Medical Engineering & Physics
Volume 34, Issue 1 , Pages 2-8, January 2012

Effects of glucocorticoid on BMD, micro-architecture and biomechanics of cancellous and cortical bone mass in OVX rabbits

  • Xuli Liu

      Affiliations

    • Department of Orthopaedics, Xijing Hospital, the Fourth Military Medical University, 15 Changle West Road, Xi’an 710032, Shaanxi, China
    • ,
  • Wei Lei

      Affiliations

    • Department of Orthopaedics, Xijing Hospital, the Fourth Military Medical University, 15 Changle West Road, Xi’an 710032, Shaanxi, China
    • Corresponding Author InformationCorresponding author. Tel.: +86 029 84771011; fax: +86 029 84771011.
    • ,
  • Zixiang Wu

      Affiliations

    • Department of Orthopaedics, Xijing Hospital, the Fourth Military Medical University, 15 Changle West Road, Xi’an 710032, Shaanxi, China
    • ,
  • Yi Cui

      Affiliations

    • Department of Orthopaedics, Xijing Hospital, the Fourth Military Medical University, 15 Changle West Road, Xi’an 710032, Shaanxi, China
    • ,
  • Baojun Han

      Affiliations

    • Department of Orthopaedics, Xijing Hospital, the Fourth Military Medical University, 15 Changle West Road, Xi’an 710032, Shaanxi, China
    • ,
  • Suochao Fu

      Affiliations

    • Department of Orthopaedics, Xijing Hospital, the Fourth Military Medical University, 15 Changle West Road, Xi’an 710032, Shaanxi, China
    • ,
  • Changli Jiang

      Affiliations

    • Clinical Lab, Kunming General Hospital of Chengdu Military Area Command of Chinese PLA, Daguan Roast, Kunming, Yunnan 650032, China

Received 10 December 2010; received in revised form 12 May 2011; accepted 18 June 2011. published online 20 July 2011.

Article Outline

Abstract 

The incidence of osteoporosis continues to increase with progressively aging populations. The purpose of this study was to detect the effects of glucocorticoid (GC) treatment on bone mineral density (BMD), biomechanical strength and micro-architecture in cancellous and cortical bone in ovariectomized (OVX) rabbits. Twenty adult female New Zealand white rabbits were randomly divided into three groups. The OVX-GC group (n=8) received a bilateral ovariectomy first and then daily GC treatment (methylprednisolone sodium succinate, 1mg/kg/day) for 4 weeks beginning 2 weeks after ovariectomy treatment. The OVX group (n=4) received a bilateral ovariectomy without GC treatment. The sham group (n=8) only received the sham operation. BMD was determined prior to and 6 weeks after the operation in the spine. Six weeks after the operation, the animals were sacrificed, and cancellous bone specimens were harvested from the femoral condyle and lumbar vertebrae. Cortical bone specimens were obtained from the femoral midshaft. The femoral specimens were scanned for apparent BMD. All specimens were tested mechanically and analyzed by microcompute tomography (micro-CT). In cancellous bone, GC treatment resulted in significant decreases in BMD, bone biomechanical strength and micro-architecture parameters in lumbar vertebrae. Similar trends in BMD and micro-architectural changes were also observed in the femoral condyle in the OVX-GC group compared with the sham group. However, there was no significant decline in any parameter in either lumbar vertebrae or femoral condyle in the OVX group. Similarly, no significant difference was found in any parameter in cortical bone among the three groups. Thus, the 4-week GC treatment in OVX rabbits could result in a significant bone loss in cancellous bone but not in cortical bone. This model is comparable to the osteoporosis-related changes in humans. OVX alone was not sufficient to induce osteoporosis.

Keywords: Osteoporosis, Rabbit, Ovariectomy, Glucocorticoids, Micro-CT biomechanical strength

 

Back to Article Outline

1. Introduction 

Osteoporosis is a disease characterized by low bone mass (osteopenia) and micro-architectural deterioration of bone tissue, which lead to an increased risk of fractures. These fractures seriously affect the life quality of elderly patients [1], [2], [3]. Animal models have played a crucial role in enhancing the knowledge of the etiology of and the development of new treatments for osteoporosis [4], [5], [6]. These models can provide more uniform experimental material and allow for extensive tests. Careful selection of an appropriate animal osteoporosis model can minimize the limitations associated with studying the disease in humans, namely time and behavioral variability, among test subjects.

