The Advantages of Bilateral Osteotomy Over Unilateral Osteotomy for Osteoporotic Bone Healing.

Most models of osteoporotic bone fractures are performed unilaterally (UL). We investigated healing of tibia osteotomy performed either UL or bilaterally (BL) in ovariectomized rats. Behavior of animals and muscle structure were assessed. Three-month-old female Sprague-Dawley rats were ovariectomized (n = 32). After 10 weeks, half the rats underwent UL osteotomy of tibia metaphysis (right limb) with plate osteosynthesis. The other rats were osteotomized BL. Half of the rats in each group received either standard pain treatment with carprofen (5 mg/kg body weight (BW), 1x/day for 2 days) or carprofen and buprenorphine (5 mg/kg BW, 1x/day and 0.03 mg/kg BW, 2x/day for 5 days) after osteotomy. The UL rats started to load the injured limb from day 27 ± 9; BL rats did this from day 4 ± 4 onward. The UL rats more frequently loaded only one hind limb; BL rats more often loaded both hind limbs. Osteotomy was not bridged in 20% of UL rats and in 4% of BL rats. Callus volume and bone volume fraction were lower in UL group. Weight and fiber size of UL-intact limb muscles were enhanced, compared to the osteotomized limb and those in BL group. Most of the other parameters which assess physiology, activity, body posture, head, or coat were not different. The effect of two pain therapies was not significant on any variable studied. Welfare of the animals was acceptable in all rats. In UL rats, bone healing was delayed. The more advanced healing in BL rats suggested a positive effect of earlier loading. In studies on bone healing, it is advisable to perform BL osteotomy.

The Effect of Vibration Treatments Combined with Teriparatide or Strontium Ranelate on Bone Healing and Muscle in Ovariectomized Rats.

The aim of the present study was to study the effect of combined therapy of teriparatide (PTH) or strontium ranelate (SR) with whole-body vibration (WBV) on bone healing and muscle properties in an osteopenic rat model. Seventy-two rats (3 months old) were bilaterally ovariectomized (Ovx), and 12 rats were left intact (Non-Ovx). After 8 weeks, bilateral transverse osteotomy was performed at the tibia metaphysis in all rats. Thereafter, Ovx rats were divided into six groups (n = 12): (1) Ovx-no treatment, (2) Ovx + vibration (Vib), (3) SR, (4) SR + Vib, (5) PTH, and (6) PTH + Vib. PTH (40 µg/kg BW sc. 5×/week) and SR (613 mg/kg BW in food daily) were applied on the day of ovariectomy, vibration treatments 5 days later (vertical, 70 Hz, 0.5 mm, 2×/day for 15 min) for up to 6 weeks. In the WBV + SR group, the callus density, trabecular number, and Alp and Oc gene expression were decreased compared to SR alone. In the WBV + PTH group, the cortical and callus widths, biomechanical properties, Opg gene expression, and Opg/Rankl ratio were increased; the cortical and callus densities were decreased compared to PTH alone. A case of non-bridging was found in both vibrated groups. Vibration alone did not change the bone parameters; PTH possessed a stronger effect than SR therapy. In muscles, combined therapies improved the fiber size of Ovx rats. WBV could be applied alone or in combination with anti-osteoporosis drug therapy to improve muscle tissue. However, in patients with fractures, anti-osteoporosis treatments and the application of vibration could have an adverse effect on bone healing.

The effects of parathyroid hormone applied at different regimes on the trochanteric region of the femur in ovariectomized rat model of osteoporosis.

This study aims to investigate the effects of two application frequencies of parathyroid hormone on the trochanteric region of rat femur. Forty-three-month-old female Sprague-Dawley rats were divided into 4 groups (n = 10/group). Three groups were ovariectomized, and 8 weeks later they were administered the following treatments (5 weeks): soy-free diet (OVX), subcutaneously injected PTH (0.040 mg/kg) 5 days a week (PTH 5x/w), subcutaneously injected PTH (0.040 mg/kg) every 2 days (PTH e2d), and a sham group. The values of the biomechanical and histomorphometric parameters showed higher results in 5x/w animals in comparison to the OVX and PTH 2ed groups. The ratio between bone diameter/marrow diameter (B.Dm/Ma.Dm) in subtrochanteric cross sections did not show any significant differences between PTH 5x/w and PTH e2d. The increased bone formation rate was observed under PTH treatment in both groups mainly at the endosteal side. The endosteum seems here to be one of the targets of PTH with an accelerate bone formation and a pronounced filling-in of intracortical cavities with higher intensity for the PTH 5x/w in comparison to PTH e2d rats.

