A 70-year-old runner had pain just above his left kneecap and weakness in the thigh that made it feel as if his leg might collapse.

After examining the leg and checking x-rays of his knee and hip, the doctor declared that he had decent cartilage in his joints but that his knee pain was caused by a small tear in a quadriceps muscle at the front of his thigh. The prescription was to rest the muscle while it healed, then stretch and strengthen it through physical therapy. That should not only get him back on the road, but prevent future deterioration of his knee cartilage.

Knee pain caused by osteoarthritis is common after age 50. It's a progressive problem that eventually results in deterioration of the cartilage tissue that lines the knee. In early stages, the person may just feel stiffness and minor soreness at certain times. When bone rubs against bone, the pain can be excruciating and chronic.

It's a common belief that the repeated impact on the knees caused by running -- putting six times body weight on the joints with each step -- wears out the cartilage. But research has demonstrated that distance runners are no more (and perhaps less) vulnerable than sedentary persons to osteoarthritis of the knee. Healthy knees are highly dependent on a team of strong thigh muscles -- the quads in front and the hamstrings in back. One study found that adults in their 60s and 70s who performed quadriceps strengthening exercises were less likely to lose knee cartilage over the course of the study than subjects performing stretching and range of motion workouts.

Quadriceps muscles tend to weaken with age, even in persons with an active lifestyle. And it's sometimes difficult to tell whether arthritic changes in the knee are a cause or an effect.

The 70-year-old's quad strain was severe enough to cause visible muscle wasting and weakness to the point that the knee was not getting the support it needed for running or walking. As the tear healed and the muscle got stronger, the knee pain faded away.

The tear may have resulted in part from muscle imbalance. With running or even walking, the body is basically propelled by the hamstrings while the quads support the knee when the foot hits the ground. The hamstrings get stronger while the quads get weaker.

Another muscle problem affecting the knee involves the iliotibial band, a thick tendon-like tissue that passes down the outside of the thigh and attaches to the outside part of the knee. When this band becomes tight because of overuse or biomechanical abnormalities, the knee joint loses some of its stability and is pulled partly out of alignment with each step, causing irritation and pain with overuse.

Pain is usually on the outside of the knee. It may go away with rest but come back at about the same point in a run every day -- whether that's two miles, six miles or eight miles.

The problem can be made worse by running on hard or uneven surfaces or in worn out shoes. Persons who pronate or have flat feet must compensate by choosing proper shoes or orthotic inserts.

What's generally known as "runner's knee" typically occurs at the front of the knee, just behind the kneecap. It's a dull, achy pain that gets worse when you go up or down stairs or try to kneel or squat. It may also flare up with prolonged sitting.

The traditional name is chondromalacia patella, meaning "soft cartilage under the kneecap," and in persons aged 50 and over developing osteoarthritis, that may well be the cause. It's now known that there are many other reasons for this kind of knee pain, most commonly overuse, a tight iliotibial band or anything that causes instability and friction between the knee cap and the groove that it passes through when the knee is flexed and straightened.

As with the other knee problems mentioned above, the short-term solution is RICE -- rest, ice, compression and elevation -- and avoidance of activities that cause the pain. The long-term solution involves maintaining strength and range of motion in the quadriceps and hip abductor muscles.

There are many exercises that strengthen the thigh and hip muscles, including leg raises and simple quad tightening for a few seconds at a time with the leg extended. Even better are exercises that engage the quads, glutes and hamstrings all at once, such as lunges and squats. The worst thing you can do is let your bad knees keep you on the couch.

This information was submitted by Northeastern Vermont Regional Hospital in St. Johnsbury and is meant to complement, not replace, the advice and care you receive from your health care provider.


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