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case_images: (A) Radiography of the right leg documenting severe bone-on-bone contact and bone bruising. (B) Lateral radiograph of the right knee documenting hyperextension with a severe anterior slope. (C) Anteroposterior radiograph documenting the extent of limb shortening. (D) Three-dimensional computed tomography (CT) scan documenting the tibial deformity and osteoarthritis.
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case_images: She was diagnosed with Grade 4 OA as per the Kellgren-Lawrence (KL) classification based on the results of radiographic imaging and the physical examination (Figure 1).
case_images: (A) T2-weighted coronal MRI depicting soft tissue at the right knee and indicating isolated osteoarthritis on the lateral side. (B) TKA implant templating process revealed inadequate viable bone stock that would be unable to support an implant.
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case_images: Figure 2), our initial plan was to perform a bicompartmental knee arthroplasty (BKA). Furthermore, as part of the preoperative procedure at our hospital, we conducted a bone density test. Magnetic Resonance Imaging (MRI) was performed to provide maximum visualization of the lesion, given the discrepancies in the anatomical structures and also to evaluate the soft tissue condition (Figure 2). Although a bicompartmental knee implant was templated, the cartilage on the medial side of the joint was found to be intact on the coronal MRI scan, thereby presenting a contraindication to this procedure (Figure 2).
case_images: (A) Perioperative photographs documenting the extent of cartilage damage at the lateral aspect of the right knee. (B) Excised portion of the proximal tibia with dimensions approximately 40 x 30 x 20 mm. (C) Placement of the trial implant with the smallest available polyethylene spacer insert. (D) Final UKA implant with cement and polyethylene insert as shown.
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case_images: Visual inspection of the knee confirmed the diagnosis of isolated lateral OA with intact medial articulation (Figure 3). The cement was molded to fill the gap observed during the trial implantation (Figure 3).
case_images: Perioperative radiographs of the trial implant taken from the anteroposterior direction during (A) extension and from the lateral direction during (B) flexion; note the visible gap between the femoral condyle and implant in the latter image.
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case_images: Perioperative radiographs revealed that, although the trial implant was slightly larger than ideal, synchronous soft tissue balance of the knee was confirmed (Figure 4).
case_images: (A) Anteroposterior and (B) lateral postoperative radiographs of the final UKA implant, documenting correction of the anterior slope. AP radiograph showing that the valgus deformity was resolved postoperation (C).
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case_images: Postoperative imaging and physical examination revealed that the anterior tibial slope was repaired and that the valgus deformity was reduced to 5  from the 14  determined preoperatively (Figure 5).
case_images: Postoperative (A) anteroposterior and (B) lateral tibial plateau lesion diagnosed as an oblique fracture of the proximal tibia. (C) Anteroposterior postoperative radiograph of the distal tibia locking plate indicating adequate fixation. (D) Lateral postoperative radiograph of the distal tibia locking plate indicating adequate fixation.
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case_images: The tibial UKA component was not displaced (Figure 6). Eight locking cortical screws were inserted; postoperative imaging documented adequate fixation and support (Figure 6).
case_images: (A) Anteroposterior and (B) Lateral radiographs at five months postoperatively revealing callus formation at the fracture site, indicative of new bone formation. Shown are images of the right knee under (C) flexion and (D) extension. The range of motion improved, and hyperextension was corrected.
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case_images: At the two-month postoperative checkup, the patient was able to walk with a full weight load without assistance (Figure 7).