In the preclinical testing of agents used to prevent or treat postmenopausal osteoporosis, OVX rats have been required as the first test model by the Food and Drug Administration guideline [7]. However, they have several disadvantages, including the lack of Haversian systems, no achievement of true skeletal maturity, and minimal intra-cortical bone remodeling [8], [9], [10], [11], [12]. Additionally, the small size of the rat is not suitable for studies that require several biopsies, multiple blood biochemical measurements, or implanting surgical prostheses [11], [12]. The large animals that have been used include non-human primates, sheep, dogs and pigs, all of which are expensive and difficult to handle and house in large numbers [12], [13].

By comparison, rabbits as an experimental model are relatively economical, docile, suitable in size, easy to handle and house, and available in large numbers for genetically homogeneous strains. Rabbits have been popular in study of bone ingrowth into implants and bone–implant interfaces [14], [15], [16]. Due to their short skeletal developmental period, faster bone turnover than primates and significant intracortical remodeling [17], [18], they are often selected for the study of osteoporosis. Osteoporosis/osteopenia rabbit models induced by OVX or GC alone have been used to study the effects of loss of bone mass and have exhibited promising results of reductions of BMD [19], [20], [21]. OVX combined with GC also induces a notable decrease in BMD [22], [23].

However, with respect to the mechanical properties of cancellous and cortical bone in OVX and GC-treated rabbits, no systemic evaluation of BMD, histomorphometric and biomechanical analysis has been done. Considering a model to be truly osteoporotic without performing biomechanical tests could be misleading.

The purpose of this study was to detect the effects of GC treatment on cancellous and cortical bone in OVX rabbits in terms of BMD, biomechanical strength and micro-architecture. This study aimed to provide new information about this model for studying how the mechanical properties of trabecular and cortical bone are affected by estrogen deficiency combined with GC treatment. This model could also be used to develop and test new strategies for spine fusion, orthopedic implants, biomaterials, and medical device research.

Back to Article Outline

2. Materials and methods 

2.1. Animals 

Twenty female, 6–7-month-old, New Zealand white rabbits were used for the study (Fourth Military Medical University, Xian, Shaanxi, China) (FMMU). Their body weight ranged from 2.5 to 3.1kg (mean 2.7kg). The experiment was approved by the Animals Ethics Committee at FMMU. The rabbits were kept individually in cages and maintained with a cycle of 12h of light and 12h of darkness. The animals were fed standard rabbit chow (FMMU) and allowed to drink tap water freely.

2.2. Osteoporotic rabbit model 

After the rabbits were acclimatized to the new situation for 2 weeks, they were randomly divided into three groups. The OVX-GC group (n=8) received bilateral ovariectomy and daily GC treatment. The OVX group (n=4) received bilateral ovariectomy without GC treatment. The sham group (n=8) only received the sham operation. The OVX operation was performed as previously described [22], and the sham operation was to only expose the ovaries without excision. Postoperatively, antibiotics (ampicillin, 0.1g/kg/day, China) were administered subcutaneously for 3 days. The daily GC (methylprednisolone sodium succinate, MPSS) injections in the OVX-GC group were performed for 4 weeks starting at 2 weeks after OVX with 1mg/kg/day, and all MPSS was used within 48h of mixing [23]. All animals were weighed and doses adjusted weekly. They were euthanized by intravenous injection of an overdose of Sumianxin II (Changchun Veterinary Institute of Military Medical Academy of Sciences, China) 6 weeks after OVX, and the femora and lumbar spine (seven lumbar vertebrae from L1 to L7) were dissected.

2.3. BMD 

Dual-energy X-ray absorptiometry (DXA) analysis was performed with a Hologic Discovery Wi using linear fan beam technology (Hologic Inc, Bedford MA, USA) and switching between two X-ray potentials (100 and 140kVp) from an X-ray source mounted beneath the subject [24]. The Hologic Discovery analysis software version 12.7 was used, and the small animal-scanning mode was applied for all scanning. For all animals, the baseline BMD was measured for lumbar vertebrae before the surgical procedure. Six weeks after OVX, the animals underwent the BMD scan again [22], [23], and then all rabbits were euthanized. Lumbar vertebrae and left femora were obtained, and the femora were underwent BMD scans for apparent BMD. The mean of L3–L5 vertebral BMD values was calculated to represent the lumbar vertebrae (Fig. 1A) [23]. In each femoral condyle, two cancellous bone–rich scanning regions of interest (ROI) were positioned (7mm×7mm) [25], [26], and one cortical bone–rich ROI was at the midshaft (8mm×12mm) (Fig. 1B) [27]. The manufacturer's CV for the instrument was 0.28% for whole body BMD.

