Do estrogen and alendronate improve metaphyseal fracture healing when applied as osteoporosis prophylaxis?

Osteoporosis is accompanied by predominantly metaphyseal fractures with a delayed and qualitatively reduced healing process. This study addressed the question of whether fracture healing in the context of osteoporosis prophylaxis is improved with estrogen (E) or alendronate (ALN). Thirty-six ovariectomized and 12 sham-operated 12-week-old rats received soy-free (osteoporotic C, sham), E-, or ALN- supplemented diets. After 10 weeks, a metaphyseal tibia osteotomy and standardized T-plate fixation were performed. After a 5-week healing process, the fracture callus was evaluated qualitatively by biomechanical bending test and quantitatively in microradiographic sections. The time course of callus formation was examined using fluorochrome-labeled histological sections. Administration of E improved the biomechanical properties of callus (stiffness [N/mm]: sham: 110.2 + or - 76.07, C: 41.28 + or - 33.70, E: 85.72 + or - 47.24, ALN: 72.07 + or - 34.68). The resistance to microfracturing seen in E-treated animals was significantly enhanced and even superior to sham (yield load [N] sham: 27.44 + or - 9.72, C: 21.04 + or - 12.47, E: 42.85 + or - 13.74(Delta), ALN: 25.28 + or - 6.4(.)) (* P < 0.05 vs. sham group, (Delta) P < 0.05 vs. C group, (*) P < 0.05 vs. E group). Trabecular bone in particular was improved, indicating the presence of physiological endosteal bridging (Tr.Dn [%] sham: 10.53 + or - 18.9, C: 1.01 + or - 0.14, E: 24.13 + or - 34.09(Delta), ALN: 3.99 + or - 8.3(.)). ALN did not help bone healing, as shown by mechanical tests. Compared to the C group, statistically, ALN did not show worse properties. The induction of callus formation under ALN treatment was slightly delayed (Tt.Cl [mm(2)] sham: 3.68 + or - 0.66, C: 3.44 + or - 0.42, E: 3.69 + or - 0.58, ALN: 3.06 + or - 0.56). Osteoporotic metaphyseal fracture healing was qualitatively and quantitatively improved by E prophylaxis. The process of fracture healing occurred nearly physiologically (shamlike). Notably, ALN hardly improved metaphyseal callus properties when assessed as osteoporosis prophylaxis, but to a lesser extent than E.

Changes in the histomorphometric and biomechanical properties of the proximal femur of ovariectomized rat after treatment with the phytoestrogens genistein and equol.

The isoflavonoids found in soy have attracted great interest as dietary phytoestrogens that might be effective for postmenopausal hormone replacement therapy. Special attention has been devoted to the hormonal effects of various isoflavonoids, like genistein (GEN) and daidzein's (DAID) potent metabolite, equol (EQ). Here we aimed to investigate the short-term effects of genistein and equol on the proximal femur of ovariectomized (OVX) rats. Forty-eight, 3-month-old female Sprague-Dawley rats were ovarectomized; after eight weeks the bilateral osteotomy and osteosynthesis (OS) of their tibiae was performed and the rats were randomly divided into the following four groups: OVX control group (C), treated with estradiol-17beta (E2) -benzoate (E; daily intake 0.086 mg/d per animal), genistein (GEN; daily intake 12.7 mg/d per animal) and equol (EQ; daily intake 4.65 mg/d per animal). At 5 weeks postoperatively (OS), the breaking test was performed on the trochanteric region of femur. Additionally, histomorphometric assessment, and trabecular and cortical bone microstructure analyses were performed. The relative gain of body weight (BW) in the EQ (24 %) group was significantly (p < 0.05) lower than in the C (33 %) and GEN (30 %) groups. After treatment for 5 weeks, the maximal load (F(max)) and yield load (yL) were higher (p < 0.05 for the weight-adapted results) in the E (188.4 N resp. 113.1 N) and EQ (177.3 N resp. 112 N) groups as compared to C (162.8 N resp. 109.1 N) and GEN (165.7 N resp. 108.8 N). In the histomorphometric tests the E- (trabecular area (Tb.Ar) = 74.93 %, trabecular nodes/mm(2) (N.Nd/mm(2)) = 48.65) and EQ-treated (Tb.Ar = 63.13 %, N.Nd/mm(2) = 43.72) animals showed significant improvement with regard to Tb.Ar and trabecular connectivity (N.Nd./mm(2)) in comparison to C (Tb.Ar = 46.84, N.Nd/mm(2) = 31.86) and GEN (Tb.Ar = 48.22 %, N.Nd/mm(2) = 34.15). There were no differences in relative cortical width (Ct.Wi) among the four groups. The treatment with EQ resulted in improved biomechanical and histomorphometric properties as compared to the treatment with GEN. Thus, of the studied substances, EQ seems to be a possible alternative to hormone replacement therapy, but further studies are needed.

