• The Korean Journal of Ceramics
• /
• v.7 no.1
• /
• pp.41-44
• /
• 2001

A composite of $Ca_3$(PO$_4$)$_2$ and MgAl$_2$O$_4$ spinel is biologically active and has enduring strength. Its strength depends on the spinel phase. The flaws in the spinel depend on the grain size of the calcium phosphate phase and are not altered by dissolution. The calcium phosphate, ${\alpha}$ tri-calcium phosphate, controls the tissue response. Bone bonds to the implant. A design for a bone graft as a replacement for a section of the diaphysis of a canine femur provides for tensile, compressive, torsional and bending load; and for the physiological processes of bonding and remodeling. A bone plate, used to stabilize the implant at time of surgery was removed after about one year. Over seven years of service have been achieved without internal or external fixation.

• Journal of the Korean Society for Precision Engineering
• /
• v.26 no.6
• /
• pp.131-135
• /
• 2009

In this study, we performed the compressive strength test of trabecular bone in knee joint for measuring the elastic modulus and ultimate strength. The main knee joint is femorotibial articulation between the lateral and medial femorotibial condyle. In the case of osteoarthritis, some patients have only medial condylar osteoarthritis. We performed the mechanical test for comparison the difference of the each condylar strength. We used diamond core-drill and linear precision saw for making the specimens. Specimens were cored from both condyle in distal femur and proximal tibia in fresh cadaver (male 10, female 12), and tested by universal test machine with temperature control saline circulation system. Results of the test in distal femoral parts, averaged elastic modulus was $360.61{\pm}159.40MPa$ for male, $150.89{\pm}70.65MPa$ for female. Averaged ultimate strength was $6.79{\pm}2.91MPa$ for male, $2.89{\pm}1.31MPa$ for female. Male was 2.4 times stronger than female. In the proximal tibial parts, averaged elastic modulus was $108.80{\pm}52.88MPa$ for male, $73.45{\pm}55.06MPa$ for female. Averaged ultimate strength was $2.59{\pm}1.39MPa$ for male, $1.75{\pm}1.16MPa$ for female. Male was 1.5 times stronger than female. In the distal femoral condyle, medial condyle had more strength than lateral condyle at middle region. But lateral condyle had more strength than medial condyle at anterior & posterior regions (p<0.02). In the proximal tibial condyle, medial condyle had more strength than lateral condyle. (p<0.01).

• Experimental and Molecular Medicine
• /
• v.50 no.12
• /
• pp.3.1-3.14
• /
• 2018

Type 1 diabetes mellitus (T1DM) is a pathological condition associated with osteopenia. $WNT/{\beta}$-catenin signaling is implicated in this process. Trabecular and cortical bone respond differently to $WNT/{\beta}$-catenin signaling in healthy mice. We investigated whether this signaling has different effects on trabecular and cortical bone in T1DM. We first established a streptozotocin-induced T1DM mouse model and then constitutively activated ${\beta}$-catenin in osteoblasts in the setting of T1DM (T1-CA). The extent of bone loss was greater in trabecular bone than that in cortical bone in T1DM mice, and this difference was consistent with the reduction in the expression of ${\beta}$-catenin signaling in the two bone compartments. Further experiments demonstrated that in T1DM mice, trabecular bone showed lower levels of insulin-like growth factor-1 receptor (IGF-1R) than the levels in cortical bone, leading to lower $WNT/{\beta}$-catenin signaling activity through the inhibition of the IGF-1R/Akt/glycogen synthase kinase $3{\beta}$ ($GSK3{\beta}$) pathway. After ${\beta}$-catenin was activated in T1-CA mice, the bone mass and bone strength increased to substantially greater extents in trabecular bone than those in cortical bone. In addition, the cortical bone of the T1-CA mice displayed an unexpected increase in bone porosity, with increased bone resorption. The downregulated expression of WNT16 might be responsible for these cortical bone changes. In conclusion, we found that although the activation of $WNT/{\beta}$-catenin signaling increased the trabecular bone mass and bone strength in T1DM mice, it also increased the cortical bone porosity, impairing the bone strength. These findings should be considered in the future treatment of T1DM-related osteopenia.

