The potential prophylactic and therapeutic impacts of niacin on ischemia/reperfusion injury of testis

INTRODUCTION

The testicular ischemia-reperfusion (I/R) injury is characterized by the excessive aggregation of un-scavenged reactive oxygen species, leading to the heightened levels of oxidative stress. This phenomenon plays a pivotal role in the pathophysiology of testicular torsion damage.

OBJECTIVE

The current study aimed to detect the prophylactic and therapeutic effects of niacin on testicular I/R injury.

STUDY DESIGN

Twenty-four healthy adult male Sprague Dawley rats were randomly allocated into three groups as follows: (1) sham group, (2) torsion/detorsion (T/D) group, and (3) treatment group which received 200 mg/kg niacin along with testicular T/D. Torsion/detorsion was induced by 2 h of torsion followed by 10 days of reperfusion period. In the treatment group, niacin was injected 30 min before the reperfusion period intraperitoneally and continued for 10 days by oral gavage.

RESULTS

T/D was associated with marked decreases in terms of sperm count, viability, and kinematic parameters versus the sham group (P < 0.05), which niacin significantly reverted the kinematic parameters (P < 0.05). I/R injury caused a significant increase in the number of abnormal epididymal sperms compared to the sham group (P < 0.05). Niacin decreased the epididymal sperm abnormality significantly compared to the T/D group (P < 0.05). Tissue abnormalities in T/D group, such as edema, hyperemia, inflammation, and necrosis were completely visible histopathologically, while the histological changes in the niacin-treated group were better than those in the T/D group. Regarding the pathological parametric evaluations, I/R injury significantly reduced the mean testicular biopsy score (MTBS), germinal epithelial cell thickness (GECT), and mean seminiferous tubular diameter (MSTD), and increased the tubular hypoplasia/atrophy (THA) compared to the sham group (P < 0.05), which niacin treatment significantly improved the MTBS and GECT compared to the T/D group (P < 0.05). T/D significantly increased the oxidative stress index (OSI) and lipid peroxidation (MDA) (P < 0.05). Niacin significantly reduced the OSI and MDA levels compared to the T/D group (P < 0.05).

DISCUSSION

The current study found that niacin has preventive/therapeutic effects against the elevation of oxidative stress markers and depletion of antioxidants during I/R injury. Following administration of niacin, a reduction in histologic injury was observed in rats. In our study, we showed the antioxidant properties of niacin and its capacity to protect against I/R damage.

CONCLUSION

The findings of the present investigation revealed that niacin, as an antioxidant agent, can suppress the oxidative stress induced by testicular I/R injury, and can be used as a supplementary agent in the treatment of those undergoing testicular torsion surgery.

The effects of allogeneic and xenogeneic lyophilized leukocyte-and platelet-rich fibrin on bone healing in rat

BACKGROUND

Critical size defects are one of the challenges in the treatment of fractures in humans and animals. Blood products such as leukocyte-SAand platelet-rich fibrin (L-PRF) are one of the alternatives to bone autograft to solve this challenge. This study aims to evaluate the effects of allogeneic and xenogeneic lyophilized L-PRF on bone healing in a critical defect of radius bone in rat.

METHODS

A defect with a diameter of 5 mm was created in the radius bone of 60 rats in four groups. The defect was left empty in the untreated group, and it was filled with autogenous bone graft, allogeneic, and xenogeneic lyophilized L-PRF, respectively, in the other three groups. Radiographic evaluation was done every two weeks, and histopathological evaluation in the 14th, 28th, and 56th days after surgery.

RESULTS

The radiographic scores of allogeneic and xenogeneic lyophilized l-PRF groups were significantly higher than the untreated group in all times (P<0.05). In connection with histopathological Emery's scoring system, the score of allogeneic lyophilized L-PRF was significantly higher than the untreated group (P<0.05) in the 14th and 28th days after surgery. The score of the xenogeneic lyophilized L-PRF group was also higher than the untreated group, but the difference was not significant (P>0.05). The allogeneic and xenogeneic lyophilized L-PRF scores were significantly higher than the untreated group (P < 0.05) on the 56th day.

CONCLUSION

The results of the present study showed that the allogeneic and xenogeneic lyophilized L-PRF can improve bone healing in the critical radius bone defect in rat model of study.

