Effects of zoledronic acid on healing of mandibular fractures: an experimental study in rabbits

Impact of osteoporosis and osteoporosis medications on fracture healing: a narrative review

Antiresorptive medications do not negatively affect fracture healing in humans. Teriparatide may decrease time to fracture healing. Romosozumab has not shown a beneficial effect on human fracture healing.

BACKGROUND

Fracture healing is a complex process. Uncertainty exists over the influence of osteoporosis and the medications used to treat it on fracture healing.

METHODS

Narrative review authored by the members of the Fracture Working Group of the Committee of Scientific Advisors of the International Osteoporosis Foundation (IOF), on behalf of the IOF and the Société Internationale de Chirurgie Orthopédique et de Traumatologie (SICOT).

RESULTS

Fracture healing is a multistep process. Most fractures heal through a combination of intramembranous and endochondral ossification. Radiographic imaging is important for evaluating fracture healing and for detecting delayed or non-union. The presence of callus formation, bridging trabeculae, and a decrease in the size of the fracture line over time are indicative of healing. Imaging must be combined with clinical parameters and patient-reported outcomes. Animal data support a negative effect of osteoporosis on fracture healing; however, clinical data do not appear to corroborate with this. Evidence does not support a delay in the initiation of antiresorptive therapy following acute fragility fractures. There is no reason for suspension of osteoporosis medication at the time of fracture if the person is already on treatment. Teriparatide treatment may shorten fracture healing time at certain sites such as distal radius; however, it does not prevent non-union or influence union rate. The positive effect on fracture healing that romosozumab has demonstrated in animals has not been observed in humans.

CONCLUSION

Overall, there appears to be no deleterious effect of osteoporosis medications on fracture healing. The benefit of treating osteoporosis and the urgent necessity to mitigate imminent refracture risk after a fracture should be given prime consideration. It is imperative that new radiological and biological markers of fracture healing be identified. It is also important to synthesize clinical and basic science methodologies to assess fracture healing, so that a convergence of the two frameworks can be achieved.

Antiresorptive agents enhance ossification of free flap reconstructions of the mandible: a radiological retrospective cohort study

Background

The aim of this study was to investigate the effect of antiresorptive agents on the ossification of reconstructed mandibles by free bone grafts for the first time.

Methods

A total of 38 reconstructions of the jaw were retrospectively evaluated for ossification between bone segments by two raters based on postoperative panoramic radiographs. The study group (n = 13) had segmental resection of the mandible and free bone flap reconstruction due to medication-related osteonecrosis of the jaw (MRONJ). The control group (noMRONJ, n = 25) comprised segmental mandibular resections and free bone flap reconstructions due to tumors, chronic osteomyelitis, or trauma without any radiation. Ossification time and influencing factors were evaluated.

Results

Both duration of surgery (346 ± 90 min. vs. 498 ± 124 min.; p < 0.001) and hospitalization (8.7 ± 2.8 days vs. 13.4 ± 5.3 days, p = 0.006) were shorter in the MRONJ group compared to the noMRONJ group. Ossification after mandibular reconstruction was significantly faster in the MRONJ study group [224 days, interquartile range (IQR) 175-287] compared to the control group (288 days, IQR 194-445; p < 0.001). Moreover, good initial contact between the segments resulted in faster ossification (p < 0.001) in the MRONJ group. Ossification rate between original and grafted bone or between grafted bone segments only did not differ in both the study and control groups (MRONJ, p = 0.705 vs. control, p = 0.292). The type of antiresorptive agent did not show any significance for ossification. The rate of wound healing disturbances did also not differ between the study and control groups (p = 0.69).

Conclusion

Advanced MRONJ (stage 3) can be resected and reconstructed safely with free microvascular bone flaps. Antiresorptive agents enhance the ossification of the bone segments. Optimal initial contact of the bone segments accelerates bone healing. Surgery and hospitalization are markedly shortened in this vulnerable group of MRONJ patients compared to oncologic patients.

