Presentation
Knee sprain while walking, with transient patellar dislocation (patella undisplaced during initial physical exam). Presents with painful swelling of the joint.
Patient Data
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Thin, crescentic cortical flake adjacent to the lateral femoral condyle anteriorly, well depicted on both views. Thickened suprapatellar soft tissue suggestive of joint effusion. Skyline view (not shown) is undiagnostic due to limited range of motion.
Altogether findings are in line with osteochondral fracture.
The joint was fixated in lightweight cast, and an MRI was requested.
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MRI performed five days later shows an about 20 mm osteochondral defect of the lateral femoral condyle, and a matching thin articular loose body on the border of the lateral recess, best depicted in the coronal plane.
Substantial inhomogeneous joint effusion indicating hemarthrosis.
Laterally subluxated patella, edema at the medial patellofemoral ligament (MPFL) attachment. Inhomogeneously fibrillar MPFL indicating high-grade rupture, resultant soft tissue edema.
Inhomogeneously edematous lateral vastus muscle compartment indicating simultaneous muscle injury.
Some sequences are degraded by motion artifacts, but the exam is altogether diagnostic, no sedation was required.
Case Discussion
Arthroscopic fixation of the detached osteochondral fragment and MPFL repair was performed.