Effect of parathyroid hormone on hypogonadism induced bone loss of proximal femur of orchiectomized rat.

PURPOSE: Management of hypogonadism-induced osteoporosis in elderly men is still a challenge. We investigated the short-term effects of parathyroid hormone (PTH) treatments on strength, micro-architecture, and mineral density of trochanteric region of orchiectomized rat femur. METHODS: Eight-month-old male Sprague-Dawley rats (n = 44) were divided into two groups: (1) orchiectomized (ORX) and (2) sham group. Twelve weeks after orchiectomy, half of the orchiectomized animals were treated with daily subcutaneously injected PTH (0.040 mg/kg/BW) (ORX-PTH) for 5 weeks. The other half remained untreated (ORX). The sham-operated group was divided and treated in the same way (sham, sham-PTH). After 5 weeks, both femurs were excised for biomechanical and histomorphometric analysis, trabecular measurements, mineral content assessment, and immunofluorescence analysis. RESULTS: The femoral trochanteric strength after PTH treatment was enhanced in the breaking test (ORX-F(max) = 158.7 N vs. ORX + PTH-F(max) = 202 N). Stiffness of treated ORX animals reached nearly the levels observed in untreated sham rats. PTH therapy improved the trabecular connectivity, width, and area (ORX-Tb.Ar = 47.79% vs. ORX + PTH-Tb.Ar = 68.47%, P < 0.05) in the proximal femur. The treated rats showed significantly improved mineral content in ashed femurs (ORX-mineral content = 43.73% vs. ORX + PTH-mineral content = 49.49%) when compared to the untreated animals. A comparison of widths of fluorescence bands in cortical bone of the subtrochanteric cross-sections showed a significant increase in oppositions after the PTH therapy. CONCLUSIONS: Our finding supports the hypothesis that PTH therapy seems to be a rational therapy in patients with hypogonadism induced bone loss and improves the bone strength of trochanteric region of rat femur.

Improvement of femoral bone quality after low-magnitude, high-frequency mechanical stimulation in the ovariectomized rat as an osteopenia model.

The treatment and prevention of osteoporosis involve great challenges. Nonpharmacological and supportive therapy procedures, sport, and physical exercises seem to prevent bone loss and improve bone mass. In the present study, we examined the effect of whole-body vertical vibration (WBVV) on femoral intertrochanteric bone quality in the rat osteoporosis model. Sixty female Sprague-Dawley rats, 3-month old, were ovariectomized (OVX) or sham-operated. After 3 months, each group was divided into two subgroups. In one of the subgroups, rats were treated with WBVV at 90 Hz (3.9 g) for 35 days; the second subgroup remained untreated. After killing the animals, biomechanical strength and trabecular bone architecture of the proximal region of femurs were analyzed. New cortical bone appositions and mineral density of femurs were additionally measured. Treatment with WBVV resulted in improved biomechanical properties. Maximal load and stiffness of the intertrochanteric region of femurs after WBVV were significantly enhanced. Maximal load and stiffness in treated OVX animals reached the levels observed in untreated sham rats. WBVV significantly improved all measured histomorphometric parameters in the trabecular area. Treated rats showed significantly improved mineral content in ashed femurs compared to untreated animals. A comparison of widths of fluorescence bands in cortical bone of subtrochanteric cross sections did not show any significant differences between the groups after WBVV. Low-magnitude, high-frequency mechanical stimulation improves bone strength in the proximal femur and may be a possible nonpharmacologic treatment option for postmenopausal osteoporosis.

Evaluation of bone quality and quantity in osteoporotic mice--the effects of genistein and equol.

