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Orthopaedic Surgery
Anterior Cruciate Ligament
The Anterior Cruciate Ligament (ACL) is one of the most important of 4 strong ligaments in the knee connecting the lower leg bone (the tibia) to the thigh bone (the femur). The function of the ACL is to provide stability to the knee and limit its rotational movement.
If the ACL is overstretched, the ligament will tear. This is usually a result of sudden stopping or twisting of the knee. An ACL can also tear if a large force is applied to the front of the knee. Patients experiencing a torn ACL will often describe a 'pop' at the time of the injury. Some patients, however, may not feel the tear at the time of the injury.
Diagnosing an ACL Injury
Physical ExaminationThe physical examination is extremely important in evaluating for an ACL tear. Children and teens cannot always express what is bothering them and answer medical questions, as well as be patient and helpful during a medical examination. The pediatric and adolescent sports medicine specialists at our Center know how to examine and treat the patients in a way that makes them relaxed and cooperative.
As in almost all acute injuries, loss of motion and instability is an important finding. The Lachman Test is performed with the knee bent 30 degrees. The physician gently pulls on the tibia to check the motion of the forward leg in relation to the lower leg. Under normal conditions, the patient's knee will have less than three mm of forward motion, with a firm stopping felt when no further movement is observed. However, a patient with a torn ACL will have significantly greater forward motion and a soft-end feel at the end of the movement. Because the ACL is torn, the patient will experience loss of restraint of the forward movement of the tibia. The anterior drawer test is the same test performed with the knee flexed to 90 degrees.
Diagnostic ImagingMagnetic Resonance Imaging (MRI) helps the physician obtain an excellent image of all parts of the knee. The MRI is not an absolute indicator for a torn ACL, however, it can document damage to the meniscus. The meniscus is composed of cartilage inside the knee, which provides cushioning and is frequently torn at the same time that an ACL tears during injury.
Treatment for an ACL Tear
Immediately After InjuryThe patient should ice the injury to prevent inflammation and compress areas around the knee to control swelling immediately after the injury. Elevation is also key in controlling and reducing swelling. Rehabilitation knee braces are often used early after the injury as well as for postoperative care. The brace plays an important role in putting the joint at rest and protecting it while still allowing appropriate but limited motion.
RehabilitationA rehabilitation program is designed to restore the patient's range of motion and muscle strength. Weight-bearing exercises can only be pursued after the swelling around the knee decreases. Increasing the range of motion of the knees is important in preventing stiffness and muscles tightness.
Platelet-Rich Plasma TherapyPlatelet-rich plasma therapy -- a treatment for aiding the regeneration of ligament and tendon injuries -- is helping to shorten rehabilitation time and often eliminates the need for surgery. Platelet-rich plasma therapy is part of a relatively new field of medicine known as orthobiologics that includes the use of stem cells and emphasizes employing the latest technologies along with the body's natural ability to heal itself.
Platelet-rich plasma (PRP) is the name given to blood plasma with a high concentration of platelets that contains huge doses of bioactive proteins, such as growth factors, that are critical in the repair and regeneration of tissues. Growth factors can dramatically enhance tissue recovery and the special proteins also initiate new blood vessel formation, bone regeneration and healing, connective tissue repair, and wound healing. There is little chance for rejection because the components used for treatment are extracted from a person's own body. This makes the procedure entirely safe. The PRP injection also carries less chance for infection than an incision, with a considerably shorter recovery time than after surgery.
Surgical TreatmentSurgical treatment for a torn ACL is not always necessary. Although surgical intervention often leads to complete success, not everyone needs the ligament to return to his or her pre-injury level of function. If the patient is not incredibly physically active, reconstruction is not necessary. Also, ACL reconstruction requires that the patient undergo many months of rehabilitation. This involves both time and commitment and should be strongly considered when making a decision.
ACL Reconstruction
The ACL has little to no capacity to heal on its own. Therefore it cannot simply be sewn back together; it must be reconstructed. This involves substitution of a new ligament for the damaged one.
Skeletal ImmaturityMany young patients who injure their ACL are still growing; this requires special consideration. The standard technique of ACL reconstruction requires drilling tunnels in the tibia and femur bones that would cross the normal growth plate (physis) of an actively growing child. Therefore, the ACL reconstruction technique requires modifications that avoid injury to the growth plate. The specialists at our center use physis sparring and respecting techniques to avoid growth disturbances.
Graft ChoiceTypically, a surgeon will take a tendon from somewhere else in the patient's own body. This is called an autograft. There are several choices for autografts including patellar tendon, hamstring tendon, quadriceps tendon, Achilles tendon and anterior tibilias tendon.
Surgeons can also use an allograft to reconstruct the ACL. This type of graft is harvested from a cadaver and is advantageous for several reasons. First, the operation takes less time because the harvesting time is removed. Also, the patient's own tissue is not disturbed, therefore leading to a less invasive procedure and less scaring, and easier early recovery.
ProcedureReconstruction of an ACL takes about one hour. A patient may under go general anesthesia, spinal anesthesia or local anesthetic with sedation. Once the patient is anesthetized, the surgeon will begin the arthroscopic procedure. An arthroscope is a thin microscope that is about the size and shape of a straw. At the end of the arthroscope, there is a miniature video camera and lens that can magnify the image it sees to about 25 to 30 times the original size. This image is sent up to a video screen where the surgeon and their team can get a clear and detailed view inside the knee. With the arthroscope and small, specialized instruments, the surgeon can reconstruct the ligaments, avoiding large incisions and trauma to surrounding tissues.
Before the surgeon begins reconstruction, he or she uses the arthroscope to map out the area being worked on. This allows the surgeon to identify key knee structures and also view any additional damage.
The procedure begins with a small tunnel drilled through the tibia and the femur. This hole is drilled in the same positions the original ACL was attached. The graft of choice is then fit into each of these tunnels. The new ACL is then secured with specialized headless screws to hold it in place.
Recovery
Right After SurgeryBecause of the minimally invasive nature of the current ACL reconstructions technique, ACL surgery is an outpatient procedure. Although crutches are given to the patient to assist in necessary mobility, it is essential that the patient rest and elevate their new, especially in the first few days. This minimizes swelling and helps the body to reestablish all pre-surgical functioning.
Physical Therapy and RehabilitationRehabilitation is essential to a successful recovery and begins soon after surgery. The ultimate goal in rehabilitation is to return to a condition where the knee provides dynamic stability, while still maintaining a full range of motion. Therefore, recovery progress is judged by the patient's perception of how stable the knee feels. Often, a surgeon will prescribe a brace for the patient to be used during the rehabilitation period. The rehabilitation brace is adjustable; it can be locked in a straight position or set to allow a certain amount of motion. The brace is normally taken off while the patient is exercising. Usually, a therapy program will begin with range-of-motion and resistive exercises. Then, when the patient is able, exercise incorporating power, flexibility, endurance and coordination is added. At last, the patients will develop speed and agility through sport-specific exercises. Most patients begin light activity, such as biking or rowing, about four weeks after surgery. Running starts at six to eight weeks and competitive activity is delayed until four to six months after surgery.