Surgical management of an aspirated bone in a Shih Tzu terrier dog: a case report

Foreign bodies in the respiratory tract (trachea/bronchus) are very rare conditions; therefore, it is not on top of the list of differential diagnoses in patients with chronic or severe cough, but its occurrence should not be considered unexpected. A 2-year-old male Shih Tzu terrier mix dog (9.20 kg) with a history of dyspnea for 6 days was referred to the Veterinary Teaching Hospital of Shiraz University, Shiraz, Iran. In the clinical examination, respiratory distress and pain during palpation of the neck area were observed. Radiology indicated a triangular radiopaque object (bone) in the trachea of the animal. The size of the foreign body, the weakness of the grasping forceps of the device, and the edges of the bone being stuck in the trachea caused tracheoscopy failure after 30 min of trying. Surgical procedure (tracheotomy) was effective to remove the foreign body using Noyes alligator tissue forceps. Aspirated foreign body is not a common condition. In the case of early recognition and immediate treatment of the aspirated foreign body, the prognosis is usually good.

Effect of direct therapeutic ultrasound exposure of ovaries on histopathology, inflammatory response, and oxidative stress in dogs

BACKGROUND

This research was designed to evaluate the effects of therapeutic ultrasound waves on ovarian germinal tissue and inflammatory cytokines (interleukin-6 (IL-6), IL1β, tumor necrosis factor-α (TNF-α)), acute phase proteins (serum amyloid A (SAA), C reactive protein (CRP)) and oxidative stress (total antioxidant capacity (TAC), and malondialdehyde (MDA)) in dogs. Twenty-six clinically healthy adult mix-breed female dogs were aligned into three groups. Laparotomy was performed in control (n = 6) and treatment (T5, n = 10; T10, n = 10) groups. The ultrasonic exposure of ovaries in treatment groups was performed during laparotomy by round motions of the therapeutic ultrasonic transducer on both ovaries (1 MHz frequency, 1.5 W⁄cm2) for 5 min in the T5 group and for 10 min in the T10 group. Blood samples were collected from the jugular vein into a plain glass tube on days 0 (before laparotomy), 3, 6, and 9 after surgery. All control and treatment groups' dogs were ovariectomized for histological evaluation on day 60 after laparotomy or laparotomy + ultrasound exposure.

RESULTS

Direct exposure of ovaries with therapeutic ultrasound waves induced inflammation and oxidative stress comparison with the control group. Histopathological evaluation of treated ovaries with ultrasound waves indicated a decreased number of primordial follicles (ovarian reserve) and oocyte preservation scores compared with ovaries in the control group.

CONCLUSIONS

These changes may cause subfertility in the long term. It seems that inflammatory response and oxidative stress are factors in the permanent damage of ovarian tissue.

Effects of concurrent use of royal jelly with hydroxyapatite on bone healing in rabbit model: radiological and histopathological evaluation

Background

Bone grafts have been used to enhance bone fracture healing in orthopedic surgery. Bone grafts enhance bone healing either by mechanical support or acting as a scaffold for bone formation. Fresh autograft is the most effective biomaterial because it is histocompatible with less complication about transmissible disease. Hydroxyapatite is a well-established material for bone repair and very comparable to natural apatite providing a strong biomechanical interlock with host tissue. Royal jelly is the principal food for the honeybee queen. This biomaterial has been demonstrated to have several pharmacological activities, such as antiallergic, antitumor and anti-inflammatory effects.

Objectives

This study was design to evaluate the effect of concurrent using of Royal jelly with hydroxyapatite on bone healing in rabbit model.

Methods

15 adult rabbits weighting approximately 2 kg had been used. They were divided into three groups randomly. In first group (N = 5) mid radius bone defect created and left empty. The second group (N = 5) filled with hydroxy apatite alone and the last group (N = 5) filled with royal jelly and hydroxy apatite combination. Radiological evaluation performed on days14th, 28th and 42nd after operation. Histopathological evaluation was done on 56^th postoperative day.

Results

Radiological evaluation showed significant superior bone healing in hydroxyapatite and hydroxyapatite-Royal jelly groups in comparison to control group. Control group was the inferior group between three groups. There were not any significant differences between three groups in histopathological group.

Conclusion

In conclusion our study showed the best results with using the hydroxyl apatite and Royal-jelly group because they provide not only scaffold for bone healing but also do, they provide some osteoinduction materials for bone healing.

