Lateral knee collapse may be caused by tissue laxity and patellar fracture. 1. Tissue laxity: its causes are mainly seen in age factors, dietary factors, muscle diseases, joint lesions, intracranial lesions and other conditions. When the muscle tissue, ligament, because of the injury and laxity, can appear the phenomenon of lateral collapse of the knee joint. 2. Patella fracture: It is mainly caused by trauma, car accident, etc. Due to muscle pulling, the fracture broken end will be separated and displaced, resulting in lateral collapse of the knee joint. In addition, patients with lateral collapse of the knee joint should go to the regular hospital in time, under the guidance of the doctor for treatment, to avoid delaying the condition. It is recommended that patients eat more fresh vegetables and fruits, high protein food, which is conducive to the recovery of the condition.