Ramp lesions are defined as a vertical (longitudinal) tear of the peripheral capsular attachment of the posterior horn of the medial meniscus at the meniscocapsular junction 1. As it is a minor injury and has a hidden location using standard anterolateral and anteromedial arthroscopic portals, its identification guides the orthopedic surgeon to identify it on arthroscopy by probing the posterior horn of the medial meniscus, which may require an additional portal 3.
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Epidemiology
In ACL-deficient knees, the incidence is reported at ~12.5% (range 9-17%) 3.
Pathology
Ramp lesions most frequently occur in the setting of a pivot shift mechanism of injury (e.g. anterior cruciate ligament (ACL) injuries) 2. It is suggested to be due to disruption of the meniscotibial ligaments, or as a result of a tear of the peripheral attachment of the posterior horn of the medial meniscus 2.
Associations
The presence of ramp lesions is associated with 3,6:
- ACL rupture
- ACL graft failure
- increased risk of developing osteoarthritis
Radiographic features
MRI
Ramp lesions appear as an abnormal signal at the peripheral most portion of the posterior horn of the medial meniscus. These lesions can be difficult to identify if there is little or no posterior meniscocapsular tissue separation.
The most specific sign (although with only moderate diagnostic accuracy) is complete thin linear fluid signal between the posterior horn of the medial meniscus and posteromedial capsule 3,7. Posterior meniscal irregularity has mixed results in regards to significance 3,7. Posteromedial tibial plateau marrow edema may be present as an additional indicator of a ramp lesion 6.
Treatment and prognosis
If unstable, ramp lesions can be repaired arthroscopically 6.
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