Dr Jessica Sammut
The ACL and how we test it
The ACL (anterior cruciate ligament) is a vital component of the knee joint, providing stability and support for the joint during activities such as walking, running, and jumping. The ACL is one of the four main ligaments in the knee, and it is located in the centre of the joint, connecting the femur (thigh bone) to the tibia (shin bone).
Injury to the ACL is common, especially in sports that involve sudden stops or changes in direction, such as basketball, soccer, and football. When the ACL is injured, the knee may become unstable, and the person may experience pain, swelling, and a limited range of motion.
There are several ways in which the ACL can be injured. One of the most common is through a sudden twisting or pivoting motion, which can cause the ligament to tear. This type of injury often occurs during sports activities when the foot is planted on the ground, and the body rotates around it.
Another common cause of ACL injury is a direct blow to the knee, such as a collision with another player or a fall onto a hard surface. This type of injury can also cause the ligament to tear or become damaged.
In some cases, an ACL injury may be a partial tear, which means that only part of the ligament is damaged. In other cases, it may be a complete tear, which means that the ligament is completely severed.
The Lachman test is a clinical test used to diagnose injury of the anterior cruciate ligament (ACL), and current research shows it is recognized as the most sensitive, reliable and valid test for ACL integrity (Benjaminse et al. 2006)
To perform this test:
Have your patient in a supine position
bring your patient’s test leg into 30 degrees of flexion.
Fixate the femur with your other hand
Bring the tibia into slight external rotation
Try to translate the tibia anteriorly
This test is positive if:
a soft or mushy end feel
if the anterior translation of the Tibia in the injured leg is at least three millimetres greater compared to the uninjured leg.
Remember that your test results in a chronic situation will always be more valid than in an acute situation. The reason for this is that swelling and muscle spasms in an acute situation will have a negative influence on your test results.
Treatment for an ACL injury depends on the severity of the injury and the individual's overall health and lifestyle. In some cases, rest and physical therapy may be enough to help the knee heal on its own. However, in more severe cases, surgery may be necessary to repair or reconstruct the ligament.
Rehabilitation after an ACL injury is crucial, as it can help restore strength and flexibility to the knee and prevent future injuries. This may include exercises to improve the range of motion, strengthen the muscles around the knee, and improve balance and coordination.
Overall, the ACL is a vital component of the knee joint, and an injury to this ligament can have a significant impact on an individual's mobility and quality of life. If you suspect that you may have injured your ACL, it is important to seek medical attention as soon as possible to ensure proper diagnosis and treatment.
Resources and references:
Monk AP, et al, ‘Surgical versus conservative interventions for treating anterior cruciate ligament injuries’, Cochrane Database of Systematic Reviews 2016, Issue 4
Renato Andrade, et al, ‘How should clinicians rehabilitate patients after ACL reconstruction? A systematic review of clinical practice guidelines (CPGs) with a focus on quality appraisal (AGREE II)’, Br J Sports Med 2020;54:512–519