The possible reasons for a fall on the knee with no trauma but pain on the inside are: soft tissue injury, bone fracture, knee ligament injury, etc. Treatment can be roughly divided into conservative treatment and surgical treatment. 1. Soft tissue injury: mild soft tissue injury only need to reduce the activity of the affected limb, after a period of time can be relieved by itself. You can use some external bruising drugs such as Yunnan Baiyao aerosol to promote tissue edema absorption and accelerate recovery. If there is a tendon tear and other serious soft tissue injuries should be timely surgical repair. 2. Fracture: Bone contusion or mild non-displaced fracture only need the affected limb braking, more rest can be. If the fracture is more serious but without obvious displacement, it can be immobilized by plaster. If there is a comminuted fracture or the fracture involves the joint surface and other serious cases, surgery should be considered. 3. Knee ligament injury: Knee ligament strain or partial tear can be treated conservatively, using a brace or plaster fixation. If the ligament is completely torn, it should be repaired as soon as possible, and nowadays most of them are repaired or reconstructed under arthroscope. Patients who have fallen on their knees and have no trauma but have pain inside are advised to go to the hospital as soon as possible to improve the relevant examinations such as X-ray film, CT, MRI, etc., to clarify the degree of injury, and choose the appropriate treatment under the guidance of a professional doctor.