This work was supported by Beijing Natural Science Foundation(7202183), National Natural Science Foundation of China(81972107), and Beijing Municipal Science and Technology Commission(D171100003217001).

This study was approved by the ethics committee of the China-Japan Friendship Hospital (approval number: 2021-12-K04). All of the following steps were performed according to standardized procedures to avoid injury to the patients and the surgeons. Informed patient consent was obtained for this study. The surgeon must be skilled in conventional core decompression procedures to ensure that the surgery can be performed in a traditional way in case of inaccurate navigation or other unexpected situations.
1. Preoperative diagnosis and grading of ONFH
<ol>
	<li>Identify patients with clinical symptoms of ONFH; typical symptoms such as persistent or intermittent pain in the groin region with ipsilateral hip or knee radiating pain. Physical examination showed deep tenderness in the groin region, Patrick&#39;s sign, a limited hip motion of internal rotation and abduction, or necrosis changes of the femoral head measured using X-ray, CT, and MRI.</li>
	<li>According to the association research circulation osseous (ARCO) staging, review patients&#39; X-ray, CT, and MRI of the hip and determine the staging of ONFH. Two doctors conduct this work independently. If disagreements arise, ask a third expert to make the final decision.</li>
	<li>Record the preoperative visual analogue scale (VAS) and Harris hip score using a questionnaire.</li>
	<li>Include patients using the following criteria: 1) patients with ONFH; 2) stage I, IIA, and IIB of ONFH confirmed by imaging examination (X-ray, CT, and MRI); 3) the femoral head core decompression surgery is planned. Exclude patients when: 1) patients reject the CD surgery; 2) preoperative routine examination indicates surgical contradictions, such as infection or poor basic condition; 3) patients refuse to be enrolled in the group.</li>
</ol>
2. System registration and accuracy testing
<ol>
	<li>Run the AR-assisted orthopedic surgery system (due to commercialization issues software details cannot be provided) and click on Orthographic Video to activate the depth camera. An image of the surgical area will be displayed on the screen after activation (Figure 5A). Position the optical tracking device so that its tracking area can completely cover the surgical area (Figure 5B).</li>
	<li>Click on NDI Setting to select the device access port, COM4. Click the Virtual Needle Length Setting (generally a Kirschner needle is 180 mm long) and a virtual Kirschner needle image will be automatically generated in the surgical area in the video.</li>
	<li>Divide the planned surgical frontal area into upper and lower levels with each level 30 cm x 30 cm in size, and with a height difference of 15 cm between the levels. The system automatically inputs this spatial information of the surgical area in the software.</li>
	<li>Evenly allocate every level with 10 matching points; for every 30 cm x 30 cm area, divide it into three equal parts, with two parts having three points each, and one part (left part) having four points. Ask the assistant to place the non-invasive body surface marking frame (Figure 2C) according to the points. Once done, click on Match. The system&#39;s own special image for registration will be automatically superimposed on the marking frame (Figure 5C). Consider the registration of this point successful when the image and the marking frame coincide completely.</li>
	<li>Move the frame to the next registration point and repeat step 2.4. until all registration points are completed. As the shape of the marking frame equipped with the puncture device (Figure 3A2) is exactly the same as the non-invasive body surface marking frame, once the registration is completed, the former can also be tracked by the optical tracking device in the surgical area.</li>
	<li>Move the puncture device randomly in the surgical area to detect the matching degree of virtual needle and tracking delay (Figure 6). As the red-blue virtual Kirschner needle body automatically fits with the actual needle in the surgical area, the augmented reality display of the Kirschner needle is successful (Figure 5D). 
	NOTE: During the registration process, the position of the optical tracking device and depth camera should not be changed at will. If so, the spatial position relationship of virtual surgery will change, causing inaccurate matching between the virtual Kirschner needle and the physical one, and registration has to be re-conducted.</li>
</ol>
