Posterior cruciate ligament tear
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Posterior cruciate ligament (PCL) tears are less common than anterior cruciate ligament tears.
Epidemiology
Posterior cruciate ligament tears account for ~10% (range 2-23%) of all knee injuries 2.
Clinical presentation
Many patients will be asymptomatic and their clinical examination is unremarkable. Sports injuries and car accidents are equally responsible for these injuries 1.
Pathology
Three mechanisms of injury have been proposed 2:
- posterior tibial displacement in a flexed knee
- hyperextension
- rotation with an abduction or adduction force
Associations
PCL injuries are isolated in only 30% of cases and are thus commonly associated with other injuries 1,2.4:
- ligamentous injury (~40%)
- meniscal tears
- posterolateral corner injury 5
- bone contusion (80%) or avulsion fracture (<10%)
- knee joint effusion
Radiographic features
MRI
Features of posterior ligament tears include 1,2:
- PCL usually remains contiguous (~70%) although there may be complete or partial ligamentous disruption
- absent PCL replaced by high T1 and T2 signal
- enlarged and swollen PCL: >7 mm AP diameter on sagittal imaging is indicative of a tear
Treatment and prognosis
PCL tears may result in chronic instability and early degenerative change 2.
Differential diagnosis
- mucoid degeneration 3
- meniscofemoral ligaments can mimic a PCL tear
-<a href="/articles/posterior-corner-injury-of-the-knee">posterolateral corner injury</a> <sup>5</sup>- +<a href="/articles/posterolateral-corner-injury-of-the-knee">posterolateral corner injury</a> <sup>5</sup>
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