Measurements of the posterior cruciate ligament (PCL) can help to identify tears in the anterior cruciate ligament (ACL).

Analysis: MRI of the knee in the sagittal plane



(1) distance between the anterior aspects of the two attachments of the PCL (femoral and tibial) in mm in the sagittal plane

(2) perpendicular distance from this line to top of the arc of the PCL in mm


PCL index =

= (distance between attachments) / (height of arc)


Interpretation (Siwinski and Ziemianski):

• Patients with normal ACL have an index of 5.01 +/- 0.76 (4.25 to 5.77).

• Patients with partial rupture of the ACL have an index of 3.09 +/_ 0.23 (2.86 to 3.32)

• Patients with complete rupture of the ACL have an index of 2.88 +/- 0.74 (2.14 to 3.62).

• Deterioration in the index indicates worsening of the tear in the ACL.

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