Orthopedic treatment with radiofrequency energy (RFE) was first used in shoulder surgery, and its effectiveness has been reported. The purpose of RFE treatment of soft tissue is to induce qualitative changes in collagen and obtain stability. Hypermobile lateral meniscus (HLM) is characterized by abnormal mobility resulting from rupture or defects of the popliteomeniscal fasciculi, but no satisfactory treatment has been reported. We followed up patients with HLM who underwent monopolar RFE treatment and confirmed its short-term effects by magnetic resonance imaging and second-look arthroscopy.