Patients with an ACL tear who have a moderately sedentary lifestyle may not require surgery if they do not have severe cartilage damage or damage to other ligaments, explains Mayo Clinic. These patients may only require rehabilitation that helps improve knee stability with exercises of the muscles around the knee. Continue ReadingA torn ACL cannot be sewn together, and individuals who wish to continue their athletic activities require surgical replacement of the ligament, according to Mayo Clinic. This usually involves using a tendon from another part of the leg or a tendon from a deceased donor. An ACL injury is a tear of the anterior cruciate ligament inside the knee. It commonly occurs during sports that involve frequent changes of direction and sudden stops, such as basketball, tennis, soccer and volleyball, explains Mayo Clinic. Immediately after the injury, patients often experience swelling, instability and the inability to put weight on the affected knee. A torn ACL is diagnosed with X-rays, magnetic resonance imaging, and an ultrasound, according to Mayo Clinic. An X-ray does not show ligaments and tendons inside the knee but is required to rule out bone fractures. An MRI uses a magnetic field and radio waves to visualize the tissues inside the knee. Doctors use the MRI to assess the extent of damage to ligaments and joint cartilage. Learn more about Breaks & Sprains