Anterior Cruciate Ligament Injury Treatment

How is an ACL Tear Treated and Can ACL Tears be Prevented?

by Steve A. Mora, MD

Orange County Orthopedic Surgeon Specializing in Sports Medicine

You have sustained a major knee ligament injury.  Your doctor said you ruptured your Anterior Cruciate Ligament (ACL).  The ACL serves to stabilizing your knee so that you can do pivoting, twisting and jumping maneuvers.

When the ACL is ruptured there may also be other associated cartilage tears in your knee that you must learn about.  About 25% of the time the articular cartilage will be damaged and 50% of the time the meniscus will be torn.A

When the injury occurs, it is like a small bomb going off in the knee.  The ACL is usually pulled right off the bone.  A “pop” is usually felt.  When the ACL is torn it cannot be stitched together but rather must be substituted with a new “graft”.  A reconstruction involves replacing the torn ligament with a new one.


ACL ruptures have been studied and attempts to prevent them have been made.  Women have a greater risk of suffering a tear. Numerous theories have been proposed to explain the higher incidence of non-contact ACL injuries in female athletes compared to males, however, exact mechanisms and risk factors have not been adequately defined. In 1999, a group of experts pooled their efforts in an attempt to shed light on these important questions (Hunt Valley Conference on ACL Prevention Strategies) (1).  Numerous variables were analyzed including environmental, anatomical, hormonal, and neuromuscular. The key risk factors were found to be diminished strength and neuromuscular control differences between male and female athletes. Additional information has also highlighted the importance of hip stability and pelvic control.  It is thought that female athletes have an imbalance of strength and power between the hamstring and quadriceps muscle around the knee (quadriceps dominance).  Males have an average hamstrings-to-quadriceps ratio of nearly 70 percent (better balance between the hamstring and the quadriceps strength).  The relative power of hamstrings in females is less than 50 percent and the time in which the hamstring contracts maximally is slower.  In addition, men flex their knees naturally as they come down from a jump thereby protecting the ACL during the landing. Women tend to keep their knees and hips in a extended and less protected position.  The lack of flexion and poor hip position predispose the knee to injury.  These, as well as a host of other less understood factors, are believed to “set-up” the female athlete for injury.


The patient helps the physician in making the diagnosis by simply recounting the injury details and providing a good history.  If the athlete felt a pop, the knee became swollen, and they were unable to continue playing there is a 80% chance of an ACL tear.  The physical examination will usually show blood in the knee (hemearthrosis) and looseness (laxity) of the knee.   X-rays are always done to evaluate for fractures and loose bodies.  An MRI allows characterization of normal and abnormal anatomy with excellent but not perfect accuracy.   The MRI will identify injuries such as bone bruises, meniscus tears and ligament tears.   There are cases where the MRI shows a partial tear.  In these cases the important factor is whether or not the knee is stable.


There have been several studies that recommend waiting 2-3 weeks and for the swelling to be down.  This is also my practice. There is usually one exception that demands sooner surgery.  In cases of a displaced meniscus tear that locks the knee not allowing any motion.  In this case the surgeon has the choice of repairing the meniscus and then doing the ACL  reconstruction at a later date when the motion is better.


Solid ACL graft fixation in the injured knee allows early movement and weight-bearing after surgery. Early knee motion has been proven to be safe and effective.  Walking with the use of crutches begins immediately.  Flexion and extension begins right away.  Running is usually allowed at 3 months.  One of the rehab hurdles patients often face being able to  fully extend their knee after surgery.  Home exercises are done daily while physical therapy is done for up to 3-4 months.  A “prevention program” such as the PEP Program is started at 5 months post-op.  The “green light” for sports participation may be given as early as 6 months from surgery but the reality is that most patients are not ready to participate in these activities for 7-8 months.  Even after the “green light” is given, some patients will need a brace for a couple of months while they get used to the new new knee mechanics.  The good news is that after the long rehabilitation program, many patients are able to play sports again.

Good luck and may you have a great surgery and recover.

Steve A. Mora, MD