Bone
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Fatigue fracture of the cuboidal bones of the foot, especially the navicular tarsal bone, is common in athletes and dancers. The racing greyhound is a naturally occurring animal model of this injury because both microcracking and complete fracture occur in the right central (navicular) tarsal bone (CTB). The right limb is on the outside when racing in a counter-clockwise direction on circular tracks, and is subjected to asymmetric cyclic compressive loading. ⋯ It was concluded that greyhounds racing on circular tracks develop site-specific bone adaptation with compaction of trabecular bone and increase in BMD in the right CTB in particular, the most common site for fatigue fracture. Our data also suggested that partial reversal of this adaptive process occurred in retired, nonracing greyhounds, after cessation of asymmetric cyclic loading at racing speed. Racing greyhounds provide a model in which to study fatigue fracture and adaptation of cuboidal foot bones subjected to cyclic loading.
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Case Reports
Diagnostic utility of magnetic resonance imaging skeletal survey in a patient with oncogenic osteomalacia.
Oncogenic osteomalacia is a rare paraneoplastic syndrome characterized by hypophosphatemic osteomalacia due to renal phosphate wasting. The same biochemical features are found in patients with X-linked hypophosphatemic rickets/osteomalacia and sporadic hypophosphatemic osteomalacia with unknown etiology. Oncogenic osteomalacia is cured by resection of the responsible tumor. ⋯ Resection of the tumor resulted in normalization of serum phosphate and renal phosphate handling. Because the most frequent causes for oncogenic osteomalacia are tumors in bone or soft tissue, magnetic resonance imaging skeletal survey is a very powerful method for detecting the responsible tumor. Vigorous search for tumors with this method in patients with hypophosphatemic osteomalacia would be helpful not only for proper management of patients, but also for clarifying the identity of sporadic hypophosphatemic osteomalacia.
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Tibolone is a synthetic steroid with tissue-specific estrogenic, progestogenic, and androgenic properties. The therapeutic effects of tibolone on bone mass and strength, bone metabolic markers, and indices of histomorphometry were investigated in ovariectomized (ovx) rats on a low (0.1%)-calcium diet in comparison with 17alpha-ethynylestradiol (EE) or 1alpha-hydroxyvitamin D3 [1alpha(OH)D3]. Tibolone (0.1-3 mg/kg/day), EE (0.1 mg/kg/day), or 1alpha(OH)D3 (0.5 microg/kg/day) was administered orally once a day for 16 weeks, starting 12 weeks after ovariectomy, when the bone mineral density (BMD) of lumbar vertebrae (L4-5) and femur (global, proximal, and distal regions) had already been decreased by the combination of ovariectomy and low dietary calcium. ⋯ Tibolone or EE decreased serum levels of osteocalcin and bone alkaline phosphatase and urinary levels of deoxypyridinoline and pyridinoline compared with the ovx control group. Furthermore, tibolone or EE decreased the mineralizing surface and bone formation rate as well as the osteoclast surface and osteoclast numbers. 1Alpha(OH)D3, however, did not affect these serum and urinary parameters. These data suggest that tibolone suppresses the accelerated bone turnover induced by a combination of ovariectomy and low dietary calcium, and indicate that tibolone may be a potentially useful drug for the treatment of postmenopausal osteoporosis.
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This study was undertaken to report the clinical experience with percutaneous minimal invasive vertebroplasty using polymethyl-methacrylcate (PMMA) for a consecutive group of patients. Over the period of the last 4 years, 40 patients were treated at 68 vertebral segment levels with the intention to relieve pain related to vertebral body lesions. Reduced vertebral body height and destruction of the posterior vertebral wall were not considered to be exclusion criterias. ⋯ Treatment failure was mostly related to insufficient pretreatment clinical evaluation, and complication due to excessive PMMA volume injection. Control of PMMA volume seems to be the most critical point for avoiding complications. A good fluoroscopy control is therefore mandatory.
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Osteoporosis in men is a disease that is increasing in incidence, and with an increasing elderly population it poses a serious health problem. Since both testosterone (T) and growth hormone (GH) have an anabolic effect on bone and both decrease with aging, we were prompted to test whether the administration of these hormones in combination would increase bone mass in orchiectomized (orx) senile rats more than administration of either agent alone. Twenty-month-old male Wistar rats were divided into five groups with seven animals each: (a) age-matched intact control, (b) orx, (c) orx+GH (2.5 mg/kg/day), (d) orx+T [10 mg/kg, subcutaneous (s.c.), injection given twice a week], and (e) orx+GH+T. ⋯ Four weeks of orx with or without GH or T administration had no significant effect on tibial metaphyseal cancellous bone volume. In conclusion, this short-term study suggests that the combined intervention of GH and T in androgen-deficient aged male rats may have an independent effect in preventing osteopenia. The significant effect of GH+T may be attributed to the prevention of intracortical porosis, and an increase in periosteal bone formation and cortical bone mass.