Propolis extract a new reinforcement material in improving bone healing: An in vivo study

BACKGROUND

Propolis is known for its antioxidant, immune response modulating, and wound healing effects. In the present study in order to determine the bone healing capacity of the propolis extract, a critical sized, nonunion, radial bone defect model was repaired in rat, using chitosan and demineralized bone matrix (DBM) scaffolds along with propolis extract.

MATERIALS AND METHODS

Seventy-two radial bone defects in 36 healthy male rats were randomly divided into 6 groups (n = 12/group). The groups included autograft, defect or untreated group, chitosan, DBM, chitosan and propolis (chitosan-propolis), and DBM and propolis (DBM-propolis). The bone repairing capability was characterized using radiography at 28th, 42nd and 56th postoperative days. Gross morphologic, histopathologic, histomorphometric and biomechanical examinations were performed following euthanasia at the 56th post-operative day.

RESULTS

The DBM-propolis group, showed better structural and biomechanical properties compared to the untreated, DBM, chitosan and chitosan-propolis groups. The defect site in the chitosan and untreated groups were mainly restored by fibrous connective tissue while the lesions in the autograft group were mostly filled by cartilage and a lesser amount of woven bone. The woven bone, and the hyaline cartilage were the main constituents of the newly formed tissues in the DBM-propolis group, at the 56th day after injury.

CONCLUSION

The results of this study showed that percutaneous injection of diluted aqueous propolis extract in the bone defect (25 mg/defect) can improve bone formation in the critical radial bone defect in rat. Since there was no significant difference between the autograft and DBM-propolis group, probably this therapeutic strategy has high potential in augmentation of autologous bone grafting.

Effects of chitosan scaffold along with royal jelly or bee venom in regeneration of critical sized radial bone defect in rat

The aim of this study was to compare the efficacy of honey bee venom (BV) and royal jelly (RJ) alongside chitosan scaffold (CS) in improving radius bone defect in rats. A total of 60 full thickness radial bone defects with a length of 5 mm were created in 60 male Wistar rats. Six healthy radial bones (3 rats) were also assigned as normal control for biomechanical studies. The defects were left empty (untreated group) or were filled by the autograft (autograft group), CS (CS group), CS alongside the BV solution (CS-BV group), and CS alongside the RJ solution (CS-RJ group). Healing of the bone defects were evaluated clinically and radiologically on days 0, 28, 42 and 56 after operation while the biomechanical testing and histopathological examination were performed on the 56th day after surgery. The autograft was more radiopaque than the untreated and CS groups at the 28th, 42nd and 56th postoperative days (P<0.05). The CS-BV and CS-RJ groups showed significantly higher radiographic outcomes than the untreated and CS groups at the 56th post-operative day (P<0.05). The density of osseous tissue (DOT) and the osteocytes and osteoblasts count of the CS-RJ and CS-BV groups were significantly higher than the CS and autograft groups (P<0.05). The biomechanical results of the CS-RJ group were significantly superior to the autograft, while the biomechanical properties of CS-BV group were not significantly different with the autograft group (P>0.05). The scaffolds in CS group were observable in the surgical site after 56 days. There was no significant difference in radiographs, DOT, cartilage tissue and fibrous tissue, and also biomechanical performances of the CS-BV and CS-RJ groups at the 42nd and 56th day after surgery. The untreated and CS groups showed weakest biomechanical results among all groups. It could be concluded that both treatment strategies in the CS-BV and CS-RJ groups were appropriate and useful in treating critical bone defects.

Dicalcium Phosphate Anhydrous: An Appropriate Bioceramic in Regeneration of Critical-Sized Radial Bone Defects in Rats

