There are multiple reasons to wear a knee wrap. Many people who exercise will wrap their knees as a means of giving their knees a bit of additional support while they exercise. Some people do it if they have had a partial tear in a ligament and are seeking some external support. Weight lifters will also wrap their knees prior to doing squats to give the joint some additional stability. If you have or think you have sustained an injury, make sure your see your doctor before performing any strenuous activity. Knee wraps are not generally used to treat a severe injury or condition. Knee wraps are used for the prevention of injury or knee issues. They provide a bit more stability and external support to the joint of your knee when it is put under extreme stress.  The only kind of treatments a knee wrap is used for are first degree sprains of the knee. This can only be diagnosed by a healthcare provider. If you sustain any injury, see your orthopedic surgeon. The risk of getting injured again or misdiagnosing can cause serious damage. There are many instances where a wrap is not needed. If you have an anterior cruciate ligament (ACL) tear or any other ligament tear, do not treat it with a knee wrap unless explicitly instructed by your orthopedic surgeon. It would also not be appropriate to simply wrap your knee with a medial or lateral meniscus tear.  If a knee wrap helps an injury and your surgeon sees no problem with using this method while you wait for an upcoming surgical repair, then you can use it. Never use this as a means to stabilize a grossly unstable joint for purposes for recreation. If you feel that, despite wrapping your knee, you have been injured, see your physician right away. Only the doctor can diagnose exactly what is wrong with your knee. The doctor may advise you to wrap your knee injury if it is a grade I injury for purposes of stabilization only. If your wish to start or resume physical activity, seek medical attention first to see if your injury has healed.
Decide if you need to wrap your knee. Use a wrap as a preventative measure. Avoid using knee wraps on serious injuries. See a doctor.