AN IMMUNOCYTOCHEMICAL STUDY OF BONE MORPHOGENETIC PROTEIN IN EXPERIMENTAL FRACTURE HEALING OF THE RABBIT MANDIBLE

A monoclonal antibody raised against bone morphogenetic protein (BMP-McAb) has been used to demonstrate the presence of bone morphogenetic protein(BMP) in experimental fracture healing. Rabbit mandibles were fractured using standardized methods and left to heal for 3, 7, 14, 21 and 24 d, respectively. The avidin-biotin complex (ABC) method demonstrated an accumulation of positively stained primitive mesenchymal cells at the fracture site in the hematoma stage of bone repair. These cells appeared to undergo differentiation into positively-stained chondroblasts and osteoblasts during the phase of callus formation. Undifferentiated mesenchymal cells showed a high positive reactivity in the early post-fracture stages but a much lower reactivity during the remodelling phase.The results of our study suggest that bone inductive processes are accompanied by the presence of BMP in osteoprogenitor cells during fracture healing of the mandible and that BMP may play a significant role in osteogenesis during bone healing.

Bone Injury and Fracture Healing Biology

Bones are organs of the skeletal system, providing shape, mechanical support, and protection to the body and facilitating the movement. In addition, bones contribute to the mineral homeostasis of the body and have recently been found to participate in endocrine regulation of energy metabolism. The well-known limitations associated with clinical use of autografts and allografts continue to drive efforts to develop bone graft substitutes, using the principles of biomaterials and tissue engineering. Under some stressful and continuous compressive conditions, the ability of the bone tissue to tolerate strength decreases. Whenever these forces overcome the toleration of the bone tissue, bone fracture occurs. years

Biodegradable Zn-2Cu-0.5Zr alloy promotes the bone repair of senile osteoporotic fractures via the immune-modulation of macrophages

Delayed bone-healing of senile osteoporotic fractures remains a clinical challenge due to the alterations caused by aging in bone and immune systems.The novel biomaterials that address the deficiencies in both skeletal cells and immune systems are required to effectively treat the bone injuries of older patients.Zinc(Zn)has shown promise as a biodegradable material for use in orthopedic implants.To address the bone-healing deficiencies in elderly patients with bone injuries,we developed a biodegradable Zn-based alloy(Zn-2Cu-0.5Zr)with enhanced mechanical properties,including a yield strength of 198.7 MPa and ultimate tensile strength of 217.6 MPa,surpassing those of pure Zn and Zn-2Cu alloys.Cytotoxicity tests conducted on bone marrow mesenchymal stem cells(BMSCs)and MC3T3-E1 cells demonstrated that the extracts from Zn-2Cu-0.5Zr alloy exhibited no observable cytotoxic effects.Furthermore,the extracts of Zn-2Cu-0.5Zr alloy exhibited significant anti-inflammatory effects through regulation of inflammation-related cytokine production and modulation of macrophage polarization.The improved immune-osteo microenvironment subsequently contributed to osteogenic differentiation of BMSCs.The potential therapeutic application of Zn-2Cu-0.5Zr in senile osteoporotic fracture was tested using a rat model of age-related osteoporosis.The Zn-2Cu-0.5Zr alloy met the requirements for load-bearing applications and accelerated the healing process in a tibial fracture in aged rats.The imaging and histological analyses showed that it could accelerate the bone-repair process and promote the fracture healing in senile osteoporotic rats.These findings suggest that the novel Zn-2Cu-0.5Zr alloy holds potential for influencing the immunomodulatory function of macrophages and facilitating bone repair in elderly individuals with osteoporosis.

Waders(Scolopacidae)surviving despite malaligned leg fractures in the wild:kinematics of bipedal locomotion

Background: Bone fracture frequencies and survival rates are essential parameters in skeleton evolution, but information on the functional consequences of naturally healed fractures is scarce. No leg bone fracture healing in the wild has been reported so far from long-legged Charadriiformes(waders), which depend on bipedal locomotion for feeding.Methods: We documented a healed but malaligned tarsometatarsus fracture in a wild Willet(Tringa [Catoptrophorus]semipalmata), and a malaligned tibiotarsus fracture in a Curlew(Numenius arquata) skeleton from a museum collection. Functional consequences of the malalignments were evaluated by kinematic analyses of videos(Willet) and in silico 3D modeling(Curlew).Results: The Willet's left tarsometatarsus exhibited an angular malalignment of 70°, resulting in a limping gait that was less pronounced at high than at low walking speed. The bird seemed unable to club the toes of the left foot together, apparently a secondary effect of the deformity. The Curlew's tibiotarsus showed an angular and an axial malalignment, causing the foot to rotate outwards when the intertarsal joint was flexed. Despite the severe effects of their injuries, the birds had survived at least long enough for the fractures to heal completely.Conclusions: Somewhat unexpectedly, leg fractures are not necessarily fatal in long-legged waders, even if deformities occur in the healing process. Bipedal locomotion on vegetated grounds must have been impeded due to the bone malalignments in both analyzed cases. The birds probably alleviated the impact of their handicaps by shifting a larger proportion of their activities to vegetation-free habitats.

Rotary self-locking intramedullary nail for long tubular bone fractures

Background Intramedullary nails had been widely used in the treatment of long-bone fractures because of less interference of fractures and center bearing biomechanical advantage. However, it had been also found many shortcomings such as broken nails, delayed healing and was modified in order to achieve better efficacy and reduce complications. The aim of the present study is to compare the efficacy of rotary self-locking intramedullary nails （RSIN） with that of interlocking intramedullary nails （IIN） in the treatment of long-bone fractures.