BACKGROUND:Conventjonally,the osteoinduction of bone substitute materials is detected in vivo,which is unsatisfactory regarding the reliability,chronergy and precision,especially for a large amount of substitute materials.OBJECTIVE:To search an in vitro assay for determining in vitro osteogenic activities of bone graft substitutes.DESIGN:Controlled cytological trials.TIME AND SETTING:The experiments were carried out in the Institute of Orthopaedics.Chinese PLA General Hospital(Beijing,China)from August 2006 to May 2007.MATERIALS:C2C 12 cells was offered by the Cell Center of Peking Union Medical College;Human decalcified bone matrix and bone protein were offered by the Institute of Orthopaedics in Chinese PLA General Hospital;Type Ⅰ collagen extracted from bovine tendon was purchased from Beijing Yierkang Bioengineering Development Center;Recombinant human bone morphogenetic protein 2 was purchased from Hangzhou Gene Technology of Huadong Medicine Group.METHODS:By means of dialysis,a composite material was prepared with the bone protein extracted from human,human decalcified bone matrix and type Ⅰ collagen of bovine tendon.The samples of decalcified bone matrix.composite material and recombinant human bone morphogenetic protein 2 were respectively co-incubated with C2C12cells for 72 hours.Negative control group comprised pure cells without materials.Then C2C 1 2 cells were lysed and the lysate were assayed for the absorbance of alkaline phosphatase(ALP)and total protein by chromatometry.ALP is (the specific mark of osteoblastic phenotype.The relative ratio of absorbance value between ALP and total protein could represent ALP activity in the unit quantitative C2C12 cells.MAIN OUTCOME MEASURES:The ratio of absorbance value between ALP and total protein.RESULTS:The ALP activity was the highest in the recombinant human bone morphogenetic protein 2 group,then in the decalcified bone matrix group and composite material group,and the lowest in the negative control group.There were significant differences in the ALP activity between the three trial groups and the negative control group(P＜0.05).CONCLUSION:The assay in vitro is effective to detect the ALP activity and it can be used to determine the osteoinduction of bone graft substitutes.

BACKGROUND:Nowadays,the internal fixation materials for the clinical treatment of femoral intertrochanteric fractures are broadly divided into two categories: intramedulary fixation system and extramedulary fixation system.Artificial femoral head replacement can be selected for unstable intertrochanteric fractures.However,the effects of diverse treatments usualy lack of macroscopical evaluation.OBJECTIVE:To investigate and compare the clinical effects of different surgical treatments for femoral intertrochanteric fractures in the elderly.METHODS:168 elderly patients with intertrochanteric fractures,who were treated in the Department of Orthopedics,Beijing Municipal Corps Hospital of Chinese People's Armed Police Forces from June 2005 to June 2010,were enroled in this study.They were treated by screw plate fixation system (dynamic hip screw,dynamic condylar screw),intramedulary fixation system (Gamma 3 nail,expandable intramedulary nail) and artificial femoral head replacement,including 69 males and 99 females,at the age of 75-94 years,averagely 81.4 years.According to Evans type,there were 20 cases of type Ⅰ,43 cases of type Ⅱ,57 cases of type Ⅲ,33 cases of typeⅣ and 15 cases of type Ⅴ.Operative time,blood loss,weight-bearing ambulation time,and hip function were compared and evaluated in patients of each group.RESULTS AND CONCLUSION:After treatment,patients were folowed up for 14-39 months.At 12 months after treatment,Harris score was used to assess hip function in the affected side.Fracture was healed within 12 months.There was no significant difference in excelent and good rate among four groups (P＞0.05).Operative time and blood loss were significantly better in the expandable intramedulary nail group than in the other groups (P＜ 0.05).Weight-bearing ambulation time was significantly better in the artificial femoral head group than in the other groups (P＜ 0.01).Results suggest that according to fracture typing,in combination with osteoporosis in elderly patients,suitable repair method could improve therapeutic effects for femoral intertrochanteric fractures,and reduce postoperative complications.Dynamic hip screw is firstly selected for Evens types Ⅰ and Ⅱ stable intertrochanteric fractures.The intramedulary fixation system can be selected for unstable intertrochanteric fractures as Evans types Ⅲ-Ⅴ.Artificial hip arthroplasty is good for elderly patients with unstable intertrochanteric fractures as wel as severe osteoporosis.