Injury to the anterior cruciate ligament (ACL) is very common and usually the result of a twisting of the leg while applying full downward pressure.
Review Date 4/9/2018
Updated by: C. Benjamin Ma, MD, Professor, Chief, Sports Medicine and Shoulder Service, UCSF Department of Orthopaedic Surgery, San Francisco, CA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.