An Anterior Cruciate Ligament (ACL) injury occurs when the ligament, which stabilizes the knee joint, is torn or sprained. This type of injury is common in sports that involve sudden stops, jumps, or changes in direction, such as basketball and soccer. Symptoms often include pain, swelling, and a feeling of instability in the knee. Diagnosis typically involves a physical examination and imaging tests like an MRI. Treatment options vary based on the severity of the injury and may include rest, physical therapy, or surgery. Rehabilitation is crucial for restoring strength and function to the knee after an ACL injury.