Not applicable.
The study was carried out as part of a non-commercial cooperation.

The protocol follows guidelines of the Human Research Ethics Committee of the Medical University of Warsaw. The patient gave informed consent to the procedure and acknowledged the fact that it will be recorded. The patient agreed to that prior to the procedure.
NOTE: The basic criterion for including the patient in the surgery project was the necessity to intervene because of the anatomical dysfunction, which made it impossible to use a standard implant. Mixed reality was aimed at better place...

Primary and revision hip arthroplasty may require personalization to ensure effectiveness of treatment. However, the use of custom implants requires longer preparation for surgery compared to standard procedures. Custom-made 3D printed implants are the solution that gives a chance to restore function in non-typical patients whose disease has caused significant bone destruction29. Standard prostheses are insufficient due to advanced degenerative disease developing rapidly, bone defects caused by pr...

The technology of three-dimensional (3D) printing and visualization of complex structures is rapidly growing in various fields of medicine. These include cardiovascular surgery, otorhinolaryngology, maxillofacial surgery, and, above all, orthopedic surgery1,2,3,4,5. Currently, this technology is used in orthopedic surgery not only in the direct implementation of 3D printed elements, but also in surgical training, preoperative planning, or intraoperative navigation6,7,8.
Total hip arthroplasty (THA) and total knee arthroplasty (TKA) are one of the most frequently performed orthopedic surgical procedures worldwide. Due to the significant improvement in the patient&#39;s quality of life, THA had been described in a previous publication as the &#34;surgery of the century&#34;9. In Poland, 49.937 THA and 30.615 TKA were performed in 201910. As life expectancy increases, there is an upward trend in the projected number of hip and knee arthroplasty surgeries. Great efforts have been made to improve implant design, surgical technique, and postoperative care. These advances led to a better chance of restoring patient function and reducing the risk of complications11,12,13,14.
However, the big challenge currently faced by orthopedic surgeons worldwide is working with non-standard patients whose anatomical defects in the hip joint make it very difficult or even impossible to implement an off-the-shelf implant15. Bone loss may be due to significant trauma, progressive degenerative osteoarthritis with an acetabular protrusion, developmental hip dysplasia, primary bone cancer, or metastasis16,17,18,19,20. The problem of implant selection specifically concerns patients who are at risk of multiple revisions, sometimes also requiring unconventional treatment. In such cases, a very promising solution is an additive-made 3D printed implant created for a specific patient and bone defect, allowing for a very precise anatomical fit20.
In the field of arthroplasty, precise implant and its sustainable fixation are crucial. Progress in preoperative and intraoperative 3D visualization has resulted in excellent solutions as augmented and mixed reality21,22,23,24. Intraoperative use of bone and implant computed tomography (CT) holograms may allow better prosthesis placement than conventional radiography images. This emerging technology may increase the chances of therapy effectiveness and reduce the risk of neurovascular complications21,25.
This case report concerns a patient subjected to hip revision surgery due to aseptic loosening. To address significant bone loss caused by multiple implant failures, the custom-made 3D printed acetabular implant was used. During the procedure, we used mixed reality to visualize the implant position to avoid damaging the at-risk neurovascular structures. Application implemented to mixed reality headset allows giving voice and gesture commands, making it possible to use it in sterile conditions during the surgical procedure.
A 57-year-old woman was admitted to the department with a preliminary diagnosis: loosening of the left hip&#39;s acetabular component. The patient&#39;s disease history was extensive. Throughout her life, she underwent numerous surgical procedures of the hip joint. The first treatment was hip resurfacing due to osteoarthritis caused by hip dysplasia (1977-15 years old), the second was a total hip arthroplasty due to implant loosening (1983-21 years old), and other two revision surgeries (1998, 2000-37 and 39 years old). Moreover, the patient was suffering from spastic left-sided hemiplegia caused by childhood cerebral palsy, and she was repeatedly operated due to left clubfoot deformity. She was also burdened with osteoarthritis of the thoracolumbar spine, carpal tunnel syndrome, and well-controlled arterial hypertension. The final diagnosis preceding the qualification for the next procedure was the pain and increasing function limitation caused by loosening of the left hip&#39;s acetabular component. The patient was highly motivated, physically active, and coping with disability.

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	<tbody>
		<tr>
			<td>CarnaLifeHolo v. 1.5.2</td>
			<td>MedApp S.A.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Custom-Made implant type Triflanged Acetabular Component</td>
			<td>BIOMET</td>
			<td>REF PM0001779</td>
			<td></td>
		</tr>
		<tr>
			<td>Head Constrained Modular Head + 9mm Neck for cone 12/14, Co-Cr-Mo, size 36mm</td>
			<td>BIOMET</td>
			<td>REF 14-107021</td>
			<td></td>
		</tr>
		<tr>
			<td>Polyethylene insert Freedom Ringloc-X Costrained Linear Ringloc-X 58mm for head 36mm / 10 *</td>
			<td>BIOMET</td>
			<td>REF 11-263658</td>
			<td></td>
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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.

