ACL Injuries

One of the main stabilizers of the knee is the anterior cruciate ligament. The role of the ACL is to hold the femur (thigh), to the tibia (leg). It prevents the tibia from migrating forward (anteriorly) from underneath the femur. It also helps prevent the tibia from rotating. This allows an athlete (or any one else) to rapidly turn, twist, and continue to run at full speed without the knee collapsing.

Without the ACL knee will give way.

Even though the ACL is very strong, injuries can cause the ligament to tear. The ligament is usually completely destroyed with this injury and can only rarely be repaired. ACL tears can occur as the athlete makes a rapid turn, landing from a jump, or can be injured as a result of a direct blow to the knee. When the athlete injures an ACL, a pop is often heard by the athlete or by others around him. The knee rapidly swells as bleeding from the ligament fills the knee.

After a few days there is often little if any pain, but the athlete will notice that their knee feels like it will "give way" or is "wobbly". It is not unusual for an athlete to ignore the injury and try to resume playing on such a knee. Over time supporting structures around the knee begin to stretch as they absorb the force once absorbed by the ACL. This leads to progressive instability of the knee causing further injury to the menisci (the pads in the knee that absorb shock) and the cartilage that covers the end of the bones. If there is continual laxity the knee will wear away the cartilage and then you have arthritis

DIAGNOSIS

The first step in treating an ACL injury is to confirm the diagnosis. An experienced orthopedic surgeon can do this simply by examining the knee and testing for laxity. Magnetic resonance imaging (MRI) is sometimes used to help make the diagnosis of an ACL injury.

TREATMENT

Once the ACL tear has been confirmed, then the athlete has to make an important decision. Some individuals can function without an ACL in their knee ("copers"), but only as long as they modify their lifestyle to avoid cutting and pivoting sports (football, soccer, lacrosse, hockey, and tennis) and some people need to wear a brace. Even with modifications the athlete can continue to have problems with instability, and lead to progressive pain due to arthritis.

If the athlete can modify their activities to those that do not require cutting and pivoting (walking, biking, swimming, weight lifting, and golf), often there will be no problems with instability.

A knee brace is prescribed to give added support to the knee. The most important function of the brace is not for support, but to give some unconscious feedback to the athlete's brain on how his knee is doing (proprioception). The normal ACL has nerve endings that relay important information to the brain so that the brain can tell the muscles around the knee how to help the ACL stabilize the knee. When the ACL is torn these nerve fibers are permanently destroyed and this function has been lost. The brace can help this important feedback function.

If an athlete does not feel that they can modify their lifestyle or has continued instability despite modification of activities, the treatment is to replace their torn ACL with a new ligament. When the ACL tears it looks like the end of a mop, and is impossible to sew back together.

The goal of this operation is to replace the ligament with a piece of tissue as strong as the original tissue and place it in the exact location where the original ligament was attached. If these two criteria are not met then the new ligament may tear again or the knee may not regain full motion. The operative technique is both challenging and difficult, but when coupled with appropriate rehabilitation the result can be excellent with return to normal sporting activity.

ACL Reconstruction (Surgery)

We like to use the athletes own patellar tendon as a graft. There are other options such as hamstring graft, quad tendon graft, fascia lata graft and even Allograft (cadaver graft). We feel that the best results are using the athletes' own Patellar tendon.

The operation involves harvesting the middle 1/3 of the patellar tendon along with small blocks of bone attached to it from the patella (kneecap) and from the tibia. This graft is then used as the athletes' new anterior cruciate ligament. Removing the middle 1/3 of the patellar tendon does not cause any significant long-term weakness of the tendon as it rapidly thickens during the healing phase after the operation.
The surgery is all done with arthroscope with 2 puncture wounds and a  3 to 5 inch incision is made directly over the patellar tendon to harvest the graft from the patellar tendon.

Using the arthroscope the exact insertion site of the normal ligament is defined on both the femur and tibia within the knee. Holes are then drilled in the bone. The graft is then placed into the knee so that the bone plugs are in the bone tunnels and the patellar tendon is sitting were the old ACL used to sit. The bone blocks are held in place with 2 screws. These screws can stay in the athlete for the rest of their life. They essentially have no weight and will not set off any airport detection systems.

