The most frequent sites of
osteoporotic fractures are the vertebrae, the hip, the forearm and the proximal humerus. Drugs that inhibit
bone resorption constitute the mainstay for the treatment of
postmenopausal osteoporosis. A recent meta-analysis indicates that
vitamin D can reduce the risk of
hip fractures only if
calcium supplements are also administered. The effect of
hormone replacement therapy on the risk of non vertebral fractures is less clear than on vertebral fractures.
Raloxifene (a
SERM) reduces the rate of vertebral fractures and of
breast cancer, but it does not protect against hip fracture.
Bisphosphonates are the most commonly used compounds to treat
postmenopausal osteoporosis. The level of evidence for currently used
bisphosphonates (
alendronate,
ibandronate,
risedronate,
zoledronate) to reduce vertebral fracture rate is maximal. Results of controlled clinical trials indicate a reduction in the risk of vertebral fractures of 40-50% and of 20-40% for non vertebral fractures, including
hip fractures. However, their relative efficacy on
hip fractures has been less well studied and remains more controversial. Long-term compliance of
bisphosphonate therapy is improved by intermittent schemes. The most recent developpements concern the
intravenous administration of
ibandronate and even more of
zoledronate (yearly infusions). The reduction in the rate of vertebral and
hip fractures has been demonstrated in the main
zoledronate trial and a prolongation of survival has been shown in the study including patients with a recent hip fracture. Whereas
hyperparathyroidism is a cause of bone loss, the intermittent administration of
parathyroid hormone or of its 1-34 fragment (
teriparatide) exerts
anabolic effects on the skeleton. The treatment is demanding and costly (daily sc
injections during 18 months), requires some monitoring (serum and urinary
calcium) but the results, at least for vertebral fractures, are quite favorable.
Strontium ranelate is a less powerful stimulator of bone formation but it also reduces
bone resorption. Its daily administration for 3 years reduces the risk of vertebral fractures and, to a lesser extent, of non vertebral fractures. Lastly,
denosumab is a high affinity antibody against
RANK Ligand that specifically blocks the formation and the activity of osteoclasts. The efficacy of this promising compound will soon be known.