Knee Arthroscopy: The "Crevice Sign," a New Pathognomonic Sign for Unstable Posterior Medial Meniscal Tear in Anterior Cruciate Ligament-Deficient Knees

Abstract

There has been increased emphasis on medial meniscus repair in the anterior cruciate ligament-reconstructed knee, as this improves stability. We describe an arthroscopic sign of an unstable medial meniscal tear that is diagnostic. The "crevice sign" is a longitudinal fissure located on the distal medial femoral condyle. In the anterior cruciate ligament-deficient knee, there is increased strain on the medial meniscus. A posterior longitudinal medial meniscal tear can occur at the time of the index injury or with subsequent instability events. During this injury, the knee pivots and the anterior edge of the unstable medial meniscus digs into the articular cartilage of the medial femoral condyle, resulting in a longitudinal split of the distal femoral condyle articular cartilage. If this sign is observed during arthroscopy, it is recommended that surgeons thoroughly probe the medial meniscus to ensure no pathology is missed.

Fig 1

Scope view right knee (medial compartment). Visualization of the “crevice sign” (arrow): 1 or 2 longitudinal fissures of the distal medial femoral condyle. The meniscal tear can be displaced to the crevice proving the meniscal involvement in the cartilage split.

Fig 2

Scope view right knee (medial compartment). The arrow shows the longitudinal cartilage split (“crevice sign”) on the medial femoral condyle.