Double PCL sign
The double PCL sign appears on sagittal MRI images of the knee when a bucket-handle meniscal tear (medial meniscus in 80% of cases) flips towards the center of the joint so that it comes to lie anteroinferior to the posterior cruciate ligament (PCL) mimicking a second smaller PCL.
A double PCL sign from a torn medial meniscus can essentially only be seen in patients who have an intact anterior cruciate ligament (ACL) as this is required to prevent the flipped fragment from migrating further laterally, or not aligning parallel to the PCL 1.
In a minority of patients, a lateral meniscus bucket handle tear, in the presence of torn ACL, may also give rise to a double PCL sign.
Identifying a double PCL sign is highly specific (98-100%) but of variable sensitivity (27-53%) for the detection of displaced bucket handle tears 1.
Associated signs include:
- flipped meniscus sign
- fragment-in-notch sign
- absent bow tie sign
- central meniscal fragment
Differential diagnosis
- accessory meniscofemoral ligament (ligament of Humphrey)
- smaller
- closely approximated to the PCL
- normal medial meniscus
- medial oblique meniscomeniscal ligament
- normal medial meniscus
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