The influence of dichloromethylene bisphosphonate on the healing of a long bone fracture, composition of bone mineral and histology of bone in the rat

Effects of bisphosphonates on appendicular fracture repair in rodents

The balance between osteoclastic bone resorption and osteoblastic bone formation is ultimately responsible for maintaining a structural and functional skeleton. Despite their strength, bones do break and the main cause of fractures are trauma and decreased bone mineral density as a result of aging and/or pathology that weakens the bone's microarchitecture and subsequently, its material properties. Osteoporosis is a disease marked by increased osteoclast activity and decreased osteoblastic activity tipping the remodeling balance in favor of bone resorption and can be caused by aging, glucocorticoids, disuse and estrogen-deficiency. Ultimately, this leads to brittle and weaker bones which become more prone to trauma or stress-induced fractures. The current treatment for preventing and treating osteoporotic fractures is the use of antiresorptive drugs such as bisphosphonates (BPs) and denosumab, but unfortunately, their long-term use, especially with alendronate and ibandronate, has been associated with increased risk of atypical femoral fractures (AFFs); femoral diaphyseal fractures distal to the lesser trochanter but proximal to the supracondylar flare. The purpose of this review is to examine the information that exists in the literature examining the effects of BPs on fracture repair of long bones in rodent (rat and mouse) models. The focus on rodents stems from the scientific community's unresolved need to develop small animal models to examine the molecular, cellular, tissue and biomechanical mechanisms responsible for the development of AFFs and how best they can be treated.

The Effects of Long-term Use of Nitrogen-containing Bisphosphonates on Fracture Healing

Nitrogen-containing bisphosphonates (N-BPs) are pharmaceutical agents that have been used for many years to treat osteoporosis, multiple myeloma, Paget's disease, metastatic bone disease, and a variety of other diseases in which bone mineral density is reduced. Given that N-BPs inhibit bone resorption, an important stage in the fracture healing process, they have been extensively studied in preclinical models for their activity. In animal models, treatment with N-BPs is associated with a larger callus formation in fracture area and delay in remodeling from primary woven bone to lamellar bone, but there is no delay in formation of the fracture callus. In humans, all existing evidence suggest that initiating treatment with N-BPs, after upper and lower limb fractures, does not appear to have a significant effect on fracture healing. Rarely, patients with long-term use of N-BPs may develop "atypical fractures" and delay in their healing. Therefore, this clinical condition is not fully understood and many questions remain unanswered. Similarly, there are few studies about the benefits of stopping a long-term treatment with them, if a fracture occurs. Although most studies support that chronic N-BP therapy may lead to fracture healing delay, this is not fully documented. On the other hand, there are studies that are in complete disagreement with them. All of the above suggest that there is a need for more detailed future research into larger patient populations and different types of fractures, with sufficient data on the type, dosage, route and duration of administration of N-BPs, and the control methods of fracture healing, in order to have a safe final conclusion on the effect of their long-term administration in this highly complex process.

A systematic review of current osteoporotic metaphyseal fracture animal models

Objectives

The treatment of osteoporotic fractures is a major challenge, and the enhancement of healing is critical as a major goal in modern fracture management. Most osteoporotic fractures occur at the metaphyseal bone region but few models exist and the healing is still poorly understood. A systematic review was conducted to identify and analyse the appropriateness of current osteoporotic metaphyseal fracture animal models.

Materials and Methods

A literature search was performed on the Pubmed, Embase, and Web of Science databases, and relevant articles were selected. A total of 19 studies were included. Information on the animal, induction of osteoporosis, fracture technique, site and fixation, healing results, and utility of the model were extracted.

Results

Fracture techniques included drill hole defects (3 of 19), bone defects (3 of 19), partial osteotomy (1 of 19), and complete osteotomies (12 of 19). Drill hole models and incomplete osteotomy models are easy to perform and allow the study of therapeutic agents but do not represent the usual clinical setting. Additionally, biomaterials can be filled into drill hole defects for analysis. Complete osteotomy models are most commonly used and are best suited for the investigation of therapeutic drugs or noninvasive interventions. The metaphyseal defect models allow the study of biomaterials, which are associated with complex and comminuted osteoporotic fractures.

Conclusion

For a clinically relevant model, we propose that an animal model should satisfy the following criteria to study osteoporotic fracture healing: 1) induction of osteoporosis, 2) complete osteotomy or defect at the metaphysis unilaterally, and 3) internal fixation.

