ABSTRACT
Bone mesenchymal stem cell is a kind of multi-potential stem cells and can differentiate into osteoblast. The differentiation has membrane bone formation and enchondral bone formation two channels, and is regulated by numerous signal transduction pathways. According to related literatures, we review the signal transduction pathways of BMP/Smads, Runx2/osterix, Hedgehog, Wnt/β-Catenin and MAPK.
ABSTRACT
Biomechanical test in vitro was performed to study the biomechanical characteristics of the femoral component in the non-stemmed anatomical total hip prosthesis (A-Fix) arthroplasty. It mimics two stages, the early stage with cementless and the later stage with cement fixation that imitates bone ingrowth. The results were compared with that of normal proximal femur by normalized coefficient analysis. Translation of femoral head after hip replacement is slightly more than normal. The strain of femoral neck after replacement is lower than that of normal. It changes flatly. The security coefficient in early stage is raised by 13% on the tensile side and by 27.6% on the compressive side of femoral neck; that in later stage is raised by 29.6% and by 22.1% separately. The maximal torsional angle of femoral head is minimal, it is 0.02 times that of normal in early stage and 0.01 times in later stage. It demonstrated that A-Fix arthroplasty has the characteristics of low stress and deformation, high intensity and rigidity, and anti-loosening, thus affording mechanical evidences for its clinical use.
Subject(s)
Adult , Humans , Male , Arthroplasty, Replacement, Hip , Methods , Biomechanical Phenomena , Cementation , Methods , Hip Prosthesis , Prosthesis Design , MethodsABSTRACT
Objective To evaluate the effects of the synthetic osteogenic growth peptide (sOGP) on the healing of tibial fractures in rabbits. Methods Fifty two tibial fracture models were produced in the tibiae of New Zealand white rabbits and immobilized with a 2 mm diameter Kirschner wire as intramedullary nail and grouped by random. sOGP was administered to experimental animals by intravenous injection (0.5 ?g?kg-1 ?d-1) from the first day after surgery until the day before sacrifice, while the control animals were injected with saline solution. 3-5 rabbits from each group were killed at 1, 2, 3, 4, 6 weeks after fracture. The serum was obtained to determine the level of ALP and BGP by biochemistry and RIA respectively. The bone mineral density at fracture healing site was detected by DXA, the anteroposterior and lateral radiographs were taken, the histological examination was done and quantitative analysis of the callus area and the relative amounts of bone, cartilage, and fibrous tissue in the callus of each section were calculated by computer program. The 6 weeks tibial sample were tested biomechanically by universal material test machine. Results The serum ALP, BGP level were higher in sOGP injected groups than those in the controls. All tibia osteotomies healed uneventfully on radiograph. The area of the external callus was larger in the experimental groups than that in controls at 3,4 weeks after fracture; the average area was 265.44 mm2 at 3 weeks, 233.10 mm2 at 4 weeks in the experimental groups compared with that of 209.95 mm2 at 3 weeks and 209.21 mm2 at 4 weeks in the controls. The average bone mineral density at fracture healing site was slightly greater in the experimental group at 3,4,6 weeks, and the difference of the bone mineral density at 4 weeks has statistical significance (P