For a type I error rate of 0.05 and a power of 0.8, with an expected prevalence of BP use of 10%, a difference in cortical thickness of 1.2 mm, and SD for cortical thickness of 2.6 mm, 49 cases would have been required. The location of maximal cortical thickness was variable, but was more anterior and less inferior in patients. On the basis of our results in the present study, patients with AFFs might have had abnormal cortical thickness before BP use. We did not perform longitudinal evaluation in control groups. Washington, DC 20036-3309, USA | We collected patients' baseline demographic data from registry records. Using the distance tool in the software of the picture archiving and communication system (PACS; Konica Minolta I‐PACS FS with core software by V1.09R04, Tokyo, Japan), the FS and cortical diameters were obtained. Therefore, our results cannot eliminate the possibility of increased cortical thickness resulting from long‐term BP use. Differences in categorical variables were assessed with the chi‐square test and Fisher's exact test. Washington, DC 20036-3309, USA | Suite 800 Thus, it was difficult to obtain follow‐up radiographs in the absence of osteoporosis treatment. In addition, follow‐up radiographs were obtained at least 1 year after baseline measurements (mean 1.4 ± 0.3 years; range 1.0 to 2.3 years) to evaluate changes in the longitudinal cortical thickness with BP treatment. The 2013 revised American Society for Bone and Mineral Research (ASBMR) case definition of AFF includes five major features and four minor features.2 Although none of the minor features is required for the diagnosis of an AFF, minor features are sometimes associated with AFFs. Statistical analysis was performed using the StatView statistical software package (version 5.0; SAS Institute, Cary, NC, USA). The proximal femurs of the remaining 172 patients (mean age, 85 years) were categorised as Dorr type A (n=29), type B (n=75), and type C (n=68). The cortical bone thickness of femurs was continuous, increasing gradually from the end to the middle part. CT 5 cm = cortical thickness measured 5 cm below the lesser trochanter; CT 12.5 cm = cortical thickness measured 12.5 cm below the lesser trochanter. Although the incidence rates of AFFs in the Japanese and white populations are similar,22 these findings might not be generalizable to other ethnic groups or representative of the population as a whole. and you may need to create a new Wiley Online Library account. Thus, we did not observe any effects of long‐term BP use on femoral cortical thickness. Reconstructed surfaces of the cortical and trabecular layers of bone were used to determine the thickness of the cortical bone over the surface of the femoral head Data collection: RN, TK, and AN. Fax: +1 (202) 367-2161 The first limitation is related to study design. asbmr@asbmr.org, 2025 M Street, NW Fax: +1 (202) 367-2161 | However, because we wanted to perform the analysis for lateral cortical stress fracture, we included all eligible patients with long‐term BP use. As the Japanese Ministry of Health, Labour and Welfare approved daily teriparatide in October 2010, weekly terparatide in November 2011, and denosumab in March 2013, several patients who had received long‐term BP treatment switched to these drugs. 1, points B and C). "Measuring Compressive Modulus of Elasticity Across Cortical Bone Thickness of Mid-Diaphysis Bovine Femur." Thickness of cortical bone at mid shaft level, thickness of individual trabeculae were measured using a calibrated ocular micrometer. In the first study describing AFF, Odvina and colleagues6 identified 5 patients who sustained low‐energy ST/FS fractures while receiving long‐term alendronate treatment. The 142 long‐term BP users were all patients who were under follow‐up at our institution. It will be essential for future analysis of bone in this region to take these effects into account. Femur cortical bone is the main contributor of femur stiffness and strength. Number of times cited according to CrossRef: Morphological profile of atypical femoral fractures: age‐related changes to the cross‐sectional geometry of the diaphysis. After a minimum of 1 year of additional BP use, we observed no significant change in cortical thickness or the cortical thickness ratio at any level of the femur, but a significant change in the region of maximal femoral cortical thickness was observed according to the results of Wilcoxon signed‐rank test (Table 3) and Bonferroni correction (data not shown). Atypical Femoral Shaft Fractures in Female Bisphosphonate Users Were Associated with an Increased Anterolateral Femoral Bow and a Thicker Lateral Cortex: A Case-Control Study. Fifth, our results showed the absence of generalized femoral cortical thickening in long‐term BP users, but there is a possibility that idiosyncratic response may occur in certain individuals. The two groups were matched for age, sex, and ADLs. Cancellous bone has a higher surface-area-to-volume ratio than cortical bone and it is less dense.This makes it weaker and more flexible. Points at which cortical thickness was measured on anteroposterior radiographs of the femurs. Functioning levels were high in 114 patients, moderate in 20 patients, and low in 8 patients in the BP group. 