Current Concepts in Viscosupplementation: New Classification System and Emerging Frontiers

Area of Science:

• Orthopedics
• Biomaterials Science
• Rheumatology

Background:

• Viscosupplementation with intra-articular hyaluronic acid (HA) is a primary treatment for osteoarthritis (OA).
• Current product classification based solely on molecular weight is inadequate, conflating chemically distinct HA formulations.
• Clinical controversies and outdated classifications hinder effective therapeutic application.

Purpose of the Study:

• To critically analyze the current landscape of HA viscosupplementation for OA.
• To propose a new, two-tiered classification framework for HA products based on chemical structure and molecular weight.
• To evaluate the clinical and biological implications of different HA formulations and combination therapies.

Main Methods:

• Comprehensive literature review and critical analysis of existing HA viscosupplementation products.
• Development of a novel classification system distinguishing between linear (non-modified) and cross-linked (chemically modified) HA.
• Evaluation of the mechanism of action, efficacy, and biological profiles of various HA formulations.

Main Results:

• A new classification framework separates HA into linear (sub-classified by molecular weight: Low, Intermediate, High) and cross-linked (hydrogels with ultra-high effective molecular weight) categories.
• High-concentration, high-molecular-weight linear HA demonstrates year-long efficacy and superior chondroprotective biological effects.
• Linear HA serves as a versatile scaffold for combination therapies with corticosteroids, PRP, bone marrow aspirate, and stromal vascular fraction.

Conclusions:

• A revised classification of HA products based on chemical structure is essential for understanding their distinct properties and clinical applications.
• High-molecular-weight linear HA formulations offer significant advantages in efficacy and chondroprotection over traditional cross-linked products.
• Combination therapies utilizing linear HA as a scaffold represent a promising frontier for advanced OA management.