Polynucleotide (PN) Knee Injection

A Non-Surgical Option for Knee Osteoarthritis

Knee osteoarthritis is one of the most common causes of persistent knee pain in Singapore. Many patients experience:

• Pain when walking or climbing stairs
• Stiffness after prolonged sitting
• Swelling
• Reduced mobility
• Difficulty exercising

While medications, physiotherapy, and hyaluronic acid (HA) injections are commonly used, some patients may wish to explore additional non-surgical options.

One such option studied internationally is Polynucleotide (PN) intra-articular injection.

What Is a Polynucleotide Injection?

Polynucleotide (PN) is a purified long-chain DNA polymer derived from salmon or trout.

When injected directly into the knee joint, it forms a viscoelastic gel structure that may:

• Reduce mechanical friction between joint surfaces
• Provide cushioning within the joint
• Support joint lubrication
• Improve functional mobility
• Reduce joint discomfort

It is administered as an intra-articular injection, typically in a prefilled syringe.

How Does Polynucleotide Work?

Polynucleotide behaves somewhat similarly to hyaluronic acid in that it creates a cushioning gel inside the joint.

Its key characteristics include:

1. High molecular weight DNA polymer with viscoelastic properties
2. Formation of a 3D gel structure inside the joint space
3. Reduction of mechanical irritation between articular cartilage surfaces

Unlike oral medications, it is delivered directly into the affected joint.

What Does Clinical Research Show?

Several clinical studies have evaluated intra-articular polynucleotide injections in knee osteoarthritis.

Randomized Double-Blind Trial (Italy, 2014)

A randomized controlled trial comparing polynucleotide injections to hyaluronic acid in knee osteoarthritis showed:

• Both treatments significantly reduced pain
• Polynucleotide showed earlier symptom improvement in certain KOOS (Knee Injury and Osteoarthritis Outcome Score) parameters
• Hyaluronic acid showed significant improvement at a later time point in some measures
• No significant serious adverse events were reported

Reference:
Giarratana LS et al. Knee. 2014;21:664-668. DOI: 10.1016/j.knee.2014.02.010

Pain Reduction (VAS Score)

In clinical evaluations:

• Polynucleotide demonstrated approximately ~67% pain reduction (VAS)
• Hyaluronic acid demonstrated approximately ~57% pain reduction

Both treatments were effective, with some evidence suggesting earlier symptom relief in certain parameters with PN.

Confirmatory Clinical Study (Korea)

A randomized, double-blind, controlled study involving over 200 patients reported:

• Significant reduction in pain
• Improvement in functional scores
• Acceptable safety profile

How Is It Different From Hyaluronic Acid?

Hyaluronic acid injections are widely used for knee osteoarthritis. Polynucleotide differs in that:

• It is a DNA-based polymer
• It forms a structured gel matrix
• Some studies suggest earlier improvement in specific outcome measures

Both fall under joint injection approaches and suitability depends on:

• Severity of osteoarthritis
• Symptoms
• Imaging findings
• Previous response to treatment
• Overall joint condition

Who May Consider This Option?

You may discuss polynucleotide injection with your doctor if:

• You have mild to moderate knee osteoarthritis
• You prefer to avoid surgery
• You want to reduce reliance on oral painkillers
• Previous hyaluronic acid injections gave limited relief
• You are seeking additional non-surgical options

Important Considerations

As with all intra-articular injections:

• Proper medical assessment is essential
• Imaging (X-ray or MRI when appropriate) may help clarify diagnosis
• Not all knee pain is due to osteoarthritis
• Results vary between individuals

Possible temporary effects may include:

• Injection site soreness
• Mild swelling
• Temporary stiffness

Serious complications are uncommon but possible with any joint injection.

Our Approach at The Pain Relief Clinic

At The Pain Relief Clinic, we focus on:

• Accurate diagnosis
• Imaging-guided clarity when needed
• Individualised treatment planning
• Clear explanation of risks and expected outcomes

We do not believe in a one-size-fits-all approach.

Instead, we assess:

• Cartilage condition
• Alignment issues
• Meniscus health
• Ligament stability
• Inflammatory features

We then discuss whether options such as:

• Physiotherapy
• Hyaluronic acid injection
• Polynucleotide injection
• Other non-invasive treatments
• Surgical referral (if required)

may be suitable.

Frequently Asked Questions

Is this a steroid injection?
No. Polynucleotide injection is not a corticosteroid.

Is it the same as PRP?
No. PRP uses your own blood. Polynucleotide is a purified DNA polymer.

How many injections are needed?
Protocols vary. Some regimens involve multiple injections spaced one week apart.

How long does it last?
Clinical trials have evaluated outcomes up to 6 months. Individual response varies.

Considering Your Options?

If you are experiencing persistent knee pain and want to explore non-surgical treatment options supported by clinical research, book a consultation for assessment.

We will evaluate whether:

• Your pain is due to osteoarthritis
• The severity level
• Polynucleotide injection may be suitable
• Or whether another approach is more appropriate