1, points B and C). Cortical bone thickness in this region of the femur, as well as over the proximal surface, was significantly greater in patients with cam FAI than control subjects. The minimum follow‐up period for patients in the BP group was 5 years (mean 6.5 ± 1.1 years; range 5.0 to 12.0 years). The protocol was in compliance with the ethical principles stated in the Declaration of Helsinki and was approved by the Ethics Committee of Tomidahama Hospital. BMI = body mass index; NTX = N‐telopeptide; PINP = procollagen type I N‐terminal propeptide. Written informed consent was obtained from all patients. We observed no significant increase in cortical thickness in either of the two groups. We did not perform longitudinal evaluation in control groups. As the Japanese Ministry of Health, Labour and Welfare approved daily teriparatide in October 2010, weekly terparatide in November 2011, and denosumab in March 2013, several patients who had received long‐term BP treatment switched to these drugs. All patients in their study demonstrated histomorphometric evidence of severely suppressed bone turnover. In humans, the thickness of the cortex varies from 2.3 to 2.8 mm, and is organized into six layers, numerated from I to VI, counting from the most external to the most internal one. Third, we measure cortical thickness at three points on radiographs. We compared cortical thicknesses between patients taking BP and controls and evaluated longitudinal changes in cortical thickness. 1, line AD). Published. Moreover, cortical thickness remained stable after an additional year of continued BP use. Using the distance tool in the software of the picture archiving and communication system (PACS; Konica Minolta I‐PACS FS with core software by V1.09R04, Tokyo, Japan), the FS and cortical diameters were obtained. S1, S2, and S3), and no differences were found in the cortical thickness, cortical thickness ratio, and femoral diameter at any level of the femur between the groups. Baseline femoral measurements were compared between the BP and control groups (Table 2, Supporting Figs. Sixth, we did not perform the longitudinal study in the control group because almost all control patients underwent osteoporosis treatment after initial evaluation. 1). The correlation (Spearman) of the results from the two assessments was also calculated as a measure of agreement. Incidence and Characteristics of Atypical Femoral Fractures: Clinical and Geometrical Data. Data were tested for normality, and, if not normal, were analyzed by nonparametric methods. Acta Orthop Scand1989;60(1):101-104 103 Table 2.The mass-related measurements in computed tomog- raphy slices and their correlations (0 to the ultimate shearing force in axial loading of the femur Region HU xcrn 3 a rb Head 5480(2210) 0.84 Neck 5640 (2050) 0.79 Cancellous bone 2090 (730) 0.73 Cortical bone 3550 (1 600) 0.69 shan 6450 (1 260) 0.65 This led to the notion that BP use may induce changes in cortical thickness around the ST area of the femur, which may in turn predispose the bone to AFF. The types of BPs used and the durations of use were as follows: alendronate (n = 132; mean 6.6 ± 1.2 years; range 5.0 to 12.0 years) and risedronate (n = 10; mean 6.0 ± 1.0 years; range 5.0 to 7.5 years). As a result, we could perform this case‐control study with a patient/control ratio of 1:3. Phoenix, Arizona, USA. To avoid selection bias, which is a major disadvantage of a matched case‐control study, we evaluated the maximum number of controls registered during the study period. This study was a matched case‐control study, and such studies have several major disadvantages, including selection and information bias, which could not be eliminated by increasing the number in the control arm. Bisphosphonates (BPs) are the most commonly prescribed medications for the treatment of osteoporosis. Accordingly, we assumed that there were no differences in the abilities of the different physicians to interpret radiographs with good reproducibility. A total of 620 potential control individuals were seen during the study period. Thresholding is the most common technique for estimating cortical thickness and density. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article. In one of several previous studies of cortical thickening in long‐term BP users, Beck and colleagues found that the mean cortical thickness ratio at the FS had increased by 1.82% after 24 months of alendronate use, whereas it had decreased by approximately 0.31% with placebo.18 In contrast, Unnanuntana and colleagues performed bone density scanning and reported that long‐term alendronate use did not alter cortical thickness on the basis of comparison with thicknesses in untreated controls.11 Koeppen and colleagues measured the femoral cortical thickness in 58 patients with AFF and 218 controls19 and reported no difference in the cortical thickness ratio between patients with AFF and controls. In one of several previous studies of cortical thickening in long‐term BP users, Beck and colleagues found that the mean cortical thickness ratio at the FS had increased by 1.82% after 24 months of alendronate use, whereas it had decreased by approximately 0.31% with placebo.18 In contrast, Unnanuntana and colleagues performed bone density scanning and reported that long‐term alendronate use did not alter cortical thickness on the basis of comparison with thicknesses in untreated controls.11 Koeppen and colleagues measured the femoral cortical thickness in 58 patients with AFF and 218 controls19 and reported no difference in the cortical thickness ratio between patients with AFF and controls. Using coefficient of variation, intraclass correlation coefficients, and as effects of long‐term BP were... Differences between age groups of 1 and 2, Supporting Figs times cited according CrossRef. 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