ACL Frequently Asked Questions

The knee is the joint between the two longest bones of the body, and the entire weight of the body is transferred to the foot through the knee. The knee is also more prone to injury because its stability decreases as it bends. Click here for more information.

The ACL is one of two ligaments inside the knee joint. This ACL runs from the top surface of the tibia diagonally into the large notch at the end of the femur and prevents the tibia from sliding too far forward underneath the femur. It also helps prevent over-straightening and overrotation of the femur on the tibia.

1. ”Pop” – Some patients hear or feel a “pop” when the ACL tears.
2. Immediate onset of swelling
3. Pain
4. Instability – Patients often describe a buckling or unstable sensation in the knee.
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An ACL injury usually occurs when the knee is sharply twisted or extended beyond its normal
range of motion.

The three grades of ACL injury range from mild to severe.
1. Sprain Trauma to the ligament is relatively minor. Some of the fibers are stretched.
2. Grade II – Partial Tear Trauma to the ligament is more severe. Some of the fibers are torn.
3. Grade III – Complete Tear This is the most severe ACL injury. The fibers of the ligament are
completely torn.
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An orthopaedic surgeon will ask for the history of the knee injury and will determine if the signs and symptoms of an ACL injury are present. Then a physical examination is performed, likely including a Lachman Test, Anterior Drawer Test, and Pivot Shift Test. An arthrometer may
be used. X-rays can reveal signs of bone fractures, chips, or arthritis. A Magnetic Resonance
Image (MRI) may be ordered to assess damage to soft tissue such as ligaments, tendons, and
cartilage. If further testing is needed to clearly evaluate the problem, an arthroscopy may be
recommended. Click here for more information.

1. To control swelling, the immediate treatment of an ACL injury is RICE:
Rest the knee by using crutches and keeping weight off of it
Ice the knee
Compress the knee with a wrap
Elevate the leg
2. The doctor may also drain the joint of excess fluid to reduce pressure.
3. After initial injury symptoms subside and diagnosis is established the orthopaedic surgeon
determine the best treatment option including, non-operative treatment with rehabilitation and
bracing and surgical treatment.
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A good physical therapy program will focus on rehabilitation of the knee in two areas; Strength
and Proprioception. A functional ACL brace will usually be prescribed to stabilize the knee
and to prevent reinjury. Click here for more information.

1. Active individuals who participate in any sport with pivoting.
2. Patients who continue to experience instability after going through a rehabilitation
program.
3. Those with injuries involving more than one ligament.
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An ACL reconstruction is a surgical procedure that involves removing the remains of the
damaged ACL and replacing it with another form of soft tissue, called a graft. The graft is either
autogenous, which comes from the patient, or an allograft, which is tissue donated by an
individual at the time of death. Click here for more information.

An ACL reconstruction is the most common surgical procedure performed today since it usually produces the best results. Click here for more information.

Following surgery, the patient will be started on a structured rehabilitation program.
Phase 1 emphasizes range of motion, which is critical to avoid knee stiffness.
Phase 2 incorporates strengthening. Approximately 6 weeks after surgery.
Phase 3 adds sport-specific exercises. Depending on the activity, approximately 3 to 5
months after surgery.
Phase 4 involves a supervised return to sports. Approximately 6 months after surgery.
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Bracing after an ACL reconstruction depends on the surgeon’s preference. Some surgeons
use no bracing while some use braces only during the rehabilitation phase. Still others recommend that patients always use a brace. Click here for more information.

Usually, a year following surgery, the doctor will evaluate the knee to measure the final results
of the reconstruction in these areas:
1. Motion
2. Stability
3. Symptoms such as pain or swelling
4. How well the knee functions in daily living
5. Whether or not the patient has been able to return to sports
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Stiffness in the joint, or lack of extension, is the most common complaint. This is why it is important to wait for motion to return and swelling to go down before surgery, and to follow the rehabilitation instructions given by the doctor and therapist. Failure of the graft, reinjury to the ACL, or injury to other structures in the knee are possible, and can cause recurrent instability. Blood clots and infection in the joint are very rare occurrences.
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Some partially torn ACLs, particularly in children and adolescents, may heal without surgery. However, a complete tear of the ACL rarely heals. Click here for more information.

Surgery is not required for all ACL injuries. Partial tears, in which a physical examination shows a relatively stable knee, may be treated with bracing and rehabilitation. Even some patients with complete ACL tears do not need reconstruction. These “copers” are typically older patients with lower physical activity, who do not participate in pivoting and cutting activities.

One reason to reconstruct the ACL is to provide knee stability that allows for return to activities and sports. Another reason is to provide knee stability in order to prevent more injury, such as a meniscal tear, which may eventually lead to degenerative joint disease.

An MRI is not always required to diagnose an ACL tear. An ACL tear can be accurately diagnosed with a physical examination. However, when the knee is very swollen and painful, an accurate examination can be difficult. Also, an MRI can be useful to reveal other associated injuries such as meniscal tears, a PCL tear, or injury to other supporting structures.

There are advantages and disadvantages to the many technical aspects of an ACL reconstruction including the type of graft, methods of securing the graft, and rehabilitation protocols. There is no clear consensus as to which graft is best. In the end, the surgeon’s experience with the chosen technique and the patient’s commitment to the rehabilitation program are probably more important factors in a functional outcome.

Rehabilitation programs after ACL reconstruction are constantly evolving, shortening the return to sports. Most patients can start to return to their sports about 6 months after reconstruction.