| Abstrakt: |
We attempted to identify risk factors for the development of lower limb stress fractures during fluoride therapy for osteoporosis (OP). We compared 18 patients who developed 41 such fractures (26 periarticular, 6 femoral neck, 5 long bone shaft, 1 greater trochanter and 3 pubic rami fractures) during fluoride therapy, with 24 similarly treated patients who did not develop stress fractures. Treatment consisted of sodium fluoride 0.99 mg/kg per day, elemental calcium 1 g/day, and vitamin D. We obtained a previous fracture history, annual radiographs of the spine (fractures), hands (metacarpal cortical index, MCI) and pelvis (Singh index, femoral cortical index), three‐monthly serum fluoride and alkaline phosphatase levels, and pretreatment transiliac bone biopsies (routine histomorphometry). The stress fracture group was found to have, before treatment: lower MCI (p< 0.05), lower trabecular bone volume (p< 0.05), a lower number of trabeculae (p< 0.05), greater trabecular separation (p< 0.05), less extensive eroded surfaces (p< 0.05), a lower double/single tetracycline label ratio (p< 0.05); and during treatment: more new spinal fractures (p< 0.05) and higher serum alkaline phosphatase levels (p< 0.01). We conclude that stress fracture patients had more severe trabecular and cortical OP and possibly a poorer bone‐forming capacity before therapy than patients without stress fractures. We suspect that fluoride therapy may temporarily further weaken bone and so lead to stress fractures in severely osteoporotic patients. To prevent stress fractures we recommend that fluoride therapy be commenced before OP is profound and that lower fluoride dosage, or intermittent therapy be employed in patients with cortical as well as trabecular OP, especially when alkaline phosphatase levels rise above 1.6 times the upper limit of normal, or when new spinal fractures develop. |
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