Effects of black cohosh (Cimicifuga racemosa) and estrogen on metaphyseal fracture healing in the early stage of osteoporosis in ovariectomized rats.

Osteoporosis and its accompanying, predominantly metaphyseal, fractures are a major health problem. Black cohosh (Cimicifuga racemosa) and estrogen positively influence osteoporotic bone. Both substances may improve fracture healing in early osteoporosis as well. In 48 twelve-week-old ovariectomized or, respectively, sham-operated (SHAM) rats, a standardized metaphyseal tibia osteotomy with bridging T-plate fixation was performed. During the healing process of 35 days, rats received soy-free (SHAM, osteopenic C), estrogen- (E) or Cimicifuga racemosa- (CR) supplemented diets. After sacrifice, the callus formation was analyzed with regard to biomechanical quality, morphology, quantity, time course of new bone built and gene expression. CR induced a high rate of metaphyseal callus formation. The biomechanical properties and the amount of new callus formation indicated that fracture healing was still in progress. Therefore, gene expression of osteoblasts was comparatively high. Body weight and the trabecular structure were influenced little by CR. Estrogen improved the biomechanical properties of the callus. Resistance to microfracturing was significantly enhanced in the E group and even superior to SHAM. Remodeling of the callus formation had already begun. The trabecular network and the typical endosteal fracture healing were especially improved. Osteoporotic metaphyseal fracture healing was improved by estrogen more than by Cimicifuga racemosa. The process of fracture healing occurred nearly physiologically. The generation of callus formation was supported by Cimicifuga racemosa as well, but the five-week duration of application was too short for Cimicifuga racemosa to show its complete potential. Already-initiated Cimicifuga racemosa therapy for menopausal symptoms could be continued during fracture healing without hesitation.

Equol but not genistein improves early metaphyseal fracture healing in osteoporotic rats.

Healing of predominantly metaphyseal fractures in postmenopausal osteoporosis is delayed and comparatively poor. Hormone replacement therapy could improve fracture healing, but, because of its potential side effects, natural alternatives are more appealing. The aim of this study was to determine if the soy metabolite equol and the native isoflavone genistein, in comparison to 17beta-estradiol, improve metaphyseal fracture healing in ovariectomy-induced osteoporotic bone of the rat. Forty-eight 12-week-old female rats developed severe osteoporosis ten weeks after ovariectomy. After metaphyseal tibial osteotomy and standardized stable internal fixation, changes in callus morphology were evaluated biomechanically, qualitatively and quantitatively in fluorochrome-labeled histological sections and microradiographs in ovariectomized rats (C) and under standardized 17beta-estradiol (E), equol (EQ) and genistein (G) supplemented rats over a period of five weeks. Estrogen and equol were able to improve the elasticity of callus formation significantly in postmenopausal osteoporotic bone (stiffness of C: 121.40 +/- 47.08 N/mm, E: 147.90 +/- 39.38 N/mm, EQ: 167.8 +/- 59.90 N/mm). The effects of estrogen were more anabolic than those of equol and were visible in changes to the trabecular bone (N.Nd of E: 6.47 +/- 7.68, EQ: 4.25 +/- 3.96). However, in terms of the whole body, equol seemed to induce less of an adverse reaction than estrogen (body weight of C: 342.20 +/- 19.91 g, E: 280.25 +/- 12.05 g, EQ: 308.75 +/- 24.28 g). Genistein as an osteoclast inhibitor influenced callus stiffness (G: 144.50 +/- 61.52 N/mm) and negatively impacted trabecular structure (N.Nd of G: 0.59 +/- 1.01) in severely osteoporotic bones. Estrogen and equol were able to improve fracture healing in ovariectomy-induced osteoporotic bones, and the extent of callus formation played only a minor role. Genistein rather negatively influenced fracture healing. The metaphyseal osteotomy model in ovariectomized rats allows an accurate study of the therapeutic effects of antiosteoporotic substances on the fracture healing process.

