Patellar instability in children and adolescents is caused by abnormalities of various knee structures. Instability of the patellofemoral joint can manifest as an acute dislocation, recurrent dislocation, habitual dislocation, and congenital dislocation. Patellar instability is associated with abnormalities in the anatomical structures around the knee, and a comprehensive analysis of the cause should be undertaken. Surgery can be performed to reconstruct any abnormal musculo-skeletal alignment. Considerable progress has been made in the treatment of patellar instability in recent years, and surgical methods include lateral release, soft tissue realignment procedure, transfer of the autologous tendon, trochleaplasty, and reconstruction of th...