Are Absorbable Plates More Resistant to Infection Than Titanium Implants? An Experimental Pre-Clinical Trial in Rabbits

• Published in: Journal of functional biomaterials Vol. 14; no. 10; p. 498
• Main Authors: Kitridis, Dimitrios, Savvidis, Panagiotis, Cheva, Angeliki, Papalois, Apostolos, Givissis, Panagiotis, Chalidis, Byron
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.10.2023; MDPI
• Subjects: absorbable implants; Animals; Antibiotics; Bacteria; Biofilms; Blood cell count; Bone implants; Bone remodeling; C-reactive protein; Clinical trials; Comparative analysis; Condition monitoring; Copolymers; Disease susceptibility; Erythrocyte sedimentation rate; Femur; Fractures; Health aspects; Housing conditions; Infection; Infections; Inoculation; Leukocytes; Metal plates; Monomers; Orthopaedic implants; Orthopedics; Periosteum; PLLA; Polylactic acid; Postoperative infection; Rabbits; Sclerosis; Screws; Stainless steel; Statistical analysis; Surgical implants; Titanium; Transplants & implants; Greece; New Zealand
• ISSN: 2079-4983; 2079-4983
• DOI: 10.3390/jfb14100498

Background: Infection of orthopaedic implants after internal fixation of bone fractures remains a major complication with occasionally devastating consequences. Recent studies have reported that the use of absorbable materials, instead of metallic ones, may lead to a lower incidence of postoperative infection. In this experimental pre-clinical animal study, we compared the infection rate between absorbable implants consisting of copolymers composed from trimethylene carbonate, L-polylactic acid, and D, L-polylactic acid monomers, and titanium implants after the inoculation of a pathogenic microorganism. Material and Methods: We used an experimental implant-related infection model in rabbits. Sixty animals were randomly and equally divided into two groups. In all animals, the right femur was exposed via a lateral approach and a 2.5 mm two-hole titanium plate with screws (Group A), or a two-hole absorbable plate and screws (Group B), were applied in the femoral shaft. Afterwards, the implant surface was inoculated with Pseudomonas Aeruginosa at a concentration of 2 × 108 CFU/mL. The primary outcome was the comparison of the incidence of developed infection between the two groups. The wound condition was monitored on a daily basis and radiographies were obtained at 12 weeks postoperatively. Infection-related laboratory markers (white blood cell count, erythrocyte sedimentation rate, and C-reactive protein values) were assessed at 3, 6, and 16 weeks postoperatively. Histologic analysis and cultures of tissue samples were also performed to evaluate the presence of infection. Results: Clinical and laboratory signs of infection were evident in 11 rabbits in Group A (36.7%), and 4 in Group B (13.3%). The difference between the groups was statistically significant (p = 0.04). Five animals in Group B (16.7%) had clinical and histologic signs of a foreign-body reaction with significantly elevated CRP and ESR values but no simultaneous presence of infection was identified (p = 0.04). Bone remodelling with thickening of the periosteum and surrounding sclerosis was demonstrated radiologically in animals developing infection or foreign-body reactions. Conclusions: Absorbable plates and screws show lower susceptibility to infection compared to titanium ones. However, their application is associated with foreign-body reaction and the potential need for a second surgical intervention.