People often say their knees are arthritic because of activity. It is a typical story to hear that a patient associates their arthritis with the fact that they have been physically active.

The truth is that knees are almost always helped by physical activity. In fact, patients who have participated in vigorous physical activity have better, healthier cartilage than patients who are not physically active. Furthermore, patients who are physically active have less of a chance of being obese, have stronger muscles, and are less likely to experience knee pain.

What does this mean for you? If you have good knees, then vigorous physical activity will help to maintain your knee health--not hurt your knees.

Related: Knee Arthritis | Ready for knee replacement?

Sources: Racunica TL, et al. "Effect of physical activity on articular knee joint structures in community-based adults" Arthritis Rheum. 2007 Oct 15;57(7):1261-8.

Backpacks are an easy way for children and teenagers to carry their books and school supplies. The purpose of a backpack is to evenly distribute the weight of these items to the large muscles that support our bodies.

Backpacks that are too heavily loaded or improperly worn can cause problems and even lead to injuries. Learn a few basic steps to keep in mind when selecting and wearing a backpack.

Related: Is your backpack too heavy? | Find a backpack that fits

Photo © Carmen Martínez Banús

Knee replacement surgery is an effective treatment for severe knee arthritis. During the procedure, an artificial knee made of metal and plastic is inserted into the knee joint.

After knee replacement surgery, it is important to perform therapy to resume normal activities. The goal of the procedure is to restore pain-free motion and to allow patients to resume their daily activities. Understanding the rehab from knee replacement surgery will aid in your recovery from this procedure.

Related: How to know when you're ready for knee replacement? | Motion Machines After Knee Replacement

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I read a column on the Internet today advocating patients with implanted metal bring x-rays to the airport to assist the TSA in screening. My opinion: Dumb idea.

Many patients with implanted metal will set off airport metal detectors. Implants including plates, screws, rods, and joint replacements can all set off airport metal detectors. However, the TSA is staffed by security specialists, not doctors. Taking x-rays to the security personnel is a waste of your time and effort. Here are the problems:

• Identity Issues
  Security personnel cannot (and should not) assume that an x-ray belongs to the person holding it. If that were the case, anyone could simply bring an x-ray of a metal implant as their reason for setting off the metal detector.

• Hospital Records
  X-rays are part of your hospital record, and removing them makes your record less complete. If those x-rays get lost on your trip it could affect your medical care down the road. Sometimes having previous x-rays for comparisons is essential, especially when dealing with implants.

• Cost
  Every time an x-ray is taken, and printed, medical costs go up. If patients are constantly getting extra x-rays taken and printed for travel purposes, this wastes medical resources.

I think this column has great tips for travel security--except the advice to bring your x-rays to the airport. Instead, use the advice of the TSA, and leave your x-rays at your doctor's office.

Related: Do metal implants cause metal detectors to go off? | TSA Recommendations

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