Professional Opinion: Knee pain -- is it normal or something else?

This week, Edward R. Blocker, a board-certified orthopaedic surgeon at Beaufort Memorial Orthopaedic Specialists, discusses knee pain and tenderness.

Question: I like to go out for a long walk or occasional run, but every so often I experience some soreness in one or both of my knees the next day. How do I know when I may have just overdone it or if I need to see someone?

Answer: Mild, temporary knee pain occurring after a long walk or any run is usually not a worry and you're probably in good company. The cause for the discomfort can be from many factors. Most commonly, mild arthritis is responsible. The definition of arthritis is simply the wearing away of the cartilage covering the ends of our bones. Cartilage is the gristle you see on the end of a drumstick. Loss of cartilage is inevitable over the decades, just as the rubber on your car tire will show some wear after 10,000 miles.

Common symptoms of arthritis are pain, stiffness, and swelling. You may feel these symptoms after a long walk or even when you first stand after prolonged sitting. Those first few stiff steps you take before you really get going is caused by arthritis. When we were 10 years old and ran all over the neighborhood, there was rarely any discomfort afterward. Do the same thing after you've had "50,000 miles" or more on your knees and you're likely to feel it afterward.

In most cases these symptoms are mild, temporary, and do not affect your activity level. It's when symptoms begin to affect what you do that it may be a good idea to see an orthopaedist.

Fortunately, the symptoms you should not ignore will be apparent. These more worrisome symptoms are often, but not always, preceded by an injury. For knees, it's usually a twisting mechanism. Even a mild twist followed by immediate pain, swelling, and subsequent catching and locking could indicate a meniscus tear.

The meniscus is a C-shaped disc of cartilage that acts as a shock absorber and helps protect the articular cartilage covering the bone that I referred to earlier. A tear in the meniscus can result in a piece of tissue that folds over and causes the knee joint to either catch briefly or, in extreme cases, lock up completely. An analogy would be sticking a metal rod into the teeth of a moving gear. The gear is either going to lock up and stop moving, or briefly catch and resume motion if the metal rod is quickly flipped back out.

Obviously, these symptoms can be fairly dramatic and most people would seek medical help at this point. For this condition, we sometimes perform an arthroscopy to remove the offending flap of cartilage.

The catching symptom I just mentioned is not the same as the popping and clicking many of us feel and sometimes hear coming from our knees. Some patients will refer to this common symptom as feeling like "Rice Krispies" in their knee. Right now, almost everyone over 40 knows what I'm referring to (and those 30 and under soon will). This is called crepitus and can occur when a joint is inflamed or is developing mild arthritis.

Again, we are all wearing away our cartilage to some degree over the years, so the crepitus that accompanies this is expected.

An exception is painful popping or clicking. Painless popping is not a worry. Painful popping that may be associated with the mechanical catching I mentioned earlier is an obvious concern and, if persistent, is worthy of having evaluated.

As I said, that mileage on our knees eventually leads to some degree of cartilage loss (arthritis) over time. It would be incorrect to conclude from this that a solution might be to limit your walking and increase your sitting. Low impact joint motion actually keeps your joints healthy. Hinges that aren't worked get rusty and stiff. Activities such as walking, swimming, rowing, hiking can help keep your knees and other joints healthy. If you don't move it, you may lose it.

So if you go for a walk or run and afterwards have mild soreness that resolves and doesn't limit you, and it is not getting progressively worse, you're probably right there with the rest of us. Keep on moving.

If that discomfort begins to cross the threshold of what you would normally tolerate and begins to slow you down more than you'd like, your orthopaedist can probably help.

This story was originally published August 31, 2015 at 1:59 PM with the headline "Professional Opinion: Knee pain -- is it normal or something else?."