PMC4660012_01
A 13-year-3-month-old female with FOPE zones at both proximal tibiae. Findings: AP radiograph of the bilateral knees at time of initial presentation shows a subtle lytic lesion abutting the articular surface of the right medial femoral condyle (arrow). The radiographs were initially interpreted as normal. Technique: AP radiograph kVp = 77, mAs = 4.
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fig1
Initial radiographs of the right knee (Figure 1) were interpreted as normal.
A 13-year-3-month-old female with FOPE zones at both proximal tibiae. Findings: coronal proton density fat-saturated image from right knee MRI obtained 9 months after initial presentation shows an osteochondral lesion (arrow) with mild surrounding marrow edema (asterisk) of the medial femoral condyle corresponding to subtle lytic lesion present on initial radiographs. Technique: coronal PD fat-saturated MRI (TR = 2,825.7, TE = 30), ST = 2.5 mm, spacing = 3.264 mm, FOV = 14 cm, and matrix = 312 x 244.
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fig2
A 1.6 x 1.4 cm osteochondral lesion of the medial femoral condyle was identified on MRI with mild marrow edema and cystic change at the interface between the osteochondral lesion and femoral condyle (Figure 2).
A 13-year-3-month-old female with FOPE zones at both proximal tibiae. Findings: coronal proton density fat-saturated image from follow-up of right knee MRI obtained 6 months after initial MRI shows decrease in the marrow edema surrounding the osteochondral lesion of the medial femoral condyle. The osteochondral lesion (arrow) is otherwise unchanged in appearance. Technique: coronal PD fat-saturated MRI (TR = 2,472.4, TE = 30), ST = 2.5 mm, spacing = 3.3 mm, FOV = 14 cm, and matrix = 312 x 244.
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fig3
The osteochondral lesion of the right medial femoral condyle was unchanged in appearance between the two MRI exams (Figure 3).
A 13-year-3-month-old female with FOPE zones at both proximal tibiae. Findings: (a) sagittal proton density fat-saturated image on the 6-month follow-up MRI of the right knee shows interval development of 9 mm in diameter area of periphyseal edema on both the epiphyseal and metaphyseal sides of the proximal tibia physis (arrow). The proximal tibia physis is narrowed but remains open. (b) Axial proton density fat-saturated image at the level of the proximal tibia physis shows the periphyseal edema located at the anterolateral aspect of the central physis (asterisk). Technique: (a) sagittal PD fat-saturated MRI (TR = 2,958.3, TE = 30), ST = 3 mm, spacing = 3.3 mm, FOV = 14 cm, and matrix = 364 x 261; (b) axial PD fat-saturated MRI (TR = 2,843.3, TE = 30), ST = 3 mm, spacing = 3.3 mm, FOV = 15 cm, and matrix = 376 x 297.
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fig4
However, in the interim, a 9 mm focal periphyseal edema (FOPE) zone developed in the anterolateral aspect of the central proximal right tibia (Figure 4).
A 13-year-3-month-old female with FOPE zones at both proximal tibiae. Findings: (a) sagittal proton density fat-saturated image of the left knee shows 13 mm in diameter area of periphyseal edema at the metaphyseal side of the proximal tibia physis (arrow). The proximal tibia physis is narrowed but remains open. (b) Coronal proton density fat-saturated image shows the periphyseal edema to be on both sides of the proximal tibia physis. The coronal image better demonstrates the periphyseal edema involvement of both the epiphyseal and metaphyseal sides of the physis (arrow). Technique: (a) sagittal PD fat-saturated MRI (TR = 2,959.1, TE = 30), ST = 3 mm, spacing = 3.3 mm, FOV = 14 cm, and matrix = 364 x 261; (b) coronal PD fat-saturated MRI (TR = 2,504.2, TE = 30), ST = 2.5 mm, spacing = 3.3 mm, FOV = 15 cm, and matrix = 312 x 244.
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fig5
A similar appearing 13 mm FOPE zone was present in the anterior aspect of the central proximal left tibia on the left knee MRI (Figures 5 and 6).
A 13-year-3-month-old female with FOPE zones at both proximal tibiae. Findings: axial proton density fat-saturated image at the level of the proximal tibia physis shows the periphyseal edema located at the anterocentral aspect of the central physis (asterisks). Technique: axial PD fat-saturated MRI (TR = 2,843.2, TE = 30), ST = 3 mm, spacing = 3.3 mm, FOV = 15 cm, and matrix = 376 x 297.
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fig6
A similar appearing 13 mm FOPE zone was present in the anterior aspect of the central proximal left tibia on the left knee MRI (Figures 5 and 6).
