Femoral trochlear dysplasia - measurements (MRI)

Case contributed by Dr Prashant Gupta


History of recurrent patellar dislocation

Patient Data

Age: 35 years
Gender: Male

Trochlear dysplasia as described below:

  • ventral trochlear prominence seen in 69% of knees with dysplastic trochlea
  • the distance between anterior femoral cortex and most ventral part of trochlear floor was >6.9 mm in all cases with dysplastic trochlea
  • the trochlea at 3 cm above joint line has a "flattened" appearance
  • average trochlear depth calculated as - (6.08+5.84/2)- 5.68= 2.7m using a cutoff of <3 mm the sensitivity using this cutoff was 100% and a specificity was 96%
  • patellar lateralisation was measured using a cutoff of >6 mm the sensitivity was 75% and  specificity was 83%
  • facet asymmetry is expressed as a percentage of medial to lateral facet ratio - in this case, it was 32%, taking a cutoff of <40% sensitivity was 100% and specificity was 96% 

Case Discussion

The above images represent most of the findings of femoral trochlear dysplasia and how the measurements should be taken.

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Case information

rID: 17683
Published: 4th May 2012
Last edited: 12th Aug 2018
Inclusion in quiz mode: Excluded

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