Clinical features

Baker's cysts can present as a chronic condition or as an acute one where the cyst ruptures.

In children it is typically an incidental finding and parents usually note a painless mass in the popliteal area (1). Adults may complain of a swelling, a mass, pain, or stiffness which is worsened by activity (2). In a study which observed 82 patients with surgically treated cysts

• a mass was the main concern in 68 patients
• local aching was seen in 46 patients
• stiffness was present in 13 patients
• swelling was present in 9 patients (2)

The swelling seen in popliteal cyst

• is present at the medial aspect of the popliteal area
• is round, smooth, fluctuant, trans-illuminates and is often tender
• increases in tension on extension of the knee and soften or disappear when the knee is flexed to 45 degrees - (Foucher's sign) (2)

Reference:

• 1. Fritschy D et al. The popliteal cyst. Knee Surg Sports Traumatol Arthrosc. 2006;14(7):623-8
• 2. Handy JR. Popliteal cysts in adults: a review. Semin Arthritis Rheum. 2001;31(2):108-18