Insall-Salvati ratio - normal patella

Case contributed by A.Prof Frank Gaillard
Modality: MRI

Sagittal images demonstrating how to measure the Insall-Salvati ratio. 

Case Discussion

patella baja ( or patella infera) is an abnormally low lying patella, which is associated with restricted range of motion, crepitations and retropatellar pain. 

The traditional number used to TL:PL is < 1.2 (between 0.8 and 1.2), although more recent literature 2 suggests that the true range of normal is more forgiving - up to 0.74 to 1.50.

Patellar length (PL) is the greatest pole - pole lenghth

Patellar tendon length (TL) is defined as the length of the post surface of the tendon from the lower pole of patella to its insertion on the tibia.

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Case Information

rID: 7159
Case created: 10th Sep 2009
Last edited: 5th Dec 2015
Tag: knee
Inclusion in quiz mode: Excluded

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