PMC8355958_01
AP and lateral radiographs of the right knee demonstrating a pathologic fracture of the right distal femur. The lesion has characteristics consistent with nonossifying fibroma: lytic, cortically based lesion.
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At the outside emergency department, plain radiographs were obtained which demonstrated a pathologic fracture of the right distal femur (Figure 1).
AP and lateral plain radiographs taken in clinic approximately 1 month postoperatively, demonstrating healing fracture.
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Given the benign appearance of the lesion, the fracture was definitively fixed using a lateral distal femoral locking (Figure 2).
Computed tomography (CT) obtained 9 months status postopen reduction internal fixation of the distal femur showing a healed fracture without any evidence of any intra-articular hardware penetration.
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There were no hardware complications (Figure 3). 16 months postoperatively, he started to notice knee effusions after he had returned to playing football.
CT obtained 16 months postoperatively showing an anterior cortical defect approximately 7 cm proximal to the distal femur.
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CT and MRI were obtained confirming a new hemarthrosis and a healed nonossifying fibroma (NOF) approximately 2.4 cm (width) by 2.1 cm (depth) and by 4.1 cm (length) proximal to the distal femoral. CT demonstrated an anterior cortical defect approximately 7 cm proximal to the distal femur (Figure 4).
Pathology of nonossifying fibroma (magnification x200). The lesion shows spindle cells in a storiform pattern with admixed multinucleated giant cells and hemosiderin-laden macrophages.
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Specimen was collected for both frozen and permanent pathology, which was consistent with NOF (Figure 5).
AP and lateral plain radiographs of the distal femur obtained at the final clinic appointment, 6 weeks postoperatively, following diagnostic arthroscopy, curettage, and bone grafting with completely healed fracture.
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He was last seen in clinic 6 weeks postoperatively, and he continued to do well with no return of symptoms, participating in activities as tolerated, with routine healing of the lesion (Figure 6).
PMC8355958_02
AP and lateral plain radiographs of the right distal femur demonstrate a sessile-appearing lesion on the anterolateral aspect of the distal femur consistent with osteochondroma.
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Case #2 is of a 12-year-old female with an isolated symptomatic distal femoral osteochondroma approximately 10 cm proximal to the distal femur (Figure 7).
Magnetic resonance images (MRI) (machine settings: thickness 5.0 mm, fat-suppressed axial, and short-T1 inversion recovery (STIR) sagittal) demonstrating a distal femoral lesion consistent with likely osteochondroma.
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An MRI was obtained to further evaluate the lesion and make final determinations regarding proceeding with resection (Figure 8).
AP and lateral intraoperative fluoroscopic images showing further resection and smoothing of the distal femoral lesion.
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The bone lesion was resected further, the cortices were smoothed again, and bone wax was applied (Figure 9).
Pathology consistent with osteochondroma with cartilage cap (magnification x40). The sessile lesion shows an intact smooth cartilaginous cap overlying bony trabeculae. The perichondrium that overlies the chondrocytes is continuous with the periosteum. The medullary cavity contains predominantly fat and fibrous tissue with minimal trilineage hematopoiesis. There are focal areas of the reactive bone with new bone formation.
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The bone pathology remained consistent with an osteochondroma (Figure 10).