A meniscal cyst is a fluid-filled sac that forms within or next to the meniscus in the knee joint, often developing alongside a meniscal tear. It contains synovial fluid, the natural lubricating fluid found in joints. While not considered serious, these cysts can cause discomfort and affect knee function.
Understanding Meniscal Cysts
The meniscus consists of two C-shaped pieces of cartilage located in the knee, positioned between the thigh bone (femur) and the shin bone (tibia). These cartilages act as shock absorbers, distribute weight across the joint, and help stabilize the knee.
A meniscal cyst develops when a meniscal tear allows synovial fluid to escape from the knee joint. This fluid collects in a sac adjacent to the tear. The fluid typically cannot flow back into the joint, leading to continuous accumulation. These cysts are most frequently associated with horizontal or complex meniscal tears and are commonly found near the joint line. While meniscal tears are common, the formation of an associated cyst is less frequent.
Recognizing a Meniscal Cyst
Individuals with a meniscal cyst often experience localized pain along the joint line. Swelling around the knee is another common symptom, and a palpable lump or firm bump may be felt directly over the affected area, which can become more noticeable when the knee is extended.
Other indicators can include clicking or locking sensations in the knee, although these are less specific to the cyst itself and more often related to the underlying meniscal tear. The pain may worsen when standing on the affected leg.
Diagnosis typically begins with a physical examination, where a doctor can often feel the discrete mass over the tender joint line. Magnetic Resonance Imaging (MRI) is considered the definitive diagnostic tool, as it can clearly show both the fluid-filled cyst and any associated meniscal tear.
Treating a Meniscal Cyst
Treatment for a meniscal cyst depends on its size, symptom severity, and the presence of an underlying meniscal tear. Conservative, non-surgical methods are often the first approach. These may include rest, applying ice to the affected area, and taking non-steroidal anti-inflammatory drugs (NSAIDs) to manage pain and swelling.
Physical therapy can also be beneficial, focusing on exercises to improve knee strength and mobility. In some cases, a doctor may perform an aspiration, which involves draining the fluid from the cyst with a needle. However, cysts may return after aspiration if the underlying meniscal tear is not addressed.
Surgical intervention is considered when conservative treatments do not provide relief or if the cyst is large and significantly symptomatic. Surgery typically involves excising (removing) the cyst and repairing or trimming the associated meniscal tear. Addressing the tear is often necessary to prevent the cyst from recurring.