PMC9897702_01
Anterior-posterior radiograph of the left knee showing a lateral patellar dislocation
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FIG1
Radiographs demonstrated a laterally displaced left patellar dislocation (Figures 1, 2).
Lateral radiograph of the left knee showing a patellar dislocation
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FIG2
Radiographs demonstrated a laterally displaced left patellar dislocation (Figures 1, 2).
Modified sunrise (patient unable to bend the knee) radiograph of the left knee showing lateral patellar dislocation with medial patellar impaction defect and avulsion fracture of the medial patella
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FIG3
Careful evaluation of the sunrise views demonstrated a medial avulsion fracture of the patella with hinging of the patella on the lateral trochlear ridge via an acute impacted medial patellar defect (Figures 3-5).
Close-up modified sunrise (patient unable to bend the knee) radiograph of the left knee showing lateral patellar dislocation with medial patellar impaction defect and avulsion fracture of the medial patella
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FIG4
Careful evaluation of the sunrise views demonstrated a medial avulsion fracture of the patella with hinging of the patella on the lateral trochlear ridge via an acute impacted medial patellar defect (Figures 3-5).
Comparison sunrise radiograph of the right knee showing laterally subluxated patella without congenital anatomic abnormality that may predispose the injured side to locked dislocation
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FIG5
Careful evaluation of the sunrise views demonstrated a medial avulsion fracture of the patella with hinging of the patella on the lateral trochlear ridge via an acute impacted medial patellar defect (Figures 3-5).
Intra-reduction fluoroscopy sunrise radiograph of the left knee confirmed a successfully reduced patella
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FIG6
Subsequent post-reduction exam under sedation was improved and displayed a ligamentously stable knee that had regained full mobility; although it displayed lateral tilt, it was found to track within the trochlea with knee flexion under sedation and was confirmed on the intra-sedation sunrise view with mini-c-arm fluoroscopy (Figure 6).
Post-reduction axial computed tomography image emphasizing the acute impaction defect of the left medial patella
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FIG7
Subsequent post-reduction treatment included computed tomography (patient or guardian declined acute MRI for soft tissue evaluation, due to ER wait times), which confirmed reduction, the lack of unrecognized fractures or intra-articular osseous bodies, the lack of previously unrecognized soft tissue injury, and better characterized the previously appreciated medial avulsion fracture and impaction defect of the patella (Figure 7).