The technology of gene manipulation is often used in mice. A crucial point for osteoporosis research is the evaluation of biomechanical and morphologic parameters. These parameters, however, are difficult to measure in mice. Nevertheless, this study demonstrates the capability of using techniques for the evaluation of bone quality and quantity after various treatments in osteopenic mice. After ovariectomy, 60 C57BL/6J mice were divided into 4 groups and were fed a soy-free diet (C) supplemented with estradiol, genistein or equol for 3 months. To analyze the osteoprotective effects of the tested supplements, we evaluated the bone biomechanical properties, histomorphometric changes and bone mineral density of the proximal tibiae metaphysis. The biomechanical parameters of genistein (GEN) were shown to be similar to those levels observed with estradiol (E). The biomechanical parameters of both GEN and E were significantly superior to those observed with C. Supplementation with equol (EQO) demonstrated higher mean biomechanical values than those observed with C. The histomorphometric evaluation demonstrated an increased number of nodes in mice treated with GEN and E as compared to the mice treated with EQO and C. Treatment with E and EQO led to improved cortical bone, which was only partly seen with the mice treated with GEN. The analysis of the bone mineral density (BMD) demonstrated that treatment with GEN and E resulted in a significant improvement as compared to the mice treated with C, while the cancellous density was significantly increased in all of the supplementation groups. This study conclusively demonstrated that bone quality and quantity parameters can be measured in mice. Furthermore, biomechanical and morphologic evaluations were shown to be reliable for use in mice. Further studies may combine these techniques with gene manipulation technology to better understand osteoporosis. Treatment with GEN resulted in improved biomechanical results and enhancement of morphologic parameters.

Effects of isoflavones equol and genistein on bone quality in a rat osteopenia model.

Phytoestrogens might be an alternative medication in prophylaxis and treatment of osteoporosis. In this study, the osteoprotective effects of genistein (GEN) and equol (EQO) were evaluated. After ovariectomy, 44 rats received soy-free food (Control, C) and developed substantial osteoporosis over the course of two months. After that period, the rats were divided into different groups and fed estradiol (E), GEN or EQO for 35 days. To analyze the osteoprotective effects of the tested substances, bone biomechanical properties and histomorphometric changes of the lumbar vertebrae were evaluated. In analyzing the vertebral body compression strength, we found that the EQO (103.8%) and GEN (96.8%) groups reached similar levels relative to the E group, while the C group reached 77.7% of the biomechanical properties of the E group. EQO was significantly superior to C. The histomorphometric evaluation demonstrated an increased number of nodes in EQO- and E-treated rats compared to GEN- and C-treated rats. E led to an improvement of cortical as well as trabecular bone, an advantage that was only partly seen in the other groups. Treatment with phytoestrogens induced improved bone quality. EQO and GEN might be alternatives for hormone replacement therapy, although further studies are needed to elucidate possible side effects.

Improvement of trochanteric bone quality in an osteoporosis model after short-term treatment with parathyroid hormone: a new mechanical test for trochanteric region of rat femur.

UNLABELLED: We have examined the changes induced in the trochanteric region of femur of ovariectomized rat after administration of estradiol and parathyroid hormone. We have developed a reproducible biomechanical test and produced trochanteric fractures to evaluate stiffness and strength of this region in addition to histomorphometry. INTRODUCTION: We investigated the short-term effects of parathyroid hormone (PTH) and estrogen (E) on the strength of the rat trochanteric region in a new mechanical test. METHODS: Forty-four 3-month-old female Sprague-Dawley rats were ovariectomized and 8 weeks later treated with soy-free diet (C), daily applications of orally supplied E (0.5 mg/kg food) or subcutaneously injected PTH (0.014 mg/kg), for 5 weeks, and an additional untreated group was added as sham-operated. The femurs were examined for biomechanical and histomorphometric changes. RESULTS: Our new mechanical test was validated in a right-left comparison. The PTH treatment induced significantly superior biomechanical results (F (max) = 225.3 N, stiffness = 314.9 N/mm) compared to E (F (max) = 182.9 N, stiffness = 237.2 N/mm), C (F (max) = 166.03 N, stiffness = 235.56 N/mm), and sham (F (max) = 192.1 N, stiffness = 267.2 N/mm). Animals of the PTH group demonstrated a significantly improved trabecular bone structure and area (75.67%) in comparison to the E (61.04%) and C (57.18%) groups. CONCLUSION: Our new biomechanical test is valid and produces trochanteric fracture. Our results show that the short-term antiosteoporotic effects of PTH are in the trochanteric region of ovariectomized rat superior to E.

Estrogen and raloxifene improve metaphyseal fracture healing in the early phase of osteoporosis. A new fracture-healing model at the tibia in rat.

