title: The Notch of Harty (Pseudodefect of the Tibial Plafond): Frequency and Characteristic Findings at MRI of the Ankle.
abstract: OBJECTIVE
  The purpose of this study is to report the frequency and characteristic findings of the notch of Harty as seen on MRI.
  
  
  METHODS
  One hundred six consecutive ankle MRI studies performed at 1.5 or 3 T were reviewed retrospectively by two radiologists. Findings relating to the notch of Harty and ankle joint were recorded and analyzed, including qualitative assessment of the presence of the notch, focal chondral thinning or focal subcortical osteosclerosis at the notch, notch width and depth, osteochondral lesions elsewhere in the ankle, subchondral edema signal or cystic change at the tibial plafond, and the presence of an ankle joint effusion.
  
  
  RESULTS
  The study group of 106 patients consisted of 48 male and 58 female patients, with a mean age of 44.5 years (SD, 17.5 years). The notch was identified in 48 of 106 patients (45%) (24 male and 24 female patients; mean age, 43.1 years; range, 7-79 years). When present, the notch averaged 6.2 mm (SD, 1.6 mm) in width and 1.2 mm (SD, 0.5 mm) in depth. The notch was graded as prominent in six of the 106 ankle MRI examinations (6%). Subchondral edemalike signal or cystic change was not localized to the notch in any case. Between patients with versus those without a notch, there was no statistically significant difference in age, sex, subjacent subcortical osteosclerosis, ankle joint effusion, osteochondral lesions elsewhere in the ankle, or subchondral bone marrow edema at the tibial plafond.
  
  
  CONCLUSIONS
  The notch of Harty can be observed as an anatomic variant on MRI and should be differentiated from a traumatic osteochondral lesion.
authors.affiliation: 1 Department of Radiology, University of California, Davis, 4860 Y St, Ste 3100, Sacramento, CA 95817.
authors.forename: Robert D
authors.initials: RD
authors.lastname: Boutin
authors.affiliation: 2 Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Chang
authors.affiliation: 1 Department of Radiology, University of California, Davis, 4860 Y St, Ste 3100, Sacramento, CA 95817.
authors.forename: Cyrus
authors.initials: C
authors.lastname: Bateni
authors.affiliation: 3 Department of Orthopaedic Surgery, University of California, Davis, Sacramento, CA.
authors.forename: Eric
authors.initials: E
authors.lastname: Giza
authors.affiliation: 4 School of Veterinary Medicine, University of California, Davis, Davis, CA.
authors.forename: Erik R
authors.initials: ER
authors.lastname: Wisner
authors.affiliation: 5 Radiology and Imaging Sciences, Clinical Center, National Institutes of Health, Bethesda, MD.
authors.forename: Lawrence
authors.initials: L
authors.lastname: Yao
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000843:Ankle Joint / Q000033:anatomy & histology* / Q000473:pathology; D002648:Child; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013977:Tibia / Q000033:anatomy & histology* / Q000473:pathology
keywords: MRI; ankle; normal variation; osteochondral lesion