Cite this article: R. M. Y. Wong, M. H. V. Choy, M. C. M. Li, K-S. Leung, S. K-H. Chow, W-H. Cheung, J. C. Y. Cheng. A systematic review of current osteoporotic metaphyseal fracture animal models. Bone Joint Res 2018;7:6–11. DOI: 10.1302/2046-3758.71.BJR-2016-0334.R2.

Use of risedronate for consolidation and callus formation in Colles fractures in postmenopausal women: SOLID study

OBJECTIVE

This open, randomized and blinded parallel-group multicenter study evaluated the efficacy of Actonel(®) (35 mg) plus calcium/vitamin D versus calcium/vitamin D alone for preserving bone mineral density (BMD) in postmenopausal women with Colles fractures.

METHODS

Patients with a Colles fracture for seven days were randomized to receive either Actonel(®) (35 mg) once a week plus calcium/vitamin D (ACD group) or calcium/vitamin D alone (CD group). The patients were evaluated after 90 and 180 days of treatment.

RESULTS

59 ACD patients and 56 CD patients completed all the evaluations. At the end of the study, the BMD of the radius at the fracture location showed a negative change in the CD group (32.8%). The loss of BMD in the ACD group (20.8%) was slightly less than that in the CD group. There was a difference in the proportions of patients with BMD losses at the end of the study period in the two treatment groups, in favor of the ACD group, although this was not statistically significant. There was no significant difference in radiological identification of callus formation between the treatment groups. In the majority of the patients, the callus could be radiologically identified after 90 days.

CONCLUSION

Postmenopausal women with Colles fractures who received risedronate sodium plus calcium/vitamin D did not show any significant difference in BMD loss in forearm fractures, in comparison with those who received calcium/vitamin D alone. Risedronate presented a tendency toward a protective effect regarding BMD loss due to immobilization. The time taken for fracture consolidation to be achieved was unaffected.

Do bisphosphonates inhibit direct fracture healing?

Fracture repair occurs by two broad mechanisms: direct healing, and indirect healing with callus formation. The effects of bisphosphonates on fracture repair have been assessed only in models of indirect fracture healing.

A rodent model of rigid compression plate fixation of a standardised tibial osteotomy was used. Ten skeletally mature Sprague–Dawley rats received daily subcutaneous injections of 1 µg/kg ibandronate (IBAN) and ten control rats received saline (control). Three weeks later a tibial osteotomy was rigidly fixed with compression plating. Six weeks later the animals were killed. Fracture repair was assessed with mechanical testing, radiographs and histology.

The mean stress at failure in a four-point bending test was significantly lower in the IBAN group compared with controls (8.69 Nmm-2 (sd 7.63) vs 24.65 Nmm-2 (sd 6.15); p = 0.017). On contact radiographs of the extricated tibiae the mean bone density assessment at the osteotomy site was lower in the IBAN group than in controls (3.7 mmAl (sd 0.75) vs 4.6 mmAl (sd 0.57); p = 0.01). In addition, histological analysis revealed progression to fracture union in the controls but impaired fracture healing in the IBAN group, with predominantly cartilage-like and undifferentiated mesenchymal tissue (p = 0.007).

Bisphosphonate treatment in a therapeutic dose, as used for risk reduction in fragility fractures, had an inhibitory effect on direct fracture healing. We propose that bisphosphonate therapy not be commenced until after the fracture has united if the fracture has been rigidly fixed and is undergoing direct osteonal healing.

Cite this article: Bone Joint J 2013;95-B:1263–8.

Comparison of radiographic fracture healing in the distal radius for patients on and off bisphosphonate therapy

PURPOSE

To compare healing rates of distal radius fractures in patients on bisphosphonate therapy at the time of injury to rates in those not on bisphosphonate therapy.

METHODS

A total of 196 consecutive patients treated for distal radius fractures were included in this study. Patients currently on bisphosphonate therapy at the time of injury (bisphosphonate group, n = 43) were compared to the remaining patient group (control group, n = 153). Demographic information was recorded from the patients' medical records, and radiographs were reviewed to determine fracture healing. Patients were further stratified according to age, gender, fracture complexity, type of treatment, and comorbidities. Univariate and multivariate regression were used to identify factors associated with time to radiographic fracture union.

