Anterior Cruciate Ligament Injury

Anterior Cruciate Ligament Injury of the Knee Joint

Commonest knee injury is an anterior cruciate ligament sprain or tear. Knee injuries are increasing with increasing sporting activities.
High demand sports like soccer, football, and basketball are more likely to injure the anterior cruciate ligaments.

Anatomy

Three bones meet to form the knee joint: the thighbone (femur), shinbone (tibia), and kneecap (patella). Patella provides protection to the knee joint.
Bones are connected to other bones by ligaments. There are four primary ligaments in the knee. They keep the bones together and stable.

Collateral Ligaments

There are 2 collateral ligaments, one on either side of the knee. The medial collateral ligament (seen inside) and the lateral collateral ligament (outside). These control the sideways motion of the knee and brace it against unusual movement.

Cruciate Ligaments

These are found inside the knee joint. They cross each other to form an “X” with the anterior cruciate ligament in front and the posterior cruciate ligament in back. The cruciate ligaments control the back and forth motion of the knee.
The anterior cruciate ligament runs diagonally in the middle of the knee. It prevents the tibia from sliding out in front of the femur, provides rotational stability to the knee.
ACL injury is often associated with injury to collateral ligaments.
Injured ligaments are considered “sprains” and are graded based on severity.

Grade 1 Sprains. The ligament is mildly damaged. It has been slightly stretched, but the knee joint is stable.
Grade 2 Sprains. A Grade 2 Sprain stretches the ligament to the point where it becomes loose. Often called partial tear of the ligament.
Grade 3 Sprains. Also called complete tear of the ligament. The ligament has been split into two pieces, and the joint is unstable.

Most ACL injuries are complete or near complete tears.

MECHANISM OF INJURY

Commonly occurs as a result of twisting force on a semi flexed knee.
Changing direction rapidly, Stopping suddenly ,Slowing down while running ,Landing from a jump incorrectly ,Direct contact or collision

Symptoms

injury to anterior cruciate ligament, might produce a “popping” noise/sound of something tearing . Other symptoms include Pain and swelling.
Swelling is due to accumulation of blood (haemarthrosis), Discomfort while walking, Loss of full range of motion and Tenderness along the joint line

Physical Examination and Patient History

Anterior drawer test and lachman test + ve.
Anterior drawer test-patient lies supine with knee flexed to 90 degree. Examiner sits on the patients foot to stabilise it, holds the tibia with both hands with fingers placed behind the knee, thenar eminence over the lateral condyles of tibia and tip of thumbs over the femoral condyles.
Tibia is gently pulled forward; normally there is a glide up to half a cm, anything more than this is suggestive of ACL injury.
Lachmann test- patient lies supine with knee flexed 15-20 degree. One hand supports thigh just above the knee, other hand holds the upper end of tibia. The extent of anterior glide indicates integrity of ACL.

Imaging Tests

X-rays: Ligaments are not visualised in x rays, but X ray is essential to rule out any associated fracture/bone avulsion.

MRI: Images soft tissues like the anterior cruciate ligament. However, it’s not always required to make the diagnosis of a torn ACL.

Treatment

Treatment- can be conservative (non-surgical) or operative

Nonsurgical Treatment

The less active, usually older, individual may be able to return to a quieter lifestyle without surgery.
A torn ACL will not heal without surgery. But nonsurgical treatment may be effective for patients who are elderly or have a very low activity level. If the overall stability of the knee is intact, the doctor may recommend simple, nonsurgical options.

Bracing- (for grade 1 and 2 injuries) Knee is immobilised for a period of 3-6 weeks followed by Physiotherapy. As the swelling reduces, rehabilitation program is started. Specific exercises will restore function of joint and strengthen the leg muscles that support it.

Surgical Treatment

Surgery may be required for full restoration of function of the knee. This will depend on several factors, such as severity of injury, activity level, and the patient’s individual needs.
For example, the young athlete involved in sports will require surgery to safely return to sports rebuilding the ligament. Most ACL tears cannot be sutured back together.
To surgically repair the ACL and restore knee stability, the ligament must be reconstructed. Torn ligament is replaced with a tissue graft, which helps new ligament to grow on.
Grafts can be obtained from several sources like the patellar tendon, Hamstring tendons quadriceps tendon, fascia lata.
Because the regrowth takes time, it may take six months or more before an athlete can return to sports after surgery.

Procedure.

Surgery to rebuild an anterior cruciate ligament is done with an arthroscope using small incisions.
Arthroscopic surgery is less invasive. The benefits of less invasive techniques include less pain from surgery, less hospital stay, and quicker recovery.
Unless ACL reconstruction is treatment for a combined ligament injury, it is usually not done right away. This delay gives the inflammation a chance to resolve, and allows a return of motion before surgery. Performing an ACL reconstruction too early increases the risk of arthrofibrosis, or scar forming in the joint, which may result in restriction of movements.

Rehabilitation

whether the treatment involves surgery or not, rehabilitation plays an important role. It will help to regain knee strength and motion.
If you have surgery, physical therapy first focuses on returning motion to the joint and surrounding muscles. This is followed by a strengthening program designed to protect the new ligament.
This strengthening gradually increases the stress across the ligament. The final phase of rehabilitation is aimed at a functional return tailored for the athlete’s sport.