What is Synvisc and How Does It Work?
Synvisc (hylan G-F 20) is a brand name for a viscosupplement, a gel-like substance injected directly into a joint space. It is primarily indicated for treating knee pain caused by osteoarthritis (OA) in adults who have not found sufficient relief from other treatments, such as exercise, physical therapy, and over-the-counter pain medications. The medication consists of cross-linked polymers of hyaluronan, a natural substance found in the body. In healthy joints, hyaluronan is a key component of synovial fluid, acting as a lubricant and shock absorber.
In osteoarthritis, the hyaluronan in the synovial fluid breaks down, leading to reduced lubrication and cushioning, which causes pain, stiffness, and a limited range of motion. By injecting Synvisc into the knee, the treatment helps to replenish and restore the joint fluid's natural properties, reducing friction between the bones and absorbing shock during movement. This mechanism of action directly addresses the mechanical aspect of OA pain by improving the knee joint's function.
The Purpose of a Viscosupplementation Therapy
Viscosupplementation, which is what the Synvisc injection provides, is not a cure for osteoarthritis but a way to manage its symptoms over time. The therapy aims to provide targeted, long-lasting relief directly at the source of the problem, rather than relying on systemic medications that may have broader side effects. It is a minimally invasive, in-office procedure that serves as a non-surgical alternative for managing moderate to severe knee OA pain. For many patients, it can be a way to delay or even avoid the need for more invasive procedures like knee replacement surgery.
Synvisc Injection Administration
There are two main formulations of the Synvisc injection, which differ in their administration protocol:
- SYNVISC®: This formulation requires a series of three injections, with each injection administered once a week. Patients receive one injection into the affected knee per week over three weeks.
- Synvisc-One®: This is a higher-dose, single-injection regimen. It is designed for convenience, providing a full course of treatment in a single office visit.
Your healthcare provider will determine the most appropriate formulation based on your condition and medical history. A numbing agent is often applied to the injection site to minimize discomfort during the procedure.
Effectiveness and Duration of Relief
The effectiveness of Synvisc injections varies among individuals, but many patients experience significant benefits.
- Onset of relief: While some patients report relief as early as a week after the first injection, more significant pain reduction is typically felt around 8 to 12 weeks after the start of treatment with Synvisc. For Synvisc-One, relief is often experienced around one month after the single injection.
- Duration of effect: Pain relief from a Synvisc or Synvisc-One treatment can last up to six months. In some long-term studies, benefits have been shown to last for a year or even longer. Treatment can be safely repeated when the knee pain returns.
Potential Side Effects and Safety Considerations
Like any medical procedure, Synvisc injections carry some risks and potential side effects, which are generally mild to moderate.
- Common Side Effects: Pain, swelling, heat, and redness at the injection site are the most frequently reported side effects. These reactions are usually temporary and can be managed with ice packs and over-the-counter medication.
- Rare Adverse Events: In rare cases, more serious side effects can occur, including allergic reactions (e.g., rash, hives, difficulty breathing), infection in the joint, and complications related to existing health conditions. Patients with allergies to bird products (feathers, eggs, poultry) should discuss these with their doctor, as Synvisc is derived from rooster combs.
- Contraindications: Synvisc should not be used in patients with knee joint infections or infections/skin diseases at the injection site. It should also be used with caution in patients with swelling in the legs due to venous or lymphatic stasis.
Comparison of Synvisc with Other Common Knee Injections
When deciding on a treatment, patients may consider different types of injections. The comparison below highlights the key differences between Synvisc, corticosteroids, and other viscosupplements.
| Feature | Synvisc (Viscosupplementation) | Corticosteroid Injection | Other Hyaluronic Acid Brands (e.g., Orthovisc, Hyalgan) |
|---|---|---|---|
| Mechanism of Action | Supplements and restores natural joint lubrication and cushioning. | Reduces inflammation by suppressing the immune response. | Same as Synvisc—supplements and restores lubrication. |
| Onset of Relief | Delayed (weeks to months). | Fast (days to weeks). | Delayed (weeks to months), depending on the brand. |
| Duration of Relief | Longer-lasting (up to 6 months or more). | Shorter (weeks to a few months). | Similar to Synvisc (up to 6 months), but can vary. |
| Treatment Focus | Addresses mechanical issues within the joint. | Primarily treats inflammation. | Addresses mechanical issues within the joint. |
| Source | Avian (from chicken combs). | Synthetic steroid medication. | Varies (Avian, bacterial fermentation, etc.). |
| Repeatability | Can be repeated safely as needed. | Limited (no more than 2-3 per year) due to risk of tissue weakening. | Can be repeated, frequency varies by brand. |
| Side Effects | Injection site reactions, rare allergic reactions. | Can cause temporary bruising, skin discoloration, and weakening of soft tissues. | Injection site reactions, potential allergic reactions based on source. |
What to Expect After a Synvisc Injection
Following your Synvisc injection, it is important to follow specific aftercare instructions to optimize your results and minimize side effects.
- Initial Aftercare (48 hours): Avoid strenuous activities, such as jogging, heavy lifting, or prolonged standing. This allows the viscosupplement to settle and integrate with the joint fluid.
- Managing Discomfort: Mild pain, swelling, or stiffness at the injection site is common. Applying a wrapped ice pack for 10-20 minutes at a time can help reduce discomfort.
- Long-Term Plan: While Synvisc can provide significant relief, it does not replace other conservative management strategies. Your doctor may recommend a combination of exercise, physical therapy, and weight management to complement the injection's effects.
Conclusion
In conclusion, the purpose of the Synvisc injection is to provide targeted, long-term pain relief and improved joint function for individuals with knee osteoarthritis who have not responded adequately to conservative treatments. As a viscosupplement, it mimics the natural hyaluronic acid in healthy synovial fluid, acting as a lubricant and shock absorber. By addressing the mechanical breakdown of joint fluid, Synvisc offers a minimally invasive alternative to surgery, with its effects often lasting six months or more. As with any medical treatment, patients should discuss their specific needs and concerns with a healthcare provider to determine if Synvisc is the right option for them, particularly if they have a history of allergies or other medical conditions. You can find more information about viscosupplementation on the official websites of manufacturers or by consulting reliable medical resources like the American Academy of Orthopaedic Surgeons (AAOS).
