Evaluation of a self-fitting, shape memory polymer scaffold in a rabbit calvarial defect model.

Area of Science:

• Biomaterials Science
• Regenerative Medicine
• Orthopedic Surgery

Background:

• Craniomaxillofacial (CMF) bone defects pose challenges due to limitations of current graft treatments in achieving optimal tissue contact.
• Biodegradable, thermoresponsive shape memory polymers (SMPs) offer a potential solution for creating self-fitting scaffolds.
• Poly(ε-caprolactone)-diacrylate (PCL-DA) based SMP scaffolds were developed for CMF defect repair.

Purpose of the Study:

• To evaluate the in vivo bone healing potential of self-fitting PCL-DA SMP scaffolds in a rabbit calvarial defect model.
• To assess scaffold biocompatibility, osseointegration, and bone formation without exogenous cells or growth factors.
• To compare the performance of SMP scaffolds against untreated defects and poly(ether ether ketone) (PEEK) implants.

Main Methods:

• Preparation of porous PCL-DA SMP scaffolds with shape memory properties.
• Creation of non-critically sized bilateral calvarial defects in New Zealand white rabbits.
• Assessment of bone formation and scaffold integration using histology and micro-CT at 4 and 16 weeks.
• Biomechanical evaluation of osseointegration via push-out tests at 16 weeks.

Main Results:

• PCL-DA SMP scaffolds maintained material integrity after gamma sterilization.
• Histological and micro-CT analyses revealed significant bone formation and ingrowth at the scaffold perimeter.
• Scaffold implantation resulted in comparable bone volume and surface area to untreated defects.
• Push-out tests demonstrated superior osseointegration for SMP scaffolds compared to PEEK implants.

Conclusions:

• Self-fitting PCL-DA SMP scaffolds are biocompatible and promote bone regeneration in CMF defects.
• The conformal fitting capability of SMP scaffolds enhances osseointegration and bone ingrowth.
• These findings support the development of biologic-free, self-fitting scaffolds as a promising off-the-shelf treatment for CMF bone defects.