An Evaluation of the Effectiveness of Local Delivery of Zoledronic Acid in Accelerating Bone Healing After the Extraction of Mandibular Third Molars

Background and objective Zoledronic acid (ZA) has been reported to aid with the formation of new bone, inhibit osteoclastic bone resorption, and improve osteoblast proliferation. This split-mouth randomized clinical research aimed to evaluate the effect of the local application of ZA on bone regeneration after the removal of bilateral mandibular third molars. Methods A randomized, split-mouth study involving 12 patients aged 19-35 years requiring extraction of bilaterally mandibular third molars was conducted. The extraction of mandibular third molars on both sides was conducted in one session for all patients. In each participant, a gelatin sponge (Gelfoam) soaked with ZA was randomly applied to one cavity of the extraction socket. A gelatin sponge soaked with normal saline was applied to the opposite cavity; all patients were blinded as to which socket the drug was applied to. The study was conducted over a period of two months. The changes in bone density (BD) in the socket were assessed through cone-beam CT (CBCT) images; two images were taken for each patient at two different time points: immediately after extraction (T0) and after two months (T1). Results BD values in the socket on both sides of extraction increased from T0 to T1. There were statistically significant differences when comparing the amount of change in radiographic BD from T0 to T1 between the two sides of the extraction (p<0.05); the increase in radial BD between the two different time points was more significant in the ZA group. Conclusions Within the limitation of this study, the local application of ZA radiographically improved bone healing in a statistically significant manner and could be a cost-effective and simple way to activate bone regeneration.

Effects of a single intravaneous dose of zoledronic acid on bone healing following tooth extraction in ovariectomized rabbits

Objective

The present study is aimed to investigate the effects of administering a single intravenous dose of zoledronic acid (ZA) on bone healing following tooth extraction in ovariectomized rabbits.

Materials and methods

Female, New Zealand rabbits were randomly divided into three groups including Control, ovariectomy + saline (OVX) and ovariectomy + zoledronic acid group (ZOL). Bilateral ovariectomy was performed to the rabbits in OVX and ZOL groups under general anesthesia. Control group underwent sham surgery. Eight weeks later, mandibular right incisors of all animals were extracted under general anesthesia. Before the procedure, Control and OVX groups were given saline and 0.1 mg/kg ZA was administered to ZOL group intravenously. All animals were sacrificed after 12 weeks.

Results

The findings of histopathological and biochemical evaluations reflected insignificant differences among study groups in vascular endothelial growth factor (VEGF), increases in osteoclasts, ossification, vascularization and mononuclear cell infiltration measures (p > 0.05). In contrast, bone morphogenic protein 2 (BMP-2), tumor necrosis factor alpha (TNF-α) and organization of the extraction wound differed significantly between groups (p < 0.05)

Conclusion

The potential beneficial effects of ZA administration on the wound healing process following tooth extraction were demonstrated via serum TNF-α, BMP-2 and VEGF levels in an osteoporotic model in ovariectomized rabbits.

Successful Non-surgical Management of a Mandible Fracture Secondary to Medication-related Osteonecrosis of the Jaw: A Unique Case Report

Background:

Medication-related osteonecrosis of the jaw (MRONJ) may be a severe side effect of bone-modifying agents.

Objective:

Pathologic fractures treatment in patients with MRONJ remains challenging. The authors reported a unique case of successful non-surgical management of a mandible fracture secondary to MRONJ.

Methods:

A 78-year-old osteoporotic woman with a 4-year history of oral bisphosphonate therapy and a compromised dental condition developed an MRONJ-related right mandibular body fracture. Treatment consisted of systemic antibiotic administration (amoxiclav and metronidazole) and chlorhexidine mouthwash.

Results:

Follow-up visits revealed progressive healing of the mandibular fracture with bone callus formation and complete recovery of the ipsilateral lip and chin sensitivity after one year.

Conclusion:

Non-surgical management of pathological fractures related to MRONJ might be of interest in patients that refuse any type of surgery, but preventive measures, such as careful dental examination, should be taken before start antiresorptive therapy and during the treatment. The authors reported the first case in the literature of successful management of a mandibular fracture secondary to MRONJ with only antibiotics and mouthwashes.

Effect of Botulinum Toxin Type A on Mandibular Fracture Healing: An Experimental Study in Rabbits

PURPOSE

The effect of botulinum toxin type A (BTX-A) on fracture healing of the long bones is controversial, and no controlled clinical or experimental study has investigated the effect of BTX-A on mandibular fractures. The purpose of this study was to investigate whether BTX-A injection into the masseter muscles affects bone healing by reducing the displacing forces in an unfavorable mandibular fracture model.

MATERIALS AND METHODS

Forty-eight male New Zealand white rabbits were used. Ten units of BTX-A was injected into each masseter muscle in the animals in the BTX-A group, whereas saline solution was injected in the animals in the control group. A unilateral osteotomy and fixation with a microplate were performed. Bone healing was evaluated by radiodensitometric, biomechanical, histologic, and histomorphometric methods after 21 days.

