Experimental Studying The Prevention Of Post-Operative Aseptic Loosening Of The Prosthetic Component With Alendronate

Recently, the study of prevention of aseptic loosening of the component post arthroplasty drew much attention.The present study will focus on studying a feasible strategy to prevention of aseptic loosening.Objective1.To develop a interface bone ingrowth chamber model which simulates the pathological response of periimplant bone to endoprosthesis.By the model,we could study the effects of alendronate on bone-implant osseointegration and periimpl ant bone ingrowth.2.To establish the in vitro osteoclastic culture model to investigate the effects of alendronate on osteoclasts.3.To establish the in vitro osteoblastic culture model to investigate the effects of alendronate on the proliferation of osteoblasts.Materials and methods1.The newly developed IC implants were implanted into bilateral metaphysis of the tibia of 20 New Zealand rabbits to establish the bone ingrowth interface model. The animals were divided into two groups. 10 animals for histological examination, the other 10 animals for biomechanical pushout test. The left side is the experimental side, 10~-7M alendronate normal saline solution was injected into the bone ingrowth interface on the 2,8,15~th day post implantation respectively. The right side is the control side, onlynormaI saline was injected into the bone ingrowth interface in thesame condition. 4 weeks post impIatalion, animaIs were.sacrificed, specimens were prePared for histomorphometry andmechanical push-out test.T test was used to evaluate the effects of,alendronate on bone formation and maximal push-out loading.2. Modified method was used to isolate and cultUre ost6oclasts. Rapups were kilIed by decaPitation, disinfected with 75% alcohol.long bones were asepticaIIy dissected out and split longitudinallyin 2mI DMEM, bone surface was curetted Wth a scaIpel blade.The cell susPension were seeded into culture vessel colltainingcortical bone slice or glass coverslip, then inCUbated in humidifiedincubator. 24-l44 hours latef, glass coversIips undement Giemsaand TraP staining, bone sIices were stained with toluidine blue toreveal resorption pits. Semi-quanitative analysis was made on themorphology and the number of osteoclasts change afteralendronate treatments. Acridine orange method was utilized todetCct aPoptotic osteoclasts.'3. Osteoblast culture system was estabIished from human iliumcancelIous bone. The fourth generation subculture of osteobIastwas seeded into tWo 96-well plates at aPProPriate density Theeffect of alendronate on osteoblast proliferation was measured byMrr AssayResultSl. No abnormality was fOund after IC imPlndion in the metaPhysis,of the tibia of rabbit.4 weeks later, IC imPlant established'osseointegration with the surmunding bone, bone ingroWthedfrom the surrounding tibia into the pores of the outer cylinder, andformed contact with inner chamber wall of IC implan. Cancellousbone fOrmation increased with the passing of time. ComParedwith control grouP, alendronat dramatically increased boneingrOwth (P<0.0l ), and the maximal pushout loading (P<0.0l ).2. By the present methd, multinuclear cells were Obtaned withcharacteristic morphological feature of osteoclast. Themultinuclear cells shOwed TraP positive Stain, which is specificStain of osteocast. The multinuclear cells could resorb bone WhencocultUre with cortical bone slice to fOrm resorption pits, which' could be revealed by toluidine blue staining. 3 l0-loMalendronate reduced osteoclast motilop and cytOplasndc sPreadingarea significantiy (P<0.0l ),$l0-"M alendrOnat6 had no this -effect. l0-7M alendronate, that have been the tyPical dose to treatoSteoporosis clinically, reduced osteoclaSt numbe and the meanarea of the resorption pits on the bone slice (P<0.01 ). Acridineorange molecule could interCaatC in DNA chains, and emitedorange yellow color When excitated with 592nm wavelength ligh,thus, the nuclear morpholOgy could be disPlayed. Alendronateincreased the number of aPopt...