Hydrogel systems in orthopedics: delivery modality as a framework for translational design

Area of Science:

• Biomaterials Science
• Orthopedic Engineering
• Drug Delivery Systems

Background:

• Hydrogels are versatile biomaterials for orthopedic applications, including pain management, drug delivery, and tissue regeneration.
• Current research often focuses on polymer composition and crosslinking, potentially overlooking critical translational factors.
• Evaluating hydrogel systems requires a framework that considers delivery modality alongside material and clinical aspects.

Purpose of the Study:

• To critically compare three hydrogel delivery modalities: patches, injectables, and implants.
• To evaluate these modalities across major orthopedic indications, considering their strengths and limitations.
• To propose a clinically useful framework for assessing orthopedic hydrogel systems based on delivery modality and translational success factors.

Main Methods:

• Comparative analysis of hydrogel patches, injectable hydrogels, and implantable hydrogels.
• Assessment of delivery paradigms based on tissue access, mechanical properties, payload capacity, invasiveness, and regulatory feasibility.
• Evaluation across key orthopedic indications such as inflammation, pain, cartilage repair, bone regeneration, and infection prevention.

Main Results:

• Hydrogel patches are suitable for superficial anti-inflammatory therapy but limited for deep regenerative delivery.
• Injectable hydrogels offer a balance of minimally invasive administration and localized control, needing improvements in retention and stability.
• Implantable hydrogels provide structural control for bone and osteochondral repair but face challenges in surgical burden and manufacturing.

Conclusions:

• Delivery modality is a clinically relevant framework for evaluating orthopedic hydrogels, but translational success hinges on material properties, mechanical requirements, and clinical feasibility.
• Each modality presents unique advantages and limitations for specific orthopedic applications.
• A shift towards indication- and delivery-modality-driven design is needed to prioritize practical translational factors for orthopedic hydrogel technologies.