In the previous issue, we will continue to talk about the rehabilitation after ACL reconstruction: 5. What is the time sequence for adjusting the angle of the knee external fixation brace? How long should I wear the brace? Do I need to wear it during sleep? Currently, no brace can simulate the physiological flexion of the knee joint in the true sense, so from the biomechanical point of view, adjusting the brace at a certain angle has a certain effect on the stability of the reconstructed ligament (we are writing an article on how to do this, so I won’t talk about it here), so since 2008, we have asked patients not to adjust the angle of the brace and to wear it at 0° for three months (at present, the rehabilitation plan elsewhere is still to adjust it at different times after surgery). This has reduced the incidence of too much postoperative loosening. The brace must be worn for three months because the reconstructed ligament is fixed in the early stages only by the pulling of the fixation device (squeeze screws and clips, etc.), and in this case the knee is always moving in flexion over 30°, which can loosen or break the newly fixed ligament, just like a wire (reconstructed ligament) is pulled out of the wall (bone), and if the wire is always pulled and shaken, the wall will break and the wire will break. And also to wear when sleeping, because after falling asleep legs are generally in a state of flexion, slowly will affect the straightening of the leg. When the active and passive leg flexion to take off the brace, when walking must be put on the brace (can be appropriate tighter), awake in the sitting can be appropriate to send some brace. Some people always hate to wear this brace at the beginning, but slowly they get used to it and dare not take it off, for fear that their legs cannot support them and fall down. 6.How can my lower limbs be weak after taking off the brace and is it normal to walk with weak legs? Is it useful to wear a knee brace? When is the best time to wear it? The muscles of the affected limb started to atrophy after the surgery (in fact, the good side will also atrophy, but the degree is not as obvious as the affected side), although some straight leg raises or ankle pump exercises were done after the surgery, but it is a drop in the bucket compared to the rate of atrophy. In addition, when the brace was taken off, the muscles had atrophied to varying degrees, which made the lower limbs feel weak and limp when walking. There is another reason for the weakness, and that is coordination. Human beings in the evolutionary process, in order to survive and adapt to different internal and external environments, has formed a different collaboration system of the body dominated by the nervous system, such as who you want to kick, do not need to direct each muscle and bone of the thigh once, but send a kicker’s command, a foot has flown out, but this action has countless parts involved, these parts form a tacit understanding constitutes the coordination of the body. When a part of the parts is injured, this coordination is broken, and other nearby parts try to compensate for it, however, there will be a negative impact on the completion of this action. So the reconstruction of the ligaments, atrophy of the muscles, in the completion of the action of walking will produce hitting soft legs. Do not worry about these situations will slowly come back to practice. It is dangerous to wear a knee brace all the time in order to increase the security of the movement, because during the rehabilitation process, the muscle strength is built back through the participation of the muscle in different movements, and the atrophied muscle can only “grow” through the continuous participation in the movement. If there is something (knee brace) that can replace him in the sport, or if the muscle participates in the sport under his protection, it affects the recovery of the muscle and the establishment of its own proprioception and its own coordination. Once the knee brace is removed, the established coordination is not coordinated, which is detrimental to normal motor recovery. It is best to wear a knee brace after the affected limb has basically recovered and you are itching to start a game, and then take the knee brace off immediately after the game is over, so that the knee joint is still protected.