Background: The use of a closed fracture model has become the preferred model to study the fracture healing process, given that the periosteum and the soft tissue surrounding the fracture site play an important role in the fracture healing process. Some techniques like osteotomy, drilling the long bones and the use of the guillotine‐like apparatus to induce fracture are characterized by some undesirable effects and complications. The aim of this study is to optimize and evaluate an in vivo fracture model using three‐point bending pliers that can be used to study secondary bone fracture healing in rats.Methods: Modified three‐point bending pliers were used as a device to create the closed rat tibial bone fracture that was prefixed with an intramedullary pin (23 G × 1¹/₂″) in rats. The exact location of the induced closed fracture was along the long bone. The presence of bone comminution, and the fracture bone alignment were immediately examined after the induction of the fracture until the 6th week.Results: All fractures induced were transverse, located in the middle to proximal one third of the tibia, and they all healed without complications. Bone union as shown radiographically occurred within 2–3 weeks postoperative. The average angle of the fracture line with the axis of the tibia was 89.41 ± 2.11°. The lateral and anterio‐posterior pin angulation views were 167.33 ± 3.67° and 161.60 ± 4.87° respectively. The average length of proximal end of the fractured bone in comparison with the whole length of intact bone was 41.02 ± 3.27%. There was a significant difference in percentage of the gross callus area and gross callus index, while there was no significant difference in X‐ray callus index. There was no significant difference of the gross callus area between slight comminution (n = 4) and non comminution (n = 21).Conclusion: The optimized rat tibial fracture model resulted in mainly transverse tibial mid‐shaft fractures with minimal bone comminution and absence of surrounding soft tissue damage. The size area of consequent soft callus formation and the extent to which the closed fracture model was reproducible are very good outcomes making it feasible for in vivo laboratory research use.

The objective of this study was to evaluate the use of Afp1m as a cryopreservative agent for skin by examining the transplanted skin histological architecture and mechanical properties following subzero cryopreservation. Thirty four (34) rats with an average weight of 208 ± 31 g (mean ± SD), were used. Twenty four (n = 24) rats were equally divided into four groups: (i) immediate non-cryopreserved skin autografts (onto same site), (ii) immediate non-cryopreserved skin autografts (onto different sites), (iii) skin autografts cryopreserved with glycerol for 72 h and (iv) skin autografts cryopreserved with Afp1m for 72 h at -4 °C. Rounded shaped full-thickness 1.5-2.5 cm in diameter skin was excised from backs of rats for the autograft transplantation. Non-cryopreserved or cryopreserved auto skin graft were positioned onto the wound defects and stitched. Non-transplanted cryopreserved and non-cryopreserved skin strips from other ten rats (n = 10) were allowed for comparative biomechanical test. All skin grafts were subjected to histological and mechanical examinations at the end of day 21. Histological results revealed that tissue architecture especially the epidermal integrity and dermal-epidermal junction of the Afp1m cryopreserved skin grafts exhibited better histological appearance, good preservation of tissue architecture and structural integrity than glycerolized skin. However, there was no significant difference among these groups in other histological criteria. There were no significant differences among the 4 groups in skin graft mechanical properties namely maximum load. In conclusion, Afp1m were found to be able to preserve the microstructure as well as the viability and function of the skin destined for skin transplantation when was kept at -4 °C for 72 h.

The study aimed to assess the effectiveness of using aloe vera gel on articular cartilage regeneration in a canine model. About 6 mm osteochondral defects were induced on the trochlear groove of the distal extremity of the left femur bone of 18 adult dogs. These animals were divided into two equal groups, of 9 animals. The induced osteochondral defects were left without treatment for the first group (control group “C G”) While for the other group (treated group “T G”), the defect was occupied with 1 ml of aloe vera gel. Clinical, macroscopic, and histopathological evaluations were conducted on the 15th, 30th, and 45th day post-surgery. Clinical outcomes exhibited rapid and clear improvement in animals’ ability to use their limbs in standing and walking positions since the end of the first week following surgery in the treated group compared to the control group. Besides, the gross observation showed a relative disappearance of the osteochondral defect in the treated group rather than the control group at the end of the study. The histopathological data showed rapid and profound proliferation of the chondroblast and new cartilage formation with more angiogenesis and little development of granulation tissue at the end of the study in the treated group compared to the control group. In conclusion, aloe vera gel can enhance and accelerate the articular regenerative healing process to repair dog osteochondral defects.

