title: Posttraumatic fat necrosis presenting as prepatellar loose bodies in an adolescent football player.
abstract: A 16-year-old high school football player presented with 4 months of anterior knee pain and small, mobile, prepatellar "lumps" after falling onto an opponent's cleat. He reported knee pain primarily during knee flexion and direct pressure during squatting and kneeling. Knee radiographs were unremarkable. Ultrasonography revealed multiple, freely mobile, subcutaneous nodules of variable size and echogenicity in the prepatellar region. Analysis of magnetic resonance imaging suggested possible fat necrosis but was nondiagnostic. The patient opted for surgical exploration, at which time multiple, opalescent subcutaneous nodules were removed. Pathology was consistent with encapsulated fat necrosis. After surgery, his symptoms resolved, and he returned to sports without restrictions.
authors.affiliation: Department of Physical Medicine and Rehabilitation, Mayo Clinic College of Medicine, Rochester, MN(∗).
authors.forename: Joshua S
authors.initials: JS
authors.lastname: Sole
authors.affiliation: Physical Medicine and Rehabilitation, Mayo Clinic College of Medicine, Mayo Clinic Sports Medicine Center, Rochester, MN(†).
authors.forename: Steve J
authors.initials: SJ
authors.lastname: Wisniewski
authors.affiliation: Orthopedics, Mayo Clinic College of Medicine, Mayo Clinic Sports Medicine Center, Rochester, MN(‡).
authors.forename: Diane L
authors.initials: DL
authors.lastname: Dahm
authors.affiliation: Radiology, Mayo Clinic College of Medicine, Rochester, MN(§).
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Bond
authors.affiliation: Department of Physical Medicine and Rehabilitation, Mayo Clinic, W14 Mayo Building, 200 1st Street SW, Rochester, MN 55905; Department of Radiology, and Department of Anatomy, Mayo Clinic College of Medicine, Mayo Clinic Sports Medicine Center, Rochester, MN(‖). Electronic address: smith.jay@mayo.edu.
authors.forename: Jay
authors.initials: J
authors.lastname: Smith
mesh_terms: D000293:Adolescent; D003937:Diagnosis, Differential; D005218:Fat Necrosis / Q000175:diagnosis* / Q000209:etiology; D005538:Football / Q000293:injuries*; D006801:Humans; D007718:Knee Injuries / Q000150:complications* / Q000175:diagnosis; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D014463:Ultrasonography