The torn meniscus is on pace to become the most pervasive injury among all athletes. Here, we tell you what—exactly—a meniscus is, why tearing it is so common and what you can do about it. Plus, we compare and contrast A-Rod and Chipper Jones’ headline-grabbing cases.

Meredith Moore knew something was wrong. It was the winter and the runner and soccer player was doing squats in the gym when she felt a peculiar pain in her right knee. She stood, squatted again, and that same knee buckled underneath her. When the pain persisted a few days later, Moore, 30, marched into her doctor’s office in Washington, D.C., hoping he’d say it was a simple IT-band inflammation and send her on her way. But an MRI revealed a diagnosis Moore had been dreading: She had torn her meniscus. She needed surgery. And it would be at least six weeks before she ran another step.

This is the diagnosis no athlete ever wants to hear. It’s the feeling no athlete ever wants to feel: A twist... a pop… a sudden sharp, knife-like pain—and then your whole knee goes weak beneath you. Menisicus tears, while not usually career-ending, are nagging injuries that, when left untreated, can weaken the knee enough to derail an entire season—or longer. Just look at Texas Rangers reliever Mike Gonzalez—his meniscus gave out on him during Game 7 of the World Series, shrouding his status for the next season with a big question mark. Former Yankees slugger Alex Rodriguez tweaked his knee after hesitating during an attempt to run to home plate, missing 38 regular-season games as result of arthroscopic surgery to remove a portion of his meniscus. And Atlanta Braves veteran Chipper Jones suffered the same injury, spending 15 days—and 12 games—on the disabled list after his surgery (see sidebar, for a side-by-side comparison). Then there are countless other baseball, football, hockey, and soccer players and other athletes who suffer similar fates each season. Meniscus tears, unfortunately, are very common among athletes in all sports. The higher the velocity of the sport, the greater the risk of injury, so we see them a lot in hockey, basketball, tennis, and any sport that involves cutting and stopping. The meniscus is a relatively mobile structure with low blood supply, that’s why it’s susceptible to injury. There are an estimated 650,000 arthroscopic meniscal procedures, with a total number of 850,000 meniscal surgeries performed in the United States every year. And with contact sports on the rise among younger athletes, the rate of meniscus tears and similar knee injuries is skyrocketing among patients under the age of 18. The Meniscus, Explained So what is the meniscus, anyway? You actually have two per knee, each situated between your femur (thigh bone) and tibia (shin bone). Named for the Greek word meniskos (“crescent”), these rubbery, C-shaped discs cushion the medial (inner) and lateral (outer) edges of each knee. Each time a basketball player pivots and shoots or a soccer pro cuts to the left to avoid an oncoming defender, the meniscus absorbs the shock, promotes the movement of lubricating fluid around the joints, and makes the knee bend smoothly. When compromised by a tear, however, it becomes exceedingly difficult to balance weight across the knee; pitchers have trouble scrambling off the mound, for example, and a slugger will feel weakness on the bad knee as he twists to hit the ball. What’s more, over time, this uneven weight distribution causes excessive bone-on-bone force which is like “sand in a gear box” and can cause early arthritis around the knee joint. More Than Just a Tweak The quiet early symptoms of this injury are actually what make it so easy to ignore. After all, what serious athlete doesn’t experience a tweaked knee from time to time? Unlike ACL injuries, which often result in searing pain, isolated meniscus tears are typically accompanied by a dull ache or a nagging pain around the joint and minor swelling. It doesn’t present as something terrible and usually only hurts with activity. Injury is typically diagnosed upon a physical examination, and then confirmed by an MRI. Many people walk around with meniscus tears for months. In the “no pain, no gain” world of professional sports, ignorance is often bliss, especially for players who will stop at nothing to boost their ERA or gain a playoff berth. Both Rodriguez and Jones played on their meniscus tears for several weeks before consulting a surgeon, and Gonzales pitched his way through the World Series after tearing his meniscus late in the regular season. And while a cortisone injection can temporarily offset the pain and swelling,  most sports medicine professionals say letting this injury linger is never the ideal approach. The longer it’s left untreated, the more limited performance will become. To Repair or Remove? As a rule, athletes never want to hear the word “tear” in a diagnosis, but the good news is that minor meniscus injuries are easily treated without incurring too much time off the field. Tiny tears may not even require surgery—a solid physiotherapy routine concentrating on stretching and strengthening the knee may bring it back to normal function. For more substantial tears, surgeons generally go two routes in terms of treatment: Repair or remove. Both are minimally-invasive arthroscopic repairs. Repairing the meniscus involves sewing it back together and at least a six-month layoff. Patients are in a brace for the first six weeks and then undergo intense physical therapy in order to regain a full range of motion. Removal, also known as a meniscectomy or debridement, is the removal of the torn portion of the meniscus, typically resulting in just four to six weeks of physical therapy before a return to sports. While this option may seem ideal—it’s what A-Rod and Chipper Jones had done last July—doctors are always concerned that going this route increases chances for developing arthritis or possibly re-tearing further down the road. Tomorrow’s Treatments Meredith’s situation is rare, but not entirely unique. Orlando Magic vet Gilbert Arenas had three surgeries on his left lateral meniscus within a year; the ensuing procedures were believed to be necessitated by overstrenuous rehabilitation from the first surgery. These cases highlight the importance of cautiously caring for this injury as well as carefully weighing which procedure is best for each individual. One factor that may prevent future re-tears in the meniscus and possibly even side-step surgery is the use of platelet rich plasma (PRP). Having gained buzz in the sports world over the past few years (Tiger Woods and Phillies pitcher Cliff Lee have used PRP to deal with a sore knee and abs, respectively), PRP is the process of centrifuging (spinning) a person’s own blood until it contains a concentrated mix of plasma cells and growth factors. That end product is then injected into the injured tissue. This, doctors say, speeds healing, improves tissue health, and rapidly creates new collagen and blood vessels—although, so far, studies on humans have failed to prove as much.

A Tale of Two Menisci: A-Rod versus Chipper Jones—A Case Study

Two professional baseball players, close in age and playing the same position, Alex Rodriguez and Chipper Jones, both had arthroscopic surgery to remove part of a torn right meniscus. Both were back on the field before season’s end. As third basemen, a position that demands frequent lateral cuts and moves that plague menisci, were they more susceptible to the injury? And how did the sluggers stack up?