Skeletal Radiology

, Volume 41, Issue 9, pp 1121–1126 | Cite as

The trochlear cleft: the “black line” of the trochlear trough

  • Robert D. WissmanEmail author
  • Jerrell Ingalls
  • Joshua Nepute
  • Nathaniel Von Fischer
  • Rupa Radhakrishnan
  • Daniel Hendry
  • Keith Kenter
Scientific Article



The “cartilage black line sign” is a recently described T2 dark cartilage lesion that we have identified appearing as a cleft in the trochlear trough. The purpose of our study was to define the MR imaging characteristics of a trochlear cleft, determine its incidence, and correlate the MR findings with arthroscopy.

Materials and methods

A total of 1,300 consecutive MR examinations of the knee were retrospectively reviewed by consensus of two fellowship-trained musculoskeletal radiologists. The MR imaging characteristics and location of a trochlear cleft were determined. Imaging results were compared to arthroscopy when available. Patient age and gender were compared to 25 randomly selected control patients without trochlear clefts.


A total of 25 (1.9%) individuals (11 females and 14 males; age range 19–45 years; mean age 28 years) were diagnosed with a trochlear cleft. The control group consisted of 11 females and 14 males; age range 19–83 years; mean age 46 years. Mean cleft length was 7 mm (range 6–12 mm); cleft location was consistently in the lower trochlear trough. No full-thickness cartilage defects were identified in the eight individuals in whom arthroscopic correlation was available. A grade 2 cartilage lesion was identified in a single individual; another progressed from grade 0 to a full-thickness trochlear lesion over an 8-month interval. Eight individuals were athletes. No significant difference in gender was noted between the two groups, however, the study group was significantly younger p < 0.0001.


A trochlear cleft is a rare finding in young active individuals. It most likely indicates an incomplete cartilage fissure which may rarely progress to a full-thickness defect.


Magnetic resonance Knee Cartilage Black line Cleft 


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Copyright information

© ISS 2012

Authors and Affiliations

  • Robert D. Wissman
    • 1
    Email author
  • Jerrell Ingalls
    • 2
  • Joshua Nepute
    • 1
  • Nathaniel Von Fischer
    • 1
  • Rupa Radhakrishnan
    • 1
  • Daniel Hendry
    • 1
  • Keith Kenter
    • 3
  1. 1.Department of RadiologyUniversity of Cincinnati Medical CenterCincinnatiUSA
  2. 2.Desert RadiologistsLas VegasUSA
  3. 3.Department of Orthopaedic SurgeryUniversity of Cincinnati Medical CenterCincinnatiUSA

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