Ask the Doctors January 2006 Issue

Ask the Doctors: 01/06

I have end-stage osteoarthritis in my right knee and am facing the prospects of a total knee replacement. I’m not anxious to undergo surgery. How long can I postpone the operation without compromising its success?

Total knee replacement is elective surgery. With few exceptions, it is not urgent and can be scheduled around important life events. Occasionally, excessive delays can result in the loss of bone and tendon tissue, which can compromise the quality of the surgery and its result.

Some studies have shown that patients with the worst function and pain at the time of surgery had comparatively worse function two years after surgery, and that performing knee replacement earlier in the course of functional decline may be associated with a more positive outcome.

Better overall physical fitness will allow quicker recuperation and return to activity after surgery. Patients typically have the procedure when pain prevents them from taking part in activities that they used to enjoy. When the basic activities of daily life—walking, shopping, or reasonable recreational pastimes—are inhibited by knee pain, it may be time to consider surgery.

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My doctor says I have degenerative changes in my spine. What does that mean?

“Degenerative” changes in the spine often refer to those that cause loss of normal structure or function. The intervertebral disc is one structure prone to degenerative changes associated with wear-and-tear aging. Degenerative disc disease (DDD) is part of the natural process of growing older. As we age, our intervertebral discs lose their flexibility, elasticity, and shock-absorbing characteristics. The fibrous outer portion of the disc, the annulus fibrosis, becomes brittle and prone to tearing. At the same time, the soft gel-like center of the disc, the nucleus pulposus, starts to dry out and shrink. The combination of damage to the intervertebral discs, the development of bone spurs, and a gradual thickening of the ligaments that support the spine can all contribute to degenerative arthritis of the spine.

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I’m a 65-year-old woman and have been diagnosed with osteopenia. Is this similar to osteoporosis, and how is it treated?

Osteopenia is a term that describes low-bone density that is not severe enough to meet the criteria for osteoporosis. Both are defined in terms of T-scores derived from a bone-density scan. A T-score compares you to a group of “normal” women at the age of peak bone mass between the ages of 20 and 40.

Osteopenia lies between a T-score of -1.0 and -2.5, which corresponds roughly to a level of calcium in the bone that is between 10 and 25 percent lower than that of “normal” women at peak bone mass. This does not mean that you have lost that much bone since you do not know what your particular bone mass was when you were age 20.

Osteoporosis is represented by a T-score of greater than -2.5. The two terms represent a continuum in the process of bone loss that occurs in all women after menopause and in men as they age.

Since more than 50 percent of all fractures occur in women with osteopenia, treatment is critical. The National Osteoporosis Foundation recommends treating women with a T-score of greater than -1.5 if factors are present that would increase the risk for fracture (i.e. body weight  over 127 pounds, family history of osteoporosis, smoking, or previous fracture). The treatment under these guidelines is calcium and vitamin D plus another agent, such as Evista, Actonel, Fosamax, or Boniva.