What is the Anterior Cruciate Ligament (ACL)?
The knee is the largest and most complex joint in the human body, and the ACL is one of the four major ligaments surrounding the knee joint. A ligament is a band of dense connective tissue that connects one bone to another bone. Other ligaments supporting the knee joint include the posterior cruciate ligament, lateral collateral ligament, and medial collateral ligament.
Functions of Anterior Cruciate Ligament
ACL is one of the primary stabilizing ligaments of the knee. Its main function is to prevent anterior displacement of the tibia relative to the femur that can result in either a partial or complete tear of the ligament. In addition, it also helps prevent medial rotation of the tibia and helps avoid hyperextension of the knee to a certain extent.
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Mechanisms of Anterior Cruciate Ligament Injury
There are two broad mechanisms by which an individual can face an ACL injury.
- Contact – Tackles or collisions, most common in sports like soccer, basketball, and American football.
- Non-contact – Sudden stops, change of direction, and bad landings.
About 70 to 75% of ACL injuries are non-contact in nature, and it almost always occurs due to an individual’s lack of ability in handling rapid deceleration. However, it is also possible for secondary injuries to the medial collateral ligament (MCL), medial meniscus, or lateral meniscus to coincide with an ACL injury.
Furthermore, individuals suffering an acute knee injury, such as ACL injury, are seven times more likely to develop knee osteoarthritis approximately 25 years following the initial damage than those with no history of an acute knee injury.
Classic Signs and Grades of the Injury
- The client hears a “pop” sound!
- The client experiences severe pain, continuing the activity becomes difficult.
- The client encounters immediate swelling and inflammation within hours around the knee joint.
Ligament injuries are called sprains, and there are three grades to them.
- Grade 1 stands for a partial tear with no change in joint instability.
- Grade 2 stands for a partial tear with minor joint instability.
- Grade 3 stands for a complete tear with total joint instability.
Injury Management
Conservative/ Non-Surgical Treatment
Introduce lifestyle modifications to avoid high-demand activities. Muscle-strengthening exercises can be started after a significant reduction in swelling. A knee brace can be used if needed.
Non-Conservative/ Surgical Treatment
For week 1
Icing and elevation are a must to reduce swelling. By the end of the week, the patient must reach full extension of the knee and 70 degrees of flexion. Add strengthening exercises for hamstrings, quadriceps, and vastus medialis oblique (VMO) muscle. Use of a crutch for locomotion is recommended.
For weeks 3-4
Introduce the patient to partial weight-bearing exercises and sustenance to walking. In addition, the use of crutches should be reduced and strengthening exercises should be continued.
Week 5
The crutch use discontinues, and the coach introduces closed chain exercises to improve proprioception and coordination and add static balance training.
Week 10
Introduce dynamic balance training and isokinetic exercises.
If you have any questions regarding Anterior Cruciate Ligament injuries, do let us know in the comments below.
Author: Pankaj Narsian (INFS Faculty)
