Research progress in mechanism of traumatic brain injury affecting speed of fracture healing / 中华创伤杂志(英文版)

In patients who have sustained traumatic brain injury with associated extremity fracture, there is often a clinical perception that the rate of new bone formation around the fracture site increases.(1) An overgrowth of callus is observed and ectopic ossification even occurs in the muscle,(2) but the mechanism remains unclear. Whether this rapidly-formed new bone is fracture callus or a variant of heterotopic ossification, a common complication of traumatic brain injury, is the subject of some debates.(3) It is generally believed that the process of fracture healing is a recapitulation of normal embryonic osteogenesis,(4) i.e. ,a series of changes in the intracellular and extracellular matrix, which start from the injury of cells, blood vessels and bone matrix to a complete reconstruction of the bone.(5) It is a complex process influenced by multi-level and multi-route regulations of the general and local environments in the body, and many growth factors participate in this process, which is the base of bone healing;(6) whatever methods are used to promote bone healing, they are based on accelerating the changes of growth factors.(7) So it is worth making a thorough study on the mechanism, by which traumatic brain injury influences the expression levels of growth factors and consequently affects the speed of bone healing.

A study on the mechanism of traumatic brain injury affecting the speed of bone fracture healing / 中华急诊医学杂志

Objective To evaluate the possible mechanism of traumatic brain injury (TB1) affecting the speed of bone fracture healing.Method TBI combined with unilateral tibial fracture (group A) was used to build multiple injury model and simple unilateral tibial fracture (group B),and the FOS,JUN,bFGF,and VEGF protein expression in different time points between the two groups were compared,and roentgenogram was used for the evaluation of bone healing.Results The expression of FOS,JUN,bFGF,and VEGF protein of the cerebral tissue was low in the normal rats,but was slightly enhanced in group B.There was consistence of development for FOS and JUN expression in the brain tissue in group A,reaching peak at post-TBI 3 hours,and then reducing to control level after 12 hours.The bFGF and VEGF reached peak at post-TBI 12 hours and 24 hours and reduced to control level after 72 hours,respectively.In group A and group B,an increase in the FOS,JUN protein expression around the fracture site was observed at 3 hours after injury,which reached the peak at 6 hours,and reduced to the control level after 24 hours;the comparison between group A,group B and the control group at 3 hours,6 hours and 12 hours had significant difference (P

Sequential changes in biomechanical competence of femoral neck and marrow cavity of proximal femur in ovariectomized rats / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To observe the sequential changes in biomechanical competence of the femoral neck and marrow cavity of the proximal femur in ovariectomized rats.</p><p><b>METHODS</b>Bone mineral density (BMD) and biomechanical properties of the femoral neck and the structural dimension of the proximal femur were measured 0, 3, 6, 9, 12, 15, 18, 21 weeks after ovariectomy (OVX) or sham operation (Sham) in 6-month-old female SD rats.</p><p><b>RESULTS</b>The BMD of femoral neck in OVX rats was significantly lower than that in Sham group 6 weeks after operation, (0.195 +/-0.028) g/mm(2) vs (0.225 +/-0.036) g/mm(2) (P=0.03). Nine weeks after operation,the failure load of femoral neck decreased about 10% in OVX group to that in Sham group, (89.6 +/-7.7)N vs (96.7 +/-7.5)N (P=0.05). The medullary cavity of proximal femur started to show difference 15 weeks after operation (3.834 +/-0.115)mm(2) vs (3.713 +/-0.114) mm(2) (P=0.03).</p><p><b>CONCLUSION</b>BMD loss after ovariectomy is associated with a medullary expansion in proximal femur and biomechanical strength deterioration in femoral neck, which might be an important factor of prostheses loosening in the postmenopausal osteoporotic women.</p>

Osteoporosis influences the middle and late periods of fracture healing in a rat osteoporotic model / 中华创伤杂志(英文版)

