Bone Morphogenetic Protein In The Biological Fixation Of Rabbit Artificial Joints

Objective: As a kind of important osteoinductive agents, bone morphogenetic proteins (BMP) have widely used in clinic trials of orthopedic surgery. But the applicability of these proteins to primary prosthetic replacement is also in the experimental phase. The purpose of this study was to explore the efficacy of BMPs inducing bone ingrowth and the biomechanical results between bone-implant interfaces in a rabbit humeral head prosthesis replacement model, and to evaluate the contribution in noncemented fixation.Methods: To design rabbit humeral head prosthesis, the cast module of humeral medullary cavity were made with the paraffin wax. According to the data measured by cast module, the rabbit humeral head prosthesises which were made of Ti alloy were manufactured by NC machine tool.In the experiment, the 30 New Zealand rabbits were divided into 2 groups at random underwent the humeral head prosthesis replacement surgery. 30mg BMPs (combined with decalcified bone matrix DBM as carrier) was implanted around the joint prosthesis in 15 rabbits as experimental group; the remaining 15 rabbits served as untreated controls. After 4, 8, and 12 weeks, 5 rabbits were sacrificed in each group. Thehumeral of the rabbits with the implants were retrieved. Bone ingrowth and the ultimate shear strength of the interface was studied and analyzed by the means of X-ray, SEM(scanning electr micrograph), none-decalcification bone ground section computer- aided image analysis procedure and biomechanical test(push-out test).Results : The prosthesis is histocompatibility and press-fit with the humeral medullary cavity, which was obey the principle of noncemented fixation.X-ray, SEM, nondecalcification bone ground section and computer-aided image analysis procedure was used in morphology study.4 weeks post-implantation, the tiny gap and fibrous tissue was observed in the interface of the control group, the newly bone was spot contacted with the metal implant. The interface of BMP group was filled with mature bone mechanical locking with the prosthesis. After 8 weeks, raritas bone grows into the gap around the control group implant. At the end of 4-week and 8-week study period, computer-aided image analysis procedure was used in histological study shows that the Osseointegration Rate of the BMP group was ( 67.11±4.84 )% and ( 70 .79±6.56 )% ,which was higher than the control group ( 34.61±5.74 ) % and...