Tissue Restoration After Implantation of Polyglycolide, Polydioxanone, Polylevolactide, and Metallic Pins in Cortical Bone: An Experimental Study in Rabbits

Abstract

We performed qualitative and histoquantitative investigations of tissue restoration after implanting polyglycolide (PGA), polydioxanone (PDS), polylevolactide (PLLA), and stainless steel pins in the intramedullary canal of rabbit femurs. The effect of bioabsorbable devices on healing of a cortical bone defect was also assessed. The cortical bone defect was created in the right femur of 80 rabbits. Bioabsorbable and metallic pins in 60 and two metallic pins alone were implanted in 20 intramedullary canals; 80 left femurs served as intact controls. Follow-up times were 3, 6, 12, 24, and 52 weeks. At all time points, collagenous connective tissue, including bone trabeculae, surrounded the implant at the tissue–implant interface, replacing hematopoiesis and fat of the intramedullary canal. The groups did not differ in the area and trabecular bone area fraction of the resulting callus. Residual fragments of PGA and PDS were observed at 24 weeks, and complete degradation occurred within 52 weeks. PGA, PDS, PLLA, and metallic implants induced a bony and fibrous walling-off response in the intramedullary cavity. No inflammation was observed. Complete tissue restoration did not occur within the follow-up, even after complete degradation of PGA and PDS, which had shorter degradation times than PLLA. The cortical bone healing effect was not different between bioabsorbable pins and metallic wires. Thus, these polymers had no specific osteostimulatory or osteoinhibitory properties compared to stainless steel. Within the follow-up period, there were no significant differences in biocompatibility between the implants and no adverse inflammatory foreign-body reactions.

In vivo evaluation of a magnesium-based degradable intramedullary nailing system in a sheep model

“…In both groups no complete restoration of the bone marrow was observed. This may have been caused by the formation of large gas bubbles in the LAE442 alloy group and the prominent fibrous tissue capsule and the bone ingrowth into the bone marrow cavity in the steel group, respectively, as it was also observed by Pihlajamäki et al [100]. In addition to the direct tissue reactions, systemic reactions to degradation products always have to be taken into account.…”

Short-Term and Long-Term Effects of Orthopedic Biodegradable Implants

“…Ultimately, there have been a series of documented long-term effects of biodegradable implants, but the principal finding in many studies is that there are limited or unsignificant associated long-term effects with biodegradable implants. 16,70–74 …”

“…For example, in a rabbit study comparing the performance of PLA and PGA screws to metallic screws, the polyester screws were shown to be inert with no significant difference in long-term biocompatibility. 16 In another study comparing the tissue response to PGA, polydioxanone (PDA), polylevolactide, and stainless steel pins, scientists determined that all exhibit non-specific walling-off in cancellous bone of distal rabbit femurs (Fig. 6).…”

Biodegradable polymers for dental tissue engineering and regeneration

“…However, recent papers reported the utilization of PGA as filler material coupled with other degradable polymer networks. Examples are the degradable suture DEXON ® [83], the internal bone pin Biofix ® [84], many published works in which PGA is used as a scaffold for bone [85][86][87], cartilage [88,89], tendon [90], vaginal [91], intestinal [92], lymphatic [93], and spinal [94] regeneration. In dentistry, Ohara et al evaluated the in vivo regeneration of porcine tooth germ-derived cells implanted in polyglycolic acid fiber and β-tricalcium phosphate porous block scaffolds for the formation of tooth bud-like structures [95].…”