PMC9045978_01
Patient case 1. (a) AP right knee X-ray at day 1 showing the avulsion fracture of the femoral insertion of the LCL (white arrow). (b) Clinical appearance at 2 weeks showing bruises over lateral aspect of the right knee. (c) Proton density coronal MRI of the right knee at day 3 showing a wavy though intact LCL (small arrows) attached to the avulsed bony fragment of the femoral insertion (large arrow). The iliotibial band (arrowhead) lies immediately superficial to the proximal LCL.
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Magnetic resonance imaging (MRI) revealed an isolated bony fragment of 11 mm (AP) x 4 mm (ML) x 13 mm (PD) in size, which was minimally displaced (3 mm) from its bed (Figure 1).
PMC9045978_02
Patient case 2. (a, b, and c) Proton density coronal and axial MRI of the right knee at day 3 showing a loose though intact ALL (gold arrows).
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This might result of a concomitant avulsion of the ALL with the LCL at their proximal insertion (Figure 2).
Patient case 2. (a) AP right knee X-ray at day 1 showing the avulsion fracture of the femoral insertion of the LCL (white arrow). (b) Lateral view of a 3D reconstruction of the right knee CT at day 1 showing the avulsed bony fragment of the femoral insertion of the LCL (white arrow). The white star shows insertion site of the popliteal tendon. (c) Proton density coronal MRI obtained at day 3 showing an intact LCL (small black arrows) attached to the avulsed bony fragment of the femoral insertion (large white arrow). Note the superior lateral genicular vessels (large black arrow) above the bony fragment.
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There was no associated soft tissue or SLGA lesion (Figure 3).
Comparative varus stress X-rays. (a and b) Patient case 1, at 14 months. Radiographic bone union of the fracture on the right knee (white arrow) as well as symmetrical side-to-side opening of the lateral compartment (white brackets). (c and d) Patient case 2, at 5 months. Radiographic bone union of the fracture on the right knee (white arrow) and 2 mm side-to-side difference between the right knee (white bracket) and the left knee (black bracket).
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Comparative varus stress radiographs at 20  knee flexion were performed at 14 months postinjury, revealing an absence of side-to-side lateral joint space opening differences and radiological evidence of complete fracture healing (Figures 4(a) and 4(b)). Comparative varus stress radiographs at 20  knee flexion revealed lateral tibiofemoral compartment gapping of approximately 2 mm greater than the opposite side (Figures 4(c) and 4(d)).
Patient case 2. Frontal plane CT assessment. (a) At day 1, showing the avulsed bony fragment of the femoral insertion of the LCL (white arrow). (b) At 4.5 months, showing bone union with mild calcification of the femoral attachment of the LCL (white arrow).
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CT-scan at 4.5 months postsurgery (Figure 5). Clinically, the patient presented no instability with varus stress test at 20  of flexion and full active ROM was achieved.