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.
Associations
PCLPosterior cruciate ligament 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
Clinical presentation
Sports injuries and car accidents (dashboard injury) are equally responsible for these injuries 1. Many patients will be asymptomatic and their clinical examination is unremarkable. However, some patients may have knee instability or posterior sag sign.
Pathology
Three mechanisms of injury have been proposed 2:
- posterior tibial displacement in a flexed knee
- hyperextension
- rotation with an abduction or adduction force
Radiographic features
MRI
Features of posterior cruciate 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 of the vertical portion on sagittal imaging is indicative of a tear
- posterior tibial translation of >2-3 mm measured in the mid medial compartment 6,7
Treatment and prognosis
PCLPosterior cruciate ligament tears may result in chronic instability and early degenerative change 2.
Differential diagnosis
- mucoid degeneration 3
- meniscofemoral ligaments can mimic a PCL tear
Practical points
-
PCLposterior cruciate ligament tears can spontaneously heal and commonly demonstrate fibre continuity on MRI, however, these fibres may heal in a non-functional, lax, elongated position, which can result in knee joint degeneration 7,8 - posterior tibial translation on kneeling posterior stress radiographs of >5 mm 9 or >2-3 mm on MRI are signs of chronic
PCLposterior cruciate ligament (PCL) or PCL graft tears 6,7
-<p><strong>Posterior cruciate ligament</strong> (<strong>PCL</strong>) <strong>tears </strong>are less common than <a href="/articles/anterior-cruciate-ligament-tear">anterior cruciate ligament tears</a>. </p><h4>Epidemiology</h4><p><a href="/articles/posterior-cruciate-ligament">Posterior cruciate ligament</a> tears account for ~10% (range 2-23%) of all knee injuries <sup>2</sup>. </p><h5>Associations</h5><p>PCL injuries are isolated in only 30% of cases and are thus commonly associated with other injuries <sup>1,2.4</sup>:</p><ul>- +<p><strong>Posterior cruciate ligament</strong> (<strong>PCL</strong>) <strong>tears </strong>are less common than <a href="/articles/anterior-cruciate-ligament-tear">anterior cruciate ligament tears</a>. </p><h4>Epidemiology</h4><p><a href="/articles/posterior-cruciate-ligament">Posterior cruciate ligament</a> tears account for ~10% (range 2-23%) of all knee injuries <sup>2</sup>. </p><h5>Associations</h5><p>Posterior cruciate ligament injuries are isolated in only 30% of cases and are thus commonly associated with other injuries <sup>1,2.4</sup>:</p><ul>
-</ul><h4>Radiographic features</h4><h5>MRI</h5><p>Features of posterior ligament tears include <sup>1,2</sup>: </p><ul>- +</ul><h4>Radiographic features</h4><h5>MRI</h5><p>Features of posterior cruciate ligament tears include <sup>1,2</sup>: </p><ul>
-</ul><h4>Treatment and prognosis</h4><p>PCL tears may result in chronic instability and early degenerative change <sup>2</sup>. </p><h4>Differential diagnosis</h4><ul>- +</ul><h4>Treatment and prognosis</h4><p>Posterior cruciate ligament tears may result in chronic instability and early degenerative change <sup>2</sup>. </p><h4>Differential diagnosis</h4><ul>
-<li>PCL tears can spontaneously heal and commonly demonstrate fibre continuity on MRI, however, these fibres may heal in a non-functional, lax, elongated position, which can result in knee joint degeneration <sup>7,8</sup>- +<li>posterior cruciate ligament tears can spontaneously heal and commonly demonstrate fibre continuity on MRI, however, these fibres may heal in a non-functional, lax, elongated position, which can result in knee joint degeneration <sup>7,8</sup>
-<li>posterior tibial translation on kneeling posterior stress radiographs of >5 mm <sup>9</sup> or >2-3 mm on MRI are signs of chronic PCL or PCL graft tears <sup>6,7</sup>- +<li>posterior tibial translation on kneeling posterior stress radiographs of >5 mm <sup>9</sup> or >2-3 mm on MRI are signs of chronic posterior cruciate ligament (PCL) or PCL graft tears <sup>6,7</sup>
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