Orthopedics Hip & Knee Meniscus Injuries An Overview of Meniscal Cysts By Jonathan Cluett, MD twitter linkedin Jonathan Cluett, MD, is board-certified in orthopedic surgery. He served as assistant team physician to Chivas USA (Major League Soccer) and the United States men's and women's national soccer teams. Learn about our editorial process Jonathan Cluett, MD Medically reviewed by Medically reviewed by Stuart Hershman, MD on January 25, 2020 linkedin Stuart Hershman, MD, is board-certified in orthopaedic surgery. He is the director of adult spinal deformity & complex spinal reconstruction at Massachusetts General Hospital and is on the faculty at Harvard Medical School. Learn about our Medical Review Board Stuart Hershman, MD on January 25, 2020 Print Table of Contents View All Symptoms Causes Diagnosis Treatment A meniscal cyst is a collection of joint fluid caused by a tear within the meniscus cartilage, the joint pad over the knee. It may have no symptoms, or it may cause pain, swelling, or mechanical issues with the knee. Meniscal cysts are most commonly reported in 20- to 30-year-old males and are usually associated with a specific type of meniscal tear called a horizontal cleavage tear, which may be caused by over-rotation of the knee or direct impact to the knee. Magnetic resonance imaging (MRI) or ultrasound may be necessary to diagnose a meniscal cyst. Treatment involves lancing and draining the cyst, although it will commonly return unless the underlying meniscus tear is also treated. Symptoms Meniscal cyst symptoms may not always appear, but when they do, the most common symptoms are: Pain in the knee when standingTenderness directly over the joint line of the kneeA bump or lump at the cyst site: Cysts are usually found near the lateral meniscus (outside of the knee)A cyst that becomes more visible as the knee extends, though the bump itself may be painlessSize fluctuations in the cyst, though it may also remain seemingly unchangedSwelling in the knee joint or locking of the knee joint Causes Cysts may be caused by degeneration of the meniscus itself (related to age or osteoarthritis) or by direct injuries, such as impact to the front or side of the knee, an over-rotation of the knee, or disproportionate force on the knees, such as when running on uneven surfaces. Any of these instances may result in a tear of the meniscus cartilage. This then allows synovial fluid to leak out of the joint. A meniscal cyst is not a true cyst, but rather an outpouching of displaced joint fluid (synovial fluid). It is part of the body's natural healing response to injury. The body is constantly making new synovial fluid and absorbing excess fluid. However, when fluid escapes the joint, it can collect and form the pouch that is a meniscal cyst. The cartilage tear can act as a one-way valve, where fluid can escape the joint into the cyst, but doesn't come back out the other way. Because of this, the cyst will continue to collect fluid. Risk factors for meniscal cysts include: Previous knee injury or meniscal injuryParticipation in contact sports or any sports in which there's a frequent twisting of the knee joint, such as football, soccer, rugby, or tennisIncreasing age or osteoarthritis, both of which cause a breakdown in menisciAssociated ligament injuries, such as a torn anterior cruciate ligament (ACL) Diagnosis A physician will ask specific questions related to knee pain, popping sounds, and any recent injuries or impact to the knee to first determine if a meniscal tear has occurred. A meniscal cyst can generally be palpated, and a doctor will then test the knee's range of motion to ensure no torn pieces of cartilage are trapped in the joint. Common tests for assessing meniscal tears and other knee injuries are the McMurray test, the Apley test, the Stienmann I test, the Payr's test, Childress' sign, and the Ege's test. Further diagnosis may be confirmed by magnetic resonance imaging (MRI) to see both the cyst and the corresponding tear. Meniscal Cysts vs. Baker's Cysts Meniscal cysts are similar to popliteal or Baker's cysts, but the latter are located in the back of the knee joint. In addition, a popliteal cyst is seen with many types of knee joint problems that lead to fluid accumulation or knee swelling. Therefore, they can occur when there is a meniscus tear, but also with arthritis, ligament injuries, and other problems that lead to knee swelling. Treatment Pain resulting from an associated meniscal cyst can be treated with occasional ice application and dosing of anti-inflammatory medications, while the cyst itself may be drained with a needle in a physician's office. However, unless the underlying cause of the tear is addressed (or the tear heals itself), the cyst will usually return. Surgery Surgery may not always be necessary for a meniscal tear, though if your doctor recommends it, the method most commonly used is a minimally-invasive arthroscopic surgical approach. Once the tear has been addressed, the meniscal cyst will usually decompress and less commonly returns. While it is possible for the cyst to come back, it is unlikely. Removing the actual cyst is not necessary; simply addressing the cause of the cyst is the better treatment for this problem. Physical Therapy for a Meniscus Tear A Word From Verywell It is important to understand that while called a cyst, a meniscal cyst is really just a pouch of dislocated joint fluid. It is not an abnormal growth and it is not a tumor. It is simply a collection of normal synovial fluid that has escaped to an abnormal location. If you aren't experiencing any pain, you may resume normal activities right away. If you do feel some pain, swelling, or locking of the knee, work with your care provider to determine the next best steps. Getting to the Bottom of Your Knee Pain Was this page helpful? Thanks for your feedback! Dealing with joint pain can cause major disruptions to your day. Sign up and learn how to better take care of your body. Click below and just hit send! Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit Article Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Crowell MS, Westrick RB, Fogarty BT. Cysts of the lateral meniscus. Int J Sports Phys Ther. 2013;8(3):340-348. Hulet C, Locker B, Beguin J, et al. Arthroscopic management lateral meniscal cysts: about 105 cysts with 5 years of follow-up. Eur J Orthop Surg Traumatol. 2000;10:125. doi:10.1007/BF02803108 Chen H. Diagnosis and treatment of a lateral meniscal cyst with musculoskeletal ultrasound. Case Rep Orthop. 2015;2015:432187. doi:10.1155/2015/432187 Kose O, Erol B, Ozyurek S, Ege T. A giant medial parameniscal cyst of the knee joint. BMJ Case Rep. 2013;2013:bcr2013009440. doi:10.1136/bcr-2013-009440 Ercin E, Kaya I, Sungur I, Demirbas E, Ugras AA, Cetinus EM. History, clinical findings, magnetic resonance imaging, and arthroscopic correlation in meniscal lesions. Knee Surg Sports Traumatol Arthrosc. 2012;20(5):851-856. doi:10.1007/s00167-011-1636-4 Demange MK. Baker's cyst. Rev Bras Ortop. 2015;46(6):630-633. doi:10.1016/S2255-4971(15)30317-7 Additional Reading Gupta Y, Mahara D, Lamichhane A. McMurray's test and joint line tenderness for medial meniscus tear: Are they accurate? Ethiop J Health Sci. 2016;26(6):567–572. doi:10.4314/ejhs.v26i6.10 Washington Orthopaedics & Sports Medicine. Meniscal cyst. 2019.