Comparison of biocompatibility and biodegradability of poly-lactic-co-glycolic acid (PLGA) combined with fibrin versus PLGA for intra-articular fixation : an in-vivo study with New Zealand white rabbits

Abstract

For the past twenty to thirty years, biodegradable devices have widely been utilized and tested in many fields of orthopaedics, including fracture fixation, cartilage and meniscus repair, drug delivery and ligaments anchorage. However, the biodegradation profile of these polymers remain unexplored especially when it comes to optimum resorption rate and host tissue restoration. New Zealand White Rabbit(NZWR) is an acceptable experimental model to study the aforementioned features as it can mimic the process in human. The objectives of this study are to observe biocompatibility of PLGA polymer with and without fibrin for fixation of defect in distal femur of NZWR together with evaluation of local reaction, macroscopic features, micro-CT scan parameters and histology assessment. The PLGA polymers, with and without fibrin, were implanted in distal femur of NZWR. Assessment done at different time frames, namely 6, 12 and 24 weeks to evaluate the objectives above and subsequently to obtain the biodegradability and biocompatibility profile. Statistical analysis done with SPSS using Wilcoxon Signed-Rank Test. There was no local reaction or any abnormality noted on gross inspection of the samples. The micro-CT scan examination revealed that mean scores at 6,12, and 24 weeks for the bone surface/volume ratio(Bs/Bv), trabecular thickness (Tb.Th), trabecular number (Tb.N) and bone surface density (BSD) were more in the PLGA(ƒ) group. The median for all the parameters above were also significantly increased in the PLGA(ƒ) group with p<0.05, except for the BSD which recorded p = 0.075. Histology analysis was done by description of the longitudinal section of the distal femur and graded by modified histological scoring. The scores were higher in the PLGA(ƒ) group, recording 4,7 and 9 compared to scores of 2,5 and 5 in the PLGA group at 6,12 and 24 weeks respectively. The median for new bone formation was significantly increased in PLGA(ƒ) group with p = 0.035. However, the median for resorption of material and marrow changes were not significantly different between the two groups, recording p = 0.655 and p = 0.107 respectively. As a conclusion, the combination of PLGA and fibrin has a better outcome compared to PLGA for intra-articular fixation generally and distal femur specifically.