3. Patient and system preparation before puncture
<ol>
	<li>After entering the operating room, ask the patient to lie down in supine position and fix the lower limb of the affected side (Figure 7). Administer general anesthesia to all patients.</li>
	<li>Prepare the surgical site with iodine and 75% alcohol, and place the non-invasive body surface positioning device (sterilized using standard procedures) on the patient&#39;s affected hip.</li>
	<li>Move the C-ARM fluoroscope to the side of the operating table and position the source above the hip joint. Align the source with the depth camera and record the position of the surgical table as position 1.</li>
	<li>After the first fluoroscopy, export the BMP format radiograph to the system workstation, open it in Photo Editing, and adjust its gray scale by clicking on the Light Scale Option. Rotate clockwise and flip horizontally once by clicking the corresponding buttons to convert to BMP. Then, open it by clicking Painting 3D and save as the JPG format, which contained non-invasive body surface marking frame, and name it image 1 (Figure 8A). 
	NOTE: This conversion process is to promote the success of the system identification. Because of the special requirements of image conversion, it is necessary to adjust the gray scale of the X-ray image for rotation and inversion.</li>
	<li>Slide the operating table directly below the depth camera to the operating area marked as position 2. Position 1 (in step 3.3) and position 2 are two points on the same horizontal plane, 30 cm apart.</li>
	<li>In the AR-assisted orthopedic surgery system, click File &#62; Front X-ray image, and select image 1. the system automatically identifies the non-invasive body surface marking frame on the skin surface of the patient, and then superimposes this image to the hip joint in the surgical video (Figure 8B).</li>
	<li>Using the augmented reality display of the X-ray image and real-time video generated above, the surgeon plans the puncture path based on this.</li>
</ol>
4. Puncture assisted by surgical system
<ol>
	<li>The surgeon stands on the affected side and performs the following steps. Hold the puncture device and determine the best insertion angle. Mark the insertion point on the skin surface, guided by the virtual Kirschner wire and the X-ray image of the hip joint in the surgical video.</li>
	<li>Select a Kirschner wire with a diameter of 2.5 mm and pierce it from the insertion point. Observe the insertion depth and angle in the video and adjust it timely.</li>
	<li>When the virtual needle has reached the target area of necrosis, stop the puncture process and retain the screen shot as image 2 (Figure 9A) for subsequent puncture accuracy evaluation.</li>
	<li>Indwell the needle. Move the operating table to position 1 for the second fluoroscopy to verify the actual puncture condition of the Kirschner wire. Record the image file as image 3 (Figure 9B).</li>
	<li>Puncture is successful when the location of the Kirschner wire meets all of the surgeon&#39;s requirements. Then, use the lancet to cut the skin around the needle, and separate every level of soft tissue till exposing sub-trochanter bone, roughly to a depth of 3 cm. Drill into the necrotic area along the Kirschner wire with a 5 mm trephine to complete the subsequent operations (artificial bone or autologous bone implantation).</li>
	<li>After finishing all the procedures, close the skin with 3-0 silk thread and cover with sterile dressing (Figure 10). After returning to the ward, provide the patients accepted common orthopedic postoperative medication, like infection prevention, analgesia, and fluid infusion. If no complication occurs, discharge the patients 3 days after surgery.</li>
</ol>
5. Operation evaluation
<ol>
	<li>Import image 2 and image 3 into an image processing software and adjust the opacity to 52%.</li>
	<li>Click the Masking button to overlap the two images, then click the Rulers button to measure the distance (Lvirtual) between the virtual tip and the puncture point of the femoral cortex, and the distance (Lture) between the tip of the Kirschner needle and the puncture point of the femoral cortex. Calculate the difference between Lvirtual and Lture to assess puncture accuracy.</li>
	<li>During the puncture, measure the positioning time as follows: the positioning time starts from the time when the Kirschner wire pierces the skin, and stops when the X-ray confirms that the Kirschner wire has successfully reached the target area of the femoral head.</li>
	<li>Three months after surgery, take the hip X-ray (Figure 11) and record the visual analogue scale and Harris hip score.</li>
</ol>

