PMC9053587_01
Pre-operative imaging data. (A) Anterior film of bilateral knee joints. (B) Lateral film of the right knee joint. (C) Full-length film of both lower limbs in heavy position. (D) CT 3D reconstruction of both lower extremities and pelvis.
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F1
Plain X-ray and computed tomography (CT) scans showing bilateral knee osteoarthritis with varus deformity, especially on the right side (Figure 1), right hip, knee, and ankle (HKA) angle, 4 degrees, medial proximal tibial angle (MPTA), 84.8 degrees.
(A) The pelvis and both lower limbs pre-operative three-dimensional digital model, the red part is the pelvis, the gray part is the bilateral femur, the light blue part is the bilateral tibia and fibula. (B) The distal femur and tibia osteotomy planes are displayed. The brown part is the distal femur osteotomy plane, and the red part is the tibial osteotomy plane. (C) The osteotomy plane and thickness of the distal femur (cyan part). The thickness of medial femoral osteotomy was 10 mm, and the thickness of lateral femoral osteotomy was 8.3 mm. (D) The tibial osteotomy plane and osteotomy thickness (pink part). The thickness of medial tibial osteotomy was 3.8 mm, and that of the lateral tibia was 7.2 mm. (E) The 3D printing models of the distal femur and the proximal tibia and fibula were printed before the operation. (F) After the completion of the osteotomy, the full length of the right lower limb was viewed on the anterior and medial side.
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F2
Three-dimensional virtual images before operation show severe articular cartilage wear and severe fixed flexion deformity of the right knee joint (Figure 2A), and this will make osteotomy lose important anatomical landmarks and seriously affect the accuracy of the osteotomy, especially for beginners. Different colors are used to distinguish different anatomical structures; thus, obtaining a "three-dimensional digital model of the knee joint" (Figure 2A). Using the digital model, the patient's disease characteristics are analyzed, and the operation plan is made, including the angle and direction of the distal femoral osteotomy plane (Figures 2B,C), the determination of the osteotomy plane of the tibia, and the location and size of the prosthesis (Figure 2D). The digital model is printed into a solid model by using 3D printing technology (Figure 2E), as the reference instrument during the operation. The digital 3D data of the anatomy of the surgical area and the reference landmarks designed before the operation are input and opened using the helmet display HoloLens 2 (Microsoft Corporation, Redmond, W A, USA) (Figure 2F), through a personal computer (Lenovo Group, Beijing, China), and a pre-designed special automatic matching system the MiDIVI intelligent cloud platform (Jinse Medical Information Technology Co., Ltd., Changzhou, China), and the whole operation process is completely simulated to have an accurate grasp of the surgical process.
The surgical procedure and intraoperative findings: (a) installing a registration reference instrument on the distal femur under the guidance of the engineer. (B) The three-dimensional virtual proximal femur structure is coincident with the patient's real femur. (C,D) Under the guidance of the virtual osteotomy surface, the osteotomy of the distal femur is completed. (E) The three-dimensional virtual proximal tibia structure is coincident with the patient's real tibia. (F,G) Under the guidance of the virtual osteotomy surface, the tibia osteotomy is completed. (H) Osteotomy is complete. (I) The prosthesis has been installed.
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Under the guidance of the engineer, the reference instrument for registration (Figure 3A) is installed on the side of the femur, and then, after wearing HoloLens 2, the operator opens the automatic registration software MiDIVI intelligent cloud platform for registration to coincident the three-dimensional virtual femur with the patient's real femur (Figure 3B). According to the position and direction of the osteotomy designed before the operation, the osteotomy positioning plate (Figure 3C) is installed, and the osteotomy is performed under guidance (Figure 3D). After the completion of the femoral osteotomy, the registration reference instrument is installed on the tibial side, and the three-dimensional virtual tibia is coincident with the real tibia (Figure 3E). Similarly, according to the position and direction of the osteotomy designed before the operation, the tibial osteotomy positioning plate (Figure 3F) is installed, and the osteotomy is performed under guidance (Figure 3G). The operative field is washed repeatedly with normal saline (Figure 3H). The tibial plateau prosthesis No. 2 is placed with bone cement (PS, Attune, DePuy Synthes, USA), followed by femoral prosthesis No. 4 until the bone cement hardened, and then 6 mm polyethylene gasket (Figure 3I) is placed.
(A) In the anterior view and medial view of the post-operative three-dimensional digital model, the yellow part is the prosthesis. X-ray film on the second day after operation: (B) Anterior film, (C) Lateral film, (D) Full-length anterior position of both lower limbs. Three months after operation: (E) Anterior film, (F) Lateral film, (G) Full-length anterior position of both lower limbs.
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The post-operative CT data on the second day after the operation are imported into the computer and reconstructed using Mimics19.0 software to obtain the "post-operative three-dimensional digital model" (Figure 4A), and compared with the pre-operative operation plan. The X-ray film on the second day after operation shows that the position of the prosthesis is satisfactory, and the force line is good (Figures 4B-D). The X-ray film 3 months after operation showed that the position of the prosthesis and the force line also was good (Figures 4E-G).