<p><b>OBJECTIVE</b>To evaluate the influence of osteoporosis on the middle and late periods of fracture healing process through observing the histomorphological changes, bone mineral density and biomechanical properties in ovariectomized rats.</p><p><b>METHODS</b>Eighty-four female SD rats of 4 months old were randomly divided into osteoporosis group and sham operation group, 42 in each. Rats in osteoporosis group were performed ovariectomy operation while those in sham operation group were given sham operation. A midshaft tibia fracture model was established 10 weeks after ovariectomy. Tibias were harvested 2, 4, 6, 12, 18 weeks after fracture for bone mineral density, histomorphological and biomechanical evaluation.</p><p><b>RESULTS</b>Compared with the sham operation group, callus bone mineral density was 12.8%, 18.0%, 17.0% lower in osteoporosis group 6, 12, 18 weeks after fracture, respectively (P<0.05); callus failure load was 24.3%, 31.5%, 26.6%, 28.8% lower in osteoporosis group, and callus failure stress was 23.9%, 33.6%, 19.1%, 24.9% lower in osteoporosis group 4, 6, 12, 18 weeks after fracture, respectively (P<0.05). In osteoporosis group, endochondral bone formation was delayed, more osteoclast cells could be seen around the trabecula, and the new bone trabecula arranged loosely and irregularly.</p><p><b>CONCLUSIONS</b>Osteoporosis influences the middle and late periods of fracture healing in the rat osteoporotic model. The impairment is considered to be the result of combined effects of prolonged endochondral calcification, high activated osteoclast cell and the deceleration of the increase in bone mineral density.</p>

Role of dual energy X-ray absorptiometry in monitoring fracture healing in a rat femoral fracture model / 中华创伤杂志(英文版)

<p><b>OBJECTIVE</b>To dynamically monitor the bone mineral density (BMD) and the histomorphological changes during fracture healing in a rat femoral fracture model and to explore the role of dual energy X-ray absorptiometry (DEXA) in evaluating bone fracture healing.</p><p><b>METHODS</b>Sixty three-month-old female Sprague Dawley rats were used to establish right femoral fracture models. The BMD of the callus of the fractured right femur were scanned by DEXA at 2, 4, 6, 8, 10 and 12 weeks after operation, respectively. A light microscope was used to evaluate the callus of each rat at the same time. The corresponding segment of the left femur was taken as a control.</p><p><b>RESULTS</b>The BMD at the fractured site increased significantly during the process of fracture healing, which shows an obvious healing trend. The callus BMDs were 29.5%, 48.3%, 85.3%, and 105.2% of the BMD of the control limb at 2, 4, 6 and 8 weeks after fracture, respectively. There was a significantly difference between the groups. A compatibility on time was found between the BMD and the histomorphological characteristics at the fractured site during the process of fracture healing. The fracture healing was almost completed at 8 weeks after fracture as assessed by its histomorphological characteristics when the callus BMD reached to 105.2% of the BMD of the control limb. The BMD of the distal metaphysis decreased until 12 weeks after fracture.</p><p><b>CONCLUSIONS</b>DEXA can evaluate the mineralization of the callus during the fracture healing process accurately and quantitatively and is more sensitive than plain radiography in detecting impaired bone unions, which indicates that it may play an important role in monitoring fracture healing.</p>

Early period of fracture healing in ovariectomized rats / 中华创伤杂志(英文版)

<p><b>OBJECTIVE</b>To evaluate the effect of osteoporosis on fracture healing through observing the histomorphological changes, bone mineral density of callus and expression and distribution of transforming growth factor beta 1 (TGF-beta1), basic fibroblast growth factor (bFGF) and bone morphogenetic protein-2 (BMP-2) in ovariectomized rats.</p><p><b>METHODS</b>Sixty female Sprague-Dawley rats (aged 12 weeks and weighing 235 g on average) were randomly divided into an ovariectomized (OVX) group (n=30) and a sham-operated (SO) group (n=30). Ovariectomy was performed in the OVX rats and same incision was made in the SO rats. Three months later, fracture of femoral shaft was made on all the rats. Then they were killed at different time points. Callus formation was observed with histological and immunohistochemical methods.</p><p><b>RESULTS</b>A reduction in callus and bone mineral density in the healing femur and a decrease of osteoblasts expressing TGF-beta1 near the bone trabecula were observed in the OVX rats 3-4 weeks after fracture. Histomorphological analysis revealed a higher content of soft callus in the OVX rats than that in the SO rats. Immunohistochemistry results showed that no remarkable difference in expression and distribution of BMP-2 and bFGF between the OVX and SO groups was found.</p><p><b>CONCLUSIONS</b>Osteoporosis influences the quantity and quality of callus during the early period of fracture healing. The effect of osteoporosis on fracture healing has no relationship with the expression of BMP-2 or bFGF. The decreased expression of TGF-beta1 in osteoblasts may cause a decrease in quality of fracture healing after osteoporosis.</p>