RESULTS

The mean time to union was 55 (+/-17) days in the bisphosphonate group versus 49 (+/-14) days in the control group. Bisphosphonate use and surgical treatment were associated with a longer time to radiographic union. Bisphosphonate use was associated with increased healing times when individually controlling for age, gender, fracture complexity, or comorbidities. Bisphosphonate use was also associated with longer time to healing after adjusting for age, gender, and treatment type. Surgical fracture fixation was associated with a longer time to healing after adjusting for bisphosphonate use.

CONCLUSIONS

Current bisphosphonate use and surgical treatment were both associated with longer times to radiographic union of distal radius fractures. However, the small differences in healing times (<1 week) are not considered clinically relevant. Although further studies are needed to better define the effects of bisphosphonate therapy on fracture healing, our results suggest that bisphosphonate therapy can be continued after distal radius fractures without notable deleterious effects.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic III.

The effect of zoledronate on bone remodeling during the healing process

PURPOSE

To check the effect of zoledronate in bone remodeling during bone healing.

METHODS

Thirty rabbits were divided into two groups of fifteen animals each (control and experimental group respectively). Shaft osteotomy was performed on the cranial portion of the fibula of each animal. In the experimental group, a single dose of 0.04mg/kg of zoledronate was administered. In the control group, the same volume of bi-distilled water was administered. After one, two and four weeks, animals of both groups were killed and histological sections of the fibular metaphyseal area were examined histomorphometrically. The parameters analyzed were tissue volume (TV), fractional trabecular bone volume (BV/TV) and fractional medullary fibrous volume (FbV/TV).

RESULTS

Tissue volume increased in the experimental group (237.2mm(2).10-2) compared to the control (166.62mm(2).10-2). Trabecular bone volume was significantly larger in the experimental (60.2%) than in the control group (34.8%). The amount of fibrosis volume decreased in the experimental group (22%) compared to the control (49.4%).

CONCLUSION

The effect of zoledronate is characterized by accentuated stimulus of bone formation in the metaphyseal area, resulting in a larger amount of trabecular bone volume and little fibrosis volume.

The effects of RANKL inhibition on fracture healing and bone strength in a mouse model of osteogenesis imperfecta

Currently, the standard treatment for osteogenesis imperfecta (OI) is bisphosphonate therapy. Recent studies, however, have shown delayed healing of osteotomies in a subset of OI patients treated with such agents. The current study sought to determine the effects of another therapy, RANKL inhibition, on bone healing and bone strength in the growing oim/oim mouse, a model of moderate to severe OI. Mice [73 oim/oim and 69 wild-type (WT)] were injected twice weekly with either soluble murine RANK (RANK-Fc) (1.5 mg/kg) or saline beginning at 6 weeks of age. At 8 weeks of age, the animals underwent transverse mid-diaphyseal osteotomies of the right femur. Therapy was continued until sacrifice at 2, 3, 4, or 6 weeks postfracture. At 6 weeks post-fracture, greater callus area (6.59 +/- 3.78 mm(2) vs. 2.67 +/- 2.05 mm(2), p = 0.003) and increased radiographic intensity (mineral density) (0.48 +/- 0.14 vs. 0.30 +/- 0.80, p = 0.005) were found in the RANK-Fc versus saline oim/oim group, indicating a delay in callus remodeling. Despite this delay, mechanical tests at 6 weeks postfracture revealed no significant differences in whole bone properties of stiffness and failure moment. Further, RANKL inhibition resulted in a greater failure moment and greater work to failure for the nonfractured contralateral WT bones compared to the nonfractured saline WT bones. Together, these results demonstrate that RANKL inhibition does not adversely affect the mechanical properties of healing bone in the oim/oim mice, and is associated with increased strength in intact bone in the WT mice.

Managing osteoporosis in patients with fragility fractures: did the British Orthopaedic Association guidelines have any impact?

INTRODUCTION

The incidence of fragility fractures could double in the next 50 years. Effective treatments for osteoporosis exist and the British Orthopaedic Association (BOA) has guidelines governing how to manage underlying osteoporosis in patients with fragility fractures. This study assessed how well two trauma units treat underlying osteoporosis and whether the BOA guidelines made any impact.

PATIENTS AND METHODS

Case notes of patients with a fracture of their proximal femur admitted during January and February in 2003, 2004 and 2005 were reviewed. The results were analysed for differences between site and year.

