More than half of all ACL injuries are accompanied by damage to other knee structures such as cartilage, meniscus, and other ligaments. Based on their severity, ACL injuries can be graded as:
- Grade 1 Sprain: In Grade 1 sprains, the ligament is only mildly damaged, and the knee joint is still stable.
- Grade 2 Sprain: This is also known as a partial tear of the ligament, where the ligament has stretched to the point it has become loose.
- Grade 3 Sprain: A Grade 3 Sprain is characterized by the knee joint becoming unstable due to the complete tear of the ligament.
Most ACL injuries are Grade 3 sprains, i.e., a complete tear of the ligament. Partial tears are very rare and uncommon.