<ol>
	<li>Cohen-Rosenblum, A., Cui, Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Osteonecrosis+of+the+femoral+head.">Osteonecrosis of the femoral head.</a> Orthopedic Clinics of North America. 50 (2), 139-149 (2019).</li><li>Migliorini, F., 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=Prognostic+factors+in+the+management+of+osteonecrosis+of+the+femoral+head:+A+systematic+review.">Prognostic factors in the management of osteonecrosis of the femoral head: A systematic review.</a> The Surgeon: journal of the Royal Colleges of surgeons of Edinburgh and Ireland. (21), 00199 (2022).</li><li>Mont, M. A., Jones, L. C., Hungerford, D. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nontraumatic+osteonecrosis+of+the+femoral+head:+ten+years+later.">Nontraumatic osteonecrosis of the femoral head: ten years later.</a> The Journal of Bone and Joint Surgery. American Volume. 88 (5), 1117-1132 (2006).</li><li>Wang, L., Tian, X., Li, K., Liu, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Combination+use+of+core+decompression+for+osteonecrosis+of+the+femoral+head:+A+systematic+review+and+meta-analysis+using+Forest+and+Funnel+Plots.">Combination use of core decompression for osteonecrosis of the femoral head: A systematic review and meta-analysis using Forest and Funnel Plots.</a> Computational and Mathematical Methods in Medicine. , 1284149 (2021).</li><li>Hua, K. 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=The+efficacy+and+safety+of+core+decompression+for+the+treatment+of+femoral+head+necrosis:+a+systematic+review+and+meta-analysis.">The efficacy and safety of core decompression for the treatment of femoral head necrosis: a systematic review and meta-analysis.</a> Journal of Orthopaedic Surgery and Research. 14 (1), 306 (2019).</li><li>Ganz, R., Krushell, R. J., Jakob, R. P., K&#252;ffer, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+antishock+pelvic+clamp.">The antishock pelvic clamp.</a> Clinical Orthopaedics and Related Research. 267, 71-78 (1991).</li><li>Yoshikawa, K., 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=Training+with+hybrid+assistive+limb+for+walking+function+after+total+knee+arthroplasty.">Training with hybrid assistive limb for walking function after total knee arthroplasty.</a> Journal of Orthopaedic Surgery and Research. 13 (1), 163 (2018).</li><li>Wu, C. T., Yen, S. H., Lin, P. C., Wang, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Long-term+outcomes+of+Phemister+bone+grafting+for+patients+with+non-traumatic+osteonecrosis+of+the+femoral+head.">Long-term outcomes of Phemister bone grafting for patients with non-traumatic osteonecrosis of the femoral head.</a> International Orthopaedics. 43 (3), 579-587 (2019).</li><li>Mont, M. A., Marulanda, G. A., Seyler, T. M., Plate, J. F., Delanois, R. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Core+decompression+and+nonvascularized+bone+grafting+for+the+treatment+of+early+stage+osteonecrosis+of+the+femoral+head.">Core decompression and nonvascularized bone grafting for the treatment of early stage osteonecrosis of the femoral head.</a> Instructional Course Lectures. 56, 213-220 (2007).</li><li>Wang, W., 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=Patient-specific+core+decompression+surgery+for+early-stage+ischemic+necrosis+of+the+femoral+head.">Patient-specific core decompression surgery for early-stage ischemic necrosis of the femoral head.</a> PLoS One. 12 (5), 0175366 (2017).</li><li>Hoffmann, M. F., Khoriaty, J. D., Sietsema, D. L., Jones, C. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Outcome+of+intramedullary+nailing+treatment+for+intertrochanteric+femoral+fractures.">Outcome of intramedullary nailing treatment for intertrochanteric femoral fractures.</a> Journal of Orthopaedic Surgery and Research. 14 (1), 360 (2019).</li><li>Dennler, 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=Augmented+reality-based+navigation+increases+precision+of+pedicle+screw+insertion.">Augmented reality-based navigation increases precision of pedicle screw insertion.</a> Journal of Orthopaedic Surgery and Research. 15 (1), 174 (2020).</li><li>Yonezawa, H., 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=Low-grade+myofibroblastic+sarcoma+of+the+levator+scapulae+muscle:+a+case+report+and+literature+review.">Low-grade myofibroblastic sarcoma of the levator scapulae muscle: a case report and literature review.</a> BMC Musculoskeletal Disorders. 21 (1), 836 (2020).</li><li>Tsukada, S., 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=Augmented+reality-+vs+accelerometer-based+portable+navigation+system+to+improve+the+accuracy+of+acetabular+cup+placement+during+total+hip+arthroplasty+in+the+lateral+decubitus+position.">Augmented reality- vs accelerometer-based portable navigation system to improve the accuracy of acetabular cup placement during total hip arthroplasty in the lateral decubitus position.