RESULTS

A total of 602 case notes were reviewed. There was a significant difference in the number of patients discharged on osteoporosis medication between the two sites (27% at LRI, 8% at KGH; P < 0.001), but not between 2003 and 2005 (22% and 16%; P = 0.16). Of the patients started on treatment, 83% were started on calcium and/or vitamin D(3) supplements.

CONCLUSIONS

The number of patients who had their underlying osteoporosis addressed was low and the type of treatment sub-optimal. This suggests the BOA guidelines have not made an impact and further work is required to improve the management of these patients.

Optimal timing of a single dose of zoledronic acid to increase strength in rat fracture repair

We hypothesized that ZA treatment would bolster fracture repair. In a rat model for closed fracture healing, a single dose of ZA at 0, 1, or 2 wk after fracture significantly increased BMC and strength of the healed fracture. Delaying the dose (1 or 2 wk after fracture) displayed superior results compared with dosing at the time of fracture.

INTRODUCTION

Bisphosphonates are known to increase bone strength and thus the resistance to fracture by decreasing osteoclastic bone resorption. These properties may enable bisphosphonates to also increase the strength of fracture repair. Zoledronic acid (ZA) is a potent bisphosphonate with a high affinity for bone mineral, allowing bolus intravenous dosing in a range of indications. In this study, we examined the application of bolus dose ZA in endochondral fracture repair.

MATERIALS AND METHODS

Carbon-14 labeled ZA was used in a closed rat fracture model. Rats were divided into five treatment groups (n = 25 per group): saline control, local ZA (0.01 mg/kg), and three systemic bolus ZA groups (0.1 mg/kg) with different administration times: at fracture, 1 wk after fracture, and 2 wk after fracture. Rats were killed 6 wk postoperatively. Postmortem analyses included radiography, QCT, microCT, biomechanical testing, scintillation counting, autoradiography, and histology.

RESULTS

Single-dose systemic ZA administration significantly increased callus volume, callus BMC, and mechanical strength. Perioperative treatment increased mechanical strength by 30% compared with controls (p < 0.05). Administering the systemic dose at 1 or 2 wk after fracture further increased mechanical strength compared with controls by 44% and 50%, respectively (p < 0.05). No significant differences in mechanical parameters were seen with local injection at the dose studied. Autoradiographic analysis indicated that ZA binds significantly to bone that is present at the time of administration. ZA quantification indicated that delayed administration significantly increased the uptake efficiency in the callus. Histological and microCT analysis showed that ZA treated calluses had a distinctive internal structure consisting of an intricate network of retained trabecular bone.

CONCLUSIONS

The timing of a single systemic dose of ZA plays an important role in the modulation of callus properties in this rat fracture model; delaying the single dose produces a larger and stronger callus.

Einfluss der Bisphosphonate auf die Frakturheilung

As the population ages and the prevalence of osteoporotic fractures increases, perioperative medical care of the elderly will continue to present challenges. Bisphosphonates, in combination with calcium and vitamin D have become the first-line therapy for patients with osteoporosis. Thus, one of the frequently asked questions concerning such patients is whether individuals who have recently sustained a fracture should take inhibitors of bone resorption. This discussion is relevant because many of the patients treated with bisphosphonates do have fractures, such as patients with osteoporosis, tumor bone disease, Paget's disease or osteogenesis imperfecta. A recent fracture should not preclude the initiation of therapy, because bisphosphonates have not been shown to interfere with overall fracture strength. Bisphosphonates appear to affect callus formation differently from either estrogen or raloxifene, but no significant difference in callus strength was seen 16 weeks after fracture. In addition, current studies demonstrate a significant reduction in periprosthetic bone loss after uncemented primary hip arthroplasty.

Intravenous pamidronate for pain relief in recent osteoporotic vertebral compression fracture: a randomized double-blind controlled study

INTRODUCTION

We performed a randomized, double-blind, controlled clinical trial comparing intravenous pamidronate and placebo for pain relief in recent osteoporotic vertebral compression fractures (VCF).