2.4. Micro-CT analysis 

Bones harvested were frozen at −70°C until the time of scanning by micro-CT (eXplore Locus SP, GE Healthcare, USA). L3 vertebrae were obtained and removed from the appendixes [28]. Right femoral condyles were harvested with the diaphysis cut off (Fig. 2) [26]. The micro-CT system was used at a spatial resolution of 14.435μm, and CT images were reconstructed in 1024×1024-pixel matrices. Micview v2.1.2 software was used. The ROI of cancellous bone was then chosen for analysis. The ROI of vertebrae (1.5mm×1.5mm) was positioned at the two sides of the longitudinal axis of the vertebral column near the endplates. The ROI of femoral condyles were positioned at the two sides of the distal part. Trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular separation (Tb.Sp), bone surface/bone volume (BS/BV) and bone volume/total volume (BV/TV) were determined [26]. The mean value of the two sides was calculated for each specimen. A 1-cm-long cylindrical cortical bone was cut from the right femoral midshaft, which is 4cm from femoral distal end. The whole cortical bone was selected as the ROI (Fig. 3), and the average of thickness and tissue mineral density (TMD) of cortical bone was detected [29]. The precision error of micro-CT was below 0.3%.

2.5. Biomechanical tests 

Bones harvested were frozen at −70°C until the time of testing. Bones were thawed and kept fully moist before the mechanical testing. Prior to testing on vertebrae (L2, L4, L6), the endplates, spinous, transverse and articulate processes were cut with a motor wafer saw to obtain a sample with parallel surfaces [28]. The vertebral samples were placed centrally between two steel parallel plates attached to the materials-testing machine (MTS 858 System Inc., MN, USA) (Fig. 4, left) and compressed at a nominal deformation rate of 2mm/min [30]. The left femora were tested in three-point bending using the same machine (Fig. 4, right). During mechanical testing, femora were placed posterior side up on supports spanning 30mm. Load (force) was applied at the mid-diaphysis on the anterior surface [20], [21], [31]. A constant displacement rate of 1mm/min was applied until failure [25]. Displacement (mm) and force (N) were measured at 10Hz until failure. Load-deformation curves were recorded during the test. The ultimate load was taken as the maximum force on the curve, and the extrinsic stiffness was determined from the slope of the linear portion [31]. The ultimate load was read in newtons, and the stiffness was expressed in N/mm. The mean of L2, L4 and L6 vertebral mechanics values was calculated for the lumbar vertebrae.

2.6. Statistic analysis 

All data are expressed as mean±SD. Multiple comparisons between different groups were performed by ANOVA with the Student–Newman–Keuls multiple-range test. A statistically significant value was chosen at p<0.05. Statistical analyses were performed through the SPSS program, version 11.5 (SPSS, Chicago, IL, USA).

Back to Article Outline

3. Results 

3.1. BMD 

The mean BMD (mg/cm2) values of the lumbar spine, femoral midshaft and condyle are shown in Table 1. Stiffness is expressed in N/mm. In the OVX and sham groups, BMD (post-OVX, LS) was not significantly different from the respective baseline values. In the OVX-GC group, BMD (post-OVX, LS) decreased by 26.7% (p<0.01) compared with the baseline value. This value was also significantly lower than that that in the sham group. The BMD values of the femoral condyle were also not significantly different between the OVX and sham groups. However, in the OVX-GC group, the BMD of the femoral condyle (18.5%) was significantly lower than that in the sham group (p<0.01). There was no significant difference in the BMD of femoral midshaft among all groups.

