1)   Mechanics of ACL tears.

The ACL is usually torn as a result of a quick deceleration, hyperextension or rotational injury that usually does not involve contact with another individual. This injury often occurs following a sudden change of direction. A person typically reports feeling a popping sensation in the knee. When hit from the side , injuries to the ACL are often associated with medial meniscus and medial collateral ligament (MCL) tears, collectively known as the “unhappy triad”.

2)   Symptoms of ACL tears.

Pain in the knee, instability of the knee, swelling, stiffness, bruising and pain on standing.

3)   Types of injuries to the ACL.  

An anterior cruciate ligament injury often is called a sprain. A sprain occurs when the threads or fibers of the ligament  stretch or are torn. An ACL injury is classified as a grade I, II, or III sprain.

• Grade I Sprain.  Ligament is stretched but there is no tear of the fibers. Patient is  in pain, there is some tenderness and swelling but the knee does not feel unstable or gives out during activity.

• Grade II Sprain. Here the fibers of the ligament are partially torn. Patient is in pain, there is some tenderness and moderate swelling. The joint may feel unstable or give out during activity.

• Grade III Sprain. Here the fibers of the ligaments are completely torn in two parts. There is tenderness (but not a lot of pain, especially when compared to the seriousness of the injury). There may be a little swelling or a lot of swelling. The ligament cannot control the knee movements. The knee feels unstable or gives out at certain times. We can sub-classify these tears in two types:

                a)    Complete retracted tears.-  In these tears the ligament has snapped back like a rubber band. While complete retracted tears are likely to require surgery, we need to be sure your tear is retracted before we decide how to treat it. 

                b) Complete non-retracted tear.- In these there is still something holding the ends of the ligament together because it has not snapped back.

 4) ACL injury treatments options.

It is important first to rest the knee and waiting for the swelling to subside. Pain medications and crutches and an ACL knee brace may be indicated.  Wearing an ACL brace can help prevent more injury to the Anterior Cruciate Ligament and help support your knee after an ACL tear or injury.

Additionally treatment includes exercises, surgery or autologus  cell therapy procedures. This last  modality can be utilized in certain types of ACL injuries. Not all ACL injuries require surgery.

• Exercises.  You should start slowly and gradually increase the

intensity of the exercises. Do not push yourself to the point that you feel pain. Talk to your doctor about how to best progress. It may include exercises such as bridging, glute seats, hamstring curls, heal raises, heal slides, quad sets, Shallow standing knee bends, straight leg raise to the front, straight leg raise to the outside.

• Surgery. Most surgery for anterior cruciate ligament (ACL) injuries

involves replacing the ACL with tissue called a graft. Usually an autograft (tendon tissue taken from another part of the body) is used. With this type of graft you get better results than with allograft. Most people who have ACL surgery have favorable results, (notice the word favorable) with reduced pain, and also good but not normal knee function and stability. Some will still have knee pain and instability. An intensive rehab program to strengthen the knee then begins. The rehab program often lasts up to a year. There can be quite a few problems with the surgically replaced ACLs. First with an autograft the muscle the graft is taken from never fully recovers its strength. Second, the operated knee never regains its normal position sense to guide normal landing. Finally, few patients ever return to their prior level of sports and 2/3 of young ACL surgery patients will have arthritis by the time they are 30 years old.

• Autologus Cell Therapy Procedure. One of the big problems with the  surgery in general is that the graft tendon is inserted at a much steeper angle than the original ACL. As a result, we often recommend to our patients that they consider newer precise biologic injection options, like stem cells, before considering a surgical ACL replacement if the fragments are not retracted.  This may be a better option that should be explored, especially if you have only a partial or complete non-retracted ACL tear.