A baker's cyst is seen as a swelling behind the knee. It forms when joint fluid collects behind the knee. The swelling may be due from inflammation or from other causes, like arthritis. The condition can be seen in both adults and children.
Review Date: 11/9/2012 Reviewed By: A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, David R. Eltz, Stephanie Slon, and Nissi Wang. Previouly reviewed by Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine; and C. Benjamin Ma, MD, Assistant Professor, Chief, Sports Medicine and Shoulder Service, UCSF Dept. of Orthopaedic Surgery (6/4/2011).