You may have seen a physiotherapist applying an ointment or gel while administering ultrasound therapy - but do you know what technique they're using? It's called the phonophoresis technique, a method that allows medicine to penetrate deep into the body using ultrasound waves. This combination enhances drug absorption, reduces pain, and promotes faster healing.
But how effective is this technique, really? 🤔
To find out whether phonophoresis truly works, we’ll explore three scientific research studies conducted on patients with low back pain. Each study compared phonophoresis with conventional ultrasound therapy and exercise alone to measure its real benefits.
So, stay tuned till the end of the article - you don’t want to miss the evidence, results, and final conclusion.
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Low back pain (LBP) is one of the most prevalent musculoskeletal problems globally, affecting nearly 80% of adults at least once in their lifetime. It is a leading cause of disability and reduced productivity across all age groups. Despite advances in rehabilitation science, clinicians still debate the most effective conservative interventions to manage both acute and chronic low back pain.
Among physiotherapeutic modalities, phonophoresis (PP) and ultrasound (US) therapy are widely used for pain relief and tissue healing. But how effective is phonophoresis compared to standard ultrasound therapy?
Recent randomized controlled trials (RCTs) have explored this question by evaluating the impact of phonophoresis using medicated gels such as Lofnac (diclofenac + methyl salicylate) and diclofenac + thiocolchicoside combinations.
What Is Phonophoresis?
Phonophoresis, also known as sonophoresis, is a non-invasive technique that uses therapeutic ultrasound waves to enhance the transdermal delivery of topical medications. By applying ultrasound energy, physiotherapists can facilitate deeper penetration of drugs such as nonsteroidal anti-inflammatory drugs (NSAIDs), Steroids and muscle relaxants into the affected tissues.
Mechanism of Action
Thermal Effect:
Ultrasound energy slightly raises tissue temperature, improving local circulation and soft-tissue extensibility.-
Mechanical Effect:
The alternating compression and rarefaction cycles of ultrasound waves increase skin permeability, allowing drug molecules to diffuse more efficiently through the epidermis. -
Synergistic Benefit:
When ultrasound and topical pharmacologic agents are combined, patients receive both the biomechanical benefits of ultrasound and the anti-inflammatory/analgesic effects of the medication.
Why Phonophoresis for Low Back Pain?
Low back pain may arise from lumbar muscle strain, ligament sprain, facet joint irritation, or intervertebral disc dysfunction. In most nonspecific cases, inflammation and muscle spasm are key contributors to pain and restricted mobility.
Phonophoresis aims to:
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Deliver anti-inflammatory drugs directly to affected tissues
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Reduce muscle spasm and pain intensity
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Improve mobility, function, and quality of life
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Minimize systemic drug side effects compared to oral medications.
Study 1: Phonophoresis vs Ultrasound Therapy in Chronic Low Back Pain
Design Overview
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Participants: 60 patients with chronic low back pain (CLBP)
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Groups:
(1) Control - Exercise only
(2) Ultrasound + Exercise(3) Phonophoresis + Exercise
- Duration: 6 weeks, 3 sessions/week
Assessment Tools
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Pain: Visual Analog Scale (VAS)
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Disability: Oswestry Disability Questionnaire (ODQ) & Pain Disability Index (PDI)
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Walking Performance: 6-Minute Walk Test (6MWT)
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Depression: Beck Depression Inventory (BDI)
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Quality of Life: SF-36
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Trunk Strength: Hand-held dynamometer
Results
All three groups improved significantly, but ultrasound and phonophoresis produced superior outcomes to exercise alone in pain, mobility, and quality of life.
However, phonophoresis was not statistically superior to ultrasound therapy.
Patients in the PP group reported slightly better improvements in vitality and pain perception on SF-36 subscales.
Clinical Implication
Phonophoresis is effective for CLBP but offers comparable rather than superior benefits to ultrasound therapy when both are combined with exercise.