</a> The Journal of Arthroplasty. 37 (3), 488-494 (2021).</li><li>Raymond, 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=Pharmacogenetics+of+direct+oral+anticoagulants:+a+systematic+review.">Pharmacogenetics of direct oral anticoagulants: a systematic review.</a> Journal of Personalized Medicine. 11 (1), 37 (2021).</li><li>Bhatt, F. R., 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=Augmented+reality-assisted+spine+surgery:+an+early+experience+demonstrating+safety+and+accuracy+with+218+screws.">Augmented reality-assisted spine surgery: an early experience demonstrating safety and accuracy with 218 screws.</a> Global Spine Journal. , (2022).</li><li>Weiss, H. R., Nan, X., Potts, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Is+there+an+indication+for+surgery+in+patients+with+spinal+deformities?+-+A+critical+appraisal.">Is there an indication for surgery in patients with spinal deformities? - A critical appraisal.</a> The South African Journal of Physiotherapy. 77 (2), 1569 (2021).</li><li>Boontanapibul, K., Amanatullah, D. F., Huddleston, J. I., Maloney, W. J., Goodman, S. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Outcomes+of+cemented+total+knee+arthroplasty+for+secondary+osteonecrosis+of+the+knee.">Outcomes of cemented total knee arthroplasty for secondary osteonecrosis of the knee.</a> The Journal of Arthroplasty. 36 (2), 550-559 (2021).</li><li>Bakircioglu, S., Atilla, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hip+preserving+procedures+for+osteonecrosis+of+the+femoral+head+after+collapse.">Hip preserving procedures for osteonecrosis of the femoral head after collapse.</a> J Clin Orthop Trauma. 23, 101636 (2021).</li><li>Ma, H. Y., 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=Core+decompression+with+local+administration+of+zoledronate+and+enriched+bone+marrow+mononuclear+cells+for+treatment+of+non-traumatic+osteonecrosis+of+femoral+head.">Core decompression with local administration of zoledronate and enriched bone marrow mononuclear cells for treatment of non-traumatic osteonecrosis of femoral head.</a> Orthopaedic Surgery. 13 (6), 1843-1852 (2021).</li><li>Hu, 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=Comparison+of+intramedullary+nailing+and+plate+fixation+in+distal+tibial+fractures+with+metaphyseal+damage:+a+meta-analysis+of+randomized+controlled+trials.">Comparison of intramedullary nailing and plate fixation in distal tibial fractures with metaphyseal damage: a meta-analysis of randomized controlled trials.</a> Journal of Orthopaedic Surgery and Research. 14 (1), 30 (2019).</li><li>Pierannunzii, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endoscopic+and+arthroscopic+assistance+in+femoral+head+core+decompression.">Endoscopic and arthroscopic assistance in femoral head core decompression.</a> Arthroscopy Techniques. 1 (2), 225-230 (2012).</li><li>Salas, A. P., 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=Hip+arthroscopy+and+core+decompression+for+avascular+necrosis+of+the+femoral+head+using+a+specific+aiming+guide:+a+step-by-step+surgical+technique.">Hip arthroscopy and core decompression for avascular necrosis of the femoral head using a specific aiming guide: a step-by-step surgical technique.</a> Arthroscopy Techniques. 10 (12), 2775-2782 (2021).</li><li>Beer, A. J., Dijkgraaf, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Editorial+European+journal+of+nuclear+medicine+and+molecular+imaging.">Editorial European journal of nuclear medicine and molecular imaging.</a> European Journal of Nuclear Medicine and Molecular Imaging. 44 (2), 284-285 (2017).</li><li>Negrillo-C&#225;rdenas, J., Jim&#233;nez-P&#233;rez, J. R., Feito, F. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+virtual+and+augmented+reality+in+orthopedic+trauma+surgery:+From+diagnosis+to+rehabilitation.">The role of virtual and augmented reality in orthopedic trauma surgery: From diagnosis to rehabilitation.</a> Computer Methods and Programs in Biomedicine. 191, 105407 (2020).</li><li>Brookes, M. 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=Surgical+Advances+in+Osteosarcoma.">Surgical Advances in Osteosarcoma.</a> Cancers. 13 (3), 388 (2021).</li><li>Cho, H. S., 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=Can+augmented+reality+be+helpful+in+pelvic+bone+cancer+surgery?+an+in+vitro+study.">Can augmented reality be helpful in pelvic bone cancer surgery? an in vitro study.</a> Clinical Orthopaedics and Related Research. 476 (9), 1719-1725 (2018).</li></ol>

