The menisci, crescent-shaped fibrous cartilage between the shinbone and thighbone, are the shock absorbers of the knee. There are two in each knee, riding along each side of the knee like shock absorbers on a car. Like ligaments, they can be injured with severe twisting or jarring, weight-bearing movement. But unlike ligament injuries, meniscal injuries are not typically the result of traumatic events. They come from chronic stress. Repeated squatting or deep knee bends performed while putting pots and pans away in the kitchen, repairing a low fence or gate, or trying to get back in shape can cause the cartilage to separate horizontally or vertically. A torn fragment may be pushed into the inner knee, where it is crushed between the shinbone and thighbone. These injuries occur more frequently in men than in women, and more often in the medial meniscus (the one in the inner knee) than in the lateral (outer) one. Though not simple cartilage, the menisci are what people are usually referring to when they say someone suffered "torn cartilage in the knee."
Pain caused by the tear itself or the crushing of the fragment between the shinbone and thighbone usually is enough to send the injured looking for a physician. Pain from menisci tears differs from that of ligament sprains in that the knee will be tender along the joint line between the shinbone and thighbone on the side of the injured meniscus. The knee may lock, release, and then lock again because of the loose fragment interfering with normal motion. The knee may even click audibly.
The menisci are crescent-shaped shock absorbers within the knee that are typically injured by repetitive stress rather than a traumatic injury. With repeated abuse, tears (top) advance to more dramatic conditions (bottom). Surgery to remove these disks is the seventh most commonly performed surgical procedure in the United States. A cutaway view of the knee (bottom) shows an intact meniscus on the right and a meniscus with a bucket handle tear on the left.
Soreness at the joint line often helps the physician tell the difference between ligament and meniscal injuries. Repair, if the tear is clean, provides the best prospect for long-term mobility, but the four months required for recovery is considered by some a high price to pay. Repair is superior to menisectomy–total removal of the meniscus–because those who underwent menisectomy in their twenties found themselves with arthritis in the knee in their late forties, a much younger age than usual for onset of arthritis. Nonetheless, menisectomy is the seventh most commonly performed operation in the United States. Ironically, if the meniscus is removed, recovery is rapid, and if you are an athlete, you may be back to your workouts in three weeks.
Partial menisectomy is also an option, and a much better solution than total removal. Often the part of the meniscus that tears is the part that bears only about 30 percent of the weight. It can be trimmed away if it cannot be repaired, and the recovery period will be about the same as for a menisectomy.
Meniscal replacements and transplants, though performed, are still experimental. No one knows what the long-term results will be.
This is a section from Dr. Jack E, Jensen′s book The One Stop Knee Shop. Read the next section Synovial Tissue Overgrowth and Irritation.