title: Pellegrini-Stieda ossification can also involve the posterior attachment of the MPFL.
abstract: OBJECTIVE
  To evaluate for development of Pellegrini-Stieda (PS)-type ossification following injury to the posterior attachment of the medial patellofemoral ligament (MPFL).
  
  
  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.
  
  
  CONCLUSIONS
  Isolated injury to the posterior MPFL also leads to PS ossification, which is slightly superior in location to the traditional PS.
authors.affiliation: The University of Colorado, Department of Diagnostic Radiology, 12631 E 17th Avenue, Mail Stop 8200, AO1 Room 2419, Aurora, CO 80045. Electronic address: tatum.mcarthur@ucdenver.edu.
authors.forename: Tatum A
authors.initials: TA
authors.lastname: McArthur
authors.affiliation: The University of Alabama at Birmingham, Department of Diagnostic Radiology, 619 19th Street South, JTN 304, Birmingham, AL 35249-6830. Electronic address: mpitt@uabmc.edu.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Pitt
authors.affiliation: The University of Alabama at Birmingham, Department of Orthopaedic Surgery, Sports Medicine, 1600 7th Avenue South, Suite 402, Birmingham, AL 35233. Electronic address: wgarthjr@uabmc.edu.
authors.forename: William P
authors.initials: WP
authors.lastname: Garth
authors.affiliation: The University of Alabama at Birmingham, Department of Diagnostic Radiology, 619 19th Street South, JTN 329, Birmingham, AL 35249-6830. Electronic address: cnarducci@uabmc.edu.
authors.forename: Carl A
authors.initials: CA
authors.lastname: Narducci
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007718:Knee Injuries / Q000150:complications* / Q000000981:diagnostic imaging; D008023:Ligaments, Articular / Q000000981:diagnostic imaging / Q000293:injuries*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009999:Ossification, Heterotopic / Q000000981:diagnostic imaging / Q000209:etiology*; D057071:Patellofemoral Joint / Q000000981:diagnostic imaging / Q000293:injuries*; D011859:Radiography; D012189:Retrospective Studies; D012307:Risk Factors
keywords: Chronic patellar instability; MRI; Pellegrini–Stieda ossification; Posterior attachment of the medial patellofemoral ligament