Posterior cruciate ligament tear
Posterior cruciate ligament (PCL) tears are less common than anterior cruciate ligament tears.
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Epidemiology
Posterior cruciate ligament tears account for ~10% (range 2-23%) of all knee injuries 2.
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
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 of the vertical portion 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
Related Radiopaedia articles
Knee pathology
The knee is a complex synovial joint that can be affected by a range of pathologies:
- bone and cartilage
-
knee fractures
- distal femoral condyle fracture
- tibial plateau fracture (classification)
- patella fracture
-
avulsion fractures of the knee
- arcuate complex avulsion fracture (arcuate sign)
- anterior cruciate ligament avulsion fracture
- biceps femoris avulsion fracture
- iliotibial band avulsion fracture
- patella fracture
- posterior cruciate ligament avulsion fracture
- reverse Segond fracture
- Segond fracture
- semimembranosus tendon avulsion fracture
- Stieda fracturechronic avulsion injuries
- dislocation
- chondromalacia patellae
- osteoarthritis of the knee
- osteochondral defects
- osteochondritis dissecans of the knee
- patterns of bone bruise in knee injury
-
knee fractures
- ligaments
- anterior cruciate ligament tear
- anterior cruciate ligament ganglion cyst
- anterior cruciate ligament mucoid degeneration
- posterior cruciate ligament tear
- medial collateral ligament tear
- lateral collateral ligament tear
- medial patellofemoral ligament tear
- posterolateral corner injury
- posteromedial corner injury
- tendons
- meniscal lesions
- bursosynovial lesions
- fat pad
- popliteal fossa
- fascia
- alignment
- knee
- patellofemoral
- gamut