The present study aimed to evaluate and compare the effectiveness of composites of calcium phosphates including β-tri calcium phosphate (β-TCP), dicalcium phosphate anhydrous (DCPA, monetite), mono-calcium phosphate monohydrate (MCPM), and hydroxyapatite (HA) with the chitosan-gelatin-platelet gel (CGP) on the healing of experimentally induced critical size radial bone defects in rats after 8 weeks of injury. Eighty bilateral bone defects were created in the radial bones of 40 adult male Sprague-Dawley rats. The defects were either left empty (untreated or defect group), or treated with autograft, CGP, CGP-DCP, CGP-TCP, CGP/β-TCP/DCPA (CGP-TD), CGP-TD/MCPM (CGP-TDM), and CGP-TDM/HA (CGP-TDMH) scaffolds. The injured forelimbs were evaluated by radiography, gross morphology, three-dimensional computed tomography scanning, histopathology, histomorphometry, scanning electron microscopy, and biomechanical testing. The materials were analyzed using X-ray diffraction to verify the crystalline nature of their structures, and their crystallinity was revealed based on the diffraction peaks achieved from the XRD analysis. The best results were achieved by the CGP-DCP scaffold and the autograft. The CGP-TCP and CGP-TDMH scaffolds were not degraded, while the CGP-DCP, CGP-TDM, CGP-TD, and CGP scaffolds were biodegraded and enhanced bone formation compared with the CGP-TCP and CGP-TDMH groups (P < 0.05). Overall, the CGP-DCP treated defects showed significant improvement in bone formation and union, bone volume, maximum load, and stiffness compared to the CGP group (P < 0.05). It could be concluded that the CGP-DCP scaffold can be considered as a suitable substitute to autograft. In fact, this study demonstrated that DCPA or monetite has high healing potential due to its biocompatibility, biodegradability and biomechanical, osteoconductive and osteoinductive properties of this bioceramic.

Effectiveness of tissue engineered based platelet gel embedded chitosan scaffold on experimentally induced critical sized segmental bone defect model in rat

BACKGROUND

Healing and regeneration of large bone defects are a challenging problem for reconstructive orthopedic surgeons.

PURPOSE

This study investigated the effectiveness of chitosan scaffold (CS), platelet gel (PG) and their combination (CS-PG) on healing process of an experimentally induced critical sized segmental bone defect model in rat.

METHODS

Fifty bilateral defects were created in the mid diaphysis of the radial bones of 25 Sprague-Dawley rats. The animals were randomly divided into five equal groups. The bone defects were either left untreated or treated with corticomedullary autograft, CS, PG or CS-PG. Plain radiographs were provided from the radial bones on weeks 2, 5, and 8 after injury. In addition, clinical examinations were done for the healing radial bones. The animals were euthanized after 8 weeks of injury, and their harvested samples were evaluated by gross morphology, histopathology, scanning electron microscopy, CT-scan, and biomechanical testing.

RESULTS

Compared with the defect group, the PG and autograft treated bone defects had significantly superior radiological scored values, bone volume and biomechanical performance which had positive correlation with their superior gross pathological, histopathological and ultra-structural features. Compared with the untreated defects, the PG and CS-PG treated defects showed significantly superior structural and functional properties so that PG had the highest value. In addition, CS had low value in bone regeneration. Although combination of CS and PG improved the healing efficacy of the CS, this strategy reduced the ability of PG to increase osteoconduction and osteoinduction during bone regeneration.

CONCLUSION

Application of PG alone enhanced bone healing and can be regarded as a promising option for bone tissue engineering in clinical settings. Chitosan was not effective in bone reconstruction surgery and further investigations should be conducted to find a suitable carrier for PG.

Comparative study on the role of gelatin, chitosan and their combination as tissue engineered scaffolds on healing and regeneration of critical sized bone defects: an in vivo study

Gelatin and chitosan are natural polymers that have extensively been used in tissue engineering applications. The present study aimed to evaluate the effectiveness of chitosan and gelatin or combination of the two biopolymers (chitosan-gelatin) as bone scaffold on bone regeneration process in an experimentally induced critical sized radial bone defect model in rats. Fifty radial bone defects were bilaterally created in 25 Wistar rats. The defects were randomly filled with chitosan, gelatin and chitosan-gelatin and autograft or left empty without any treatment (n = 10 in each group). The animals were examined by radiology and clinical evaluation before euthanasia. After 8 weeks, the rats were euthanized and their harvested healing bone samples were evaluated by radiology, CT-scan, biomechanical testing, gross pathology, histopathology, histomorphometry and scanning electron microscopy. Gelatin was biocompatible and biodegradable in vivo and showed superior biodegradation and biocompatibility when compared with chitosan and chitosan-gelatin scaffolds. Implantation of both the gelatin and chitosan-gelatin scaffolds in bone defects significantly increased new bone formation and mechanical properties compared with the untreated defects (P < 0.05). Combination of the gelatin and chitosan considerably increased structural and functional properties of the healing bones when compared to chitosan scaffold (P < 0.05). However, no significant differences were observed between the gelatin and gelatin-chitosan groups in these regards (P > 0.05). In conclusion, application of the gelatin alone or its combination with chitosan had beneficial effects on bone regeneration and could be considered as good options for bone tissue engineering strategies. However, chitosan alone was not able to promote considerable new bone formation in the experimentally induced critical-size radial bone defects.

