The anterior cruciate ligament (ACL) is one of the most important of four strong ligaments connecting the bones of the knee joint.
Ligaments are strong, dense structures made of connective tissue that stabilize a joint. They connect bone to bone across the joint
The function of the ACL is to provide stability to the knee and minimize stress across the knee joint:
· It restrains excessive forward movement of the lower leg bone (the tibia) in relation to the thigh bone (the femur).
· It limits rotational movements of the knee.
A tear of the anterior cruciate ligament (ACL) results from overstretching of this ligament when certain movements of the knee put too great a strain on the ACL
Torn ACL View
1. Introduction
The anterior cruciate ligament (ACL) is one of four ligaments in the knee. These ligaments work together to stabilize the knee during activities. Unfortunately, tears of the ACL are common and occur with twisting activities (such as playing basketball, tennis and soccer, or skiing) and direct blow injuries (such as those that occur in football).
An ACL tear usually occurs from a sudden event often accompanied by a "pop" sound. The knee will swell for a few hours and it may be uncomfortable to walk. The knee can also feel unstable. A physician can confirm the tear with a physical examination and a magnetic resonance image (MRI) scan. When the ACL is completely torn, it cannot repair itself and thus the ligament function is lost. After a few months, the ligament tissue will break down and be absorbed by the body.
2. Diagnosing An ACL
Tear
The
diagnosis of an ACL tear is based on
- The
physician's examination, as well as special tests which may
include:
- Radiographic
Evaluation
- MRI
(Magnetic Resonance Imaging)
- KT 1000
Physical Examination
The
physician will take a thorough history addressing how the injury
occurred and ascertaining when the pain may have first appeared. Questions
regarding any earlier knee injuries are important as often ligaments and
cartilage structures may have been previously strained. Any previous episodes
of knee instability or the knee giving way is important information.
The
physician can determine the integrity of the ACL by conducting special ligament
stability tests. One simple but important test is called the Lachmans test.
With the knee bent to 30 degrees, the physician gently pulls on the tibia
to check the forward motion of the lower leg in relation to the upper leg. A
normal knee will have less than two to four mm of forward movement, with a firm
stopping felt when no further movement is observed. In contrast, a knee with an
ACL tear will have increased forward motion and a soft end feel at the end of
the movement. This is because of the loss of restraint of the forward movement of
the tibia due to the torn ACL.
A
similar test, with the knee bent to 90 degrees, is called the anterior
drawer test. A more complex test is called the pivot shift test, in
which greater stresses are put on the knee as it is straightened by the
physician from a bent and inwardly rotated position. If the knee
"gives," this is an indication that other stabilizing structures
inside the knee must be torn besides the ACL. This test can sometimes only be
done when the knee is completely relaxed. Because of this it may best be
observed under anesthesia during the surgical procedure.
Radiographic Evaluation
Acute
knee injuries generally warrant x-ray films. They are carefully
evaluated for any possible tearing away of bone where the ligaments attach.
Also, the x-ray will show any loose bone fragments or other fractures if they
are present.
Magnetic
resonance imaging is a noninvasive test that produces an excellent image of all
parts of the knee. In this test, the individual lies in a hollow cylinder while
powerful magnets create signals from inside the knee. These signals are then
converted into a computer image that clearly shows any damage to the structures
inside the joint. The images are valuable not only to determine the presence of
an ACL tear, but also the degree of the tear along with any damage to related
structures, such as the meniscus and other ligaments.
For
further information about mri, go to MRI.
3. Do I need surgery for an ACL tear?
Treatment
decisions for ACL tears are always individualized - tailored to each
individual. The decision whether to offer surgery is based on the person's age,
activity level, how unstable the knee is, and whether other structures in the
knee have been injured.
It
is important to keep in mind that surgery to reconstruct a torn ACL is not an
emergency for most people. Many people with a torn ACL do not need surgery at
all. Even though the chances for complete success from surgery are now
excellent, surgery is not for everyone. This is because not everyone needs the
ligament repaired to return to his or her pre-injury level of function. It is
important to distinguish whether the work, recreational, and athletic
activities of the person is light, moderate, or strenuous. Another important
issue that needs to be understood by the individual considering ACL
reconstruction is that it requires many weeks and months of hard work in
rehabilitation following the reconstruction. This needs commitment and time.