This operation is routinely scheduled as an overnight stay for pain control, although most patients are comfortable enough go home that night. We start our patients with crutches for the first week, putting part of their weight on the leg. Everyone goes into a brace that keeps the knee straight when they are walking but is removed for therapy 3 times a day to work on bending. Oral pain medications are quite effective in controlling discomfort for the next few days following surgery.

AFTER THE OPERATION

One of the greatest challenges following the reconstruction of the knee is to regain motion and strength that the knee had before the operation. The motion in the knee rapidly diminishes after an operation because of scarring inside the knee. The key to regaining motion is to start an early motion program. Immediately following surgery we start the patient in a continuous passive motion (CPM) machine to help regain the motion. Everyone is scheduled for therapy 2-3 times a week for the first month to help regain the motion and strength of the knee.

After the first week the sutures or staples are removed. The patient no longer needs a brace at night. The brace is worn when the patient is up and about. After the first week the brace is unlocked to allow full range of motion for the knee.

After the first month the brace is discontinued. Therapy continues to work on the strengthening of the surrounding muscles of the knee. At 5-6 weeks the patient begins a running and agility program as prescribed.

THERAPY AND REHABILITATION

Perhaps the single most important ingredient of a successful knee reconstruction is therapy and rehabilitation. Those patients most dedicated to following the rehabilitation program prescribed have the best results. Failure to follow the program may lead to a poor result.

Therapy starts the day following surgery. For the first 10 days therapy focuses on helping the patient regain knee motion. Ten days following the surgery, outpatient therapy usually commences under the watchful eye of a sports physical therapist. Initially therapy is dedicated to improving range of motion and strengthening the muscles around the knee, often with the help of electrical stimulation.

Three weeks following surgery more aggressive strengthening occurs with the use of light weights and other specialized exercise equipment. The rate at which a patient progresses from lighter to heavier weights and to more advanced machine weight training is a function of each patient's progress.  When the patient ultimately achieves strength that approaches 60% of the normal knee then a progressive program of running and agility drills are started.

When the strength in the muscles around the operative knee approaches that of the non-operative knee the patient is allowed to return to sports. This can occur as early as four months, but usually takes between five and eight months from date of surgery. Some patients require a full year of rehabilitation before they can return to sports.

We do not routinely recommend Braces for our patients when they return to sports. Braces have never been shown to prevent ACL Injuries. Many athletes' feel that the brace is awkward and alters their normal running. If an athlete would like one we arrange for them to get a special brace for sports.

POTENTIAL COMPLICATIONS

As with any surgery, there are certain risks that must be well understood by a patient considering knee reconstruction. While slight, the risk of anesthesia is present.  It is important for the patient to let  both the anesthesiologist and us know of any history of anesthetic complications or significant medical problems.

The risk of infection with this operation is very small (approx. 1%), but it can occur. Antibiotics are given before the operation to minimize this risk.

There have been reports of fractures in the patella (kneecap) during the harvesting of the new ligament. We have never encountered this complication, but, should it occur, the fracture would be wired together and would not limit the speed of healing and rehabilitation.

Fractures of the kneecap can occur for months following the surgery during a fall or violent extension of the knee. This happened to Jerry Rice, the famous receiver for the San Francisco 49'ers, in 1997 when he hit the ground during a game three months after ACL surgery. Fractures of the kneecap are very rare and usually occur when the patient tries to do more than their strength allows following surgery. Pain under the kneecap and even some popping and crunching is a normal phenomenon several months following the operation. This almost always works itself out as the patient continues with their rehabilitation and further strengthens their muscles around the knee.

Some decreased sensation around the incision site on the front of the knee is very common following the operation. Most of this sensation returns some months following the operation, but there may always be some decreased sensation in this area. This is rarely a source of any difficulty for the patient.

Perhaps the single greatest risk following the operation is loss of range of motion. As discussed earlier a large part of rehabilitation is dedicated to regaining full range of motion. Rarely a patient is not able to regain full range of motion. If this occurs then we are very aggressive with the treatment.

CONCLUSION

A few short years ago serious knee injuries would cause professional athletes to end their careers, college athletes to give up scholarships, high school athletes to give up the opportunity to try different sports and laborers to change jobs. With new reconstruction techniques we can now rebuild the knee and get it back to nearly full function. We can never return the knee to its previous perfect state. When the athlete is dedicated to working hard in their rehabilitation, together we can return their knee to a level of function that allows participation in all sports and work activities without a brace and without pain or instability.