HOLLYWOOD PARK

I’ve moved to a different desk, so a new set of colleagues gets to witness my two cool party tricks: No. 1, bending my thumbs back till they touch the wrists, and No. 2, bending the last joints of my fingers forward while keeping the rest of the fingers straight--until the second joint finally buckles with a nasty clunking sound. (My new neighbors don’t seem overly impressed.)

Growing up, I’d often heard that those who indulge repeatedly in such silliness would damage their joints and increase their risk of arthritis. And ditto for those who--yuck! awful habit!--crack their knuckles.

We spoke to orthopedic surgeon Dr. Donald Longjohn and rheumatologist Dr. Daniel Arkfeld, both of USC, to learn more about what we may be doing to our joints.

Longjohn says he’s come across people who develop the ability--perhaps after an accident--to dislocate a shoulder or some other joint at will, and who get into the habit of doing it as a party trick. Such practices can damage the joint and make it even more prone to popping out of place--and this increased joint instability can be difficult to treat.

Also, people who have had certain jobs--such as corking champagne bottles by hand before the process was automated or driving heavy, hard-to-steer school buses--are more prone to arthritis in certain joints because of the pressure put on those joints, Arkfeld says.

But any link between arthritis and knuckle-cracking is unproved, both docs say. (Arkfeld recalls reading of one enterprising individual who used his own body for an informal test: He repeatedly cracked knuckles on just one hand--not the other--and decades later, when he’d grown up and become a doc, he X-rayed his hands and found no difference between them.)

And what about my two tricks? As far as my thumb-bending feat goes, I have “ligamentous laxity,” which sounds like some Victorian moral failing but is actually a greater flexibility of the ligaments. (“Some people are a little more loose than others,” comments Longjohn. My degree of looseness is nothing special: One woman I met could pull her arms right over her head, from in front of her stomach to the small of her back, while holding her hands.)

The finger trick, meanwhile, comes from my ability to bend one joint while keeping the other joint straight with a tendon--until that tendon finally slides over to one side and the joint bends. (Longjohn says he can do it too.)

Neither doctor thinks that these habits will cause me any harm if not done to ridiculous excess. Unless, they say, my friends decide to hit me.

Standing Guard Against Hospital Infections

We’ve recently been corresponding with reader Steven Schweon, coordinator of infection control at St. Luke’s Hospital in Bethlehem, Pa. Ever curious about people’s jobs (could Schweon’s be even more fun than being a reporter?), we decided to grill him about just what a coordinator of infection control does for a living.

Basically, he’s there to make sure that infections, when they arise in hospitals (and inevitably they sometimes do), don’t spread out of control.

So-called nosocomial infections--ones acquired in hospitals, in other words--crop up in more than 1.8 million patients in U.S. hospitals every year, Schweon tells us. Such infections include pneumonia and infections at the site of a surgery, and kill 88,000 people annually.

Ever since the 1960s, workers such as Schweon have passed their days educating staff on small but important matters like washing hands, getting vaccinated and properly handling soiled linen; figuring out which patients have infections and where they came from; and stopping infection spread by, for instance, isolating patients in private rooms and getting staff to disinfect the bejesus out of floors, bedding and equipment. Very glad you’re there, Mr. Schweon.