BACKGROUND: Fracture healing in osteoporosis is delayed. Quality and speed of fracture healing in osteoporotic fractures are crucial with regard to the outcome of patients. The question arises whether established antiosteoporotic drugs can further improve fracture healing. MATERIALS AND METHODS: Osteoporosis manifests predominantly in the metaphyseal bone. Nevertheless, an established metaphyseal fracture model is lacking. A standardized metaphyseal fracture-healing model with stable plate fixation was developed for rat tibiae. The healing process was analyzed by biomechanical, gene expression, and histomorphometric methods in ovariectomized (OVX) and sham-operated rats (SHAM), compared to standardized estrogen (E)- and raloxifene (R)-supplemented diets. RESULTS: Estrogen and raloxifene improved the biomechanical properties of bone healing compared to OVX (Yield load: SHAM = 63.1 +/- 20.8N, E = 60.8 +/- 17.9N, R = 44.7+/-17.5N, OVX = 32:5 +/- 22.0N). Estrogen vs OVX was significant based on a denser trabecular network. Raloxifene greatly induced total callus formation ((R = 5.3 +/- 0.9 mm2, E = 4.7 +/- 0.5 mm2, SHAM = 4.51 +/- 0.61 mm2, OVX =4.1 +/- 0.6 mm2), whereas estrogen mainly enhanced new endosteal bone formation. There was no correlation between the gene expression (osteocalcin, collagen1alpha1, IGF-1, tartrate-resistant phosphatase) in the callus and the morphology and quality of callus formation. CONCLUSION: Raloxifene and estrogen improve fracture healing in osteoporotic bone significantly with regard to callus formation, resistance, and elasticity. The biomechanically stable metaphyseal osteotomy model with T-plate fixation presented here has proven to be appropriate to investigate fracture healing in osteoporosis.

Effects of low-magnitude, high-frequency mechanical stimulation in the rat osteopenia model.

SUMMARY: In this study, short-term, whole-body vertical vibration at 90 Hz improved trabecular bone quality. There was an improvement of bone quality and density in both osteoporotic and control rats. This treatment may therefore be an attractive option for the treatment of osteoporosis. INTRODUCTION: Aside from pharmacological treatment options, physical exercise is known to augment bone mass. In this study, the effects of whole-body vertical vibration (WBVV) on bone quality and density were evaluated using an osteoporotic rat model. METHODS: Sixty female Sprague Dawley rats were ovariectomized (C) or sham (SHAM) operated at the age of 3 months. After 3 months, both groups were divided into two subgroups that received either WBVV at 90 Hz for 35 days or no treatment. After sacrificing the rats, we evaluated vertebral bone strength, histomorphometric parameters, and bone mineral density (BMD). RESULTS: Treatment with WBVV resulted in improved biomechanical properties. The yield load after WBVV was significantly enhanced. According to yield load and Young's modulus, the treated OVX rats reached the level of the untreated SHAM animals. In all measured histomorphometric parameters, WBVV significantly improved bone density. Treatment with WBVV demonstrated greater effects on the trabecular bone compared to the cortical bone. The ash-BMD index showed significant differences between treated and untreated rats. CONCLUSION: Using WBVV as a non-pharmacological supportive treatment option for osteoporosis demonstrated an enhancement of bone strength and bone mass. This procedure may be an attractive option for the treatment of osteoporosis.

Effect of testosterone, raloxifene and estrogen replacement on the microstructure and biomechanics of metaphyseal osteoporotic bones in orchiectomized male rats.

INTRODUCTION: Currently, osteoporosis research is rarely undertaken in males but an increase in male life expectancy in the company of hypogonadism suggests the necessity for potential therapeutic options. MATERIALS AND METHODS: In this study, the changes in bone structure under standardized testosterone- (T), raloxifene- (R) and estrogen (E)-supplemented diets were analyzed in osteoporotic castrated male rats. RESULTS: Unexpected biomechanical results could be only explained by the histomorphometry, but not by BMD measurements obtained from the qCT. All tested substances showed a significant improvement in the trabecular network (trabecular bone area for C: 2.55 mm(2), T: 4.25 mm(2), R: 4.22 mm(2) and E: 4.28 mm(2)), and suggests that the bone structure was preserved. For the metaphyseal cortical bone, a significant loss was detected in T (CBP: 18.7%) compared to R (CBP: 30.0%), E (CBP: 26.8%) and even to the osteoporotic control (CBP: 28.6%). This explains the observed early mechanical final failure after T supplementation. However, due to the preserved trabecular bone in T, the occurrence of the first microfractures (yL: 49 +/- 21.4 N) was significantly later than in the osteoporotic control (yL: 39.5 +/- 15.5 N). Raloxifene performed well in hindering the bone loss associated with osteoporosis. However, its effect (yL: 83.3 +/- 16.5 N) did not approach the protective effect of E (yL: 99.2 +/- 21.1 N). CONCLUSION: Testosterone only preserved the deterioration of the trabecular bone but not of the cortical bone. Raloxifene prevented the bone loss associated with osteoporosis at all bony structures. This effect did not approach the protective effect of estrogen on trabecular bone, but it is more suitable for male individuals because it has no feminizing effects on the subject.

