case_images: PMC8100416_01
case_images: A 90-year-old female with a fracture of the distal femur with lateral knee osteoarthritis. (a) AP view, (b) lateral view, and (c) axial view.
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case_images: PMC8100416_01_CRIOR2021-5576955.001.jpg
case_images: fig1
case_images: Plain radiographs of the right knee showed a fracture of distal femur with lateral knee osteoarthritis (Figure 1). Prior to this injury, the patient had been treated at another hospital for lateral knee osteoarthritis (OA) (Krackow classification type I (Figure 1) with conservative treatments such as intra-articular injections, but there were no signs of improvement.
case_images: Two dimensional computed tomography (2DCT) scan demonstrating a fracture line from the trochlea to the femoral groove (AO Foundation/Orthopedic Trauma Association classification: type B2) (white and black arrow). (a) Coronal view, (b) sagittal view, and (c) axial view.
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case_images: PMC8100416_01_CRIOR2021-5576955.002.jpg
case_images: fig2
case_images: Two-dimensional and three-dimensional computed tomography (CT) revealed a fracture line from the trochlea to the intercondylar notch (AO Foundation/Orthopedic Trauma Association classification type B2) (Figure 2).
case_images: The fracture line (white arrow) is fixed using two bury pin threads (4.0 mm) and anatomy of the femoral condyle were mapped by "painting" the surfaces with an optical probe. The surface was coated with an optical probe, but it was reduced and there was no separation of the fracture. (a) Intraoperative photograph and (b) image free registration.
case_images: CRIOR2021-5576955.003.jpg
case_images: PMC8100416_01_CRIOR2021-5576955.003.jpg
case_images: fig3
case_images: Temporary fixation with two bury pin threads (4.0 mm) was initially used to fix the fracture line (Figure 3), and tracker fixation of the tibia was performed from the anteromedial tibia to 6 cm from the incision. The osteophytes on the femur and tibia were resected. Landmark registration and anatomy of the femoral condyle and tibial plateau were mapped by "painting" the surfaces with an optical probe without separation of the fracture site (Figure 3).
case_images: Patient-specific planning. (a) A varus/valgus stress test was performed with a manual max through a full range of motion. (b) The medial gap was enlarged with flexion, and mild lateral contracture was observed. Due to reduction as much medial looseness from extension to flexion and lateral contracture from extension to midflexion, femoral and tibial components were performed in valgus alignment and we fine-tuned the amount of osteotomy. (c) Medial and lateral gaps became constant.
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case_images: PMC8100416_01_CRIOR2021-5576955.004.jpg
case_images: fig4
case_images: Prosthesis size (femoral component: 4, tibial component: 3), alignment (femoral and tibial component valgus aligned), positioning, and volume of bone removal were determined intraoperatively by the surgeon (Figure 4). As a result, soft tissue balance (extension:medial: -0.2 mm, lateral: -0.1 mm; flexion:medial: 0 mm, lateral: 0.1 mm) was identified (Figure 4). No loosening of the medial soft tissue was observed at extension and 90 degrees of knee flexion (Figure 4).
case_images: (a) Intraoperative photograph. (b) Navio screen allowing the surgeon to continually assess the patient anatomy against the plan. The articular cartilage and bone being removed using a hand-held sculptor. Green: approximately 1 mm or more and less than from target surface; white: near the target surface (less than 1 mm); red: below the target surface. (c) After immobilizing the fracture site with a bone grasper before removing the pin tracker, reaming of the femur and insertion of a stem prosthesis were performed.
case_images: CRIOR2021-5576955.005.jpg
case_images: PMC8100416_01_CRIOR2021-5576955.005.jpg
case_images: fig5
case_images: The arthritic cartilage and bone were then methodically removed using the handheld sculptor while holding the medial and lateral condyles of the femur, to prevent the fracture site from separating (Figure 5). After immobilizing the fracture site with a bone grasper before removing the pin tracker, reaming of the femur and insertion of a stem prosthesis were performed (Figure 5).
case_images: Postoperative radiographs showing total knee arthroplasty using the semiconstrained lesion prosthesis (Smith & Nephew). (a) AP view, (b) lateral view, and (c) axial view.
case_images: CRIOR2021-5576955.006.jpg
case_images: PMC8100416_01_CRIOR2021-5576955.006.jpg
case_images: fig6
case_images: However, the semiconstrained lesion prosthesis (Smith & Nephew, Memphis, TN) (femoral component:4 (stem extension; 12 mm x 160 mm); tibial component:3 (stem extension; 12 mm x 100 mm)) was chosen to ensure the stability of the fracture (Figure 6).