The Ultimate Deciding Factors...
- Whether
the injury is a recent tear or an old ACL problem, individuals need to
consider their present activity level and decide if their daily activities
and livelihood would be affected by the injury. The question of whether to
have surgery to reconstruct the torn ACL arises most frequently with less
athletically inclined older persons. Generally in such people, if the
instability is severe, and the knee is constantly buckling, the decision
to offer surgery is intended to prevent further damage to the knee and
stop the daily discomfort of the knee giving way.
- On the
other hand, if the knee instability can be controlled by avoiding
activities that the individual doesn't really mind avoiding, then going
the "conservative" route and avoiding surgery is often a very
good choice - and many people are satisfied with it. Certainly, there are
many older athletes who are willing to avoid basketball, soccer, or
racquetball, and stick to jogging or biking for fitness. As long as their
knees are stable and pain-free for these activities, they are happy. Also
with the use of a functional brace, many of these people find they can do
most of what they wish to do without significant problems.
- For those
people who choose not to have surgery, this does not mean going without
any treatment at all. There is still a treatment program to be followed
emphasizing strengthening the leg muscles and learning to better control
the knee and to avoid those situations most likely to cause instability.
Many people benefit from this kind of rehabilitation.
- If
athletics is a regular part of your life, or if your work is likely to be affected
by mild instability of the knee (for example, construction workers or
other non-sedentary type jobs), your physician will lean toward
reconstructing the torn ligament.
- In general, stronger and fitter is better - and this applies to operated and non-operated knees equally.
4. Surgical Details
Nonsurgical Treatment of ACL Tears
A small percentage of people will do well after an isolated ACL tear without surgical reconstruction. These individuals tend to be older and less active. They are not involved with activities or sports that involve pivoting or "cutting." Knee braces can help prevent instability episodes by "hobbling" the knee and assisting with sensory feedback. However, most active people will continue to have instability even with the most expensive custom knee brace.
Before deciding to pursue nonsurgical treatment in a knee that is ACL deficient, it is important to make sure that there is no other damage to the meniscal cartilage pads or other ligaments. An MRI scan can determine with excellent accuracy whether additional damage is present. If there is significant damage to the menisci, surgery is usually recommended. If knee surgery is scheduled for other problems, then most people decide to reconstruct the ACL at the same time.
Surgical Reconstruction of the ACL
Most people with a torn ACL will experience instability, a feeling that the knee gives way or feels loose. This instability commonly results in a reduction in activities, especially sports. More importantly, the instability will usually lead to additional damage to the knee.
Meniscal cartilage pad tears, articular surface cartilage injuries and additional ligament damage are common following untreated ACL tears. Some studies have shown that during the five years following an untreated ACL tear that 80 percent of individuals will have suffered additional damage because of instability. This damage often results in arthritis, a wearing out of the articular cartilage surfaces, which results in pain, stiffness and deformity. Most people with a torn ACL are unwilling to give up their activities and have a strong desire to prevent further damage to the knee. Therefore, most people elect to reconstruct the ACL.
The surgery to reconstruct the ACL involves taking a piece of tendonous tissue to replace the ACL. Tendons and ligaments share similar tissue composed primarily of collagen protein. The underlying concept behind the reconstructive surgery is that a tendon is surgically placed into the knee exactly into the position where the torn ACL was located. The tendon is fixed to the bone with biodegradable screws. Approximately 95 percent of the time, the body will then reestablish the blood supply to the tendon and over the weeks following the surgery this blood supply will bring new fibroblast cells that will repopulate the tendon bringing it back to life. As a result, the "new living ACL" is seemingly just as good as the original and should last a lifetime. Follow-up studies, which show maintenance of stability and active lifestyles for many years after ACL reconstruction, support this theory.