The authors declare that they have no competing interests.

Although THA has developed rapidly in recent years and become an effective ultimate method for ONFH, hip preservation therapy still plays an important role in treating early-stage ONFH18,19. CD is a basic and effective hip preservation surgery, which can release hip pain and delay the development of femoral head collapse20. The puncture positioning of the focal necrosis is the crucial procedure of CD, as it determines the success or failur...

Osteonecrosis of the femoral head (ONFH) is a common disabling disease occurring in young adults1. Clinically, it is necessary to determine the staging of ONFH based on X-ray, CT, and MRI to decide the treatment strategy (Figure 1). For early-stage ONFH, hip preservation therapy is usually adopted2. Core decompression (CD) surgery is one of the most frequently used hip preservation methods for ONFH. Certain curative effects of core decompression with or without bone grafting in treating early-stage ONFH have been reported, which can avoid or delay subsequent total hip arthroplasty (THA) for a long time3,4,5. However, the success rate of CD with or without bone grafting was reported differently among previous studies, from 64% to 95%6,7,8,9. The surgical technique, especially the accuracy of drilling position, is important for the success of hip preservation10. Due to the blindness of the puncture and positioning procedure, the traditional techniques of CD have several problems, such as more fluoroscopy time, repeated puncture using Kirschner wire, and injury of normal bone tissue11,12.
In recent years, the augmented reality (AR)-assisted method has been introduced in orthopedic surgery13. The AR technique can visually show the anatomy of the surgical field, guide the surgeons in planning the operating procedure, and consequently reduce the difficulty of the operation. The applications of the AR technique in pedicle screw implantation and joint arthroplasty surgery have been reported earlier14,15,16,17. In this study, we aim to apply the AR technique to the CD procedure and verify its safety, accuracy, and feasibility in clinical practice.
System hardware components 
The main components of the AR-based navigation surgical system include the following: (1) A depth camera (Figure 2A) installed directly above the surgical area; the video is shot from this and sent back to the workstation for registration and cooperation with the imaging data. (2) A puncture device (Figure 2B) and a non-invasive body surface marking frame (Figure 2C), both with passive infrared reflectors. A special reflective coating of marking balls (Figure 3) can be captured by infrared equipment to achieve accurate tracking of surgical equipment in the surgical area. (3) An infrared positioning device (Figure 2D) is responsible for tracking markers in the surgical area, matching the body surface marking frame and puncture device with high accuracy (Figure 4). (4) The host system (Figure 2E) is a 64-bit workstation, installed with the independently developed AR-assisted orthopedic surgery system. Augmented reality display of hip joint and femoral head puncture operation can be completed with its assistance.

<table><tbody><tr><td>AR-assisted Orthopedic Surgery System</td><td>Self development</td><td>None</td><td>An operating software that implements AR for orthopedic surgery</td></tr><tr><td>Depth camera</td><td>Stereolabs</td><td>ZED depth camera(ZED mini)</td><td>shoot video and sent back to the workstation.</td></tr><tr><td>Image processing software</td><td>Adobe Systems Incorporated</td><td>Adobe Photoshop CS6</td><td>Image processing software</td></tr><tr><td>Infrared positioning device</td><td>Northern Digital Inc.</td><td>NDI Polaris Spectra optical tracking device</td><td>Tracking markers in the surgical area.</td></tr><tr><td>Puncture device</td><td>Stryker</td><td>Stryker System 7 Cordless driver and Sabo</td><td>Insert kirschner wire into the necrotic area.</td></tr></tbody></table>

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.

Operation characteristics 
The surgical navigation system was applied in continuative 10 hips of nine patients. The average total positioning time of the surgery was 10.1 min (median 9.5 min, range 8.0-14.0 min). The mean C-ARM fluoroscopies was 5.5 times (median 5.5 times, range 4-8 times). The mean error of puncture accuracy was 1.61 mm (median 1.2 mm, range -5.76-19.73 mm; Table 1). The results show that the positioning time and fluoroscopy times are obviously shortened compared ...