Table 1. BMD in lumbar spine, femoral midshaft and femoral condyle.
GroupBMD (lumbar spine)BMD (femoral midshaft)BMD (femoral condyle)
Pre-OVXPost-OVX
Sham (n=8)266.7±38.58271.8±39.22349.5±38.65537.7±45.89
OVX (n=4)270.1±25.38248.9±36.14336.2±27.32496.7±24.11
OVX-GC (n=8)272.8±27.08199.9±30.76a313.7±40.25438.1±36.11a

aSignificantly different from sham group, p<0.01.

3.2. Micro-CT 

The three-dimensional micro-CT reconstructions showed lower bone volume in the trabecular bone and greater spacing between the trabeculae in the OVX-GC group compared with the other two groups (Fig. 5, Fig. 6, Fig. 7). The micro-CT data are summarized in Table 2. The micro-architectural parameters of specimens in the OVX group were not significantly lower than those in the sham group in lumbar vertebrae and femoral condyle. In the OVX-GC group, in lumbar vertebrae, Tb.Th (33.3%), Tb.N (42.8%), BV/TV (57.1%) and Tb.Sp (65.2%) changed significantly (p<0.01) as compared with those in the sham group. BS/BV in the OVX-GC group was 45.0% higher than that in the sham group (p<0.05). There was no significant difference between the sham and OVX groups in structural parameters. For the femoral condyle, the parameters all changed significantly, expect for BS/BV, between the sham and OVX-GC groups. In cortical bone of the femoral midshaft, no significant micro-architectural parameter change was found among all groups (Table 3).

Table 2. Micro-architectural parameters from femoral condyle and vertebral body specimens.
GroupTb.Th (mm)Tb.N (1/mm)Tb.Sp (mm)BS/BV (%)BV/TV (%)
Lumbar spine
Sham (n=8)0.09±0.0073.22±0.270.23±0.0222.78±1.670.28±0.02
OVX (n=4)0.08±0.0052.89±0.190.26±0.0226.54±5.290.25±0.03
OVX-GC (n=8)0.06±0.006a1.84±0.23a0.38±0.06a33.04±3.02b0.12±0.02a
Femoral condyle
Sham (n=8)0.17±0.042.61±0.220.22±0.0612.36±2.700.44±0.13
OVX (n=4)0.15±0.012.34±0.180.26±0.0713.08±1.890.40±0.03
OVX-GC (n=8)0.11±0.02b1.56±0.16a0.38±0.04a17.21±3.010.19±0.05a

Tb.Th, average trabecular thickness; Tb.N, trabecular numbers per square millimeter; Tb.Sp, average distance between trabeculae; BS/BV, bone surface/bone volume; BV/TV, bone volume/total volume.

aSignificantly different from sham group, p<0.01.

bSignificantly different from sham group, p<0.05.

Table 3. Micro-architectural parameters from femoral midshaft specimens.
GroupMean thickness (mm)TMD (mg/cm3)
Sham (n=8)0.74±0.07904.28±75.62
OVX (n=4)0.73±0.05890.96±59.11
OVX-GC (n=8)0.7±0.06886.82±41.81

3.3. Mechanical tests 

In the vertebral compression test results shown in Table 4, the values of ultimate load and stiffness in the OVX-GC group decreased by 53.2% and 49.1%, respectively, compared with control group (p<0.01 for both). No significant difference was found between the OVX and control groups. The results of femoral midshaft three-point bending tests showed no significant difference in ultimate load or stiffness among all groups.

Table 4. Biomechanical results of femoral condyle and vertebral body specimens.
GroupLumbar spineFemoral midshaft
Ultimate load (N)Stiffness (N/mm)Ultimate load (N)Stiffness (N/mm)
Sham (n=8)631.2±162.281045.81±307.09304.0±14.01392.74±71.41
OVX (n=4)553.7±133.31890.28±225.88293.7±18.31385.53±97.39
OVX-GC (n=8)295.8±87.79a523.50±143.13a274.2±26.92358.59±91.10

aSignificantly different from sham group, p<0.01.

Back to Article Outline

4. Discussion and conclusion 

In previous studies, the osteopenia in OVX and GC-treated rabbits was principally measured by densitometry [22], [23]. In this study, in the OVX-GC group, substantial changes were shown in the bone mass, bone structure and mechanical properties of cancellous bone. However, these changes were not induced in the OVX group. No significant changes were found in cortical bone among all groups analyzed.

