Clinical and radiographic findings in adults with persistent hypophosphatasemia.

A serum alkaline phosphatase value below the age-adjusted lower limits of normal (hypophosphatasemia) is uncommonly encountered in clinical practice. The electronic and paper medical records of 885,165 patients treated between 2002 and 2012 at a large, rural, multispecialty health clinic were interrogated to estimate the prevalence and characterize the clinical and radiographic findings of adults whose serum alkaline phosphatase was almost always low (persistent hypophosphatasemia). We hypothesized that some of these patients might harbor previously unrecognized hypophosphatasia, a rare, inherited condition of impaired mineralization of bones and teeth. Persistent hypophosphatasemia (serum alkaline phosphatase ≤ 30 IU/L) was found in 1 of 1544 adult patients. These adult patients had more crystalline arthritis, orthopedic surgery, chondrocalcinosis, calcific periarthritis, enthesopathy, and diffuse idiopathic skeletal hyperostosis than a general adult patient population. A gender effect was observed. The clinical and radiographic findings of adult patients with persistent hypophosphatasemia resemble those of the adult form of hypophosphatasia. Clinicians should take notice of persistent hypophosphatasemia, consider the diagnosis of hypophosphatasia, and be cautious when considering potent anti-remodeling therapy in these adults. This population warrants further evaluation.

A long femur scan field does not alter proximal femur bone mineral density measurements by dual-energy X-ray absorptiometry.

A longer dual-energy X-ray absorptiometry (DXA) femur scan field might be useful for the detection of atypical, subtrochanteric femur fractures (ASFF). Thirty adult subjects underwent triplicate measures of femoral neck (FN) and total hip (TH) bone mineral density (BMD) by DXA using a conventional (i.e., short) and a longer femur scan field. Differences in measured BMD between the 2 scan field lengths were small and less than the precision error inherent in DXA testing. A longer proximal femur scan field does not substantially alter BMD measurements made at the FN and TH and may be useful for the detection of ASFF in clinical practice.

Severely suppressed bone turnover and atypical skeletal fragility.

CONTEXT: Since their introduction into clinical medicine, bisphosphonates have revolutionized clinical osteoporosis care. Ironically, in rare circumstances, long-term, combined anti-remodeling therapy may be associated with skeletal harm. EVIDENCE ACQUISITION: We report atypical skeletal fragility in three subjects after long-term, combined anti-remodeling therapy. EVIDENCE SYNTHESIS: Three subjects experienced spontaneous or minimal-trauma chalk-stick type metadiaphyseal femoral fractures while on long-term bisphosphonate therapy. The fracture location, type, bilaterality, prodromal pain, and delayed healing were atypical for uncomplicated postmenopausal osteoporosis. All three subjects had concomitant circumstances (endogenous estrogen) or medications (glucocorticoids, hormone replacement therapy, and raloxifene) that likely suppressed bone remodeling beyond the effect of the bisphosphonate alone. Biochemical markers of bone turnover were very low or in the low premenopausal range. Double tetracycline-labeled bone biopsy showed very low activation frequency in one subject and limited single tetracycline label in a second consistent with severely suppressed bone turnover (SSBT). These three cases resemble previous descriptions of SSBT. CONCLUSION: Atypical skeletal fragility may signify SSBT in the setting of long-term, combined anti-remodeling therapy. We speculate that osteoclast tolerance for pharmacological suppression may vary among individual patients and that in some cases combined anti-remodeling therapy may result in skeletal harm.

Antecedent 99mTc-MDP and 99mTc-sestamibi administration corrupts bone mineral density measured by DXA.

Previous reports of the effect of antecedent administration of radionuclide on bone mineral density (BMD) measurements have yielded inconsistent results. Ten subjects scheduled for (99m)Tc-methylene diphosphonate ((99m)Tc-MDP) bone scanning and 10 scheduled for (99m)Tc-sestamibi cardiac scanning had BMD measured by dual X-ray absorptiometry (DXA) (GE/Lunar) before and within 5 hours of diagnostic radionuclide injection. Paired t test and Wilcoxon-signed rank tests were used to compare the measured differences in BMD at multiple skeletal sites. Differences were subjected to multivariate analysis of demographic factors. Mean change in measured BMD following (99m)Tc-sestamibi administration (DeltaBMD-(99m)Tc-sestamibi) was -0.216+/-0.113 g/cm(2) at the total body and -0.348+/-0.300 g/cm(2) at the lumbar spine (p<0.005). Mean change in measured BMD following (99m)Tc-MDP administration (DeltaBMD-(99m)Tc-MDP) was -0.058+/-0.037 g/cm(2) at the total body and -0.053+/-0.049 g/cm(2) at the lumbar spine (p<0.05). Mean DeltaBMD-(99m)Tc-sestamibi exceeded least significant change (LSC) in all skeletal sites except the femoral trochanter. Mean DeltaBMD-(99m)Tc-MDP exceeded LSC only at the lumbar spine. The effect was correlated with (99m)Tc dose but not with gender, age, body mass index, baseline BMD, or time interval from injection to scan acquisition. In conclusion, BMD measured by the GE/Lunar Prodigy densitometer is corrupted by antecedent (99m)Tc-sestamibi and to a lesser extent by (99m)Tc-MDP. This effect is greater at the total body and lumbar spine than at the hip. Caution is warranted in scheduling and interpreting DXA studies when (99m)Tc has been recently administered.

A simple gait-stabilizing device reduces outdoor falls and nonserious injurious falls in fall-prone older people during the winter.

OBJECTIVES: To determine whether Yaktrax Walker (YW), a nonmedical gait-stabilizing device, prevents outdoor falls and injurious falls in fall-prone older people during the winter. DESIGN: Prospective, randomized, interventional trial. SETTING: Community-based, northern United States, winter, outdoors. PARTICIPANTS: Ambulatory, community-dwelling, fall-prone people aged 65 and older. INTERVENTION: Participants were randomized to wear YW or their usual winter footwear (UWF) outdoors during the winter of 2003/2004. MEASUREMENTS: The number of indoor and outdoor slips, falls, and injurious falls was recorded daily in a fall diary. Winter footwear satisfaction survey was completed after study completion. RESULTS: One hundred nine subjects completed 10,724 diary days. Mean age was 74.2. There were 93 indoor slips, 13 indoor falls, 714 outdoor slips, and 62 outdoor falls. The tendency for both groups to slip/fall indoors was comparable. The relative risk (RR) of outdoor slip for YW was 0.50 (P<.04) for all diary days and 0.61 (P=.14) when only days walked on snow and ice was the exposure variable. The RR of outdoor fall for YW was 0.42 (P<.03) when only days walked on snow and ice was the exposure variable. RR of injurious falls per day walked on snow and ice for YW was 0.13 (P<.02). Twelve of 19 outdoor falls occurred when YW subjects were not wearing their assigned device. No serious injury or fracture occurred in either group. The number needed to treat for the YW to prevent one nonserious injurious fall in one winter was six. CONCLUSION: YW may reduce the risk of outdoor winter falls, and of nonserious injurious falls, in older community-dwelling people with a history of previous falls.