Experimental Study Of The Does-effect Relations And Prevention Measures On The Osteolysis Around Imitative Prosthesis Resulted From Wear Particles

Objective: To explore does-effect relations between the level of polyethylene particles in the articular cavity and the osteolysis around imitative prostheses after the prosthesis implantation; to examine the existence of saturated concentration; to find a minimally invasive and creative method to effectively prevent and delay the osteolysis and loosening of the imitative prostheses after prosthesis implantation; and to open a therapy approach to improve the long-term effect of prosthesis and prolong its service life.Method: on the first stage, choosing 30 healthy male adult New Zealand rabbits, with the body weight ranging from 2 to 2.5kg; dividing these rabbits into three groups at random, (every group 10 rabbits), then again dividing the three groups into six subgroups from both sides of the knee joints: A_left, A_right, B_left, B_right, C_left, C_right(every subgroup ten knee joints). After intravenous anesthesia for these rabbits by pentobarbital sodium, cutting the inside of anterior knee joints of both sides into the knee joints respectively; drilling a tunnel with the diameter of 3mm drill bit from femoral intercondylar along the axis of the femoral shaft (with the depth of 1.5cm); implanting the diameter of 3mm and the length of 15mm titanium alloy bar (imitative prostheses)into the bone tunnel of the femoral intercondylar and the suture of joint of capsule. Injecting 0.5ml germ free experimental liquid into the knee articular cavity of every group from the both sides at 2^nd, 4^th, 6^th, 8^th, 10^th, and 12^th postoperative weeks, among them, injecting normal saline into the A_left group, and injecting 0.5ml polyethylene wear particles with different concentrations(fromlx10⁸-1×10¹² /ml ). Killing these animals fourteen weeks later, and distal ends of the femur were taken for the examination of the situation of the osteolysis around the imitative prostheses. On the second stage, according to the method adopted by the first stage, implanting twenty titanium alloy bars (imitative prostheses) into the both sides of the distal femur of ten adult New Zealand rabbits; injecting 0.5ml polyethylene wear particles with the concentration of (1×10¹⁰个h/ml) into the knee articular cavity of both sides at the 2^nd, 4^th, 6^th, 8^th, 10^th, 12^th postoperative weeks; injecting normal saline into the left knee joints of the model animals of the group to wash them at the 3^rd, 5^th, 7^th, 9^th, 11^th, 13^th postoperative weeks, and using polarizing microscope to examine whether there is some polyethylene wear articles in the lavage fluid; fourteen weeks later, killing the animals and taking the distal ends of the femur to examine the situation of bone osteolysis around the imitative prosthesis; explore prevention functions of the joint lavage.Result: (1) The interfacial tissues around the imitative prostheses of the group A_left is a layer of compact collagenous tissue, and no osteolysis is found. The interfacial tissues around the imitative prostheses of from group A_right to C_right are a layer of foreign body reactive granulation tissue, and different degrees of osteolysis are found in the interfacial tissues around the imitative prostheses. From group A_left to C_right, with the increasing of the concentration of the wear particles, the amount of macrophages and osteoclast in the interfacial tissues also increase (P< 0.01) ; From group A_left to C_right. with the increasing of concentration of the polyethylene particles, the biggest dissolution width and the area of the dissolved bone around the imitative prostheses increase, among them, the differences between the group A_right and group B_left have no statistical meanings (P>0.05) , the differences among the group B_left, B_right, C_left, C_right have statistical meanings (P<0.05 ); from group A_left to C_right, with the increasing of concentration of wear particles, the content of TNF-a and IL-1 also increase, among them, the differences between group A_right and group B_left have no statistica(?) meanings (P>0.05) , the differences among the group B_left, B_right, C_left , C_right have statistical meanings (P< 0.05); (2) after joint lavage, there is polyethylene wear particles in the lavage fluid, and the amount of the macrophages, the biggest dissolution width, the area of dissolved bone, and the content of TNF-a and the IL-1 are obviously lower than the right side (P<0.01) .Conclusion: (1) there is croissant does-effect relation between the wear particles and osteolysis around the imitative prosthesis, but there is no saturated concentration; (2) joint lavage can effectively reduce the loosening of the prostheses of the bone-ostelysis animal models around the imitative prosthesis.