The most common cause of knee swelling and pain is a meniscal tear. Fortunately, not all meniscal tears are created equally, and some are fairly well tolerated by individuals. At best, they can cause some painless clicking and a little soreness, but the severe ones can result in severe pain, swelling and popping with activity.
Within the knee there are two menisci, which are semi lunar fibrocartilaginous discs that serve as shock absorbers to lessen the stress transmitted across the knee. There is one meniscus on the inner (medial) portion of the knee and another on the outer (lateral) portion. Together, they are able to withstand the daily twisting and pounding our bodies’ experience. Mere walking, for instance, can generate forces across the knee ranging from two to five times body weight. When one considers that the average person takes more than one million steps a year you start to realize how durable these structures are meant to be.
There are an estimated 850,000 meniscal procedures performed in the United States yearly by orthopedists. As clinicians, it is important for us to distinguish between sports-related meniscal injuries in younger more active individuals versus degenerative tears in older individuals. Sports-related meniscal injuries account for roughly one third of all patients with torn menisci. Pivoting sports such as football and basketball are associated with the greatest number of injuries.
Most patients report an acute onset of sharp pain in the knee, usually following a twisting injury in which the knee is flexed and the foot firmly planted on the ground. Typical symptoms may include swelling, catching, and pain when squatting or climbing stairs. The onset of swelling is generally delayed a couple of days in isolated meniscal injuries, which differs from the immediate swelling seen with ligament tears such as the ACL (anterior cruciate ligament). Once the suspected diagnosis has been confirmed by thorough examination and appropriate imaging studies such as an MRI, the decision can be made whether to treat the meniscal disease operatively or non-operatively.
Arthroscopic surgery allows direct visualization of the entire knee joint to identify the tear and also recognize any additional problems such as associated ligament tears or cartilage damage that can co-exist with meniscal tears. A relatively large amount of work can be done within the knee utilizing only a few small incisions. In general, the guiding principle in the surgical treatment of a torn meniscus is to remove only the torn unstable meniscal fragments while preserving as much of the intact portion as possible. On some occasions, if the meniscal tissue is not severely damaged, the meniscus can be repaired to allow the tissue to heal.
The arthroscopy is done as an outpatient procedure and patients typically go home the same day with crutches. Soreness after debridement of a torn meniscus lasts anywhere from five to ten days and a post-operative course of physical therapy is started immediately to regain motion and decrease swelling.
Meniscal tears are extremely common, and once they become symptomatic, they can be properly diagnosed and treated. Arthroscopic surgery is a safe and reliable way to trim the irritating meniscal tear in order to initiate rehabilitation and a return to normal activities.