Surgical Choices for ACL Reconstruction: Autograft vs. Allograft
After deciding to undergo surgical reconstruction of the ACL, you must decide from where the reconstruction tissue will come. When the tissue comes from the same patient, it is called an autograft. When the tissue is taken from a different human donor, it is called an allograft. Tendons, such as the patellar tendon and hamstring tendon, can be used for autografts. The Achilles tendon, patellar tendon and hamstring tendon can be taken and used for allografts.
· Autograpt Reconstruction of the ACL
The first autograft reconstruction of the ACL was performed around 1918. The more common procedures, which are now performed with the use of arthroscope, became popular in the early 1970s. The most common autograft used is the central-third-patellar-tendon graft. This graft is actually comprised of a piece of the patella bone (kneecap), the central third of the patellar tendon and a piece of tibia bone (shinbone). The graft is usually 10 millimeters wide (3/8 inch) and 8 centimeters (4 inches) long. The patellar tendon defect created from taking this graft is usually closed with sutures and the donor site will heal during the months following surgery. The healing of the patellar tendon defect can lead to excessive scarring and sometimes pain.
Hamstring tendons from the back of the thigh can also be used to reconstruct the ACL. The most common hamstring tendon used is the semitendinosus. Often a second hamstring tendon, the gracilis, is also taken if the semitendinosus is not large enough. The donor hamstring muscles seem to tolerate the removal of their tendonous attachment but permanent hamstring weakness is expected following surgery.
The major disadvantage of autograft tendons is the additional damage to the knee from harvesting the tendon at the donor site. The donor site can become a source of pain, scarring and weakness. Excessive scarring can permanently reduce motion. The donor site can take longer to heal than the reconstructed ligament. Longer surgical times are needed with larger incisions. Early return to activities, while often safe for the reconstructed ACL, can cause injuries to the donor site.
The major advantage of using autograft tendons are that they have been used for the longest period of time and because they come from the injured person they do not have any chance of carrying organisms, which may cause infectious diseases.
The first autograft reconstruction of the ACL was performed around 1918. The more common procedures, which are now performed with the use of arthroscope, became popular in the early 1970s. The most common autograft used is the central-third-patellar-tendon graft. This graft is actually comprised of a piece of the patella bone (kneecap), the central third of the patellar tendon and a piece of tibia bone (shinbone). The graft is usually 10 millimeters wide (3/8 inch) and 8 centimeters (4 inches) long. The patellar tendon defect created from taking this graft is usually closed with sutures and the donor site will heal during the months following surgery. The healing of the patellar tendon defect can lead to excessive scarring and sometimes pain.
Hamstring tendons from the back of the thigh can also be used to reconstruct the ACL. The most common hamstring tendon used is the semitendinosus. Often a second hamstring tendon, the gracilis, is also taken if the semitendinosus is not large enough. The donor hamstring muscles seem to tolerate the removal of their tendonous attachment but permanent hamstring weakness is expected following surgery.
The major disadvantage of autograft tendons is the additional damage to the knee from harvesting the tendon at the donor site. The donor site can become a source of pain, scarring and weakness. Excessive scarring can permanently reduce motion. The donor site can take longer to heal than the reconstructed ligament. Longer surgical times are needed with larger incisions. Early return to activities, while often safe for the reconstructed ACL, can cause injuries to the donor site.
The major advantage of using autograft tendons are that they have been used for the longest period of time and because they come from the injured person they do not have any chance of carrying organisms, which may cause infectious diseases.
· Allograft Reconstruction of the ACL
The primary advantage of allograft tissue is that there is no additional damage to the knee and stronger grafts can be used.
The most common allografts use the patellar tendon and Achilles tendon. The Achilles tendon is the strongest and largest tendon in the body. Allograft tissues are taken from tissue donors through tissue banks. The donors are people usually under 40 years of age, often who have died from an accident. The donors are screened by tissue banks and are tested for infectious diseases. Screening histories, blood tests and cultures are obtained during tissue processing. These screening procedures must be clear of infectious disease or the tissues are rejected by the tissue bank.