Watch this Scientific Journal Video about Augmented Reality Navigation-Guided Core Decompression for Osteonecrosis of Femoral Head at JoVE.com

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

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 ...

augmented-reality-navigation-guided-core-decompression-for

Research

JoVE Journal

Medicine

3.6K Views.  Peking University. Ons systeem kan het slagingspercentage en de efficiëntie bij kerndecompressiechirurgie voor femorale hoofdnecrose verbeteren. Het vermindert ook aanzienlijk de intraoperatieve positioneringstijd en de fluoroscoopbron. Met VR-technologie kunnen we het punctieproces gebruiken, de moeilijkheidsgraad van de operatie verminderen en minder extra schade aan de patiënt veroorzaken dan traditionele chirurgische resultaten.Het systeem kan worden uitgebreid naar andere orthopedische chirurgie m...

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

A Teleoperated Robotic System-Assisted Percutaneous Transiliac-Transsacral Screw Fixation Technique

Transiliac-transsacral screw fixation is challenging in clinical practice as the screws need to break through six layers of cortical bone. Transiliac-transsacral screws provide a longer lever arm to withstand the perpendicular vertical shear forces. However, the screw channel is so long that a minor discrepancy can lead to iatrogenic neurovascular injuries. The development of medical robots has improved the precision of surgery. The present protocol describes how to use a new teleoperated robotic system to execute transiliac-transacral screw fixation. The Robot was operated remotely to position the entry point and adjust the orientation of the sleeve. The screw positions were evaluated using postoperative computed tomography (CT). All the screws were safely implanted, as confirmed using intraoperative fluoroscopy. Postoperative CT confirmed that all the screws were in the cancellous bone. This system combines the doctor's initiative with the Robot's stability. The remote control of this procedure is possible. Robot-assisted surgery has a higher position-retention capacity compared with conventional methods. In contrast to active robotic systems, surgeons have full control over the operation. The robot system is fully compatible with operating room systems and does not require additional equipment.

Teleoperated robotic system-assisted percutaneous transiliac-transsacral screw fixation is a feasible technique. Screw channels can be implemented with high accuracy owing to the excellent freedom of movement and stability of the robotic arms.

Transiliac-transsacral screw fixation is challenging in clinical practice as the screws need to break through six layers of cortical bone. ...

Engineering

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 ...

Cone Beam Intraoperative Computed Tomography-based Image Guidance for Minimally Invasive Transforaminal Interbody Fusion

Transforaminal lumbar interbody fusion (TLIF) is commonly used for the treatment of spinal stenosis, degenerative disc disease, and spondylolisthesis. Minimally invasive surgery (MIS) approaches have been applied to this technique with an associated decrease in estimated blood loss (EBL), length of hospital stay, and infection rates, while preserving outcomes with traditional open surgery. Previous MIS TLIF techniques involve significant fluoroscopy that subjects the patient, surgeon, and operating room staff to non-trivial levels of radiation exposure, particularly for complex multi-level procedures. We present a technique that utilizes an intraoperative computed tomography (CT) scan to aid in placement of pedicle screws, followed by traditional fluoroscopy for confirmation of cage placement. Patients are positioned in the standard fashion and a reference arc is placed in the posterior superior iliac spine (PSIS) followed by intraoperative CT scan. This allows for image-guidance-based placement of pedicle screws through a one-inch skin incision on each side. Unlike traditional MIS-TLIF that requires significant fluoroscopic imaging during this stage, the operation can now be performed without any additional radiation exposure to the patient or operating room staff. After completion of the facetectomy and discectomy, final TLIF cage placement is confirmed with fluoroscopy. This technique has the potential to decrease operative time and minimize total radiation exposure.

The purpose of this article is to provide image-guidance for minimally invasive transforaminal interbody fusion.

Transforaminal lumbar interbody fusion (TLIF) is commonly used for the treatment of spinal stenosis, degenerative disc disease, and spondylolisthesis. ...

