Wounded Knees

“The culprits range from traumatic sports injuries, such as that suffered by the New England Patriots quarterback, to damage done over a lifetime that reduces the once super-slick tissue covering the knee into something more closely resembling Swiss cheese. We're asking our knees to do more than ever before: At one end of the age spectrum, girls are participating in sports in unprecedented numbers - and sustaining all the injuries that come with it. At the other end, many older Americans are no longer content to surrender to aches, pains, and immobility - or sacrifice their golf and tennis games. And at the same time, the nation is in the midst of an obesity epidemic, forcing knees to carry substantially more weight than they're designed to. Cranky, creaky knees generate upward of 20 million visits to the doctor each year in the United States, and they're the single most common reason that patients see orthopedic surgeons. Researchers estimate that by 2030, the number of total knee replacements - used in patients with severe degenerative arthritis - will soar to 3.5 million, a six fold increase. ‘The knee is an amazing piece of engineering,’ said Dr. Martha Murray, a Children's Hospital Boston researcher developing better ways of fixing broken knees. ‘It can tolerate stress year after year after year, and for the most part, it continues to function extremely well through 100 years of life.’ To understand the unremitting stress that a knee must endure, consider this: If you gain an extra 10 pounds, your knee interprets that as an additional 50 to 70 pounds because of the biomechanical demands placed on it. Ligaments can tear when they're asked to do something they're not really designed to handle. ‘In terms of the most dangerous thing that the knee has to do,’ said Dr. Jennifer Baima, a physical rehabilitation specialist at Brigham and Women's Hospital, ‘it's quick pivot-shift activity.’ That means fast-moving games like basketball and soccer. Not that the risk is shared evenly. Gender plays a role: Depending on the sport, women can be as much as five times more likely to snap a ligament. Different researchers point to different reasons for that, but the suspects include hormones and the fact that women have wider hips and a narrower notch in the knee, which can act like a guillotine.”

http://www.boston.com/news/health/articles/2008/09/22/wounded_knees/?page=3