Wrisberg rip
Wrisberg rips, also known as zip tears or zipper tears, are longitudinal vertical meniscal tears. They occur at the junction of the ligament of Wrisberg and the posterior horn of the lateral meniscus and are commonly associated with anterior cruciate ligament tears 1.
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Pathology
The ligament of Wrisberg is attached to the lateral aspect of the medial femoral condyle and to the posterior horn of the lateral meniscus, coursing posteriorly to the PCL. In case of the ACL tear, anterior tibial translation occurs, resulting in traction of the ligament of Wrisberg against the PCL and tearing a longitudinal fragment of the lateral meniscus, hence the term 'zip tear'.
Location
It occurs at the posterior horn of the lateral meniscus, starting from the posterior root and extending anteriorly.
Radiographic features
MRI
It is visible on fluid-sensitive sequences, best visualized on sagittal and often on axial images, as a cleft extending anteriorly from the posterior root of the lateral meniscus on several consecutive slices.
Practical points
The pitfall in diagnosing this type of tear is that normally there is a cleft at the attachment site of the ligament of Wrisberg to the posterior horn of the lateral meniscus, which can be mistaken for a tear. Due to variability in the ligament attachment site, this cleft can extend variably far, and as a result the discrimination between a true tear and a 'pseudo-tear' may pose a challenge. It has been postulated by some authors that the average attachment site lies approximately 14 mm laterally from the lateral edge of the PCL 1, and that any cleft extending farther is suspicious for a tear.
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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
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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