The risk of disease transmission through allografts while never non-existent is extremely small. Allografts are poor vectors for disease transmission. The graft tissue has no living cells. It is frozen and kept in a deep freezer until used. The fact that the tissue has only a few cells and no living cells makes the donor graft tissue a poor transmitter of living bacteria or viruses that are responsible for transmitting most diseases. Because this tissue has no living cells, it is not necessary to match the donor and recipient, nor is it necessary to give anti-rejection drugs.
The primary advantage of allograft tissue is that there is no additional damage to the knee and stronger grafts can be used.
The most common allografts use the patellar tendon and Achilles tendon. The Achilles tendon is the strongest and largest tendon in the body. Allograft tissues are taken from tissue donors through tissue banks. The donors are people usually under 40 years of age, often who have died from an accident. The donors are screened by tissue banks and are tested for infectious diseases. Screening histories, blood tests and cultures are obtained during tissue processing. These screening procedures must be clear of infectious disease or the tissues are rejected by the tissue bank.
The risk of disease transmission through allografts while never non-existent is extremely small. Allografts are poor vectors for disease transmission. The graft tissue has no living cells. It is frozen and kept in a deep freezer until used. The fact that the tissue has only a few cells and no living cells makes the donor graft tissue a poor transmitter of living bacteria or viruses that are responsible for transmitting most diseases. Because this tissue has no living cells, it is not necessary to match the donor and recipient, nor is it necessary to give anti-rejection drugs.
After Surgery
After surgery you will be asked to stay in the outpatient surgical facility for a period of one to two hours to recover from any drugs you may have been given. You will also be allowed to sip some water and eat crackers. You will have a large bandage on your knee and a brace. You will need someone else to drive you home, as well as to be with you during the first 12 to 24 hours after the procedure.
It is important to do only what is necessary once you are home. You can use the restroom, get something to eat or answer the phone, but otherwise you should try to lie down with the leg elevated above the heart as much as possible. Take pain pills and anti-inflammatory medications immediately and regularly to help control pain. It is usually better to start taking the pain pills before the pain comes, so as not get "behind" the pain. Resume taking all medications, which you normally take.
Start the CPM machine once you get settled at home. The range of motion is preset at zero to 40 degrees. Please stay within this range. If you increase the motion too fast you may experience more pain the next day when the local anesthetic wears off. Also, if you chose to use the ice machine, continue for 24 to 48 hours.
· First Postoperative Day
The day following surgery may be a lot tougher than the day of surgery. The numbing medicines used during surgery will wear off and there may be more pain. Try and use the CPM machine as much as possible while increasing the CPM range of motion as pain dictates. Ice bags or the ice machine should be used continuously. The leg should be elevated as much as possible above the heart. Try to do as little activity as possible and take your pain medication regularly. Do not get behind your pain, or it may get quite severe.
Remember, it is normal for bloody drainage to appear on the outer bandages. The drainage is mostly absorbed water mixed with small amounts of blood. The bandage should be shifted slightly so that dry bandage covers the draining portal. You can also place new bandages around the knee.
The day following surgery may be a lot tougher than the day of surgery. The numbing medicines used during surgery will wear off and there may be more pain. Try and use the CPM machine as much as possible while increasing the CPM range of motion as pain dictates. Ice bags or the ice machine should be used continuously. The leg should be elevated as much as possible above the heart. Try to do as little activity as possible and take your pain medication regularly. Do not get behind your pain, or it may get quite severe.
Remember, it is normal for bloody drainage to appear on the outer bandages. The drainage is mostly absorbed water mixed with small amounts of blood. The bandage should be shifted slightly so that dry bandage covers the draining portal. You can also place new bandages around the knee.
· Nausea and Pain Medication
Remember that surgery is not painless. Try to take your pain pills as directed even before you experience pain. Nausea and vomiting are very common postoperative problems. If you start to get nauseated, try and minimize the use of the codeine pain medication (hydrocodone or vicodin) and use Tylenol and Motrin for pain control. (Codeine products can make you nauseated.) Start eating more slowly beginning with soup and crackers. If you're prone to nausea, ask for anti-nausea medication prior to surgery.
