Meniscal tears are a common cause of knee pain. The meniscus is a soft cartilage cushion that sits between the two bones of the knee, and providing cushioning and reducing the stress on the bone and hard cartilage surfaces. There are two menisci in the knee, the inner one called the medial meniscus, and the outer one being called the lateral meniscus. The inner edge of the meniscus is thin, and is the most common area where a tear will develop. Tears may be caused by a single traumatic event, particularly in young active individuals. Tears may also develop from repetitive trauma, particularly with repetitive kneeling, squatting or flexed knee activities. Finally, tears may develop in patients who have significant arthritis, which puts increased pressure on the meniscus and eventually leads to tearing. The blood supplied to the meniscus is localized to the outer third of the meniscus, near its attachments and into the lining of the joint. Therefore once the meniscus tears, there is a limited ability for healing to occur spontaneously. Most meniscal tears will remain symptomatic and will often progressively enlarge over time.
A tear may be suspected on physical examination but is confirmed by the MRI scan. A Grade III signal on MRI scan has a 95% chance of being a true cartilage tear. However, this does not automatically require arthroscopic surgery. As many as 40 percent of patients with torn cartilage (meniscus) can improve clinically without surgery through proper rehabilitation and medical management. This may include but is not limited to:
- anti-inflammatory medications to control swelling
and pain. - therapeutic exercises either under supervision
of a physical therapist or independently after
proper instruction:- this may include low resistance cycling
to allow the nutrients in the joint
fluid to penetrate the cartilage and
encourage healing - weight training to develop strength in
surrounding musculature - aerobic conditioning to improve endurance
- this may include low resistance cycling
- braces for support and to control swelling
- drainage of knee fluid and/or cortisone
injection if needed
A torn cartilage cannot “mend” itself but clinical improvement occurs if the “defective cartilage” no longer irritates the joint. It is possible that sometime later, the knee could again be aggravated by this same cartilage and require treatment.
Arthroscopic surgery becomes necessary if the knee does not respond to therapy, cannot tolerate the treatment, or symptoms recur frequently. A referral to the most appropriate specialist will be made when necessary.
The main concern with meniscal resection is the increased stresses on the joint surface, which may lead to progressive arthritis. In patients in whom the meniscus has been totally resected, a significant percentage will develop arthritic changes in the joint by 15 to 20 years after surgery. This arthritic progression so far does not appear to be as much of a problem in patients in whom a partial meniscectomy has been performed, particularly if it is possible to preserve the outer cushioning rim of the meniscus. However, even patients with a partial meniscectomy may go on to develop arthritic changes in the future. The best situation is clearly to have an intact meniscus in the knee.