The aim of this study was a histopathological evaluation of the effects of nano magnesium oxide and platelets-rich fibrin on induced radial fracture bone healing in local stray dogs. We used 18 adult animals weighing 17.5±0.6 kg and aged 2.0±0.1 years; these experimental animals were divided into three main equal groups. In the first group (Control), the fracture was left without treatment of any bioactive materials; in the second group (nano magnesium oxide), the fracture line was injected with 20µg of nano magnesium oxide, the third group (platelets rich fibrin) the fracture line was surrounded by platelet-rich fibrin. The bone specimens were taken from all experimental animals 6 and 10 weeks after the surgical operation. A Colorimetric method was used for measuring the alkaline phosphatase enzyme and calcium concentrations in all trial animals. The histopathological results at the 6th and 10th weeks showed that the best response was in the platelets-rich fibrin group, then the nano magnesium oxide group, and lastly, the control group according to the formation of fibrocartilaginous tissue, trabeculae, and woven bone. The concentration rates of alkaline phosphatase enzyme and calcium were increased in the weeks that followed the surgical operation. In conclusion of this study, platelets-rich fibrin and nano-magnesium oxide accelerated the healing of the radial fracture.

The article was designed to evaluate the efficiency of lyophilized bovine pericardium and acellular bovine skin for repairing diaphragmatic hernia in dogs. Twelve local breed adult dogs were used. In all animals, the diaphragmatic hernia was induced by removing 5cm diameter circular piece the diaphragm. The animals were divided into two equal groups (n=6). In the first group, the diaphragmatic hernia was repaired using lyophilized bovine pericardium, and in the second group, acellular bovine skin was applied. The results were evaluated studying the gross and histopathological changes on the 15th and 30th postoperative days. The gross results showed a different degree of adhesion at the site of hernial repair. The adhesion rate was developed more severely in the second group animals compared to the first group. The histopathological manifestation of the first group showed excessive and more mature granulation tissue formation with few inflammatory cell infiltrations with good angiogenesis comparable to the second group, which revealed moderate granulation tissue formation and blood vessel formation with sever infiltration of inflammatory cells. In conclusion, we can use lyophilized bovine pericardium and acellular bovine skin to repair diaphragmatic hernias in dogs, although lyophilized bovine pericardium is regarded as the best option despite its high cost.

Background: Chondrocytes in the growth plate (GP) undergo increases in volume during different cascades of cell differentiation during longitudinal bone growth. The volume increase is reported to be the most significant variable in understanding the mechanism of long bone growth.Methods: Forty‐five postnatal Sprague‐Dawley rat pups, 7‐15 days old were divided into nine age groups (P7‐P15). Five pups were allocated to each group. The rats were sacrificed and tibia and metatarsal bones were harvested. Bone lengths were measured after 0, 24, 48, and 72 hours of ex vivo incubation. Histology of bones was carried out, and GP lengths and chondrocyte densities were determined.Results: There were significant differences in bone length among the age groups after 0 and 72 hours of incubation. Histological sectioning was possible in metatarsal bone from all age groups, and in tibia from 7‐ to 13‐day‐old rats. No significant differences in tibia and metatarsal GP lengths were seen among different age groups at 0 and 72 hours of incubation. Significant differences in chondrocyte densities along the epiphyseal GP of the bones between 0 and 72 hours of incubation were observed in most of the age groups.Conclusion: Ex vivo growth of tibia and metatarsal bones of rats aged 7‐15 days old is possible, with percentage growth rates of 23.87 ± 0.80% and 40.38 ± 0.95% measured in tibia and metatarsal bone, respectively. Histological sectioning of bones was carried out without the need for decalcification in P7‐P13 tibia and P7‐P15 metatarsal bone. Increases in chondrocyte density along the GP influence overall bone elongation.