Standardized bending and breaking test for the normal and osteoporotic metaphyseal tibias of the rat: effect of estradiol, testosterone, and raloxifene.

UNLABELLED: The fracture of bone plays a key role in osteoporosis. BMD measurement, however, is only an indirect parameter of this phenomenon. We therefore developed a highly sensitive three-point bending test for the metaphyseal tibias in rats to evaluate stiffness and strength. This was validated in a right-left comparison and a bioassay with soy-free food, estradiol, raloxifene, and testosterone in orchidectomized rats. INTRODUCTION: Osteoporosis becomes manifest predominantly in the metaphyseal rat tibia. The anti-osteoporotic character of substances should, therefore, be tested (mechanically) in this bone area. MATERIALS AND METHODS: We evaluated a new three-point bending test for the metaphyseal tibia in rats in a right-left trial. In an animal experiment, we studied the change of bone quality under estradiol (E)-, raloxifene (R)-, and testosterone (T)-supplemented food and compared it with trabecular BMD (qCT). RESULTS: In the right-left comparison, the mean difference between the metaphyseal loads of both tibias in 37 rats was 8.43% for the maximum load (Fmax) and 6.46% for the failure load (fL). These results show the high reproducibility of the test, because they are close to the usual intraindividual difference of the two extremities. In a second experiment, four groups of 11 3-month-old male orchidectomized rats were fed with soy-free food only (C) or with the additives E, T, or R for 12 weeks. E and R were similar for Fmax and fL. There were significant differences in the stiffness (E = 406.92 N/mm versus R = 332.08 N/mm), the yield load (yL; E = 99.17 N versus R = 83.33 N), and the ratio between yL and Fmax (E = 86.33% versus R = 76.37%). T was similar to the controls concerning F(max), fL, and stiffness. There were significant differences in yL (T = 49.00N versus C = 39.5N) and the ratio between yL and Fmax (T = 64.28% versus C = 51.28%). CONCLUSIONS: Estradiol is superior to raloxifene concerning stiffness and yield load, and both are superior to testosterone. We conclude that the described three-point bending test for the metaphyseal tibia is a highly sensitive method to study hormones and substances with regard to their osteoprotective character. The precision and the low SD of the presented results are superior to the data from qCT and the calculated index of stiffness (SSI).

The Elastic Bridge Plating of the Forearm Fracture: A Prospective Study.

Rigid plate osteosynthesis with compression is still the treatment of choice for forearm fractures to gain anatomic reposition, provide proper rotation and avoid a bridging callus. Due to necessary operative dissection there is a serious risk for infection and malunion. Based on good clinical results with elastic bridge plating at femur, humerus and tibia, this technique was also started to be used for forearm fractures in our clinic in 1995. In a prospective study, 86 of 124 consecutive patients at the age of 35.2 ± 14.7 years with 129 diaphyseal fractures of the radius or ulna (AO: 37 type A, 36 type B, 13 type C) were analyzed between January 1998 and December 2003. All fractures were stabilized by bridge plating. Radiographic union and clinical outcome were documented. Of the 129, 122 diaphyseal fractures (94.5%) healed within 10.2 ± 3.4 weeks without complications (no nerve lesions, nonunion, synostosis callus). One re-osteosynthesis, one secondary lag screw, and five cancellous bone grafts were necessary before final healing. About 79.1% of the patients had a perfect clinical outcome; 17.4% had additional severe injuries of the same arm. Bridge plating without interfragmentary compression is a reliable surgical procedure even for forearm fractures with low risk of infection and nonunion.

