It usually takes 1 to 4 months to recover from a knee injury to the tendon. Knee injury to the tendon, the medical term for patellar ligament injury. Recovery from patellar ligament injury depends on the degree of injury. If the injury is mild and is only a bruise, recovery is usually possible in about one month through braking for one to two weeks and then functional exercises for about two weeks. If the injury is more serious, the patellar ligament rupture, need to perform surgical treatment after the cast for fixation for about 4 weeks, about 8 weeks of damage to the ligament is basically repaired, but can not be weight-bearing activities, it will take about 4 months to fully recover. Knee injury should be timely to the regular hospital, the doctor according to the symptoms, signs and auxiliary examination to determine the specific condition, according to the condition to give the correct treatment, in order to shorten the recovery time.