Our study aimed to create a rabbit osteoporosis model without other serious side effects of GC treatment while maintaining the bone loss after GC cessation. GC-induced osteoporosis might show a reversal in bone loss after GC cessation [32], so the combination of OVX and GC administration was applied [22], [23]. The conditions used, including the 4-week GC treatment time, allowed for the demonstration of significant changes in bone loss but without advanced lesions at controlled GC doses [23], [28], [33]. However, with high GC exposure, necrosis might occur in this time span, whereas lower doses do not produce significant bone changes in either trabecular or cortical bone [23], [28]. A GC dose of 1mg/kg/day for 4 weeks induces significant bone loss without serious side effects [22], [23]. In rabbits, osteoporosis cannot be induced by OVX in 4 weeks or after longer time periods [23], [34]. In this study, the OVX group was selected as an OVX control. According to a previous study [33], [35], four rabbits were sufficient for the statistical calculations and study requirements, so we selected four rabbits for the OVX group.

In the present study, compared with the control group, significant decreases in cancellous bone BMD were found in the OVX-GC rabbits (26.8% in vertebrae, 18.5% in femur) but not in OVX rabbits (11.6% in vertebrae, 7.6% in femur), which is consistent with previous reports [23], [34]. The reduction of cancellous bone BMD in the OVX-GC group was greater than the previously observed bone loss of 12% in humans with GC-induced osteoporosis [36].

GC can cause significant loss of osteoblastic-lineage cells, which play a fundamental role in GC-induced osteoporosis [37]. The mechanisms underlying GC-induced osteoporosis consist mainly of a decrease in the number and function of osteoblasts [37]. The decreased number of osteoblasts is caused by impairing the differentiation of mesenchymal cells toward cells of the osteoblastic lineage and preventing the terminal differentiation of osteoblastic cells [38], [39]. Enhanced apoptosis of mature osteoblasts also contributes to the decrease in number of osteoblasts [40]. In addition to causing depletion of mature osteoblasts, GC alters the function of bone-forming cells by inhibiting the synthesis of type I collagen, which results in a decrease in bone matrix available for mineralization. The decrease in type I collagen synthesis occurs by transcriptional and posttranscriptional mechanisms [41]. Significant bone loss and decreased osteoblast function would increase the risk of fractures at trabecular sites.

The decrease in the number of osteoblasts can be observed by histomorphometric analysis. In comparing the changes of bone micro-architectural parameters of osteoporotic rabbits with osteoporotic humans [42], we were able to detect some similarities and some differences. Ito et al. [42] investigated bone samples from the iliac crest of humans and compared osteoporotic and nonosteoporotic patients. In osteoporotic patients, Tb.N decreased by 12% as compared with the nonosteoporotic group, while in this study, decreases of 42.9% and 40.6% were observed in lumbar vertebrae and femoral condyle in the OVX-GC groups, respectively, compared with the control group. Ito et al. [42] found an increase of 20% in osteoporotic humans in Tb.Sp. A similar trend was found in this study. Compared with the control group, the Tb.Sp increased by 65.2% in lumbar vertebrae and 72.7% in femoral condyle in the OVX-GC group. In the osteoporotic patients, the BV/TV ratio decreased 22% as compared with normal subjects [42], while decreases of 57.1% and 56.8% were found in lumbar vertebrae and femoral condyle, respectively, in the OVX-GC group as compared with the control group. Therefore, greater changes in bone parameters were seen in GC-induced osteoporosis rabbits than in postmenopausal osteoporosis humans, which is in agreement with one previous report [43]. Visible trabecular thinning was also found (see Fig. 5, Fig. 6, Fig. 7).

The most important marker of osteoporosis is the severe decrease in bone strength, which reflects the decrease in the number and function of osteoblasts and directly results in bone fractures. In this study, a significant difference between the control and OVX-GC groups was found in vertebral biomechanics tests, which is in agreement with the results of a previous study [28]. Compared to the control group, 53.1% and 49.4% decreases were detected in vertebral ultimate load and stiffness, respectively, in the OVX-GC group, whereas only 13.3% and 14.9% reductions were found in the OVX group. Therefore, patients receiving GC may suffer vertebral and hip fractures at higher bone mineral density values than patients with postmenopausal osteoporosis [44]. In our study, the percentage decrease in BMD was also much lower than that in micro-architectural parameters and bone strength.