Selection of animal models for pre-clinical strategies in evaluating the fracture healing, bone graft substitutes and bone tissue regeneration and engineering

In vitro assays can be useful in determining biological mechanism and optimizing scaffold parameters, however translation of the in vitro results to clinics is generally hard. Animal experimentation is a better approximation than in vitro tests, and usage of animal models is often essential in extrapolating the experimental results and translating the information in a human clinical setting. In addition, usage of animal models to study fracture healing is useful to answer questions related to the most effective method to treat humans. There are several factors that should be considered when selecting an animal model. These include availability of the animal, cost, ease of handling and care, size of the animal, acceptability to society, resistance to surgery, infection and disease, biological properties analogous to humans, bone structure and composition, as well as bone modeling and remodeling characteristics. Animal experiments on bone healing have been conducted on small and large animals, including mice, rats, rabbits, dogs, pigs, goats and sheep. This review also describes the molecular events during various steps of fracture healing and explains different means of fracture healing evaluation including biomechanical, histopathological and radiological assessments.

Spinal fusion with demineralized calf fetal growth plate as novel biomaterial in rat model: a preliminary study

Background

Spinal fusions are being performed for various pathologies of the spine such as degenerative diseases, deformities, tumors and fractures. Recently, other bone substitutes such as demineralized bone matrix (DBM) have been developed for spinal fusion. Therefore, this study was conducted to evaluate the intertransverse posterolateral fusion with the Bovine fetal growth plate (DCFGP) and compare it with commercial DBM in rat model.

Methods

A total of 16 mature male rats (aged 4 months and weighing 200-300 g) were randomly divided in two groups. After a skin incision on posterolateral site, two separate fascial incisions were made 3 mm from the midline. A muscle-splitting approach was used to expose the transverse processes of L4 and L5. Group I (n = 8) underwent with implanted Bovine fetal growth plate among decorticated transverse processes. In group II (n = 8) commercial DBM was placed in the same manner. Fusion was evaluated by manual palpation, radiographical, gross and histopathological analysis.

Results

The manual palpation, radiological, gross and histopathological findings indicate high potential of the DCFGP in spinal fusion. At the 42nd postoperative day, new bone formation as evidenced by a bridge between L4 and L5 was visualized in all rats implanted with DCFGP and commercial DBM. The newly formed bone tissue was observed in all implanted areas on the 42nd day after operation in the two groups.

Conclusions

The spinal fusion of the animals of both groups demonstrated more advanced osteogenic potential and resulted in proper fusion of the transverse process of lumbar vertebra.

Hydroxyapatite and demineralized calf fetal growth plate effects on bone healing in rabbit model

Background

Synthetic hydroxyapatite (HA), beta-tricalcium phosphate (β-TCP) and their composite are promising biomaterials, specifically in the orthopedic and dental fields, as their chemical composition is similar to that of bone. Due to the need for safer bone graft applications, these bone graft substitutes are gradually gaining increased acceptability. To stimulate the process of bone healing, several methods have been used previously, including ultrasound, electrical stimulation, exposure to electromagnetic fields, bone grafts, interporous hydroxyapatite (as a bone graft substitute) and bone growth factors. The following study was designed to evaluate the effects of the concurrent usage of hydroxyapatite with demineralized calf fetal growth plate (DCFGP) on the bone healing process.

Materials and methods

Fifteen female New Zealand white rabbits were used in this study. A mid-radius bone defect was created and in the first group (n = 5) was filled with hydroxyapatite, in the second group (n = 5) with hydroxyapatite and DCFGP, and finally in the third group (n = 5) with DCFGP alone. Radiological and histopathological evaluations were performed blindly and the results scored and analyzed statistically.

Results

There was a significant difference for bone formation and remodeling at the 8th post-operative week radiographic assessment (P< 0.05), when the hydroxyapatite–DCFGP group was superior to other groups. On the contrary, macroscopical and histopathological evaluation did not revealed significant differences between the three groups

Conclusion

Given the contrasting results of the radiographic assessment and the macro-/microscopic analysis of the healing response, further studies are needed before considering DCFGP-HA as a feasible alternative to HA alone, especially considering the potential hazards and costs of animal-derived biomaterials.

