Written by: Dr. Frederick Buechel, Jr.
What Is A Meniscus?
The meniscus is a tough, smooth, rubbery C-shaped piece of cartilage (fibrocartilage) that is wedged shaped and sits between the cartilage surfaces of the bones. It distributes your body weight more evenly across the knee joint and improves the stability of the joint. Each knee has two menisci, the medial (inside) and the lateral (outside). They attach to the top of the shin bone (tibia) and make contact with the thigh bone (femur). They act as shock absorbers during weight-bearing activities.
- The front ⅓ is called the “anterior horn”.
- The middle ⅓ is called the “body”.
- The back ⅓ is called the “posterior horn”.
The wedged shaped profile helps maintain the stability of the joint by keeping the rounded femur surface from sliding off the flat tibial surface. The meniscus is nourished by small blood vessels coming in from the outer edges (vascular zone). The meniscus also has a large area in the inner ⅓ that has no direct blood supply (avascular zone). Between these zones is an area where the blood supply is minimal.
What Is A Torn Meniscus?
A torn meniscus occurs when the meniscus develops structural damage from an acute traumatic event or repetitive microtraumatic events. Tears can occur in different parts of the meniscus and with different tear patterns. Tears are commonly described as radial, transverse, horizontal, flap, bucket handle, macerated, root, and intrasubstance tears. When there is an injury to the meniscus in the avascular areas, these tears tend not to heal. Some tears in the vascular zone have the potential to heal, sometimes. Some tears cause significant pain and symptoms, while other small tears sometimes go unrecognized.
What Are The Causes Of A Meniscus Tear?
People sometimes know exactly when they tore their meniscus, others have no recollection of a specific event that may have caused the tear. Tears can be from an acute event. These include:
- A sudden twist or turn of the knee, tripping and twisting the knee, squatting or twisting during an aerobic exercise class, getting tackled in a sports event.
- Tears can occur from several microtraumatic events that culminate in structural integrity loss and an eventual tear of the meniscus.
- Tears can occur from a degenerative condition of the knee bone surface cartilage like osteoarthritis, that causes mechanical damage and tearing of the meniscus.
What Are The Signs And Symptoms Of A Torn Meniscus?
The most common symptom of a meniscus tear is knee pain. The pain occurs from several different activities including twisting, squatting, rising and sitting, and with pressure against your other knee when sleeping.
- Knee Pain along the joint line.
- Pain on the joint line with twisting, squatting, rising and sitting.
- Pain when applying pressure against your other knee when sleeping.
- Popping or clicking in the knee at the level of the joint line.
- Tenderness when pressing on the meniscus at the joint line.
- Limited Motion of the knee from pain that occurs with pressure on the meniscus during full extension or deep flexion.
- Torn fragments of meniscus may catch in the joint, causing locking, catching, reduced motion, sudden giving away, or sharp pain.
- Knee Swelling can be the seen in the front of the knee or behind the knee.
- Inside the knee, the swelling occurs from joint fluid overproduction as the knee responds to the irritation of the torn meniscus by making extra lubricating fluid.
- Once fluid increases inside the knee joint, it can escape out the back of the joint capsule through a valve that allows the pressure to be relieved. This fluid then accumulates behind the knee and is referred to as a popliteal cyst or “Bakers Cyst”.
- Popliteal cysts can increase and decrease throughout the day or weeks as the fluid gets resorbed and produced
It is common for patients to have a meniscus tear with symptoms that may be significant in the beginning but subside within days or weeks to a much more tolerable level. Sometimes the symptoms get worse and worse over days or weeks and do not improve with time.
Can You Leave A Meniscus Tear Untreated?
Some tears that are asymptomatic and small can be left alone and treated without surgery initially. This may include a temporary knee brace and rehabilitation to keep the knee muscles strong while the knee is not bearing as much weight. This approach is most effective for small tears (5 millimeters or less) that are minimally symptomatic. Taking orally or injecting anti-inflammatories to reduce swelling can be done if surgery is not an option or if surgery is not wanted by the patient. Larger tears and painful tears are commonly treated arthroscopically due to the irritating symptoms that make the patient uncomfortable with activities of daily living, sports activities and difficulty with sleeping without pain.
How Do You Repair A Meniscus Tear?
What Are The Treatments For A Torn Meniscus?
- Knee Arthroscopy – a procedure in which the doctor examines your knee with an instrument called an arthroscopy to diagnose or treat the cause of pain, swelling, tenderness, or weakness in your knee.
- Knee Chondroplasty – a procedure in which the worn or damaged articular cartilage surfaces are trimmed and smoothed of their degenerated edges in arthritic knees, while debris is removed with suction shaving devices.
- Knee Synovectomy – An arthroscopic synovectomy is the removal of inflamed inner lining tissues of the knee joint (the synovium) that is abnormally growing, and can cause swelling and pain in the knee.
Select Relevant Publications
Buechel F., Buechel F., Conditt M. (2016) Robotic-Arm Assisted Unicompartmental Knee Arthroplasty (MAKO). In: Scuderi G., Tria A. (eds) Minimally Invasive Surgery in Orthopedics. Springer, Cham. Link to Article
Buechel FF Sr, Buechel FF Jr, Pappas MJ, Dalessio J. Twenty-year evaluation of the New Jersey LCS Rotating Platform Knee Replacement. The journal of knee surgery. 2002 Spring;15(2):84-9. Link to Article
Buechel, Frederick F. Sr. MD; Buechel, Frederick F. Jr. MD; Pappas, Michael J. PhD; D'Alessio, Jerry MS. Twenty-Year Evaluation of Meniscal Bearing and Rotating Platform Knee Replacements. Clinical Orthopaedics and Related Research. July 2001 - Volume 388 - Issue - pp 41-50. Link to Article