In vivo effectiveness of polymer hydrogels impregnated with an antibacterial drug in chronic osteomyelitis

Introduction Polymethyl methacrylate (PMMA) is a common depot system in the treatment of chronic osteomyelitis. However, a lot of its shortcomings do not allow us to consider it ideal.Purpose of the work was to study in vivo the effectiveness of a polymer hydrogel containing an antibiotic for chronic osteomyelitis of the tibia in a rabbit model and compare it with PMMA.Materials and methods The study was performed on the lower leg of 25 mature Chinchilla rabbits. A model of chronic osteomyelitis of the tibia was created. A methicillin-sensitive strain of Staphylococcus aureus (MSSA), highly active against cefazolin, was chosen as an infectious agent. Surgical debridement started 21 days after the clinical, laboratory, radiological and microbiological confirmation of the diagnosis, the technique for all animals was the same. The experimental group (n = 11) was treated by implantation of a polymer hydrogel, the comparison group (n = 11) with PMMA, and the control group (n = 3) had no implanted substance. In the postoperative period, monitoring of the local status, weight and body temperature of the animals, microbiological and radiological studies were carried out. Animals were taken out of the experiment by stages. Biopsies were sent for bacteriological and histomorphometric studies. Statistical comparison of the groups was performed using the Mann - Whitney, Kruskell - Wallis and Tukey criteria, descriptive statistics were used for the control group.Results In the experimental group, in all cases, postoperative wounds healed in a timely manner, the levels of WBC and CRP significantly (p = 0.040) decreased from 14 and 21 days, respectively. Microbiologically, the growth of microflora from the wound discharge and biopsy specimens was not detected; radiographic progression of chronic osteomyelitis was not observed; histomorphometry revealed a significant (p = 0.002) effective relief of the inflammatory process. In the comparison group, systemic antibiotic therapy was required from postoperative day 7. Levels of inflammatory markers decreased less effectively than in the experimental group. MSSA was verified from wound discharge and biopsy specimens at almost every follow-up time-point. X-rays and histomorphometry (p = 0.001), on average, detected exacerbation of osteomyelitis. In the control group, systemic therapy did not give positive dynamics.Discussion A comparative analysis showed that the hydrogel impregnated with an antibacterial agent, unlike PMMA, reliably arrests chronic osteomyelitis without auxiliary systemic antibiotic therapy and does not cause material-associated bone resorption. The clinical and laboratory picture is fully consistent with the data of microbiology, radiology and histomorphometry.Conclusion Hydrogel impregnated with an antibiotic reliably and effectively stops chronic osteomyelitis compared to PMMA.