METHODS

Patients suffered from recent (<21 days), painful, osteoporosis-related VCF. They were randomized to receive daily intravenous infusions of either placebo or 30 mg pamidronate for three consecutive days (total pamidronate: 90 mg). The main criterion for efficacy was improvement in standing pain on a 100-mm visual analogical scale (VAS) at day 7. Secondary criteria were standing pain at days 3 and 30; supine pain at days 3, 7, and 30; patients' overall assessment of improvement; mobility index; and number of "20% responders" and "50% responders" (respectively, 20% and 50% improvement in standing pain at days 7 and 30). Statistical analysis with non-parametric tests was carried out on an intention to treat basis.

RESULTS

Thirty-two patients were enrolled in the study; 16 were given placebo and 16 pamidronate. Thirty-one patients were evaluated at day 7 and 26 patients at day 30. VAS pain decreased significantly in both groups at day 7 (placebo -23 mm, pamidronate -42 mm, p<0.01). The difference in pain scores between groups was -23.25 mm (confidence interval (CI) [-42.3; -4.2], p=0.018) at day 7 and -26 mm at day 30 (p=0.03), in favor of pamidronate. At day 7, there were 4 versus 12 "50% responders," respectively, in the placebo and in the pamidronate groups (likelihood ratio: 8.372; p=0.004) and 9 versus 14 "20% responders" (likelihood ratio: 4.038; p=0.044). At day 30, there were 5 versus 10 "50% responders," respectively, in the placebo and in the pamidronate groups, and 7 versus 11 "20% responders." Patients' overall assessment of improvement at day 7 was 37+/-26 mm in the placebo group and 59+/-30 mm in the pamidronate group (p=0.019), and 42+/-26 mm and 72+/-21 mm at day 30 (p=0.07). The two groups did not differ significantly at days 7 and 30 for supine pain, Schober index, or finger-ground distance. No significant adverse reaction related to treatment occurred.

CONCLUSION

Pamidronate provides rapid and sustained pain relief in patients with acute painful osteoporotic VCF and is well tolerated. Further investigations are needed to better define the place of pamidronate in the management of painful recent osteoporotic collapse.

New model for simulation of fracture repair in full-grown beagle dogs: model characterization and results from a long-term study with ibandronate

INTRODUCTION

Given that bisphosphonates reduce bone turnover, it is important to establish that their long-term administration does not impair bone quality. This paper describes a new model for simulation of fracture repair to evaluate several aspects of bone quality following long-term administration (34 or 36 weeks) of ibandronate in full-grown beagle dogs.

METHODS

The treatment schedule consisted of continuous daily subcutaneous administration of a pharmacologically active dose (1 microg/kg/day) and two cyclical intermittent regimens providing a similar total dose per animal at the end of the experiment. Seven or 8 weeks before study end, 10 holes were drilled in the left tibia and bone marrow ablation was performed in the ipsilateral femur. Serial measurements for blood biochemistry (osteocalcin and iso-alkaline phosphatase) and bone mineral density (BMD; whole body and L1-L7) by dual-energy X-ray absorptiometry (DEXA) were performed during the experiment. Bone quality was determined at the end of the experiment by assessing early and late stage defect healing and structural, cellular, and dynamic histomorphometry (femur, tibia, and lumbar vertebrae L3 and L4).

RESULTS

Healing of the drill hole defects, which simulate the first stage of fracture healing, was neither qualitatively nor quantitatively influenced by ibandronate. The same was true for the activation of cortical remodeling that occurs in the later stage of fracture healing, which started in Week 4 after surgery and declined after Week 8 in all groups. Additionally, no difference was found between the various regimens and the controls with respect to DEXA analyses, trabecular bone volume, cancellous bone tissue area, cancellous bone perimeter, osteoclast count, serum osteocalcin, or bone-specific alkaline phosphatase.

DISCUSSION

In conclusion, the presence of the first and second steps of fracture healing and the fact that the histological features closely resemble those of fracture repair validate the development and characterization of a new model for simulation of fracture repair. A long-term study with a therapeutically active dose of ibandronate shows that ibandronate does not impair BMD, bone structure, bone repair, coupling, and serum parameters for bone formation and turnover after long-term administration.

Zoledronic acid prevents osteopenia and increases bone strength in a rabbit model of distraction osteogenesis

Prolonged healing times and stress-shielding osteopenia remain problematic in distraction osteogenesis. In this study of 30 rabbits, zoledronic acid increased regenerate volume, mineralization, and tibial strength and prevented osteopenia over a 6-week period. Translation to the clinical setting, if safe, could improve outcomes in distraction osteogenesis in children.

