The anterior cruciate ligament injury, or ACL injury for short, is usually the result of the excessive twisting of the knee that occurs when the athlete suddenly changes direction while his foot is still firmly planted on the ground. Being a ligament that forms the connection between the femur and the tibia, an ACL injury is considered a sprain and is graded according the following scale:
- Grade 1 Sprain: Grade 1 sprain occurs when the ligament is only slightly damaged. Thus, it can still provide stability to the knee joint.
- Grade 2 Sprain: Grade 2 sprain occurs when there is a partial tear in the ligament to the point that it becomes loose.
- Grade 3 Sprain: Grade 3 sprain occurs when there is a complete tear in the ligament or when the ligament is completely cut in half. Instability of the knee joint is the main symptom.
The ACL, which is located inside the knee joint, serves as the primary restraint to limit the anterior translation of the tibia and also serves as the secondary restraint to tibial rotation. When the ACL is injured, a combination of anterior translation and rotation of the tibia is observed. An ACL injury brought about by contact and high-energy impact is usually associated with injuries to other structures in the knee such as the articular cartilage, meniscus and other ligaments.
Apart from the high demand and high contact sports mentioned above, females have been shown by studies to be at greater risk for an ACL injury due to the femorotibial angle created by their wider hips.
Symptoms of an Anterior Cruciate Ligament Injury
An Anterior Cruciate Ligament injury is usually accompanied by an audible pop when the athlete suddenly changes direction or lands from a jump. Instability as described by buckling or walking on uneven surfaces is often the main complaint of the athlete. Other typical symptoms include:
- Pain that is often accompanied by swelling
- Loss of full range of motion of the knee joint
- Tenderness around the knee joint area
Diagnosis of an Anterior Cruciate Ligament Injury
Diagnosing an Anterior Cruciate Ligament injury involves a physical examination conducted by a health professional in addition to imaging studies.
For the physical examination, the examiner may do one of the following tests:
- Lachman Test: The Lachman test is the most sensitive test for an ACL injury and is done with the knees flexed at a 30-degree angle. The examiner holds the femur with one hand while he tries to anteriorly translate the tibia with the other hand. A translation of at least 1.0 centimeter anteriorly is indicative of an ACL injury.
- Anterior Drawer Test
- Pivot Shift Test
The gold standard for diagnosing an ACL injury is the Magnetic Resonance Imaging (MRI) scan with a sensitivity of around 90 to 98%. An MRI may also identify bone bruising which is often present in ACL injuries.
Treatment of an Anterior Cruciate Ligament Injury
First Aid Treatment for an Anterior Cruciate Ligament Injury includes RICE – raise, elevate, compress and elevate. Treatment options for an Anterior Cruciate Ligament injury depends highly on the patient’s needs given that a torn ACL cannot heal without surgery. An athlete trying to return to sports will most likely require more invasive procedures than a less active individual who just wants to walk comfortably.
Nonsurgical treatment options include:
- Knee brace to prevent instability
- Physical therapy to restore function of the knee joint and to strengthen the leg muscles that surround it
Invasive procedures include:
- Surgical repair using hamstring tendon grafts: This surgical procedure comprises the majority of the surgeries performed for ACL tears and offers the fastest recovery time with less anterior knee pain
- Intra-articular reconstruction standard for treating ACL tears is usually done when the injury happened within the past six hours
The anterior cruciate ligament injury is one of the most common types of knee injuries that usually occur in high demand sports such as football, soccer and basketball.