Despite the extensive analysis of cancellous bone in GC-induced osteoporosis, little is known about this steroid's effects on cortical bone. Some studies have suggested a significant effect of GC on cortical bone [22], [23], [28]; however, in the present study, there were no marked bone changes in cortical bone. Compared with the control group, the BMD decreased 10.2% in the OVX-GC group. In micro-architectural parameters, only femoral midshaft thickness and TMD decreased as compared with the control group. The mechanical strength of the femoral midshaft showed 9.8% and 8.7% lower ultimate load and stiffness, respectively, in the OVX-GC group as compared with the control group. Differences observed in the study described here with other previous studies might have occurred for the following reasons. Grardel et al. [28] used growing rabbits as a model animal, which are more sensitive to GC than the adult rabbits used in our study. Moreover, the study lasted for 5 months, much longer than our study period. In the study of Castaneda et al. [22], the lateral cortex of the proximal metaphysis of the tibia was selected as the main reference for cortical bone which might not precisely represent the cortical bone, while in this study, the femoral midshaft was determined. In agreement with the results from this study, GC affects the trabecular bone earlier and more severely than in cortical bone, but with prolonged use, the cortical bone is also affected [25], [45].

There are several limitations of the current animal model. First, whether osteopenia would rebound after GC treatment cessation was not examined, although one previous study has shown that bone loss continues after GC treatment cessation [23]. Second, during and after the GC treatment, detrimental effects might be increased as the immune system is suppressed, although we did not observe this in our rabbits. Third, the GC treatment might have been too short to induce significant changes in cortical bone. Further investigation of these issues might be necessary.

In conclusion, the micro-architectural characteristics, mechanical competence and mineralization of the bone tissues in OVX rabbits after 4 weeks of GC treatment were similar to osteoporosis-related changes in humans. Therefore, we think that the OVX-GC rabbit is a successful osteoporosis model characterized by osteoporosis that is consistent, easy to induce within a short period of time, and highly reproducible.

Back to Article Outline

Conflict of interest statement 

No financial or personal relationships (employment, consultancies, stock ownership, honoraria, paid expert testimony, patent applications/registrations, or grants or other funding) with other people or organizations that could inappropriately influence (bias) this study or its results exist.