PMC4660012_02
A 14-year-2-month-old female with FOPE zone of the proximal tibia. Findings: AP radiograph of both knees shows bilateral symmetric partial closure of the central portion of the proximal tibial physis (ovals). Technique: AP radiograph kVp = 70, mAs = 7.
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fig7
There was no abnormality on presenting knee radiographs, which showed bilateral symmetric partial closure of the central portion of the proximal tibial physis (Figure 7).
A 14-year-2-month-old female with FOPE zone of the proximal tibia. Findings: (a) sagittal proton density image shows 14 mm in diameter area of periphyseal edema involving both sides of the proximal tibia physis (arrow). Edema is greater along the epiphyseal side of the physis. (b) Axial proton density image at the level of the proximal tibia physis shows the area of periphyseal edema within the anteromedial aspect of the central proximal tibia (asterisk). Technique: (a) sagittal PD fat-saturated MRI (TR = 2,922.8, TE = 30), ST = 3 mm, spacing = 3.3 mm, FOV = 14 cm, and matrix = 364 x 261; (b) axial PD fat-saturated MRI (TR = 2,803.1, TE = 30), ST = 3 mm, spacing = 3.3 mm, FOV = 15 cm, matrix = 376 x 297.
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fig8
A 14 mm FOPE zone was present in the anteromedial aspect of the central proximal tibia physis on MRI (Figure 8).
A 14-year-2-month-old female with FOPE zone of the proximal tibia. Findings: Sagittal T1 weighted image shows partial closure of the proximal tibia physis centrally (red arrow) with the physis still open along the periphery of the tibia (yellow arrows). The distal femur physis is narrowed but still open by comparison. Low T1 signal intensity corresponding to the periphyseal edema is again seen spanning the proximal tibia physis. Technique: sagittal T1 MRI (TR = 621.991, TE = 15), ST = 3 mm, spacing = 3.3 mm, FOV = 14 cm, and matrix = 340 x 277.
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fig9
The proximal tibia physis was partially closed centrally on the knee MRI (Figure 9).
PMC4660012_03
A 13-year-10-month-old female with FOPE zone of the distal right femur. Findings: presenting radiographs of the knees were normal. There is partial closure centrally of the bilateral proximal tibia physes. The bilateral distal femur physes are narrowed but remain open. Technique: AP radiograph kVp = 70, mAs = 8.
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fig10
Presenting radiographs of the right knee were normal (Figure 10).
A 13-year-10-month-old female with FOPE zone of the distal right femur. Findings: (a) sagittal proton density fat-saturated image shows pivot-shift pattern of bone marrow edema at the weight-bearing aspect of the lateral femoral condyle and posterior aspect of the lateral tibial plateau (asterisks). (b) Coronal proton density fat-saturated image shows increased signal in the lateral meniscus posterior horn root ligament (arrow) consistent with tearing of the ligament. Tear of the root ligament was confirmed on arthroscopy. Technique: (a) sagittal PD fat-saturated MRI (TR = 2,557, TE = 30), ST = 3 mm, spacing = 3.3 mm, FOV = 14 cm, and matrix = 364 x 261; (b) coronal PD fat-saturated MRI (TR = 2,826.1, TE = 30), ST = 2.5 mm, spacing = 3.3 mm, FOV = 15 cm, and matrix = 312 x 244.
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fig11
MRI of the right knee showed pivot-shift bone marrow contusion pattern in the lateral compartment and root ligament avulsion of the lateral meniscus posterior horn (Figure 11).
A 13-year-10-month-old female with FOPE zone of the distal right femur. Findings: (a) coronal proton density fat-saturated image shows a 5 mm area of periphyseal edema slightly eccentrically located on both sides of the distal femur physis (arrow). The edema is slightly more prominent on the epiphyseal side of the physis. (b) Sagittal proton density fat-saturated image again shows the eccentrically located area of periphyseal edema in the distal femur physis (arrow) with the edema again slightly more prominent on the epiphyseal side. The distal femur physis is narrowed but remains open. Technique: (a) coronal PD fat-saturated MRI (TR = 2,826.1, TE = 30), ST = 2.5 mm, spacing = 3.3 mm, FOV = 15 cm, and matrix = 312 x 244; (b) coronal PD fat-saturated MRI (TR = 2,826.1, TE = 30), ST = 2.5 mm, spacing = 3.3 mm, FOV = 15 cm, and matrix = 312 x 244.
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fig12
A 5 mm FOPE zone was also present in the central portion of the distal femur physis (Figure 12).