Real-Time Dynamic Navigation System for the Precise Quad-Zygomatic Implant Placement in a Patient with a Severely Atrophic Maxilla

Zygomatic implants (ZIs) are an ideal way to address cases of a severely atrophic edentulous maxilla and maxilla defects because they replace extensive bone augmentation and shorten the treatment cycle. However, there are risks associated with the placement of ZIs, such as penetration of the orbital cavity or infra-temporal fossa. Furthermore, the placement of multiple ZIs makes this surgery risky and more difficult to perform. Potential intraoperative complications are extremely dangerous and may cause irreparable losses. Here, we describe a practical, feasible, and reproducible protocol for a real-time surgical navigation system for precisely placing quad-zygomatic implants in the severely atrophic maxilla of patients with residual bone that does not meet the requirements of conventional implants. Hundreds of patients have received ZIs at our department based on this protocol. The clinical outcomes have been satisfactory, the intraoperative and postoperative complications have been low, and the accuracy indicated by infusion of the designed image and postoperative three-dimensional image has been high. This method should be utilized during the entire surgical procedure to ensure ZI placement safety.

Here, we present a protocol to achieve precise quad-zygomatic implant placement in patients with severely atrophic maxilla using a real-time dynamic navigation system.

Zygomatic implants (ZIs) are an ideal way to address cases of a severely atrophic edentulous maxilla and maxilla defects because they replace extensive ...

Transtubular Endoscopic Posterolateral Decompression for L5-S1 Lumbar Lateral Disc Herniation

We report a novel technique for C-arm free transtubular L5 nerve decompression under CT-based navigation to reduce the radiation hazard. This procedure is performed under general anesthesia and neuromonitoring. The patient is placed in a prone position on an operating carbon table. A navigation reference frame is placed percutaneously into the contralateral sacroiliac joint or spinous process. Then, CT scan images are obtained. After instrument registration, the L5-S1 foraminal level is confirmed with a navigated probe, and the entry point is marked. Using an approximately 2 cm skin incision, the subcutaneous tissue and muscles are dissected. The navigated first dilator is aimed at the L5-S1 Kambin&#39;s triangle, and sequential dilation is performed. The 18 mm tube is used and fixed to the frame. The bone around the Kambin&#39;s triangle is removed with a navigated burr. For lateral disc herniation, the L5 nerve root is identified and retracted, and the disc fragment is removed. The navigation-guided tubular endoscopic decompression is an effective procedure. There is no radiation hazard to the surgeon or the operating room staff.

Presented here is a novel technique of C-arm free transtubular posterolateral decompression for lumbar foraminal stenosis and lateral disc herniation under O-arm navigation.

We report a novel technique for C-arm free transtubular L5 nerve decompression under CT-based navigation to reduce the radiation hazard. This procedure is ...

Neuroscience

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 ...

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.

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, ...

Orthopedic Robot-Assisted Femoral Neck System in the Treatment of Femoral Neck Fracture

Cannulated screw fixation is the main therapy for femoral neck fractures, especially in young patients. The traditional surgical procedure uses C-arm fluoroscopy to place the screw freehand and requires several guide wire adjustments, which increases the operation time and radiation exposure. Repeated drilling can also cause damage to the blood supply and bone quality of the femoral neck, which can be followed by complications such as screw loosening, nonunion, and femoral head necrosis. In order to make fixation more precise and reduce the incidence of complications, our team applied robot-assisted orthopedic surgery for screw placement using the femoral neck system to modify the traditional procedure. This protocol introduces how to import a patient's X-ray information into the system, how to perform screw path planning in software, and how the robotic arm assists in screw placement. Using this method, the surgeons can place the screw successfully the first time, improve the accuracy of the procedure, and avoid radiation exposure. The whole protocol includes the diagnosis of femoral neck fracture; the collection of intraoperative X-ray images; screw path planning in the software; precise placement of the screw under the assistance of the robotic arm by the surgeon; and verification of the implant placement.

This article introduces a method of robot-assisted orthopedic surgery for screw placement during the treatment of femoral neck fracture using the femoral neck system, which allows for more accurate screw placement, improved surgical efficiency, and fewer complications.

Cannulated screw fixation is the main therapy for femoral neck fractures, especially in young patients. The traditional surgical procedure uses C-arm ...

