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Anterior Cruciate Ligament Reconstruction
Preparing For Surgery
The anterior cruciate ligament was ignored for a long period of time and regarded as an unimportant structure within the knee. Many patients with low activity did fine without surgical reconstruction. It was not until the 1980's that we understood the full role of the anterior cruciate ligament. A successful reproducible surgery with the use of the arthroscope during the late 80's has now lead to a final solution for this most difficult knee injury. It is no longer considered "the curse of the knee" to have an anterior cruciate ligament tear. I would like to provide you in a question/answer format a better understanding of the anterior cruciate ligament injury and treatment. This will allow you to make an educated decision regarding surgery.
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What is the function of the anterior cruciate ligament?
How do I know if my anterior cruciate ligament is torn?
If you determine that my anterior cruciate ligament is injured what are your recommendations?
If I have a complete ACL tear or nonfunctional ACL what are your treatment recommendations?
How is the anterior cruciate ligament repaired?
If I elect for surgery what is my responsibility prior to surgery?
How long does the surgery take, and what are my expectations immediately after surgery?
What is the function of the anterior cruciate ligament?
The anterior Cruciate ligament is most commonly abbreviated ACL.
A = Anterior (front)
C = Cruciate (crossing)
L = Ligament
The term best describes a front crossing ligament within the knee. The ligament comes into play with cutting or pivoting type activities with the foot planted and the body rotating around a planted foot. It is known that approximately 80% of the support required to resist displacement of the lower leg from the thigh is provided by the ACL. With straight ahead walking activities there is very little support and patients do quite well without an ACL. If rotation is added or sometimes uneven surfaces patients may complain of the knee "giving way" if they do not have a functional ACL.
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How do I know if my anterior cruciate ligament is torn?
If the injury occurred within 3 weeks of my exam it is difficult to assess whether the anterior cruciate ligament is completely torn. After that time I can usually determine if the anterior cruciate ligament is torn by simple examination in the office. A test we perform to evaluate the amount of displacement of the tibia on the femur can be done in the office and should provide you with an answer. In difficult or questionable cases, additional information can be obtained from a "KT-1000" which can quantify the amount of displacement. On rare occasions, I will obtain an MRI which is a magnetic scanning of the knee which will visualize the anterior cruciate ligament inside the knee and determine it's status.
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If you determine that my anterior cruciate ligament is injured what are your recommendations?
You should think of an anterior cruciate ligament injury as two basic types.
- Partial tear with good functional knee support.
- Complete tear or complete stretch of the anterior cruciate ligament with inadequate function support.
If you have a partial tear with adequate function to the knee, rehabilitation in the form of physical therapy and exercise is recommended in addition to swelling reduction techniques. I protect most patients with a sports brace for the first 1 -2 years following injury and then allow them to be brace free.
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If I have a complete ACL tear or nonfunctional ACL what are your treatment recommendations?
Treatment is divided into two categories.
- Surgical
- Non-surgical
To determine which category is best for you I have outlined the five categories which should help in making the final decision.
Age - In general the younger the patient the more likely we are to recommend surgery. Because the ACL resists rotational forces with younger patients and therefore surgery is recommended. In general patients over the age of 50 are not considered candidates for an ACL reconstruction.
Activity level - This is by far the most important consideration in anterior cruciate ligament reconstruction. With any sports activities especially on a competitive level we find that with an anterior cruciate insufficient knee additional injuries to the knee are often common in the form of cartilage tears or further ligament damage. With this information if one participates in sports on a regular basis and is highly active in sports we recommend surgical reconstruction. Individuals that do not participate in recreational or weekend athletics may consider rehabilitation alone.
Functional level - If you have an acute anterior cruciate ligament injury it is sometimes difficult to know how your knee will function early during the rehabilitation course. For those who are greater than six weeks after injury, you may experience a giving way of the knee with simple rotational type activities. If you experience instability to the knee this usually signifies that the knee is a setup for further damage and at that point we would recommend an anterior cruciate ligament reconstruction. Normally we ask that if the instability is occurring on a regular basis this would be an indication for surgical reconstruction.
