Background: Several epidemiological studies have shown a lower
prevalence of osteoporotic hip fractures in patients with osteoarthritis.
Other studies have demonstrated elevated bone mineral density in patients with
osteoarthritis. The prevailing view is that there may be an inverse
relationship between osteoarthritis and osteoporosis. The purposes of the
present study were to describe a subgroup of patients with osteoarthritis who
were found to have osteoporosis and to assess the vitamin-D status and other
risk factors for low bone density in osteoarthritic subjects with and without
osteoporosis.
Methods: The bone mineral density of the spine, the proximal part of
the femur, and the total body was measured with dual-energy x-ray
absorptiometry in sixty-eight postmenopausal white women who were scheduled to
undergo total hip replacement for advanced osteoarthritis. The serum levels of
25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, intact parathyroid hormone,
osteocalcin, and bone-specific alkaline phosphatase and the urinary level of
N-telopeptide were measured. Information from validated lifestyle, dietary,
and demographic questionnaires was also evaluated.
Results: Seventeen (25%) of the sixty-eight women had occult
osteoporosis (as indicated by a T score of less than —2.5). Fifteen
(22%) of the sixty-eight subjects had vitamin-D deficiency, and three (4%) had
an elevated serum parathyroid hormone level. Only two of the seventeen
osteoporotic women had vitamin-D deficiency. On the basis of these numbers,
vitamin-D status was not correlated with bone density (p = 0.32). Analysis of
the relationship between the number of years since menopause and osteoporosis
or markers of elevated bone turnover showed that osteoporosis was detected
throughout the postmenopausal period.
Conclusion: A substantial portion of these sixty-eight white women
with osteoarthritis of the hip had occult osteoporosis and hypovitaminosis D.
Vitamin-D deficiency was not restricted to the group with low bone density.
These results support the need to consider the presence of both osteoporosis
and vitamin-D deficiency in women with advanced osteoarthritis.
Level of Evidence: Therapeutic study, Level III-1
(case-control study). See Instructions to Authors for a complete description
of levels of evidence.