INTRODUCTION

Because the external fixators for limb lengthening and reconstruction are designed to control the positions of bone fragments accurately, they also produce stress-shielding effects on the forming regenerate and surrounding bone. Osteopenia, leading to refracture and limitations on rehabilitation, are common consequences, potentially increasing morbidity and detracting from final clinical outcome.

MATERIALS AND METHODS

We examined the effect of zoledronic acid on distraction osteogenesis in 42 immature male NZW rabbits. The model chosen results in reliable regenerate formation and stress-shielding osteopenia. Fourteen animals received either Saline, zoledronic acid 0.1 mg/kg at surgery (ZOL), or another dose 2 weeks postoperatively (Redosed ZOL). Rabbits underwent DXA for bone mineral content and bone mineral density in regenerate and surrounding segments of operated and contralateral tibias. After death at 6 weeks, 30 pairs of tibias underwent quantitative computerized tomography (QCT) and four-point bend testing, and 12 were examined by histomorphometry. The study was powered at 0.8 to show differences of 1.3 SDs for mineral and mechanical parameters.

RESULTS

Osteopenia observed in tibias of the Saline group was absent in ZOL and Redosed ZOL tibias, the latter exhibiting higher bone mineral density and bone mineral content over contralateral regions (p < 0.01). Regenerate bone mineral content was higher in ZOL and Redosed ZOL versus Saline groups at 4 and 6 weeks (p < 0.01). Cross-sectional area was 49% and 59% greater at 6 weeks in ZOL and Redosed ZOL regenerates compared with the Saline group (p < 0.01). ZOL and Redosed ZOL tibias were 29% and 89% stronger by four-point bending than the Saline group (p < 0.01). Histomorphometry in the regenerate of ZOL and Redosed ZOL groups revealed higher trabecular bone volume and trabecular number compared with the Saline group (p < 0.001).

CONCLUSIONS

Zoledronic acid administration led to significantly greater bone area, mineral content, strength, and trabecular number with reduced stress-shielding osteopenia in this model of distraction osteogenesis. These data suggest that intraoperative and postoperative zoledronic acid administration could improve outcomes in children undergoing limb lengthening.

Long-term administration of clodronate does not prevent fracture healing in rats

Clinicians have been concerned that fractures do not heal properly in individuals exposed to bisphosphonate treatment, a treatment that strongly affects bone metabolism. The current study attempted to clarify the long-term effects of clodronate (dichloromethylene bisphosphonate) treatment on fracture healing in growing rats. Clodronate was administered subcutaneously twice a week in a dose of 2 mg/kg or 10 mg/kg. Physiologic saline served as a control. After 24 weeks of treatment, the tibiae were fractured, and the treatment was continued for another 4 weeks and 8 weeks. At both end points the cross-sectional areas of the callus, measured by peripheral quantitative computed tomography, were greater in the clodronate-treated rats than in controls, but there were no significant differences in bone mineral density. There were no significant differences between treatments in radiologic healing, histomorphometry, or in mechanical failure load of the callus with the exception of increased tensile stiffness at a dose of 2 mg/kg at 4 weeks. Clodronate treatment does not seem to prolong the fracture healing process, even when administered on a long-term basis before the fracture. Clodronate increases the size of the callus, but has only a minor effect on its biomechanical properties. The current results suggest that long-term clodronate treatment does not inhibit fracture healing.

Effects of clodronate on vertebral fracture risk in osteoporosis: a 1-year interim analysis