RESULTS

The mean bone mineral density in the fracture area was significantly higher in the BTX-A group (P = .038). The mean failure load and bending modulus values were significantly higher in the BTX-A group than in the control group (P = .032 and P = .005, respectively). The mean histologic bone healing scores, bone volume-total volume values, and trabecular diameter values were significantly higher in the BTX-A group than in the control group (P = .001, P = .001, and P = .026, respectively).

CONCLUSIONS

BTX-A application into the masseter muscles improves bone healing of a unilateral mandibular fracture in rabbits.

Histological evaluation of the healing process of autografted mandibular bone defects in rats under treatment with zoledronate

OBJECTIVE

This study aims to evaluate the healing process of autografted mandibular bone defects in rats treated with zoledronate (ZOL).

SUBJECTS AND METHODS

A total of 180 Wistar rats were divided into four groups: group L received intravenous infusion of two doses of 0.06 mg/kg ZOL, nine weeks apart; group H received 0.06 mg/kg ZOL, while groups C and NC received normal saline at three-week intervals for nine weeks. Three weeks following the last infusion, a unilateral mandibular bone defect (5 mm) was created. Except in the NC group, all defects were repaired with autologous iliac bone graft. Fifteen animals from each group were sacrificed on postoperative Day 20, Day 40, and Day 60. Graft healing was scored using a histological grading system (ranging from 1 to 6).

RESULTS

Histological evaluations performed on postoperative Day 60 showed that the mandibular defects were mainly repaired with fibrous tissue in the NC and H groups (93.00% ± 7.51% and 82.67% ± 13.08%, respectively) and with bone in the C and L groups (75.33% ± 14.20% and 92.67% ± 8.84%, respectively). The percentage of fibrous tissue and bone as well as the healing score of the NC and H groups were significantly different (P = 0.001) from those of the C and L groups. However, these were not different between neither the NC and H groups nor the C and L groups.

CONCLUSION

Based on the results of the present study the hypothesis can be established that there also might be a dose-dependent effect of ZOL on the healing of bone grafts in humans. This hypothesis has to be verified or rejected in clinical trials.

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.

Case report of maxillofacial fracture in a patient under bisphosphonates in the absence of ONJ disease: Guidelines?

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Case consisting of traumatic fracture in patient under bisphosphonates.

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No MRONJ, so no pathological fracture.

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No guidelines available for patients ‘at risk’.

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Best treatment avoids periosteal stripping.

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Fixation using external fixation or locking reconstruction plate.

Introduction

Inspired by the presented case, this paper investigates treatment options for patients under active bisphosphonate therapy, suffering from a traumatic fracture in the absence of MRONJ (patients classified as ‘at risk’). We review literature in search of standardized protocols and in combination.

Presentation of case

A 75-year-old woman, suffering from osteoporosis for over a decade and being treated with alendronate for about 10 years, stumbled and fell and ended up with a displaced fracture on the right side of her extremely atrophied mandible. Under general anesthesia, using a limited submandibular approach with minimal reflecting of the periosteum, an external fixation device was placed. The patient recovered well from surgery and was discharged after 2 days. Long term follow-up shows good healing with a mouth opening of 46 mm in the absence of any sensory of functional deficits.

Discussion

We conclude from our literature review that there are no clear guidelines regarding fixation of traumatic (non-pathologic) maxillofacial fractures in patients under active antiresorptive therapy. Literature suggests that damaging the periosteum needs to be avoided since this would endanger the already fragile blood supply in the area. This could make an intra-oral approach unfavourable.

Conclusion

We prefer an extra-oral approach whenever possible. The choice between the use of supraperiostally placed locking reconstruction plates or external fixation should be based on the overall medical condition of the patient, the regional osseous anatomy and the specific fracture morphology.

Systemic and local zoledronic acid treatment with hydroxyapatite bone graft: A histological and histomorphometric experimental study

