Arthroplasty

Bone- and soft-tissue sparing short stems are increasingly used in total hip arthroplasty (THA). However, there are a large variety of models of short stems, differing in design and function. Calcar-guided short stems provide an anatomical curvature in the medial calcar region, thus, positioning is done individually alongside the calcar in the "round-the-corner" technique. Depending on the level of the neck's osteotomy, stems can be aligned individually in a large bandwidth of varus- and valgus anatomies. This differs from conventional total hip arthroplasty and potentially includes a severe learning curve. Given that a great variety of caput-collum-diaphyseal (CCD)-angles can be retained, the reconstruction of femoro-acetabular offsets can be achieved precisely. However, particularly extensive varus- and valgus positioning has raised concerns in regard to stability and bone remodeling. The purpose of the present manuscript is to showcase the implantation technique in calcar-guided short-stem THA and to summarize short-term clinical and radiological results.

This protocol describes the round-the-corner technique and the individualized stem-positioning of calcar-guided short stems alongside the medial calcar, depending on the level of the osteotomy. This differs from conventional total hip arthroplasty and includes a learning curve.

Bone- and soft-tissue sparing short stems are increasingly used in total hip arthroplasty (THA). However, there are a large variety of models of short ...

Three-Dimensional Printing Guide Template Assisted Percutaneous Vertebroplasty (PVP)

Percutaneous vertebroplasty (PVP) is considered an effective treatment for the back pain caused by osteoporotic vertebral compression fracture. The accuracy of PVP mainly depends on the surgeons&#39; experience and multiple fluoroscopes during a traditional procedure. Puncture related complications were reported all over the world. To make the surgical procedure more precise and decrease the rate of puncture-related complications, our team applied a three-dimensional printing guide template to PVP to modify the traditional procedure. This protocol introduces how to model target vertebrae DICOM imaging data into three-dimensions in the software, how to simulate operation in this 3-D model, and how to use all of the surgical data to reconstruct a patient specific template for application. Using this template, surgeons can identify suitable puncture points accurately to improve the accuracy of the operation. The whole protocol includes: 1) diagnosis of the osteoporotic vertebral compression fracture; 2) acquisition of CT imaging of the target vertebra; 3) simulation of the operation in the software; 4) design and fabrication of the 3-D printing guide template; and 5) application of the template into an operation procedure.

Three-Dimensional Printing Guide Template Assisted Percutaneous Vertebroplasty PVP

Herein, we present a three-dimensional printing guide template for percutaneous vertebraplasty. A patient with a T11 vertebral compression fracture was selected as a case study.

Percutaneous vertebroplasty (PVP) is considered an effective treatment for the back pain caused by osteoporotic vertebral compression fracture. The ...

A Postoperative Evaluation Guideline for Computer-Assisted Reconstruction of the Mandible

Valid comparisons of postoperative accuracy results in computer-assisted reconstruction of the mandible are difficult due to heterogeneity in imaging modalities, mandibular defect classification, and evaluation methodologies between studies. This guideline uses a step-by-step approach guiding the process of imaging, classification of mandibular defects and volume assessment of three-dimensional (3D) models, after which a legitimized quantitative accuracy evaluation method can be performed between the postoperative clinical situation and the preoperative virtual plan. The condyles and the vertical and horizontal corners of the mandible are used as bony landmarks to define virtual lines in the computer-assisted surgery (CAS) software. Between these lines the axial, coronal, and both sagittal mandibular angles are calculated on both pre- and postoperative 3D models of the (neo)mandible and subsequently the deviations are calculated. By superimposing the postoperative 3D model to the preoperative virtually planned 3D model, which is fixed to the XYZ axis, the deviation between pre- and postoperative virtually planned dental implant positions can be calculated. This protocol continues and specifies an earlier publication of this evaluation guideline.

Here, we propose a practical, feasible and reproducible evaluation guideline for computer-assisted reconstruction of the mandible in order to create uniformity between studies regarding postoperative accuracy evaluation. This protocol continues and specifies an earlier publication of this evaluation guideline.

Valid comparisons of postoperative accuracy results in computer-assisted reconstruction of the mandible are difficult due to heterogeneity in imaging ...

3D Planning and Printing of Patient Specific Implants for Reconstruction of Bony Defects

We are in the midst of the 3D era in most aspects of life, and especially in medicine. The surgical discipline is one of the major players in the medical field using the constantly developing 3D planning and printing capabilities. Computer-assisted design (CAD) and computer assisted manufacturing (CAM) are used to describe the 3D planning and manufacturing of the product. The planning and manufacturing of 3D surgical guides and reconstruction implants is performed almost exclusively by engineers. As technology advances and software interfaces become more user-friendly, it raises a question regarding the possibility of transferring the planning and manufacturing to the clinician. The reasons for such a shift are clear: the surgeon has the idea of what he wants to design, and he also knows what is feasible and could be used in the operating room. It allows him to be prepared for any scenario/unexpected results during the operation and allows the surgeon to be creative and express his new ideas using the CAD software. The purpose of this method is to provide clinicians with the ability to create their own surgical guides and reconstruction implants. In this manuscript, a detailed protocol will provide a simple method for segmentation using segmentation software and implant planning using a 3D design software. Following the segmentation and stl file production using segmentation software, the clinician could create a simple patient specific reconstruction plate or a more complex plate with a cradle for bone graft positioning. Surgical guides can be created for accurate resection, hole preparation for proper reconstruction plate positioning or for bone graft harvesting and re-contouring. A case of lower jaw reconstruction following plate fracture and nonunion healing of a trauma sustained injury is detailed.