Vitex agnus castus as prophylaxis for osteopenia after orchidectomy in rats compared with estradiol and testosterone supplementation.

Osteoporosis research undertaken in males is rare and there are only a few therapeutic options. Phytoestrogens might be a safe alternative for prophylaxis. Sixty 3-month-old male rats were orchidectomized and divided into five groups. The groups either received soy-free food (C), estradiol (E), testosterone (T) or Vitex agnus castus in different concentrations (AC high/AC low) for 12 weeks. The tibia metaphysis was tested biomechanically and histomorphometrically. The AC high group reached 87% of the biomechanical values of the estradiol group and was significantly superior to the control group. Testosterone supplementation resulted in poor biomechanical properties. The cortical bone parameters of the AC group were similar to the control group, while supplementation with estradiol and testosterone demonstrated a reduction of cortical bone. The AC high group reached 88.4% of trabecular bone area, 80.7% of trabecular number and 66.9% of the number of trabecular nodes compared with estradiol supplementation. Vitex agnus castus demonstrated osteoprotective effects in males. It preserves the cortical as well as the trabecular bone and might be a safe alternative for HRT. Testosterone supplementation has positive effects on trabecular bone, which are concurrently counteracted by the loss of cortical bone.

Pre-operative dynamic interactive exploration of complex articular fractures using a novel 3D navigation tool.

OBJECTIVES: Trauma surgeons possess specific anticipative pathoanatomical and procedural domain knowledge that can be used for information extraction from original CT image data. This knowledge so far remains unused in clinical workflow and surgeons do not take an active part in the process of image generation and processing. The objectives of our work are to propose and employ a strategy to directly involve surgeons in a dynamic image exploration process and to exemplarily assess the clinical use of this approach for pre-operative diagnosis of complex articular fractures. METHODS: We used an interactive 3D navigation tool with a novel human-computer interface for the exploration of articular fractures of two selected anatomical structures. The system offers dynamic interaction with a virtual 3D reconstruction model and the possibility to create on-the-fly oblique multiplanar reformations by tracking hand movements. Three expert surgeons performed exemplary explorations and rated the use of the method for preoperative diagnosis in informal interviews. RESULTS: The approach and the system were well received by the three surgeons. The dynamic interaction was rated to be helpful in understanding fracture morphology. Two examples--a radius and a calcaneal fracture--are presented. CONCLUSIONS: Surgeons with their specific domain knowledge should be involved in the process of image processing. The benefit of using oblique multiplanar reformations for pre-operative planning in articular fractures appears to be substantial and they should therefore be included in radiological and surgical textbooks. Further evaluation is necessary to assess the use of interactive exploration systems in routine diagnosis.

Autologous osteoblasts enhance osseointegration of porous titanium implants.

The goal of this study was to assess the osseointegration of porous titanium implants by means of coating with autologous osteoblasts. Titanium implants (8 x 5 x 4 mm) having drill channels with diameters of 400, 500, and 600 microm were coated with autologous osteoblasts obtained from spongiosa chips. The implants were inserted into the distal femora of 17 adult Chinchilla Bastard rabbits (group I). Uncoated implants were inserted as controls in the contralateral femur (group II). The animals were sacrificed after 5, 11, and 42 days. Intravital fluorochrome labeling and microradiography were used for the assessment of bone ingrowth into the titanium channels. In both groups, no bone tissue was formed in the channels up to day 5. On day 11, group I exhibited significantly more (p<0.05) bone tissue (19.8+/-14.0% vs. 5.8+/-9.1%) with greater bone-implant contact (13.3+/-15.1% vs. 5.7+/-5.3%, p<0.05) at the channel mouths than group II. Bone tissue was formed mainly between day 15 and 30 in group I, in group II between day 25 and 40. Six weeks after implantation, bone tissue filled on an average 68.8+/-15.1% of the mouths of the drill channels in implants in group I, the filling for group II was 49.8+/-18.1% (p<0.05). The average bone-implant contact at the channel mouths after six weeks was 56.5+/-13.5% in group I, 40.2+/-21.9% in group II (p<0.05). 600-microm channels showed at this time point the best osseous integration (p<0.05). Coating with autologous osteoblasts accelerates and enhances the osseointegration of titanium implants and could be a successful biotechnology for future clinical applications.