Patellar ligament rupture is a relatively serious injury to the knee, and recovery is relatively slow, as follows: 1, most patellar ligament ruptures require surgery to repair the ligament, or even tendon transplantation to restore the integrity of the patellar ligament; 2, after surgery or in the treatment must do functional exercise of the thigh muscles, because the thigh muscles will atrophy more after patellar ligament rupture, so in the early in the brace After restoring the continuity of the patellar ligament, we must also restore the mobility of the knee joint and carry out functional rehabilitation exercises for knee flexion and extension. After the patellar ligament rupture, and even for a period of time after the rupture, there is a process of upward and downward movement of the patellar track during the recovery process of the knee extension device and finally to the normal position again, and this process is relatively long, so many patients will have a delay in knee extension. In the process of knee extension, the knee joint cannot be fully straightened, or cannot be fully straightened actively, but can be straightened passively. The knee extension delay will gradually disappear after the continuity of the patellar ligament is restored, about six months to a year, or even a year and a half later.