Level of evidence

Not applicable.

Bone morphogenetic proteins: a powerful osteoinductive compound with non-negligible side effects and limitations

Healing and regeneration of large bone defects leading to non-unions is a great concern in orthopedic surgery. Since auto- and allografts have limitations, bone tissue engineering and regenerative medicine (TERM) has attempted to solve this issue. In TERM, healing promotive factors are necessary to regulate the several important events during healing. An ideal treatment strategy should provide osteoconduction, osteoinduction, osteogenesis, and osteointegration of the graft or biomaterials within the healing bone. Since many materials have osteoconductive properties, only a few biomaterials have osteoinductive properties which are important for osteogenesis and osteointegration. Bone morphogenetic proteins (BMPs) are potent inductors of the osteogenic and angiogenic activities during bone repair. The BMPs can regulate the production and activity of some growth factors which are necessary for the osteogenesis. Since the introduction of BMP, it has added a valuable tool to the surgeon's possibilities and is most commonly used in bone defects. Despite significant evidences suggesting their potential benefit on bone healing, there are some evidences showing their side effects such as ectopic bone formation, osteolysis and problems related to cost effectiveness. Bone tissue engineering may create a local environment, using the delivery systems, which enables BMPs to carry out their activities and to lower cost and complication rate associated with BMPs. This review represented the most important concepts and evidences regarding the role of BMPs on bone healing and regeneration from basic to clinical application. The major advantages and disadvantages of such biologic compounds together with the BMPs substitutes are also discussed.

Effects of osteogenic medium on healing of the experimental critical bone defect in a rabbit model

Today, finding an ideal biomaterial to treat the large bone defects, delayed unions and non-unions remains a challenge for orthopedic surgeons and researchers. Several studies have been carried out on the subject of bone regeneration, each having its own advantages. At the same time, a variety of disadvantages still remain. The present study has been designed in vivo to evaluate the effects of osteogenic medium on healing of experimental critical bone defect in a rabbit model. Twenty New Zealand albino rabbits, 12 months old, of both sexes, weighing 2.0±0.5 kg were used in this study. An approximately 10mm segmental defect was created in the mid portion of each radius as a critical size bone defect. In the osteogenic medium group (n=5) 1 ml osteogenic medium, in the maintenance medium group (n=5) 1 ml maintenance medium, and in the normal saline group (n=5) 1 ml normal saline were injected in the defected area while the defects of the rabbits of the control group (n=5) were left empty. Radiological evaluation was done on the 1st day and then at the 2nd, 4th, 6th and 8th weeks post injury. Biomechanical and histopathological evaluations were done 8 weeks post injury. The radiological, histological and biomechanical findings of the present study indicated a superior bone healing capability in the osteogenic and maintenance medium groups, by the end of 8 weeks post-surgery, in comparison to the normal saline and control groups. In conclusion, this study demonstrated that the osteogenic medium and maintenance medium could promote bone regeneration in long bone defects better than the control group in rabbit model.

Basic concepts regarding fracture healing and the current options and future directions in managing bone fractures

Fracture healing is a complex physiological process, which involves a well-orchestrated series of biological events. Repair of large bone defects resulting from trauma, tumours, osteitis, delayed unions, non-unions, osteotomies, arthrodesis and multifragmentary fractures is a current challenge of surgeons and investigators. Different therapeutic modalities have been developed to enhance the healing response and fill the bone defects. Different types of growth factors, stem cells, natural grafts (autografts, allografts or xenografts) and biologic- and synthetic-based tissue-engineered scaffolds are some of the examples. Nevertheless, these organic and synthetic materials and therapeutic agents have some significant limitations, and there are still no well-approved treatment modalities to meet all the expected requirements. Bone tissue engineering is a newer option than the traditional grafts and may overcome many limitations of the bone graft. To select an appropriate treatment strategy in achieving a successful and secure healing, more information concerning injuries of bones, their healing process and knowledge of the factors involved are required. The main goals of this work are to present different treatment modalities of the fractured bones and to explain how fractures normally heal and what factors interfere with fracture healing. This study provides an overview of the processes of fracture healing and discusses the current therapeutic strategies that have been claimed to be effective in accelerating fracture healing.