The aim of this study was to determine whether clodronate reduced the incidence of vertebral fractures in patients with osteoporosis. We report here the interim analysis after 1 year of a 3-year double-blind placebo-controlled study. The objectives of the interim analysis were to determine whether there was a trend in fracture frequency and to examine the effects of clodronate on bone mineral density (BMD). Patients with densitometrically proven osteoporosis (T-score <-2.5 and <-3 for women and men, respectively) or with at least one prevalent vertebral fracture were recruited to a 3-year double-blind, controlled study. Patients were randomized to three strata, namely women with postmenopausal osteoporosis (stratum I, n = 483), women with secondary osteoporosis (II, n = 110), and men with osteoporosis of any causation (III, n = 84). They received either clodronate 800 mg daily by mouth or an identical placebo, and all patients received a calcium supplement of 500 mg daily. BMD was measured at six monthly intervals, and lateral spine radiographs for vertebral morphometry were obtained at baseline and 1 year. Treatment with clodronate was associated with a significant increase in BMD at the spine of 3.2 +/- 0.3% (p < 0.0001 vs. baseline) compared with a nonsignificant change of 0.5 +/- 0.3% in the placebo group (p < 0.0001 between treatments). At the hip, clodronate was associated with a significant increase in total hip BMD of 1.3 +/- 0.3% (p = 0.018 vs. baseline) compared with a small decrease of 0.4 +/- 0.3% in the placebo group (p = 0.027 for the difference between treatment groups). The mean changes at the spine and hip were similar in all three strata. Incident vertebral fractures were observed in 27 patients at 1 year in the placebo group (9.0%) and in 14 patients receiving clodronate (4.9%) (relative risk 0.54; 95% CI 0.29-1.02; p = 0.07). A trend was observed in all treatment strata. Treatment was well tolerated, with no significant adverse events attributable to clodronate treatment. We conclude that clodronate 800 mg daily is effective in preventing bone loss, and at 1 year, there is a trend consistent with antifracture efficacy in patients with established osteoporosis regardless of causation.

Long-term effect of incadronate disodium (YM-175) on fracture healing of femoral shaft in growing rats

The aim of this study was to investigate the long-term effect of incadronate on fracture healing of the femoral shaft in rats. Female Sprague-Dawley 8-week-old rats were injected subcutaneously (sc) with either vehicle (V group) or two doses of incadronate (10 microg/kg and 100 microg/kg) three times a week for 2 weeks. Right femoral diaphysis was then fractured and fixed with intramedullary stainless wire. Just after fracture, incadronate treatment was stopped in pretreatment groups (P groups: P-10 and P-100) or continued in continuous treatment groups (C groups: C-10 and C-100). All rats were killed at 25 weeks or 49 weeks after surgery. Fractured femur was evaluated radiologically and mechanically and then stained in Villanueva bone stain and embedded in methyl methacrylate. Undecalcified cross-sections from the fracture area were evaluated microradiologically and histomorphometrically. Radiographic observation showed that the fracture line disappeared in all groups. Cross-sectional area in the C-100 group was the biggest among all groups and in the C-10 group was larger than that in the V group at 25 weeks. Histological and histomorphometric observations showed that the process of fracture healing was delayed under continuous treatment with incadronate as evidenced by the delay of both lamellar cortical shell formation and resolution of original cortex in C groups. Percent linear labeling perimeter, mineral apposition rate (MAR), and bone formation rate (BFR) in C groups significantly decreased compared with the other groups, indicating that the callus remodeling was suppressed under continuous treatment, especially with a high dose. Mechanical study showed that the stiffness and ultimate load of the fractured femur in the C 100 group were the highest among all groups at both 25 weeks and 49 weeks. In conclusion, this study showed that long-term continuous treatment with incadronate delayed the process of fracture healing of femur in rats, especially under high dose but it did not impair the recovery of mechanical integrity of the fracture.

No adverse effects of clodronate on fracture healing in rats

Clodronate was administered daily 28 days before and after an experimental tibial fracture in 35 male rats, and the effect on fracture healing and posttraumatic bone loss was studied. 5 groups were tested. The clodronate/clodronate group received clodronate in daily doses of 10 mg/kg body weight for 28 days before being subjected to a standardized fracture of the right tibia, and during the fracture healing period of 28 days. The clodronate/saline group received clodronate before fracture and saline during the healing period. The saline/clodronate group received saline before and clodronate after fracture. The saline/saline group received saline only, while the control group served as unfractured, untreated controls. After 28 days of fracture healing, the tibias were evaluated with dual energy x-ray absorptiometry, and tested mechanically in a 3-point ventral bending test. Bone mineral content and bone mineral density were approximately 30% higher in the groups receiving clodronate during the experiment, compared to the untreated groups. The weight and cross-sectional area of the fracture callus were equal in all groups. Whether clodronate was administered before the fracture, after the fracture or both, did not affect the bone mineral. Ultimate bending moment, energy absorption, stiffness and deflection were not significantly different between the groups. Our findings suggest that clodronate increases bone mineral both when given before and after a tibial shaft fracture, without affecting fracture healing at 28 days.