Managing knee osteoarthritis (OA) presents a significant clinical challenge, often impacting patient mobility, function, and overall quality of life. While conservative measures like physical therapy, weight management, and pharmacologic agents form the foundation of care, many patients require additional interventions to achieve adequate symptom control. Intra-articular viscosupplementation has emerged as a valuable component within the knee OA treatment algorithm for patients who have failed to respond adequately to simpler therapies.

Among the established viscosupplements, Synvisc® and Synvisc-One®, both based on hylan G-F 20, are widely recognized options. Synvisc® utilizes a traditional three-injection protocol, while Synvisc-One® offers the convenience of a single-injection regimen. This guide, grounded in evidence-based practice, aims to provide clinicians with a comparative overview of these two formulations, facilitating informed patient selection based on clinical evidence, patient factors, and treatment goals.

Understanding Hylan G-F 20: The Science Behind Synvisc® and Synvisc-One®

Synvisc and Synvisc-One belong to the hylan class of viscosupplements, derived from hyaluronan (sodium hyaluronate).

• Mechanism of Action: While often described as simple joint lubricants, the benefits of hylan G-F 20 likely extend beyond mechanical effects. These agents possess unique viscoelastic properties that help restore the shock-absorbing and lubricating qualities of healthy synovial fluid.¹ Emerging evidence also suggests potential chondroprotective and anti-inflammatory effects, although the precise mechanisms in vivo are still under investigation.
• Unique Formulation: Hylan G-F 20 is distinguished by its composition of chemically cross-linked hyaluronan derivatives – hylan A (higher molecular weight fluid) and hylan B (hydrated gel). This cross-linking contributes to its high molecular weight and residence time within the joint compared to non-cross-linked hyaluronan.²
• Source: Critically, hylan G-F 20 is avian-derived, sourced from rooster combs. This necessitates careful patient screening for known hypersensitivities to avian proteins, feathers, and egg products, which are contraindications for its use.^3,4

Clinical Evidence Review: Efficacy and Safety

Both Synvisc® and Synvisc-One® have been extensively studied for the treatment of knee OA pain.

• Synvisc® (3-Injection): Multiple pivotal trials and extensive clinical use have demonstrated the efficacy of the 3-injection Synvisc regimen in providing significant pain relief and improvements in functional outcomes compared to placebo or arthrocentesis alone.¹ The therapeutic effect typically lasts for up to 6 months following the completion of the injection series. Key studies have consistently shown statistically significant reductions in pain scores (e.g., WOMAC) and improved patient-reported function.
• Synvisc-One® (Single-Injection): Clinical trials were designed to evaluate the efficacy and safety of the single 6mL injection compared to placebo. Studies have demonstrated significant improvements in knee pain and function compared to saline controls, with effects lasting up to 6 months. Further research and systematic reviews suggest comparable efficacy between single-injection hylan G-F 20 and multi-injection HA regimens for appropriate patients, supporting the single-injection approach.
• Safety Profile: Both formulations share a similar safety profile, primarily characterized by local, transient intra-articular injection site reactions. These may include pain, swelling, stiffness, and joint effusion, typically mild to moderate and self-limiting.^3,4 Systemic reactions are rare. The most clinically significant risk factor remains the potential for hypersensitivity reactions related to its avian origin. Thorough patient screening for avian allergies is paramount before considering either Synvisc or Synvisc-One.

Patient Selection Criteria: Tailoring the Regimen

Choosing between Synvisc® and Synvisc-One® involves considering both clinical evidence and individual patient circumstances.

• Indications: Both products are FDA-approved for the treatment of pain in osteoarthritis (OA) of the knee in patients who have failed to respond adequately to conservative nonpharmacologic therapy and simple analgesics (e.g., acetaminophen).^3,4 Off-label use in other joints is not the focus of this discussion.
• Factors Favoring Synvisc® (3-Injection):
  • Patients who are comfortable with, or prefer, a multi-visit injection schedule.
  • Patients with a history of positive response to previous multi-injection HA regimens.
  • Clinician or patient preference for a potentially more gradual introduction of the viscosupplement (though robust evidence supporting a clinical benefit difference based on this is limited).
  • Specific reimbursement or insurance coverage structures that may favor a multi-injection protocol.
• Factors Favoring Synvisc-One® (Single-Injection):
  • Enhanced patient convenience and potentially improved compliance due to the single-visit requirement.
  • Patients facing travel, mobility, or time constraints that make multiple appointments challenging.
  • Improved practice efficiency and workflow optimization.
  • Patients for whom established efficacy makes the convenience of a single-injection HA appealing.
• Contraindications: These are critical for patient safety and are largely shared:^3,4
  • Known hypersensitivity to hyaluronan preparations.
  • Crucially: Known hypersensitivity to avian proteins, feathers, or egg products.
  • Active infection in or around the knee joint.
  • Skin diseases or infections at the proposed injection site.
  • Significant bleeding disorders (use with caution).

Administration & Practical Considerations

• Technique: Strict adherence to aseptic intra-articular injection technique is mandatory to minimize infection risk. Clinicians should refer to the official prescribing information for detailed administration instructions, including needle gauge recommendations and proper joint space access.^3,4 Arthrocentesis to remove effusion prior to injection may be considered.
• Patient Expectations: It is essential to manage patient expectations. Explain that pain relief is typically not immediate and may take several weeks to become apparent. Reinforce the expected duration of relief (up to 6 months).
• Post-Injection Care: Advise patients to avoid strenuous activities (e.g., jogging, tennis, heavy lifting) or prolonged weight-bearing for approximately 48 hours post-injection. Localized reactions can be managed with ice and simple analgesics.
• Multimodal Management: Emphasize that Synvisc/Synvisc-One is part of a comprehensive multimodal OA management plan, which should include physical therapy, exercise, weight management (if applicable), and potentially other pharmacologic agents as appropriate.

Conclusion

Synvisc® and Synvisc-One® represent effective and well-established hylan G-F 20 viscosupplementation options for managing knee OA treatment. They offer clinicians proven therapies that can significantly improve patient symptoms and function for up to six months.

The decision between the 3-injection Synvisc® protocol and the single-injection Synvisc-One® regimen should be individualized. It requires balancing the robust clinical evidence supporting both approaches with practical considerations such as patient preference, lifestyle factors affecting compliance, potential travel limitations, and practice logistics.

Critically, the avian origin of hylan G-F 20 necessitates meticulous patient screening for allergies to eggs, feathers, or poultry products prior to initiating treatment with either formulation. By carefully selecting appropriate candidates and integrating these therapies into a broader OA management strategy, clinicians can effectively leverage Synvisc and Synvisc-One to improve the quality of life for their patients suffering from knee osteoarthritis. Personalized care remains the cornerstone of successful OA treatment.

Doris Dickson

About the Author: Doris Dickson is a specialist writer for Health Supplies Plus, focusing on the aesthetic medicine industry. She diligently researches cosmetic treatments and products to provide clear, concise information relevant to licensed medical professionals. Her work supports Health Supplies Plus’s commitment to being a reliable informational resource and trusted supplier for the aesthetic community.

 

Disclaimer: The content provided in this article is intended for informational purposes only and is directed towards licensed medical professionals. It is not intended to be a substitute for professional medical advice, diagnosis, or treatment, nor does it constitute an endorsement of any specific product or technique. Practitioners must rely on their own professional judgment, clinical experience, and knowledge of patient needs, and should always consult the full product prescribing information and relevant clinical guidelines before use. Health Supplies Plus does not provide medical advice.