Short-term effects of parathyroid hormone on rat lumbar vertebrae.

STUDY DESIGN: This study is an experimental study in the rat osteopenia model. OBJECTIVE: The aim of this study was to evaluate the short-term effects of daily application of parathyroid hormone (PTH) on bone quality and quantity using a new biomechanical compression test for intact rat lumbar vertebrae. SUMMARY OF BACKGROUND DATA: Because of their high clinical relevance, trabecular content and thick cortical shell vertebrae are of high interest for osteoporosis research. Biomechanical stability depends on both trabecular and cortical bone. Anabolic effects on bone after long-term application of PTH have already been proven. METHODS: After an intraindividual comparison (n = 20), the capability of a new test to identify biomechanical properties of the mature rat model was assessed. In the following, 33 three-month-old rats were ovariectomized. After 10 weeks, the animals were divided into 3 groups. The control group (C) received no additional food supplementation. The other groups received hormone treatment with either estradiol (E) or PTH for another 5 weeks. The effects on bone biomechanical properties and bone microstructure were analyzed. RESULTS: After establishing the new biomechanical test for intact rat lumbar vertebrae, PTH-treated (yield stress: 2.95 N/mm, elastic limit: 2.39 N/mm) and then E-treated (yield stress: 2.13 N/mm, elastic limit: 1.68 N/mm) animals showed superior biomechanical results. Compression strength was significantly improved in these rats in comparison to the control group rats (yield stress: 1.86 N/mm, elastic limit: 1.38 N/mm). In the microradiographic evaluation, PTH significantly improved the morphologic results to produce thicker trabeculae. E led to a more densely branched trabecular network, which was not as important as trabecular thickness for bone stability. CONCLUSION: After a short-term application, PTH is superior to E in recreating bone biomechanical propertiesand lumbar vertebral microstructure in advanced osteoporosis. The cortical shell and trabecular thickness are primarily responsible for the biomechanical strength of vertebrae.

The use of flat panel volumetric computed tomography (fpVCT) in osteoporosis research.

RATIONALE AND OBJECTIVES: Improvements in imaging technology have led to the increased use of computed tomography (CT). For example, micro-CT and quantitative CT (QCT) are now often used in osteoporosis research, in which micro-CT is able to analyze small bones or bone samples with high spatial resolution. In contrast, QCT is able to investigate large samples with low spatial resolution. The aim of this study was to test the usefulness of flat-panel volumetric CT (fpVCT) in a rat model of osteopenia. MATERIAL AND METHODS: Twenty-two 3-month-old rats underwent ovariectomy and were either left untreated or supplemented with estradiol for 15 weeks. After sacrificing, the rats' second lumbar vertebral body bone mineral density (BMD) was analyzed using fpVCT and ashing. The results were compared to those of a microstructural analysis of the first lumbar vertebrae and a biomechanical evaluation of the fourth lumbar vertebrae. RESULTS: BMD measurements using both fpVCT (0.39 vs 0.35 mg/cm(3)) and ashing (0.52 vs 0.48 mg/cm(3)) demonstrated a significant improvement after estradiol supplementation. The correlation coefficient of the two methods was 0.858. After estradiol supplementation, the bone microstructural and bone biomechanical parameters were improved, compared to no treatment. The correlations of both the microstructural and the biomechanical evaluations were closer for BMD measured using fpVCT (r = 0.482-0.769) than on the basis of ashing (r = 0.345-0.573). FpVCT was not able to display the trabecular microstructure of the rat lumbar vertebrae. CONCLUSION: The use of fpVCT demonstrated a close relationship between morphologic and biomechanical evaluations in a rat model of osteopenia. Because of its different proportions, fpVCT might be able to bridge the gap between micro-CT and QCT in analyzing larger animals.