Knee exam findings - I will perform an examination in the office and determine functionally how stable your knee is on a scale from 0-10. In general the more unstable the knee, based on my examination, the greater the recommendations are going to be to proceed with surgery. Just as all joints in the body are different, all joints among individuals are different. These patients with more loose or lax joints will have greater functional deficits after an anterior cruciate ligament loose and will have a very loose knee requiring surgical reconstruction. There are some rare individuals who after an anterior cruciate ligament tear have fairly tight or stable knee and will not require surgery.
Other associated injuries to the knee: If you have a meniscual injury or additional ligamentous injury associate with the anterior Cruciate ligament this will often times require us to perform surgery. At that point we recommend an anterior cruciate ligament reconstruction. In general it should be remembered that if you have additional injuries to the knee most likely surgery will be recommended to you. If you have an isolated anterior cruciate ligament injury there is a possibility of physical therapy or rehabilitation as long as the knee is not instable, or you do not fit the categories above.
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How is the anterior cruciate ligament repaired?
After years of attempted repair of the anterior cruciate ligament throughout the 1960's and 1970's it became obvious that going in and simply suturing the ligament was unsuccessful. The structure of the anterior cruciate ligament acts like a rubber band on tension. Once the ligament tears both ends pull apart. The current technique is to reconstruct or replace the anterior cruciate ligament even if the tear has just occurred in an acute injury. The only time we will repair an anterior cruciate ligament is if there is a piece of bone is pulled off with the ligament that we may reattach surgically.
The current anterior cruciate ligament reconstruction is performed by harvesting tissue from the tendon directly underneath your kneecap or from the tendons that lie along the inside of the knee that make up the hamstring group. Both of these tendon sources have shown to be equal in strength and have demonstrated an excellent material to reconstruct the anterior cruciate ligament. An incision is made through the skin to harvest these tendons and the tendons are then prepared outside the body for implantation through the knee. All reconstructions are then done through the arthroscope by making two small portals that enter the knee joint.
Initially the remnant or stump of the ligament is removed and preparation is made to replace the tendon graft in the exact position that your original ligament was located. This is done through a series of measuring devices and instruments that allow us to replace the tendon graft in the exact position of your old anterior cruciate ligament. A drill hole is then made through the bottom bone exiting out through the middle of the knee. A second drill is brought from inside the knee into the upper bone to create two tunnels that will house the graft.
Most common reconstructions are performed with a small guide pin that exits above the knee that will allow the graft to be brought in from the lower bone into the upper bone. The graft is then secured with two screws that actually lie within the bone tunnels adjacent to the graft and therefore there is no metal or screw outside the bone. The body reacts in a very positive fashion to a screw within the bone and usually there are no side affects such as pain or swelling because the screw remains within the bone.
After the graft is 6 -12 months old the body will actually grow new blood vessels within the graft and change it into your own ligament. The body will provide it's own blood supply to the graft which is acting as a scaffold and transform it into a ligament.
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If I elect for surgery what is my responsibility prior to surgery?
In general we recommend at least three weeks after an acute ACL tear before performing reconstruction. This is to allow the swelling to leave the knee and provide full return of range of motion. It is our recommendations that swelling reduction and range of motion techniques be performed if you have an acute injury. If you do not have an acute injury we recommend aggressive strengthening through an exercise program prior to surgery. This will ensure a fast recovery.
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How long does the surgery take, and what are my expectations immediately after surgery?
As stated previously, surgery is performed with the use of the arthroscope and in general will last between 1- 2 hours. The longer surgical times are for patients with additional injuries such as cartilage or other ligament injuries. Immediately after surgery you will be in a soft tissue dressing and a brace that is locked or does not allow you to bend your knee. Usually a cold compressive wrap that is connected to a cooler will provide both compression and cooling to your knee during the first week post operative. Discharge instructions are as follows:
- Crutches will be required during the first 7 -10 days and you will be allowed to put partial weight down.
- Elevation of your knee, 6 inches above your heart is required during the first 72 hours with the use of the ice compression machine. Plan on staying off your feet for a minimum of 72 hours after the surgery.
- A drain will be exiting your knee with it's own collection device and is generally removed on the first post-operative day. At that time a dressing change will be performed. Showering will not be allowed until the fifth post-operative day at which time all dressings will be removed.
- If you have staples they will be removed on the 5th - 10th day following surgery.
- Exercises in the form of quad sets, straight leg raises and simple bending or flexing of the knee will be allowed on the first post-operative day and encouraged everyday following.
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