Injury to the posterior horn of the medial meniscus of the right knee can be accurately determined by magnetic resonance imaging. If the injury is relatively mild, conservative treatment can be chosen by temporarily avoiding strenuous exercise, excessive knee flexion, stairs and hiking activities. You can use medications to activate blood circulation and remove blood stasis, such as Yunnan Baiyao aerosol. You can also apply some creams, such as pain-relieving creams. For non-serious one-time injuries there is a possibility of recovery in 2-3 months. If the medial meniscus of the right knee is a third-degree injury, conservative treatment is generally less effective, and arthroscopic surgery, such as arthroscopic repair and suturing or resection and shaping surgery, can be chosen. Post-operative rest is also needed for more than 2-3 months to avoid premature exertion, weight bearing and excessive knee flexion.