Anatomy & Background
The knee is the largest joint in the body. It was designed for bearing weight, stability and mobility. The knee is composed of four bones and three bone-to-bone joints. These are the patella-femoral joint, tibio-femoral joint and the tibio-fibular joint. Attached to the joint surface of the tibia are two fibro-cartilagenous structures called menisci. The menisci lie between the tibia and femur. There is a medial meniscus on the inner aspect of the knee and a lateral meniscus on the outside aspect of the knee.
Function of Menisci
- The menisci are “C” shaped fibro-cartilage wedges. The wedge shape keeps the rounded joint surface of the femur from sliding off the flat tibia. This adds stability to the knee joint.
- The menisci also function to cushion the knee joint during weight bearing activities.
- Both medial and lateral menisci help distribute the body’s weight evenly over the knee joint and prevent wear and tear of the chondral (joint) cartilage of the femur and tibia.
Cause of a Meniscal Tear
- Traumatic injury to the knee like getting hit on the outside or inside of the knee. Sometimes this trauma can be associated with medial collateral or cruciate ligament injuries.
- Degeneration or age related wear-and-tear of the knee and meniscus.
- The most common occurance of injury is a combination of a bending and a twisting motion while the foot is planted firmly on the ground.
- Knee pain, especially over the joint line that varies, based on which meniscus is injured, the medial or lateral.
- Loss of motion specifically flexion (bending) and extension (straightening).
- Swelling of the knee joint.
- Pain with walking and weight bearing, especially with bending and twisting movements.
- A popping or clicking sound within the knee.
- Weakness, locking and buckling of the knee can be reported with meniscal injuries.
- A clinical examination that includes a good medical history and a clinical examination that uses several special tests can often be used to diagnose a meniscal or cartilage injury or tear.
- X-rays cannot visualize a meniscus, but they can determine if there is any degeneration or arthritis affecting the joint.
- An MRI can be useful for diagnosis because it can visualize the ligaments and menisci in the knee.
Degree of Tear
There are three degrees of meniscal or cartilage tears:
- Small tears often cause mild pain while walking, squatting and during activities like rising from a chair. Symptoms typically improve in two to three weeks. There may be discomfort with twisting and bending motions.
- Moderate tears result in joint line pain, swelling, pain with walking and squatting. These symptoms may improve in two to four weeks with medication and physical therapy. If significant enough, these tears can get worse with time.
- Large tears result in pieces of the meniscus interfering with the joint mechanics. This can cause locking, buckling and an unstable feeling in the joint. The knee can also feel stiff. There can be moderate swelling, loss of motion, and difficulty walking, squatting and kneeling.
Treatment Meniscus Injuries
Treatment of a meniscal tear can be dependent upon many factors. These include the size of tear, the patient’s age, the patients activity level, motion restrictions, and pain level. When surgery is necessary, it can be done arthroscopically, which is minimally invasive. Some treatment options include:
- Conservative nonsurgical treatment including rest, ice, anti-inflammatory medication and physical therapy.
- Surgical repairs can usually be performed in younger patients and for longitudinal tears only in areas where circulation is prevalent. The outer or lateral meniscus responds better to a surgical repair than the medial meniscus on most occasions.
- Partial Meniscectomy can be performed to remove the torn sections of the meniscus.
- Complete Meniscectomy is usually avoided if possible to prevent early joint degeneration and early onset of osteoarthritis.
- A meniscal implant is a new treatment option. Patients must meet certain criteria for this procedure:
- Individuals should be under 40 years of age.
- There is no evidence of arthritis in the knee.
- There is good alignment of the knee.
- Pain and swelling is present and there is no response to other treatments.
Following a physical examination, your pain management specialist may recommend the following:
- Rest, to reduce the stress placed on the knee and meniscus.
- Crutches to reduce stress on the meniscus and knee joint.
- Ice to reduce swelling and inflammation.
- NSAIDS (non-steroidal anti-inflammatory drugs) to reduce inflammation.
- Physical therapy to reduce pain and swelling, and restore motion and strength to the knee.
- Surgical intervention depending on the severity of the tear and response to conservative non-operative treatment. (For more information on surgical interventions, see above).
Recovery from a meniscus or cartilage injury will depend on several factors:
- Age of patient
- Severity of injury
- Surgical vs. Nonsurgical intervention
- Condition of joint (for example: arthritic vs. non-arthritic)
- Activity level of the patient
- Any other procedures performed on the knee
- The general health and condition of the patient
As a general rule it takes 4-8 weeks to recover from a meniscus tear. If there are degenerative changes or arthritis of the knee it can take longer to recover. In general, the older the patient, the longer the recovery time tends to be.