In this study, the aim was to compare the relative efficacy of systemic and local zoledronic acid (ZA) on a hydroxyapatite (HA) bone graft in a rat critical-size calvarial bone defect. In total, 84 female rats were divided into four groups: Empty control (EC) group with no treatment applied; HA group, in which only HA bone graft material was used in the calvarium; and HA plus local ZA (HA+LZA) and HA plus systemic ZA (HA+SZA) groups, in which animals received ZA locally or systemically, respectively, with HA bone graft material in the calvarium. A 5-mm standardised critical-size calvarial bone defect was created with a standard trephine drill and the respective treatment was applied. Rats were sacrificed 7, 14 and 28 days later. The numbers of osteoclasts and osteoblasts, and degree of bone formation were evaluated histopathologically and histomorphometrically. Statistically significant differences were detected between the HA, HA+LZA and HA+SZA groups and the EC group for new bone formation (P<0.05). Osteoblast numbers in the HA+LZA and HA+SZA groups were significantly higher compared with those in the EC and HA groups (P<0.05). No statistically significant difference was detected between the HA+LZA and HA+SZA groups in new bone formation or osteoblast number (P>0.05). Bone formation was significantly higher in the HA group than in the EC group (P<0.05). The numbers of osteoclasts in the HA+LZA and HA+SZA groups were significantly higher than those in the groups EC and HA (P<0.05); however, there was no significant difference between groups HA+LZA and HA+SZA (P>0.05). Within the limitations of this study, systemic or local administration of ZA enhanced new bone formation with a HA bone graft in a rat critical-size calvarial defect model.

How do bisphosphonates affect fracture healing?

Bisphosphonates (BPs) have been in use for many years for the treatment of osteoporosis, multiple myeloma, Paget's disease, as well as a variety of other diseases in which there is reduced bone mineral density. Given that bisphosphonates inhibit bone resorption, an important stage of fracture healing; this class of compounds has been widely studied in preclinical models regarding their influence on fracture healing. In animal models, bisphosphonate treatment is associated with a larger fracture callus, coincident with a delay in remodeling from primary woven bone to lamellar bone, but there is no delay in formation of the fracture callus. In humans, de novo use of bisphosphonate therapy after fracture does not appear to have a significant effect on fracture healing. Rarely, patients with long term use of Bisphosphonates may develop an atypical fracture and delay in fracture healing has been observed. In summary, bisphosphonates appear safe for use in the setting of acute fracture management in the upper and lower extremity in humans. While much remains unknown about the effects on healing of long-term bisphosphonates, use prior to "typical" fracture, in the special case of atypical fracture, evidence suggests that bisphosphonates negatively influence healing.

Comparison of osteoconductive properties of three different β-tricalcium phosphate graft materials: a pilot histomorphometric study in a pig model

AIMS

The aim of this study was to compare the de novo bone formation ability and osteoconductive effects of three different β-tricalcium phosphate (β-TCP) graft materials. The micro-architectural parameters of the newly formed bone tissues were also compared among the different graft materials.

MATERIAL AND METHODS

Eight male Swiss domestic pigs were used in the study. Five bony defects were made with a trephine bur. Three of the defects were filled with Cerasorb®, Kasios® and Poresorb®. The fourth defect was filled with an autogenous bone graft. The last defect remained empty. All subjects were sacrificed after 8 weeks.

RESULTS

When compared to a negative control group, significant healing was observed in all the groups except the Cerasorb group. The osteoconductivity of the Poresorb group was better than that of the other groups (p < 0.05). The difference in the osteoconductivity of the Kasios and Cerasorb groups was statistically significant (p < 0.05). Comparison of the micro-architectural properties of newly formed bone tissues retrieved from the defects showed that those filled with Poresorb were the best.

CONCLUSION

β-TCP materials show different results in terms of the volume and characteristics of new bone formation, although they have a similar chemical structure.

Effects of zoledronic acid on physiologic bone remodeling of condylar part of TMJ: a radiologic and histomorphometric examination in rabbits

Objective. The purpose of the present study is to evaluate the effects of systemically administered zoledronic acid (ZA) on the physiological bone remodeling and the microarchitectural parameters of the condylar part of TMJ in a rabbit model. Study Design. Thirty skeletally mature male New Zealand white rabbits were randomly divided into two groups. The experimental group was administered an intravenous, single dose of 0.1 mg/kg ZA diluted with 15 mL of saline in a 15-minute perfusion with an infusion pump. The control group was administered only saline infusion for 15 minutes. All rabbits were sacrificed on the 21st postoperative day. Radiodensitometric and histomorphometric examinations were performed on the harvested mandibular condyles. The data were analyzed statistically. Results. Radiodensitometric findings showed that ZA treatment resulted in a significant increase in the mineralization of mandibular condyle. This result was supported by the histomorphometric findings. Conclusion. The present study has revealed that a temporary delay in the physiological bone remodeling using single dose of ZA increases bone mineral content and makes the microarchitecture of the mandibular condyle more compact. These effects may be regarded as base data and considered in numerous clinical situations including TMJ.

