Study On Bone Growth Promoting Behavior At The Interface Between Hydroxyapatite Coating And Bone Under Fretting Stimulation

Cementless joint replacement surgery can avoid bone cement implantation syndromes such as the toxicity of bone cement monomer and the aseptic loosening of bone cement abrasive particles,and has gradually become the first choice for joint replacement.Because cementless joint replacement requires a long recovery time after surgery,and the short-term stability of the fixed interface after surgery is low,its development is greatly restricted.Based on the physiological behavior of increasing the volume and density of bone in a mechanical environment,the surface of the cementless artificial joint prosthesis material is coated with a hydroxyapatite coating.Study the application of fretting-manipulation between the bone tissue and the cementless fixation interface of the artificial joint prosthesis to promote the growth of the bone tissue,which accelerates the combination of the bone tissue and the cementless fixation interface of the artificial joint prosthesis,and shortens the recovery time after artificial joint replacement,prolonging the life of artificial joint prosthesis has important research significance.Based on 3D model reconstruction and finite element analysis,this paper studies the fretting,stress distribution and stress and strain changes of the bone tissue under different mechanical stimulation parameters.The maximum fretting amplitude of the interface between the femur and the artificial prosthesis is about 50 ?m,and the stress range is 20?50 MPa,which provides a basis for evaluating the fretting stimulation parameters of bone growth at the fixed interface.Taking rat bone tissue and titanium-based hydroxyapatite coating as the research object,the biocompatibility and bone growth mechanism at the interface of the hydroxyapatite coating are analyzed.The results show that the surface of the hydroxyapatite coating is easier for cells to adhere and grow on it,which is more conducive to cell survival.The bone growth experiment of rat bone tissue and titaniumbased hydroxyapatite coating was carried out by alternating compression fretting stimulation and alternating tangential fretting stimulation,to study the influence of culture period,different compressive loads,tangential fretting amplitude and normal load on the growth rate of bone tissue and the stable quality of the bonding interface.The experiment of alternating compression fretting stimulation of rat bone tissue in vitro showed that the binding force of the bone tissue and hydroxyapatite interface measured under the stimulation of 4N compression fretting for 15 days was the largest.That the bone tissue integrity under the stimulation was the highest,the trabecular bone structure was evenly distributed and tightly connected,and the trabecular bone separation was the lowest.There are more osteocytes in bone tissue,and osteoblasts synthesize and secrete more bone glue fibers and organic bone matrix,indicating that the trend of bone growth is more obvious.That is,4N compression fretting stimulation has a certain promoting effect on the growth of bone tissue and the stable quality of the bonding interface.The alternating tangential fretting experiment of rat bone tissue in vitro shows that the binding force of the bone tissue and the hydroxyapatite interface measured under5N/±40?m tangential fretting stimulation is the largest.It can be concluded that the trabecular bone under the stimulation of fretting is evenly arranged,the structure is complete and the connection is tight,there is basically no cavity inside the bone trabecula,and its separation is low,and the bone The total area of the beam is large.The more osteocytes and osteoblasts on the bone tissue,and the more collagen fibers at the interface between bone tissue and hydroxyapatite,the more obvious the tendency of bone growth.That is to say,this condition has a certain promoting effect on the growth of bone tissue and the stable quality of the bonding interface.