In situ formation of porous space maintainers in a composite tissue defect

Abstract

Reconstruction of composite defects involving bone and soft tissue presents a significant clinical challenge. In the craniofacial complex, reconstruction of the soft and hard tissues is critical for both functional and aesthetic outcomes. Constructs for space maintenance provide a template for soft tissue regeneration, priming the wound bed for a definitive repair of the bone tissue with greater success. However, materials used clinically for space maintenance are subject to poor soft tissue integration, which can result in wound dehiscence. Porous materials in space maintenance applications have been previously shown to support soft tissue integration and to allow for drug release from the implant to further prepare the wound bed for definitive repair. This study evaluated solid and low porosity (16.9 ± 4.1%) polymethylmethacrylate space maintainers fabricated intraoperatively and implanted in a composite rabbit mandibular defect model for 12 weeks. The data analyses showed no difference in the solid and porous groups both histologically, evaluating the inflammatory response at the interface and within the pores of the implants, and grossly, observing the healing of soft tissue defect over the implant. These results demonstrate the potential of porous polymethylmethacrylate implants formed in situ for space maintenance in the craniofacial complex, which may have implications in the potential delivery of therapeutic drugs to prime the wound site for a definitive bone repair.

Evaluation of antibiotic releasing porous polymethylmethacrylate space maintainers in an infected composite tissue defect model

“…The primary differences in formulation between the samples in this study and the samples used in previous studies are the use of gelatin as a porogen and the delivery of antibiotics. [9,10] These dehiscences could therefore be due to the presence of gelatin, colistin, or their combination. Although gelatin cannot be excluded as a cause of dehiscence, it is perhaps a less likely culprit as previous studies have not shown dehiscence when gelatin is implanted in the oral and maxillofacial region, though these studies are not extensive.…”

“…[7,8] The porosity of these constructs was generated by using a carboxymethylcellulose or gelatin hydrogel as a porogen, and the resulting porosity allowed for greater cumulative release of antibiotic. [7][8][9][10] In these studies, colistin, a polypeptide antibiotic, was incorporated into either gelatin or PLGA microparticles. Colistin was selected due to its efficacy against Acinetobacter baumannii, a commonly multi-drug resistant bacterial strain that has been observed to have increased incidence of infection in traumatic combat wounds [11][12][13][14][15].…”

Effects of Local Antibiotic Delivery from Porous Space Maintainers on Infection Clearance and Induction of an Osteogenic Membrane in an Infected Bone Defect

“…24 Sclafani et al demonstrated that biomaterials exposed to bacteria at the time of implantation are more vulnerable to infection than implants inoculated 14 days after implantation, and resistance to infection correlated with histologic evidence of fibrovascular ingrowth into the material implants. 25 However, since porosity may also confer the benefits of improved tissue attachment and fibrovascular ingrowth compared to solid PMMA, 26 efforts should be made to balance tissue integration and infection prevention for tissue engineering applications such as formation of induced membranes. Although one infection did occur in a treated group in this study, infection was significantly mitigated compared to the control group, demonstrating that the controlled release of antibiotics through a porous space maintainer was successful in preventing infection in the majority of cases.…”

Biomaterials for Tissue Engineering

“…27 Spicer et al mixed polymethylmethacrylate (PMMA) bone cement with carboxymethylcellulose porogen to yield a porous space maintainer that polymerized in situ within a rabbit mandibular defect. 81 Soft tissue healing was observed 12 weeks post-implantation, and inflammatory responses were not exacerbated relative to that of solid PMMA space maintainers.…”