• Imaging Science in Dentistry
• /
• v.33 no.2
• /
• pp.113-119
• /
• 2003

Purpose : To evaluate the relationship between morphometric analysis of bone microstructure from digital radiographic image and trabecular bone strength. Materials and Methods : One hundred eleven bone specimens with 5 mm thickness were obtained from the mandibles of 5 pigs. Digital images of specimens were taken using a direct digital intraoral radiographic system. After selection of ROI (100 × 100 pixel) within the trabecular bone, mean gray level and standard deviation were obtained. Fractal dimension and the variants of morphometric analysis (trabecular area, periphery, length of skeletonized trabeculae, number of terminal point, number of branch point) were obtained from ROI. Punch sheer strength analysis was performed using Instron (model 4465, Instron Corp., USA). The loading force (loading speed 1 mm/min) was applied to ROI of bone specimen by a 2 mm diameter punch. Stress-deformation curve was obtained from the punch sheer strength analysis and maximum stress, yield stress, Young's modulus were measured. Results: Maximum stress had a negative linear correlation with mean gray level and fractal dimension significantly (p<0.05). Yield stress had a negative linear correlation with mean gray level, periphery, fractal dimension and the length of skeletonized trabeculae significantly (p < 0.05). Young's modulus had a negative linear correlation with mean gray level and fractal dimension significantly (p < 0.05). Conclusions : The strength of cancellous bone exhibited a significantly linear relationship between mean gray level, fractal dimension and morphometric analysis. The methods described above can be easily used to evaluate bone quality clinically.

• The Korean Journal of Food And Nutrition
• /
• v.18 no.1
• /
• pp.72-80
• /
• 2005

To prevent and treat the osteoporosis, diverse therapies have been applied, which is still need to solve negative side effects. We investigated the effects of the extract from alternative medicine(AM) on the progress of bone loss in ovariectomized-rats fed with Ca-deficient diet for 7 or 14 weeks. Ovariectomy(OVX) concomitant with Ca-deficiency caused bone loss evidently decreased in bone mineral density and bone strength of femoral epiphysis and vertebrae, which were ameliorated with administration of AM extract. Also, the effect of AM extract on the biochemical markers were measured. The increased serum alkaline phosphatase caused by OVX and Ca-deficiency were observed, which were not affected by administration of AM extract. Administration of AM extract may have preventive effect on the elevated serum acid phosphatase concentrations caused by OVX and Ca-deficiency at 14 wks, implicating that AM extract possibly acts toward reducing born resorption, even though the results were not statistically significant. Serum osteocalcin and urinary deoxypyridinoline, the markers of bone turn over, were not changed by estrogen deficiency or AM extract. We concluded that the AM extract treatment had potently preventive effects on the decreased bone density and bone strength induced by OVX and Ca-deficiency. The changes of biochemical markers related to the effect of AM extract were not manifested but it still suggest that AM extract may inhibit the bone resorption derived from OVX and Ca-deficiency.

• Journal of Nutrition and Health
• /
• v.41 no.3
• /
• pp.206-215
• /
• 2008

The purpose of this study was to investigate the effect of manganese (Mn) supplementation on bone status and calcium balance in ovariectomized rats according to the calcium intake levels. Total of 50 Sprague Dawley female rats (6 weeks) were divided into 5 groups and bred for 12 weeks: sham operated control group (SACa), OVX Ca deficiency group (OLCa) with Ca deficiency diet (0.1% Ca modified AIN-93N diet), OVX Ca deficiency & Mn supplement group (OLCaMn), OVX adequate Ca group (OACa; 0.5% Ca AIN-93N diet) and OVX adequate Ca & Mn supplement group (OACaMn). BMD (bone mineral density) of the femur was increased by Mn supplementation in OVX adequate Ca group. However, BMDs of spine, femur and tibia were lowered in OLCa compared to the OLCaMn group. Bone strength of tibia in OLCaMn group was significantly lower than OLCa group. Serum ALP (alkaline phosphatase) and CTx (C-telopeptide of collagen cross-links) levels were significantly higher in ovariectomized rats than those in the sham group, but they were not changed by Mn supplementation. Ca retention rate and Ca absorption rate did not differ among the experimental groups. Urinary Ca excretion was increased by Mn supplementation in Ca deficiency rats. In summary, Mn supplementation resulted in positive effects on bone mineral density ovariectomized rats with which intake adequate Ca. However, Mn supplementation on Ca deficiency ovariectomized rats resulted in decrement of BMO and bone strength by increasing Ca excretion. Therefore, it is encouraged to consider calcium intake levels in supplementation of manganese in order to prevent postmenopausal osteoporosis and to keep bone healthy. (KoreanJNutr2008; 41(3): 206~215)

