Purpose: To evaluate for development of Pellegrini-Stieda (PS)-type ossification following injury to the posterior attachment of the medial patellofemoral ligament (MPFL).
Materials and methods: This retrospective study evaluated 27 patients with acute knee injury with initial radiographs, magnetic resonance imaging within 1 week of injury, and follow-up radiographs assessing for development of PS.
Results: Of the 27 patients who developed PS ossification, 7 patients (25.9%) had isolated MPFL injury with the ossification slightly more proximal than the traditional PS.
Conclusion: Isolated injury to the posterior MPFL also leads to PS ossification, which is slightly superior in location to the traditional PS.
Keywords: Chronic patellar instability; MRI; Pellegrini–Stieda ossification; Posterior attachment of the medial patellofemoral ligament.
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