The advantages of a synthetic bone-graft substitute include reduction of risks due to immunological rejection and transmission of diseases, such as AIDS. A satisfactory synthetic material must be non-toxic, allow adequate re-vascularization, and be capable of bearing weight and tolerating strain. Our experiments using a resorpable, zinccalcium- phosphorous-ceramic oxide (ZCAP) in composite with malic acid, vitamin E, and gentamicin sulfate, indicate that this zincbased bioceramic implant fulfills the requirements of an osteoconductive filler between two fractured ends of rat femurs.Assessment of the suitability of ZCAP involved the following techniques :
1) Radiological examination showing the position of the implant, bridging of the defect with bone, and dissolution of the bioceramic.
2) Histology of serial sections indicating resorption of the ZCAP (a few granules remain after 10 weeks) and replacement by endochondral ossification.
3) Scanning electron microscopy revealing that the intact ZCAP first becomes surrounded by fibrous tissue and then infiltrated by cell processes.
A b s t r a c t -T h e o b j e c t i v e o f t h i s investigation was to develop a resorbable zinc calcium phosphorous ceramic oxide (ZCAP)-organic acid-vitamin E composite containing an antibiotic for orthopedic and/or dental application, including nearly all cases of trauma of hard tissues. A composite consisting of 3.0 g ZCAP, 1.2 g malic acid, 0.6 g Ca(OH),, 9.6 mg gentamicin sulfate and 20 pl of Vitamin E oil was compressed in a 5/16" die into 0.1 g pellets at a load of 2000 lbs in a hydraulic press. Right femur of experimental animals was accessed by routine surgical procedures. A mid-diaphyseal fracturc: was created under direct vision using a surgical bone saw. A 0.62 threaded K-wire was inserted into the intramedullary canal and retrograded through the knee using a drill.The implant was placed between the two ends of the fracture and the Rwire antegraded through the pellet into the proximal end of the femur and tested to assure good fixation. The K-wire protruding from the bone was cut flush with the end of the bone using wire cutters. The surgical site was closed using routine surgical proceduresPost surgery, each rat showed normal movement during the ten week experimental period. Gross morphological examination of euthanized animals showed filling of the defect. Radiographic examination of the bones showed resorption of the composite, evidence of bone healing and cancellous bone ingrowth. However, the new bone ingrowth appeared less dense than the cortical bane on either side of the defect. The data collected to date suggest that ZCAP composites can be used as osteoconductive fillers between two fractured ends of a bone.
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