A Sectioning, Coring, and Image Processing Guide for High-Throughput Cortical Bone Sample Procurement and Analysis for Synchrotron Micro-CT

Bone is a dynamic and mechanically active tissue that changes in structure over the human lifespan. The products of the bone remodeling process have been studied substantially using traditional two-dimensional techniques. Recent advancements in X-ray imaging technology via desktop micro-computed tomography (&#181;CT) and synchrotron radiation micro-computed tomography (SR&#181;CT) have allowed for the acquisition of high-resolution three-dimensional (3D) scans of a larger field of view (FOV) than other 3D imaging techniques (e.g., SEM) providing a more complete picture of microscopic structures within human cortical bone. The specimen should be accurately centered within the FOV, however, to limit the appearance of streak artifacts known to impact data analysis. Previous studies have reported procurement of irregularly shaped rectilinear bone blocks that result in imaging artifacts due to uneven edges or image truncation. We have applied a geological sampling protocol (coring) to procure consistently sized cortical bone core specimens for SR&#181;CT experiments from the anterior aspect of human femora. This coring method is efficient and minimally destructive to tissue. It creates uniform cylindrical samples that decrease imaging artifacts by nature of being isometric during rotation and providing a uniform path length for X-ray beams throughout scanning. Image processing of X-ray tomographic data of cored and irregularly shaped samples confirms the potential of the technique to improve visualization and analysis of cortical bone microarchitecture. A goal of this protocol is to deliver a reliable and repeatable method for the extraction of cortical bone cores that is adaptable for various types of high-resolution bone imaging experiments. An overarching goal of the work is to create a standardized cortical bone procurement for SR&#181;CT that is affordable, consistent, and straightforward. This procedure may further be adapted by researchers in related fields who commonly evaluate hard composite materials such as in biological anthropology, geosciences, or material sciences.

We employed a geological (coring) sampling protocol to procure cortical bone specimens of uniform size for SR&#181;CT experiments from the anterior aspect of human femora. This method is minimally destructive, efficient, results in cylindrical specimens that minimize imaging artifacts from irregular sample shapes and improves microarchitectural visualization and analysis.

Bone is a dynamic and mechanically active tissue that changes in structure over the human lifespan. The products of the bone remodeling process have been ...

Biology

Pedicle Screw Placement Using an Augmented Reality Head-Mounted Display in a Porcine Model

This protocol helps assess the accuracy and workflow of an augmented reality (AR) hybrid navigation system using the Magic Leap head-mounted display (HMD) for minimally invasive pedicle screw placement. The cadaveric porcine specimens were placed on a surgical table and draped with sterile covers. The levels of interest were identified using fluoroscopy, and a dynamic reference frame was attached to the spinous process of a vertebra in the region of interest. Cone beam computerized tomography (CBCT) was performed, and a 3D rendering was automatically generated, which was used for the subsequent planning of the pedicle screw placements. Each surgeon was fitted with an HMD that was individually eye-calibrated and connected to the spinal navigation system.
Navigated instruments, tracked by the navigation system and displayed in 2D and 3D in the HMD, were used for 33 pedicle cannulations, each with a diameter of 4.5 mm. Postprocedural CBCT scans were assessed by an independent reviewer to measure the technical (deviation from the planned path) and clinical (Gertzbein grade) accuracy of each cannulation. The navigation time for each cannulation was measured. The technical accuracy was 1.0 mm &#177; 0.5 mm at the entry point and 0.8 mm &#177; 0.1 mm at the target. The angular deviation was 1.5&#176; &#177; 0.6&#176;, and the mean insertion time per cannulation was 141 s &#177; 71 s. The clinical accuracy was 100% according to the Gertzbein grading scale (32 grade 0; 1 grade 1). When used for minimally invasive pedicle cannulations in a porcine model, submillimeter technical accuracy and 100% clinical accuracy could be achieved with this protocol.

The augmented reality head-mounted display, Magic Leap, was used in combination with a conventional navigation system to place pedicle screws in a porcine model by adhering to a novel workflow. With a median insertion time of &lt;2.5 min, submillimeter technical accuracy and 100% clinical accuracy were achieved according to Gertzbein.

This protocol helps assess the accuracy and workflow of an augmented reality (AR) hybrid navigation system using the Magic Leap head-mounted display (HMD) ...

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

Samenvatting

Meer video's verkennen

Hoofdstukken in deze video