Remember that surgery is not painless. Try to take your pain pills as directed even before you experience pain. Nausea and vomiting are very common postoperative problems. If you start to get nauseated, try and minimize the use of the codeine pain medication (hydrocodone or vicodin) and use Tylenol and Motrin for pain control. (Codeine products can make you nauseated.) Start eating more slowly beginning with soup and crackers. If you're prone to nausea, ask for anti-nausea medication prior to surgery.
Postoperative Risks
Potential Risks with ACL Reconstruction
· Wound Infection
Signs of infection include redness around the incision area, discharge of pus from the wound, increased pain and a fever of more than 101 degrees with chills and/or sweating.
Signs of infection include redness around the incision area, discharge of pus from the wound, increased pain and a fever of more than 101 degrees with chills and/or sweating.
· Blood Clots
Blood clots (thrombophlibitis) can occur after arthroscopic knee surgery. Usually, but not always, they occur in individuals with risks such as people who are more than 50 years of age, smoke or are overweight. Signs of blood clots include increased calf pain and the inability to put weight on the leg due to pain, as well redness and swelling of the calf.
Blood clots (thrombophlibitis) can occur after arthroscopic knee surgery. Usually, but not always, they occur in individuals with risks such as people who are more than 50 years of age, smoke or are overweight. Signs of blood clots include increased calf pain and the inability to put weight on the leg due to pain, as well redness and swelling of the calf.
· Risk of Graft Failure
The signs of a graft not forming a blood supply and weakening are not obvious. However, they are usually discovered during the postoperative evaluations.
The signs of a graft not forming a blood supply and weakening are not obvious. However, they are usually discovered during the postoperative evaluations.
· Loss of Motion
After surgery, it is very important to obtain and maintain full extension (getting the leg as straight as the nonsurgical leg)
After surgery, it is very important to obtain and maintain full extension (getting the leg as straight as the nonsurgical leg)
Risks
ACL reconstruction surgery is generally safe. Complications that may arise from surgery or during rehabilitation (rehab) and recovery include:
· Problems related to the surgery itself. These are uncommon but may include:
· Numbness in the surgical scar area.
· Infection in the surgical incisions.
· Damage to structures, nerves, or blood vessels around and in the knee.
· Blood clots in the leg.
· The usual risks of anesthesia.
· Problems with the graft tendon (loosening, stretching, reinjury, or scar tissue). The screws that attach the graft to the leg bones may cause problems and require removal.
· Limited range of motion, usually at the extremes. For example, you may not be able to completely straighten or bend your leg as far as the other leg. This is uncommon, and sometimes another surgery or manipulation under anesthesia can help. Rehab attempts to restore a range of motion between 0 degrees (straight) and 130 degrees (bent or flexion). It's important to be able to get your knee straight so you can walk normally.
· Grating of the kneecap (crepitus) as it moves against the lower end of the thighbone (femur), which may develop in people who did not have it before surgery. This may be painful and may limit your athletic performance. In rare cases, the kneecap may be fractured while the graft is being taken during surgery or from a fall onto the knee soon after surgery.
· Pain, when kneeling, at the site where the tendon graft was taken from the patellar tendon or at the site on the lower leg bone (tibia) where a hamstring or patellar tendon graft is attached.
· Repeat injury to the graft (just like the original ligament). Repeat surgery is more complicated and less successful than the first surgery.
Recovery Period
The weeks following ACL reconstruction surgery will be somewhat difficult but also rewarding. It is important to follow these instructions. In general, listen to your body. Your first goal is to regain full extension (straightening the knee) and prevent postoperative complications such as infection, blood clots and stiffness.
You can begin putting weight on the leg while it is in the brace and using crutches until you are stable walking without them. Generally, it is best to stop using the crutches first and walk with your leg in the brace. The brace can be removed when you know you will not slip or fall. Usually, the only way to hurt an ACL graft is to slip suddenly or fall.
Most patients go to physical therapy three times per week, but exercises should be performed daily. The more you work without increasing your pain or swelling, the faster you will recover. Some patients are off their crutches in a few days and out of the brace within a week, biking in 10 days and able to jog in six weeks. In most cases, you will be able to return to all sports without a brace.
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