ACL tear and its managment
This injury is a total disruption of the most important stabilizing ligament in the knee: the anterior cruciate ligament (ACL). The ACL is located centrally within the knee behind the kneecap, making it difficult to specifically localize the injury. The most common mechanism of injury is a knee hyperextension with a twist. This may occur while the knee is momentarily unprotected by the surrounding musculature, especially the hamstrings (muscles in the back of the thigh). The injury typically occurs during cutting and twisting sports such as skiing, basketball, or soccer, and may occur with surprisingly low force.
An x-ray can rule out any fractures. The physical exam is most helpful in determining knee instability, but your physician may wish to order an MRI to evaluate the ACL. MRI scans are a good diagnostic tool for a ruptured ACL.
Typical symptoms may include the dreaded “pop” at the time of initial injury, followed by instability and swelling which appear within the first 24 hours. Pain may be minimal initially if the ACL alone is damaged. Athletes who attempt to return to action may experience a second episode of instability, or a sensation that their knee “pivoted.”
ACL injuries may be prevented by maintaining consistent lower extremity strength. Hamstrings in particular should be focused on to offset the naturally more powerful quadriceps. When possible avoid knee positions that expose the ACL to injury. A slight bent knee position is preferable to a fully extended knee.
Surgery should be performed once full range of motion is obtained; Arthroscopic ACL reconstruction is usually undertaken in young, active patients because the ACL will not heal unless surgically restored. With each episode of instability, more cartilage damage may occur; ligaments can be repaired quite well, but native cartilage cannot be replaced. A brace will also not guarantee prevention of further knee “pivot” injuries. The ACL must be reconstructed with a biological graft that can heal fully by regaining full blood supply. Graft options include: A) Autograft tissue from a patellar tendon graft or a hamstring graft; B) Allograft tissue from the patellar tendon, hamstring, or achilles tendon.
Surgery may not be recommended for older, less active patients who do not participate in cutting and twisting sports. An ACL is typically not needed for easy hiking, walking, swimming, or cycling. In this case, bracing of the knee may be selected as optimal treatment, as long as instability is not present. This patient group should also avoid aggressive sports in the future.
Recovery from Surgery
Once surgery is performed, your surgeon may have you non-weightbearing for a time and in a brace. CPM’s or continuous passive motion devices may sometimes be used. The first week after surgery typically involves ice and elevation. Try to limit how much time you get up when possible.
Physical therapy is generally started about a week after surgery and initially focuses on range of motion. Later phases concentrate on strength and proprioception. Agility drills may be used in preparation for return to sport. This may take from four to six months depending on your doctors protocol. Your doctor may suggest the use of a sports brace for a period of time as you transition to full activity.
Outcomes of Surgery
ACL surgery is very successful at stabilizing the knee. Meniscal damage or chondral injuries (injury to the surface cartilage that lines the bones), may have some long term consequences on what activity you should or shouldn’t pursue. You and your doctor can make that decision together.