• Korean Journal of Exercise Nutrition
• /
• v.23 no.4
• /
• pp.36-42
• /
• 2019

[Purpose] The study aimed to determine the effects of bone-specific physical activity on body composition, bone mineral density (BMD), and health-related physical fitness in middle-aged women. [Methods] One hundred eighty-six middle-aged women aged 31-49 years participated in this study. The subjects were divided into tertile groups according to the level of physical activity (low-score group, n=62; middle-score group, n=62; high-score group, n=62). Bone-specific physical activity participation was assessed using the bone-specific physical activity questionnaire. Body composition and BMD were measured using dual-energy X-ray absorptiometry. Health-related physical fitness test included isometric muscle strength (grip strength), muscular endurance (sit-ups), flexibility (sit and reach), and cardiorespiratory fitness (maximal oxygen uptake [VO_2max]). [Results] The high-score group had a significantly higher fat-free mass (p=.045, partial eta-squared value[η_p²]=.033) than the middle- and low-score groups, whereas the high-score group had significantly lower percent body fat (p=.005, η_p²=.056) than the other two groups. Whole-body BMD (p=.034, η_p²=.036) and lumbar BMD (p=.003, η_p²=.060) were significantly higher in the high-score group than in the low-score group. The high-score group performed significantly better for grip strength (p=.0001, η_p²=.101), sit-ups (p=.0001, η_p²=.108), and VO_2max (p=.0001, η_p²=.092) than the other two groups. [Conclusion] The present study suggests that bone-specific physical activity could be useful in improving body composition, BMD, and health-related physical fitness in middle-aged women, significantly enhancing their BMD and health conditions.

• Journal of Biomedical Engineering Research
• /
• v.23 no.6
• /
• pp.451-458
• /
• 2002

Osteoporosis is a systemic skeletal disease caused by low bone mass and the decrease of bone density in the microstructure of trabecular bone. Drug therapy(PTH Parathyroid hormone) may increase the trabecular thickness and thus bone strength. Vertebroplasty is a minimally invasive surgery foy the treatment of osteoporotic vertebral compression fracture. This Procedure includes Puncturing vertebrae and filling with Polymethylmethacrylate(PMMA). Although altering recommended monomer-to-Powder ratio affects material properties of bone cement, clinicians commonly alter the mixture ratio to decrease viscosity and increase the working time. The Purposes of this study were to analyze the effect of 4he monomer-to-powder ratio on the mechanical characteristics of trabecular. In this paper, the finite element model of human vertebral trabecualr bone was developed by modified Voronoi diagram, to analyze the relative effect of hormone therapy and vertebroplasty at the treatment of osteoporotic vertebrae. Trabeuclar bone models for vertebroplasty with varied monomer-to-Powder ratio(0.40∼1.07 ㎖/g) were analyzed. Effective modulus and strength of bone cement-treated models were approximately 60% of those of intact models and these are almost twice the values of hormone-treated models. The bone cement models with the ratio of 0.53㎖/g have the maximum modulus and strength. For the ratio of 1.07㎖/g, the modulus and strength were minimum(42% and 49% respectively) but these were greater than those for drug therapy. This study shows that bone cement treatment is more effective than drug therapy. It is found that in vertebroplasty, using a monomer-to-powder ratio different from that recommended by manufacturer nay significantly not only reduce the cement's material Properties but also deteriorate the mechanical characteristics of osteoporotic vertebrae.

• The Journal of the Korea Contents Association
• /
• v.9 no.5
• /
• pp.214-223
• /
• 2009

In this study we investigated the impact of exercise program through the grip strength, the balance and the bone mineral density of elderly women in rural community. A total of number 56 elderly women were divided into two groups, the experimental group(n=33) and the control group(n=23). The experimental group participated exercise program during 13 weeks from 3 Oct to 29 Decem in 2005, twice a week 60 minutes per session. Among the experimental group, 33 people who participated over 20 times exercise program were chosen as the subjects of analysis. The results of this study were as follows: The grip strength was significantly increased in the experimental group compared with the control group(p<0.05). The Timed up and go test and Bone Mineral Density were significantly increased in the experimental group compared with the control group(p<0.01). In conclusion, there has been a substantial improvement in 13 weeks by exercise program is recommended to elderly women in aspect of increasing the grip strength, the balance and the bone mineral density.

• Korean Journal of Adult Nursing
• /
• v.25 no.1
• /
• pp.105-112
• /
• 2013

Purpose: The purpose of this study was to examine the effects of Tai Chi exercise on muscle strength, balance, flexibility and bone mineral density among community dwelling elderly women. Methods: A quasi-experimental pretest-posttest design with a nonequivalent comparison group was utilized, Elderly women were recruited from the community settings and assigned to either the treatment group (n=30) or the comparison group (n=34). Both groups completed the pretest and the posttest measures at six months with an 29.7% of dropouts. Tai Chi exercise was performed for 60 minutes, three times a week for 24 weeks. The study participants were referred to the sports clinic of the university hospital where an exercise therapist and a technician measured muscle strength, balance, flexibility, and bone mineral density without the knowledge of the group assignment. Data were collected from June 14, 2010 to May 27, 2011. Results: At the completion of 6 month Tai Chi exercise, the experimental group showed a significant difference in knee flexor strength (t=3.26 p=.002), flexibility (t=-2.93, p=.005), and bone mineral density in femur (t=2.20, p=.032), compared to the control group. Conclusion: Tai Chi exercise could be performed safely to community dwelling elderly women and effective for preventing declining in physical function in this population. Whether or not this health benefits would lead fall prevention will require further study.