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Background: Self-reinforced absorbable implants have been developed recently to use in hard tissue reconstructive surgery. Polyglycolide is a biocompatible polymer from which the suture Dexon is made and widely used., Aims: To study histologically the behaviour of self-reinforced polyglycolide membrane (SR-PGA) in rabbits' ears., Material and Methods: SR-PGA membranes, 0.4 mm thick, were implanted in the subcutis of the ears of 24 New Zealand white rabbits. Sham operations were carried out on the contralateral ear of each rabbit. The rabbits were followed-up for 4, 12 and 20 weeks. Attention was directed towards external macroscopic changes in the rabbits' ears. After sacrifice, the ears were taken as specimens, inspected for any evidence of infection, sinus formation or fluid accumulation and histological examination was carried out., Results: No complications such as infection, fluid accumulation or sinus formation were observed. Histologically, the membranes induced a foreign-body reaction involving fibrous tissue encapsulation, macrophages and giant cells. Fibrous tissue and inflammatory cells were seen between the PGA fibres. The membranes underwent progressive degradation throughout the follow-up period. However, PGA material could be still seen 20 weeks postoperatively, with a small amount of fibrous tissue and macrophages and giant cells. The implant-cartilage interface comprised fibrous and fatty tissue., Conclusions: SR-PGA membranes are biocompatible when implanted in the subcutis of the ears of rabbits.

Background and Aims: To investigate the healing of sternotomies fixed with biodegradable self-reinforced poly-L-lactide (SR-PLLA) wire and comparing it with steel wire fixation., Material and Methods: Sixteen rabbits (15 Chinchilla and one New Zealand White rabbit) were operated on. Two parallel holes of 1.5 mm in diameter were drilled in the sternum at the level of the second and third rib and similar holes of 0.8 mm were drilled at the level of the third and fourth rib. A transverse sternotomy was created between both drill hole pairs. The sternotomy with larger drill holes was fixed with 1.1-mm thick SR-PLLA wire. The sternotomy between the smaller drill holes was fixed using 2.0 steel wire. The animals were sacrificed at 2, 7, 26 and 52 weeks postoperatively and specimens were taken, radiographed and studied by both light and scanning electron microscopy., Results: One rabbit died at four months postoperatively as a result of gastrointestinal problems. No other complications were seen. The SR-PLLA wire was slowly degraded. There was no disturbance of bone healing. The implants were surrounded by a fibrous tissue capsule, which also contained chronic inflammatory cells. Both SR-PLLA and steel wires provided sufficient fixation security. No differences in the healing of the sternotomies were observed between SR-PLLA and steel wire fixation., Conclusions: SR-PLLA wires are biocompatible and useful for sternotomy fixation. They may be suitable for use in clinical applications.

Background: Poly(L-lactide/epsilon-caprolactone) [P(L-LA/epsilon-CL)] 50/50 membranes is an absorbable membrane which has been developed recently for possible use in tissue engineering., Aims: To look at histological tissue reactions to the membrane and its behaviour upon its in vivo implantation in rats., Material and Methods: P(L-LA/e-CL) 50/50 membranes, 0.4 mm thick, were implanted subcutaneously in the dorsal neck of 20 Wistar rats. The rats were followed-up for 1, 3, 6, 12 and 28 months. After sacrifice, subcutaneous tissues with implants were taken as specimens, inspected for any gross abnormality and histological examination was carried out., Results: No significant macroscopic changes were noticed except for two implants that were grossly rounded. Histologically, the membranes had undergone cracking, fragmentation and progressive degradation. Cracks appeared initially at the periphery of the implant. Large cracks progressed mainly in longitudinal planes. Cracks occurred in the middle of implants and led to membrane bending in some cases. "Neomembrane" formation, comprised of fibrous tissue and the implant, was seen. The foreign-body reaction to the membrane involved macrophages and foreign-body giant cells. In one case an acute type of polymorphonuclear cell reaction was observed and in a second case a predominantly lymphocytic reaction was seen at three months. They were thought to be the results of infection. No other adverse effects were seen., Conclusions: P(L-LA/e-CL) 50/50 membrane was found to be biocompatible when implanted subcutaneously in rats. It was degraded to a great extent but not completely in 28 months.