Effectiveness of synthetic hydroxyapatite versus Persian Gulf coral in an animal model of long bone defect reconstruction

BACKGROUND

There is a continuing search for bone substitutes to avoid or minimize the need for autogenous bone grafts. Hydroxyapatite, a crystalline phase of calcium phosphate found naturally in bone minerals, has shown tremendous promise as a graft material. Coral is an osteoconductive material used as a bone graft extender. This study examined the effect of hydroxyapatite and Persian Gulf coral on osteogenesis in vivo using a rabbit model of bone healing.

MATERIALS AND METHODS

A critical-size defect of 10 mm elongation was created in the radial diaphysis of 36 rabbits and supplied with either hydroxyapatite or coral or left empty (control group). Radiographs of each forelimb were taken postoperatively on day 1 and then at 2, 4, 6, and 8 weeks postinjury to evaluate bone formation, union, and remodeling of the defect. The operated radiuses were removed on the 56th postoperative day and were grossly and histopathologically evaluated. In addition, biomechanical testing was conducted on the operated and normal forelimbs of half of the animals of each group.

RESULTS

In radiological evaluation, bone formation and union were significantly superior in the coral and hydroxyapatite groups in comparison with the control group on the 42nd and 56th day postinjury (P < 0.05). There were no statistical differences between groups in remodeling criteria at the 56th day postinjury (P > 0.05). In histopathological evaluation, the union scores of the rabbits administered hydroxyapatite or coral were statistically superior to those of the animals of the control group on the 56th day postinjury (P < 0.05). In biomechanical evaluation, the control group showed weakness of biomechanical properties in comparison with the coral and hydroxyapatite groups (P < 0.05).

CONCLUSIONS

According to this study, significant difference was not observed between hydroxyapatite and natural coral and these two materials were significantly better than the control group at 8 weeks postinjury.

Evaluation of bone healing in canine tibial defects filled with cortical autograft, commercial-DBM, calf fetal DBM, omentum and omentum-calf fetal DBM

The present study was conducted to compare the effects of xenogenic bovine fetal demineralized bone matrix (DBM), commercial DBM, omentum, omentum-calf fetal DBM, cortical autograft and xenogenic cartilage powder on the healing of tibial defects in a dog model to determine the best material for bone healing. Seven male adult mongrel dogs, weighing 26.2 ± 2.5 kg, were used in this study. Seven holes with a diameter of 4-mm were created and then filled with several biomaterials. Radiographs were taken postoperatively on day 1 and weeks 2, 4, 6, 8. The operated tibias were removed on the 56th postoperative day and histopathologically evaluated. On postoperative days 14, 42 and 56, the lesions of the control group were significantly inferior to those in the other group (p < 0.05). On the 28th postoperative day, the autograft group was significantly superior to the control and omentum groups (p < 0.05). Moreover, calf fetal DBM was significantly superior to the control group. There was no significant difference between the histopathological sections of all groups. Overall, the omentum and omentum-DBM groups were superior to the control group, but inferior to the autograft, commercial-DBM, calf fetal DBM and calf fetal cartilage groups.

Effects of adipose tissue stem cell concurrent with greater omentum on experimental long-bone healing in dog

Repair of large bone defects resulting from trauma, tumors, and osteitis is a current challenge to surgeons. Adipose-derived adult stem cells (ASCs) are multipotent cells that are able to differentiate into osteoblasts in the presence of certain factors. In this study, the role of greater omentum as a scaffold incorporation of ASCs was evaluated in long-bone defect healing in dog model. Sixteen 3-4-year-old, male adult mongrel dogs, weighing 25.2 ± 3.5 kg, were used in this study. In the control group (n = 4), the defect was left empty. In the omental group (n = 4), the defect was filled with harvested omentum. In the omental-ASCs group (n = 4), the defect was filled with omentum and 1 mL of ASCs was injected into the grafted omentum. In the omental-culture medium group (n = 4), 1 mL of culture medium was injected into the grafted omentum. Finally, the injured radial bones were fixed with plate and screw. Radiographs of each forelimb was taken postoperatively on the first day and at the second, fourth, sixth, and eighth weeks postinjury to evaluate bone formation, union, and remodeling of the defect. The operated radii were removed on the 56th postoperative day and were histopathologically evaluated. In this study, both omental-culture medium and omental-ASCs groups demonstrated superior osteogenic potential in healing the radial bone defect. Compared to those of the omental and control groups, more advanced bone healing criteria were present in the omental-culture medium and omental-ASCs groups at radiological and histopathological levels at 8 weeks postsurgery.