Back to Article Outline

References 

  1. Adachi JD, Loannidis G, Berger C, Joseph L, Papaioannou A, Pickard L, et al. The influence of osteoporotic fractures on health-related quality of life in community-dwelling men and women across Canada. Osteoporos Int. 2001;12(11):903–908
  2. Hall SE, Criddle RA, Comito TL, Prince RL. A case-control study of quality of life and functional impairment in women with long-standing vertebral osteoporotic fracture. Osteoporos Int. 1999;9(6):508–515
  3. Lyles KW, Gold DT, Shipp KM, Pieper CF, Martinez S, Mulhausen PL. Association of osteoporotic vertebral compression fractures with impaired functional status. Am J Med. 1993;94(6):595–601
  4. Geddes AD. Animals models of bone disease. In:  Bilezikians JP,  Raisz LG,  Rodan GA editor. Principals of Bone Biology. San Diego: Academic Press; 1996;p. 1343–1354
  5. Bonjour JP, Ammann P, Rizzoli R. Importance of preclinical studies in the development of drugs for treatment of osteoporosis: a review related to the 1998 WHO guidelines. Osteoporos Int. 1999;9(5):379–393
  6. Egermann M, Goldhahn J, Schneider E. Animal models for fracture treatment in osteoporosis. Osteoporos Int. 2005;16(2):S129–S138
  7. Food and Drug Administration . Guidelines for Preclinical and Clinical Evaluation Agents Used in the Prevention or Treatment of Postmenopausal Osteoporosis. Rockville, MD, USA: Division of Metabolic and Endocrine Drug Products, Food and Drug Administration; 1994;
  8. Kalu DN. The ovariectomized rat model of postmenopausal bone loss. Bone Miner. 1991;15(3):175–191
  9. Wronski TJ, Yen CF. The ovariectomized rat as an animal model for postmenopausal bone loss. Cells Mater. 1992;129(4):69–74
  10. Mosekilde L. Assessing bone quality – animal models in preclinical osteoporosis research. Bone. 1995;17(4 Suppl.):S343–S352
  11. Turner RT, Maran A, Lotinun S, Hefferan T, Evans GL, Zhang M, et al. Animal models for osteoporosis. Rev Endocr Metab Disord. 2001;2(1):117–127
  12. Turner AS. Animal models of osteoporosis – necessity and limitations. Eur Cell Mater. 2001;1:66–81
  13. Reinwald S, Burr D. Review of nonprimate, large animal models for osteoporosis research. J Bone Miner Res. 2008;23(9):1353–1368
  14. Mori H, Manabe M, Kurachi Y, Nagumo M. Osseointegration of dental implants in rabbit bone with low mineral density. J Oral Maxillofac Surg. 1997;55(4):351–361discussion 362
  15. Zaffe D, Rodriguez YBR, Rizzo S, Brusotti C, Soncini M, Pietrabissa R, et al. Behavior of the bone–titanium interface after push-in testing: a morphological study. Biomed Mater Res J A. 2003;64(2):365–371
  16. Deglurkar M, Davy DT, Stewart M, Goldberg VM, Welter JF. Evaluation of machining methods for trabecular metal implants in a rabbit intramedullary osseointegration model. J Biomed Mater Res B: Appl Biomater. 2007;80(2):528–540
  17. Gilsanz V, Roe TF, Gibbens DT, Schulz EE, Carlson ME, Gonzalez O, et al. Effect of sex steroids on peak bone density of growing rabbits. Am J Physiol. 1988;255(4 Pt 1):E416–E421
  18. Kimmel DB. Animal models for in vivo experimentation in osteoporosis research. In:  Marcus R,  Feldman D,  Kelsey J editor. Osteoporosis. San Diego: Academic Press; 1996;p. 671–690
  19. Lindgren JU, DeLuca HF, Mazess RB. Effects of 1,25(OH)2D3 on bone tissue in the rabbit: studies on fracture healing, disuse osteoporosis, and prednisone osteoporosis. Calcif Tissue Int. 1984;36(5):591–595
  20. Cao T, Shirota T, Ohno K, Michi KI. Mineralized bone loss in partially edentulous trabeculae of ovariectomized rabbit mandibles. J Periodontal Res. 2004;39(1):37–41
  21. Cao T, Shirota T, Yamazaki M, Ohno K, Michi KI. Bone mineral density in mandibles of ovariectomized rabbits. Clin Oral Implants Res. 2001;12(6):604–608
  22. Castaneda S, Largo R, Calvo E, Rodriguez-Salvanes F, Marcos ME, Diaz-Curiel M, et al. Bone mineral measurements of subchondral and trabecular bone in healthy and osteoporotic rabbits. Skeletal Radiol. 2006;35(1):34–41
  23. Castaneda S, Calvo E, Largo R, Gonzalez-Gonzalez R, de la Piedra C, Diaz-Curiel M, et al. Characterization of a new experimental model of osteoporosis in rabbits. J Bone Miner Metab. 2008;26(1):53–59
  24. Covey MK, Smith DL, Berry JK, Hacker ED. Importance of cross-calibration when replacing DXA scanners: QDR4500W and Discovery Wi. J Nurs Meas. 2008;16(3):155–170
  25. Schorlemmer S, Ignatius A, Claes L, Augat P. Inhibition of cortical and cancellous bone formation in glucocorticoid-treated OVX sheep. Bone. 2005;37(4):491–496