Bisphosphonates induce the osteogenic gene expression in co-cultured human endothelial and mesenchymal stem cells

Bisphosphonates (BPs) are known to affect bone homeostasis and also to have anti-angiogenic properties. Because of the intimate relationship between angiogenesis and osteogenesis, this study analysed the effects of Alendronate (AL) and Zoledronate (ZL) in the expression of endothelial and osteogenic genes on interacting endothelial and mesenchymal stem cells, an issue that was not previously addressed. Alendronate and ZL, 10(-12) -10(-6) M, were evaluated in a direct co-culture system of human dermal microvascular endothelial cells (HDMEC) and human bone marrow mesenchymal stem cells (HMSC), over a period of 14 days. Experiments with the respective monocultures were run in parallel. Alendronate and ZL caused an initial dose-dependent stimulation in the cell proliferation in the monocultures and co-cultures, and did not interfere with their cellular organization. In HDMEC monocultures, the expression of the endothelial genes CD31, VE-cadherin and VEGFR2 was down-regulated by AL and ZL. In HMSC monocultures, the BPs inhibited VEGF expression, but up-regulated the expression of the osteogenic genes alkaline phosphatase (ALP), bone morphogenic protein-2 (BMP-2) and osteocalcin (OC) and, to a greater extent, osteoprotegerin (OPG), a negative regulator of the osteoclastic differentiation, and increased ALP activity. In co-cultured HDMEC/HMSC, AL and ZL decreased the expression of endothelial genes but elicited an earlier and sustained overexpression of ALP, BMP-2, OC and OPG, compared with the monocultured cells; they also induced ALP activity. This study showed for the first time that AL and ZL greatly induced the osteogenic gene expression on interacting endothelial and mesenchymal stem cells.

Early inhibitory effects of zoledronic acid in tooth extraction sockets in dogs are negated by recombinant human bone morphogenetic protein

PURPOSE

This study was conducted with 2 purposes. The first was to determine the effect of a single dose of zoledronic acid (ZA) on the healing of a tooth extraction socket in dogs. The second was to determine if placement of recombinant human bone morphogenetic protein-2 (rhBMP-2)/absorbable collagen sponge (ACS) - INFUSE, (Medtronic, Memphis, TN) into these extraction sockets would inhibit the inhibition on bone healing and remodeling by ZA.

MATERIALS AND METHODS

Nine adult female beagle dogs (2 to 3 yr old) were placed into 3 groups of 3 dogs each. Group I received 15 mL of sterile saline intravenously; group II received 2.5 mg of ZA intravenously; and group III received 5 mg of ZA intravenously. Forty-five days after treatment, all dogs underwent extraction of noncontiguous right and left mandibular first molars and second premolars. In group I, the right mandibular extraction sockets had nothing placed in them, whereas the left mandibular sockets had only ACS placed in them. In groups II and III, the right mandibular sockets had rhBMP-2/ACS placed in them, whereas the left mandibular sockets had only ACS placed. All extraction sockets were surgically closed. Tetracycline was given intravenously 5 and 12 days later, and all animals were euthanized 15 days after tooth extraction. The extraction sockets and rib and femur samples were harvested immediately after euthanasia, processed, and studied microscopically.

RESULTS

A single dose of ZA significantly inhibited healing and bone remodeling in the area of the tooth extractions. The combination of rhBMP-2/ACS appeared to over-ride some of the bone remodeling inhibition of the ZA and increased bone fill in the extraction sites, and remodeling activity in the area was noted. The effects of rhBMP-2/ACS were confined to the area of the extraction sockets because bone activity at distant sites was not influenced.

CONCLUSIONS

A single dose of ZA administered intravenously inhibits early healing of tooth extraction sockets and bone remodeling in this animal model. The combination of rhBMP-2/ACS significantly increased bone fill and bone remodeling in these areas, negating much of the effect of the ZA.

The effect of systemically administrated zoledronic acid on the osseointegration of dental implants

OBJECTIVE

The aim of conducting this study was to evaluate the effect of zoledronic acid (ZA) on the new bone formation (NBF) after the insertion of a titanium dental implant, which is very popular treatment in dentistry.

STUDY DESIGN

Twelve New Zealand white rabbits were used in this study. The rabbits were divided in two groups. ZA was systemically administered to the study group. Titanium implants were placed to the left and right tibias of the rabbits.

RESULTS

The data from the ZA group revealed a statistically significant increase in the bone mineral content and the bone mineral density. A non-decalcified histomorphometric examination conducted on the study group revealed a significant increase of NBF and bone-implant contact (BIC) at 2 and 4 weeks.

CONCLUSION

A single dose of systemic ZA administration increases the rate of NBF and augments the quality of the bone.