Posterior cruciate ligament tears of the knee are uncommon and are often caused by greater violence. Once it occurs, the symptoms of knee playing soft leg, weakness and instability are more obvious and harmful than ACL tear, and it is more important to rebuild it as early as possible. Li Guodong, Department of Orthopedics, Shanghai Tenth People’s Hospital, clinic tip: Specialist clinic hours: Monday afternoon, Thursday morning. Specialized outpatient time: Monday morning, Wednesday all day. Hospital Address: No. 301, Yanchang Middle Road, Shanghai