Image preprocessing 
Binary masks of the pelvic bone, femur, and endoprosthesis were semi-automatically segmented from CT DICOM images by experienced radiologic technologists using thresholding and region growing algorithms with available software33. The prepared label maps were also manually corrected by a radiologist. Label maps were used to enhance the visualization by adding them to the CT scan in the next step. This approach made it possible to merge the volumetric rende...

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

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 ...

This technique involves the integration of mixed reality technology and custom made implant which allows for exiting the precise menting of Endotipsitis best increasing your chance of successful treatment. The main advantage of the method used is the great precision in implantation of the endo prosthesis. Proper visualization gives the surgeon a better chance of successful surgery.The integration of mixed reality technology and custom made implants can prove useful in endoplastic traumatology of the musculoskeletal system oncological surgery, etcetera. In areas where the best possible visualization of the operated structures is important The method can be improved and developed in the field of operational activities and various fields of orthopedics andrology of the musculoskeletal system. With the support of the engineers the use of technology is not demanding and it can affect the success of the therapy.It is worth taking care of the team because this type of action requires the cooperation of several people. To begin, take a pelvic CT scan and acquire DICOM files as described in the text protocol. To process the pelvic CT DICOM file into a holographic representation open the holographic DICOM viewer.Then, select the folder containing CT DICOM files. Check the IP that is displayed when the mixed reality headset is switched on and enter it into the holographic DICOM viewer. Click on the connect button to see the visualization in the mixed reality headset.To segment the pelvis bone tissue structures, manually enable the scissors option. Click on the left mouse button and move the mouse around to remove the structures that are selected with this tool. End the selection with another click of the left mouse button.Confirm that the selected structures are cut out from the selection. From the list of available functions, choose the predefined transfer function CT bone endo prosthesis, which contains color visualization parameters dedicated to orthopedic procedures. Adjust the visualization by changing the window and level using the right mouse button connected with mouse movement in the 3D visualization window.Adjust the image using voice commands such as rotate, zoom, cut smart, and hand gestures. Use the cut smart command to adjust a cutting plane that is perpendicular to the line of sight of the user. Observe, that the plane goes deeper as the user moves the head closer into the hologram.Perform these movements to see the inner parts of the visualization. First, use the hardinge access to release the connective tissue adhesions to the hip joint and remove the loose implant. Then, use a wider access to perform the operation in the same way as other revision procedures of the hip joint.Remove all soft tissues from the surface of the acetabulum so that the shape exactly matches the model provided. Ensure that the implant model perfectly adheres to the surface of the acetabular bone. Fix the new, uncemented implant using specially designed screws that stabilize the implant.Perform a femoral nerve block after surgery. Next, load the visualization of the DICOM CT scan prepared in the previous section to the mixed reality application. Connect the mixed reality headset to the mixed reality application to see the prepared visualization in the 3D holographic space.Use intraoperative holographic visualization of the processed images to achieve adequate and precise pelvic bone surface preparation, as well as to remove the excess of connective tissue that developed as a response to loosening of the acetabular component. Ensure that the operator looks at the holographic visualization as a reference image. Use a scalpel, an electrosurgical knife with a coagulator, a lure tool and cutters for the operation.For postoperative care, make the patient undergo a standard rehabilitation and recovery protocol, including rehabilitation and mobilization on the first day after surgery. Using this protocol, an interactive visualization was generated that displayed tissues and potential fixation of the implant in the pre-operative planning process. The blue color in the visualization showed the border of the implant.On the basis of the CT, the position of the screws was planned such that it avoided the contact of the screws with the vascular nerve structures and their damage. Colors were used to distinguish bolts having different parameters, such as length and cross section. Before the surgery, CT 3D reconstruction showed visible degeneration and destruction of bone structures and pelvic asymmetry.X-ray conducted six weeks after the surgery showed that the implant was fitted correctly, confirming the success of the surgery. The mixed reality technology allowed a safe and non-invasive way to accurately visualize the pelvis, bones, and soft tissues, increasing the chances of good implant placement. By manipulating the image, such as by zooming in the selected fragments of the complex anatomical structures, one can exclude the imperfections of the surgeon's eye.The procedure of auto plaster is carried out in accordance with generally accepted standards. Each element of preparation of surgery, including cooperation with engineers, implant preparation, patient preparation, and subsequent step by step surgical procedures are very important. The integration of mixed reality and custom made implants may open a new chapter in orthopedics andrology of the musculoskeletal system.Where appropriate visualization and precision of implant replacement are very important.

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

Abstract