  26. Wu ZX, Lei W, Hu YY, Wang HQ, Wan SY, Ma ZS, et al. Effect of ovariectomy on BMD, micro-architecture and biomechanics of cortical and cancellous bones in a sheep model. Med Eng Phys. 2008;30(9):1112–1118
  27. Cohen S, Levy RM, Keller M, Boling E, Emkey RD, Greenwald M, et al. Risedronate therapy prevents corticosteroid-induced bone loss: a twelve-month, multicenter, randomized, double-blind, placebo-controlled, parallel-group study. Arthritis Rheum. 1999;42(11):2309–2318
  28. Grardel B, Sutter B, Flautre B, Viguier E, Lavaste F, Hardouin P. Effects of glucocorticoids on skeletal growth in rabbits evaluated by dual-photon absorptiometry, microscopic connectivity and vertebral compressive strength. Osteoporos Int. 1994;4(4):204–210
  29. Bagi CM, Hanson N, Andresen C, Pero R, Lariviere R, Turner CH, et al. The use of micro-CT to evaluate cortical bone geometry and strength in nude rats: correlation with mechanical testing, pQCT and DXA. Bone. 2006;38(1):136–144
  30. Ikeda S, Tsurukami H, Ito M, Sakai A, Sakata T, Nishida S, et al. Effect of trabecular bone contour on ultimate strength of lumbar vertebra after bilateral ovariectomy in rats. Bone. 2001;28(6):625–633
  31. Akhter MP, Cullen DM, Gong G, Recker RR. Bone biomechanical properties in prostaglandin EP1 and EP2 knockout mice. Bone. 2001;29(2):121–125
  32. Ding M, Cheng L, Bollen P, Schwarz P, Overgaard S. Glucocorticoid induced osteopenia in cancellous bone of sheep: validation of large animal model for spine fusion and biomaterial research. Spine (Phila Pa 1976). 2010;1(Suppl. 1):363–370
  33. Eberhardt AW, Yeager-Jones A, Blair HC. Regional trabecular bone matrix degeneration and osteocyte death in femora of glucocorticoid-treated rabbits. Endocrinology. 2001;142(3):1333–1340
  34. Saito M, Marumo K, Soshi S, Kida Y, Ushiku C, Shinohara A. Raloxifene ameliorates detrimental enzymatic and nonenzymatic collagen cross-links and bone strength in rabbits with hyperhomocysteinemia. Osteoporos Int. 2009;21(4):655–666
  35. Southard TE, Southard KA, Krizan KE, Hillis SL, Haller JW, Keller J, et al. Mandibular bone density and fractal dimension in rabbits with induced osteoporosis. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2000;89(2):244–249
  36. Manolagas SC, Weinstein RS. New developments in the pathogenesis and treatment of steroid-induced osteoporosis. J Bone Miner Res. 1999;14(7):1061–1066
  37. Sambrook PN. Anabolic therapy in glucocorticoid-induced osteoporosis. N Engl J Med. 2007;357(20):2084–2086
  38. Pereira RC, Delany AM, Canalis E. Effects of cortisol and bone morphogenetic protein-2 on stromal cell differentiation: correlation with CCAAT-enhancer binding protein expression. Bone. 2002;30(5):685–691
  39. Pereira RM, Delany AM, Canalis E. Cortisol inhibits the differentiation and apoptosis of osteoblasts in culture. Bone. 2001;28(5):484–490
  40. Weinstein RS, Jilka RL, Parfitt AM, Manolagas SC. Inhibition of osteoblastogenesis and promotion of apoptosis of osteoblasts and osteocytes by glucocorticoids. Potential mechanisms of their deleterious effects on bone. J Clin Invest. 1998;102(2):274–282
  41. Delany AM, Gabbitas BY, Canalis E. Cortisol downregulates osteoblast alpha 1 (I) procollagen mRNA by transcriptional and posttranscriptional mechanisms. J Cell Biochem. 1995;57(3):488–494
  42. Ito M, Ohki M, Hayashi K, Yamada M, Uetani M, Nakamura T. Trabecular texture analysis of CT images in the relationship with spinal fracture. Radiology. 1995;194(1):55–59
  43. Dalle Carbonare L, Arlot ME, Chavassieux PM, Roux JP, Portero NR, Meunier PJ. Comparison of trabecular bone microarchitecture and remodeling in glucocorticoid-induced and postmenopausal osteoporosis. J Bone Miner Res. 2001;16(1):97–103
  44. Van Staa TP, Laan RF, Barton IP, Cohen S, Reid DM, Cooper C. Bone density threshold and other predictors of vertebral fracture in patients receiving oral glucocorticoid therapy. Arthritis Rheum. 2003;48(11):3224–3229
  45. Lill CA, Gerlach UV, Eckhardt C, Goldhahn J, Schneider E. Bone changes due to glucocorticoid application in an ovariectomized animal model for fracture treatment in osteoporosis. Osteoporos Int. 2002;13(5):407–414

PII: S1350-4533(11)00147-0

doi:10.1016/j.medengphy.2011.06.010

Medical Engineering & Physics
Volume 34, Issue 1 , Pages 2-8, January 2012

Article Tools

* Image Usage & Resolution