Cyst, Baker

Symptoms

Although a Baker cyst is generally not a dangerous condition, it can impair an athlete's ability to train. This cyst, characterized by excess swelling in the back of the knee, presents as a smooth, compressible bulge and has the feeling of a fluid-filled sac. The cyst will be more prominent with the extension of the knee. Cysts will frequently soften with flexion of the knee to 45 and may sometimes disappear. The area of swelling can be quite painful, especially if the cyst ruptures. In addition, larger, painful cysts can limit the range of motion of the knee, thus limiting the athlete's ability to participate in training. Although the medical community generally views this condition as benign, it can be debilitating to active individuals.

Baker cysts are found in both children and adults; however, their prevalence tends to increase with age. There are two peaks in incidence, one occurring between ages 4 and 7, the second between ages 35 and 70. Interestingly, younger patients rarely have any associated joint problems, while older patients often have a variety of conditions affecting the knee. The presence of a Baker cyst may actually be an indication that there are other mechanical or inflammatory problems with the knee. Meniscal tears, arthritis, and ligament damage are all conditions that have been associated with Baker cysts in adults. Athletes who develop a cyst after trauma to the knee should be wary of possible soft tissue damage within the joint.

While there are several injuries that can lead to the development of a Baker cyst, there are also separate conditions that may imitate it, such as [Page 343]deep vein thrombosis (blood clots), aneurysms, muscle strains, and soft tissue tumors. Some of these conditions, especially blood clots, are more serious and may require prompt evaluation by a physician.

Anatomy and Pathophysiology

To understand how a Baker cyst is formed, it is important to understand the anatomy of the knee. The knee is a compound joint involving three bones: the tibia, the femur, and the patella, otherwise known as the kneecap. The medial and lateral menisci are structures composed of cartilage that cushion the impact between the two heads of the femur and the tibia. As noted earlier, injuries of the menisci can be related to the development of a Baker cyst.

...