A contribution to Pisani's sign for diagnosing lateral meniscal cysts: a technical report.

This article describes modified physical examination maneuvers for diagnosing lateral meniscal cysts. The typical presentation of lateral meniscal cysts usually makes their clinical diagnosis simple, but a wide variation in size may sometimes lead to misdiagnosis. We evaluated the effect of leg rotations on the cystic swelling at 45 degrees of knee flexion. Eleven consecutive patients with positive Pisani's sign were evaluated prospectively. Lateral mid-third joint-line swelling was most prominent at 30-45 degrees of knee flexion. With the knee held at 45 degrees of flexion, the prominence was also inspected during internal and external rotation of the leg. The masses became noticeably more prominent with external rotation, and completely disappeared with internal rotation. With external rotation of the leg, even doubtful lateral meniscal cysts became apparent. Disappearance of the cystic mass with internal rotation further confirms the diagnosis.