Meniscal Cysts

Summary

A meniscal cyst is a small lump that can form on the side of your knee when fluid leaks out through a tear in the cartilage called the meniscus (Figure 1). This can happen if you hurt your knee, especially while playing sports. The cyst may cause pain, swelling, or a bump near the joint. Doctors use tests like an MRI scan to see the cyst and the tear. Some cysts go away with rest and medicine, but others may need surgery to fix the tear and remove the cyst. Most people get better and can go back to normal activities after treatment.

Introduction

A meniscal cyst is a small, fluid-filled lump that forms next to the knee joint. It usually develops when there is a tear in the meniscus, the cartilage that helps cushion and stabilize the knee. When the meniscus is torn—especially in a horizontal pattern—joint fluid can leak through the tear and collect outside the meniscus, forming a cyst. It tends to develop in the meniscus on the outer (lateral) side of the knee. People who are active or play sports are more likely to develop meniscal cysts, especially young to middle-aged adults. The cyst may cause symptoms like knee pain, swelling, or a small bump on the side of the knee. Some people may also feel tightness or a catching sensation when bending the knee.

How Meniscal Cysts Are Diagnosed?

To diagnose a meniscal cyst, a doctor will examine the knee and ask about any pain, swelling, or injuries. They may feel for a lump near the joint line or check for signs of a meniscus tear. If a cyst is suspected, the doctor may order an MRI scan, which is the best imaging tool for seeing soft tissues like cartilage and cysts. An MRI can show both the cyst and any tear in the meniscus. In some cases, an ultrasound may also be used to check for the presence of fluid near the knee joint.

Treating a Meniscal Cyst

Treatment for a meniscal cyst depends on how severe the symptoms are. If the cyst is small and not causing much pain, it may be treated with rest, ice, and anti-inflammatory medications to reduce swelling. Sometimes, a doctor may drain the cyst using a needle, but this usually only helps temporarily if the meniscus tear is not repaired. In many cases, treatment also focuses on managing the underlying meniscal tear, since the cyst often comes from that tear.

When Surgery Is Needed

Surgery may be needed if the cyst is large, painful, or keeps coming back. The most common surgical option is an arthroscopic procedure, where a small camera and tools are inserted through tiny incisions to repair or trim the torn meniscus. If the cyst is large or persistent, the surgeon may also remove it during the same procedure. Surgery is usually done as an outpatient procedure, meaning the patient can go home the same day.

What to Expect Long-Term

Most people who have a meniscal cyst recover well, especially if the underlying meniscus tear is properly treated. After surgery or other treatments, the pain and swelling usually go away, and the knee returns to normal function. However, if the tear is not repaired, the cyst may come back. With proper care and follow-up, the long-term outlook is very good for most people, and they can return to their usual activities without long-term problems.

Edited by Stephen Pinney MD, July 30th 2025.