This protocol describes the use of 3D planning and printing for reconstruction of bony defects. We use segmentation tools to create 3D models followed by 3D design software to create patient specific implants for reconstruction purposes concomitant to ablative surgery or as a second stage.

We are in the midst of the 3D era in most aspects of life, and especially in medicine. The surgical discipline is one of the major players in the medical ...

Treatment of Facial Deformities using 3D Planning and Printing of Patient-Specific Implants

Technological advancements in surgical planning and patient-specific implants are constantly evolving. One can either adopt the technology to achieve better results, even in the less experienced hand, or continue without it. As technology develops and becomes more user-friendly, we believe it is time to allow the surgeon the option to plan his/her operations and create his/her own patient-specific surgical guides and fixation plates allowing him full control over the process. We present here a protocol for 3D planning of the operation followed by 3D planning and printing of surgical guides and patient-specific fixation implants. During this process we use two commercial computer-assisted design (CAD) software. We also use a fused deposition&#160;modeling printer for the surgical guides and a selective laser sintering printer for the titanium patient-specific fixation implants. The process includes computed tomography (CT) imaging acquisition, 3D segmentation of the skull and facial bones from the CT, 3D planning of the operations, 3D planning of patient-specific fixation implant according to the final position of the bones, 3D planning of surgical guides for performing an accurate osteotomy and preparing the bone for the fixation plates, and 3D printing of the surgical guides and the patient-specific fixation plates. The advantages of the method include full control over the surgery, planned osteotomies and fixation plates, significant reduction in price, reduction in operation duration, superior performance and highly accurate results. Limitations include the need to master the CAD programs.

As technology develops and becomes more user-friendly, planning of operations and patient-specific surgical guides and fixation plates should be performed by the surgeon. We present a protocol for 3D planning of orthognathic skeletal movements and 3D planning and printing of patient-specific fixation plates and surgical guides.

Technological advancements in surgical planning and patient-specific implants are constantly evolving. One can either adopt the technology to achieve ...

Digital Hybrid Model Preparation for Virtual Planning of Reconstructive Dentoalveolar Surgical Procedures

Virtual, hybrid three-dimensional (3D) model acquisition is presented in this article, utilizing the sequence of radiographic image segmentation, spatial registration, and free-form surface modeling. Firstly cone-beam computed tomography datasets were reconstructed with a semi-automatic segmentation method. Alveolar bone and teeth are separated into different segments, allowing 3D morphology, and localization of periodontal intrabony defects to be assessed. The severity, extent, and morphology of acute and chronic alveolar ridge defects are validated concerning adjacent teeth. On virtual complex tissue models, positions of dental implants can be planned in 3D. Utilizing spatial registration of IOS and CBCT data and subsequent free-form surface modeling, realistic 3D hybrid models can be acquired, visualizing alveolar bone, teeth, and soft tissues. With the superimposition of IOS and CBCT soft tissue, thickness above the edentulous ridge can be assessed about the underlying bone dimensions; therefore, flap design and surgical flap management can be determined, and occasional complications may be avoided.

A workflow for creating three-dimensional (3D) virtual hybrid models has been designed based on cone-beam computed tomography dataset and intraoral optical scans utilizing radiographic image segmentation methods and free-form surface modeling. Digital models are used for the virtual planning of reconstructive dentoalveolar surgical procedures.

Virtual, hybrid three-dimensional (3D) model acquisition is presented in this article, utilizing the sequence of radiographic image segmentation, spatial ...

The Use of Mixed Reality in Custom-Made Revision Hip Arthroplasty: A First Case Report

The technology of 3D printing and visualization of anatomical structures is rapidly growing in various fields of medicine. A custom-made implant and mixed reality were used to perform complex revision hip arthroplasty in January 2019. The use of mixed reality allowed for a very good visualization of the structures and resulted in precise implant fixation. According to the authors' knowledge, this is the first described case report of the combined use of these two innovations. The diagnosis preceding the qualification for the procedure was the loosening of the left hip's acetabular component. Mixed reality headset and holograms prepared by engineers were used during the surgery. The operation was successful, and it was followed by early verticalization and patient rehabilitation. The team sees opportunities for technology development in joint arthroplasty, trauma, and orthopedic oncology.

A complex revision hip arthroplasty was performed using a custom-made implant and mixed reality technology. According to the authors&#39; knowledge, this is the first report of such procedure described in the literature.

The technology of 3D printing and visualization of anatomical structures is rapidly growing in various fields of medicine. A custom-made implant and mixed ...

Augmented Reality Navigation-Guided Core Decompression for Osteonecrosis of Femoral Head

Osteonecrosis of the femoral head (ONFH) is a common joint disease in young and middle-aged patients, which seriously burdens their lives and work. For early-stage ONFH, core decompression surgery is a classical and effective hip preservation therapy. In traditional procedures of core decompression with Kirschner wire, there are still many problems such as X-ray exposure, repeated puncture verification, and damage to normal bone tissue. The blindness of the puncture process and the inability to provide real-time visualization are crucial reasons for these problems.
To optimize this procedure, our team developed an intraoperative navigation system on the basis of augmented reality (AR) technology. This surgical system can intuitively display the anatomy of the surgical areas and render preoperative images and virtual needles to intraoperative video in real-time. With the guide of the navigation system, surgeons can accurately insert Kirschner wires into the targeted lesion area and minimize the collateral damage. We conducted 10 cases of core decompression surgery with this system. The efficiency of positioning and fluoroscopy is greatly improved compared to the traditional procedures, and the accuracy of puncture is also guaranteed.

Augmented reality technology was applied to core decompression for osteonecrosis of the femoral head to realize real-time visualization of this surgical procedure. This method can effectively improve the safety and precision of core decompression.

Osteonecrosis of the femoral head (ONFH) is a common joint disease in young and middle-aged patients, which seriously burdens their lives and work. For ...

3D Printing Model of a Patient's Specific Lumbar Vertebra

Selective dorsal rhizotomy (SDR) is a difficult, risky, and sophisticated operation, in which a laminectomy should not only expose an adequate surgical field of view but also protect the patient&#39;s spinal nerves from injury. Digital models play an important role in the pre-and intra-operation of SDR, because they can not only make doctors more familiar with the anatomical structure of the surgical site, but also provide precise surgical navigation coordinates for the manipulator. This study aims to create a 3D digital model of a patient-specific lumbar vertebra that can be used for planning, surgical navigation, and training of the SDR operation. The 3D printing model is also manufactured for more effective work during these processes.
Traditional orthopedic digital models rely almost entirely on computed tomography (CT) data, which is less sensitive to soft tissues. Fusion of the bone structure from CT and the neural structure from magnetic resonance imaging (MRI) is the key element for the model reconstruction in this study. The patient&#39;s specific 3D digital model is reconstructed for the real appearance of the surgical area and shows the accurate measurement of inter-structural distances and regional segmentation, which can effectively help in the preoperative planning and training of SDR. The transparent bone structure material of the 3D-printed model allows surgeons to clearly distinguish the relative relationship between the spinal nerve and the vertebral plate of the operated segment, enhancing their anatomical understanding and spatial sense of the structure. The advantages of the individualized 3D digital model and its accurate relationship between spinal nerve and bone structures make this method a good choice for preoperative planning of SDR surgery.

This study aims to create a 3D-printed model of a patient-specific lumbar vertebra, which contains both the vertebra and spinal nerve models fused from high-resolution computed tomography (HRCT) and MRI-Dixon data.

Selective dorsal rhizotomy (SDR) is a difficult, risky, and sophisticated operation, in which a laminectomy should not only expose an adequate surgical ...

Virtual Reality-3D Modeling for Minimally Invasive Neuro-Interventional Planning

Pioneering Patient-Specific Approaches for Precision Surgery Using Imaging and Virtual Reality

Endovascular treatment of complex vascular anomalies shifts the risk of open surgical procedures to the benefit of minimally invasive endovascular procedural solutions. Complex open surgical procedures used to be the only option for the treatment of a myriad of conditions like pulmonary and aortic valve replacement as well as cerebral aneurysm repair. However, due to advancements in catheter-delivered devices and operator expertise, these procedures (along with many others) can now be performed through minimally invasive procedures delivered through a central or peripheral vein or artery. The decision to shift from an open procedure to an endovascular approach is based on multi-modal imaging, often including 3D Digital Imaging and Communications in Medicine (DICOM) imaging datasets. Utilizing these 3D images, our lab generates 3D models of the pathologic anatomy, thereby allowing the pre-procedural analysis necessary to pre-plan critical components of the catheterization lab procedure, namely, C-arm positioning, 3D measurement, and idealized road-map generation. This article describes how to take segmented 3D models of patient-specific pathology and predict generalized C-arm positions, how to measure critical two-dimensional (2D) measurements of 3D structures relevant to the 2D fluoroscopy projections, and how to generate 2D fluoroscopy roadmap analogs that can assist in proper C-arm positioning during catheterization lab procedures.

Author Spotlight: Segmentation and VR for Advanced Neurovascular Interventions

Advancements in endovascular treatment have replaced complex open surgical procedures with minimally invasive options, like valve replacement and aneurysm repair. This paper proposes using three-dimensional (3D) modeling and virtual reality to aid in C-arm positioning, angle measurements, and roadmap generation for neuro-interventional catheterization lab procedural planning, minimizing procedure time.