Study 2: Therapeutic Efficacy of Lofnac Gel Phonophoresis in Chronic Nonspecific Low Back Pain
(Ojoawo et al., 2019; PMCID: PMC6385132)
Background
In sub-Saharan Africa, chronic nonspecific low back pain is common, yet access to pharmacologic pain relief is limited. Lofnac Gel, containing diclofenac and methyl salicylate, is a topical NSAID formulation used to manage musculoskeletal pain. Researchers examined whether phonophoresis using Lofnac Gel enhances treatment efficacy compared to ultrasound with a neutral coupling medium.
Methodology
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Sample: 70 patients with mechanical LBP > 3 months’ duration
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Groups:
(1) Experimental: Phonophoresis with Lofnac Gel + Exercis.
(2) Control: Ultrasound with water gel + Exercise
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Treatment frequency: 2 sessions/week for 6 weeks
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Outcomes: Pain Intensity (VAS), Disability Index (ODI)
Findings
Both groups improved, but phonophoresis with Lofnac Gel produced significantly greater reductions in both pain intensity (F = 28.76, p < 0.001) and disability (F = 39.817, p < 0.001) compared with ultrasound alone at week 6.
Interpretation
Adding Lofnac Gel to ultrasound therapy significantly enhanced outcomes, confirming that drug-assisted phonophoresis provides superior therapeutic benefit in chronic nonspecific low back pain.
Study 3: Diclofenac + Thiocolchicoside Gel Phonophoresis vs Ultrasound in Acute Low Back Pain
(Altan et al., 2018; DOI: 10.1016/j.ultras.2018.08.008)
Purpose
To evaluate whether combining NSAIDs (diclofenac) with a muscle relaxant (thiocolchicoside) via phonophoresis yields better outcomes than standard ultrasound therapy in acute low back pain (ABP).
Study Design
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Participants: 60 patients with acute LBP
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Groups:
(1) PP Group: US with diclofenac + thiocolchicoside gel (10 min × 10 sessions)
(2) US Group: US with neutral gel (same settings)
- Evaluation: Visual Numeric Scale (VNS), Oswestry Disability Index (ODI), and Shober test for lumbar flexibility
Results
Both groups showed improvement, but the PP group had significantly superior outcomes in pain and disability at both 2 and 6 weeks (p < 0.05). At week 6, PP outperformed US in nearly all parameters except lumbar flexibility.
Conclusion
Phonophoresis with a combination of NSAID + muscle relaxant gel is superior to conventional ultrasound therapy in short-term management of acute low back pain.
Combined Evidence Analysis
| Study | Sample | Duration | Drug Used | Pain Type | Outcome |
|---|---|---|---|---|---|
| Study 1 | 60 | 6 weeks | Not specified | Chronic | PP = US > Exercise only |
| Study 2 | 70 | 6 weeks | Lofnac Gel (Diclofenac + Methyl Salicylate) | Chronic Nonspecific | PP > US |
| Study 3 | 60 | 6 weeks | Diclofenac + Thiocolchicoside Gel | Acute | PP > US |
Summary:
Phonophoresis consistently provides better or equal outcomes to ultrasound therapy, particularly when medicated gels containing anti-inflammatory and muscle-relaxant agents are used. The benefit is most pronounced in acute pain and nonspecific chronic cases.
Mechanistic Insights
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Enhanced Drug Delivery: Ultrasound facilitates penetration of both lipophilic and hydrophilic molecules into deeper tissues.
Synergistic Drug Action: Diclofenac reduces prostaglandin synthesis, while thiocolchicoside relaxes muscles - a combination ideal for acute pain.
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Inflammation Control: Methyl salicylate complements diclofenac’s anti-inflammatory effect, promoting faster recovery.
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Improved Circulation: Thermal effects of ultrasound increase perfusion, aiding tissue oxygenation and nutrient exchange.
Clinical Implications for Physiotherapists
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For Acute LBP:
Phonophoresis with combined NSAID + muscle relaxant gel is highly effective for rapid pain relief. -
For Chronic or Nonspecific LBP:
Lofnac Gel phonophoresis and therapeutic exercise provide superior outcomes to ultrasound alone. -
For Maintenance & Rehabilitation:
Core stabilization, postural training, and ergonomic education remain the foundation of long-term management.
Advantages of Phonophoresis
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Non-invasive, safe, and painless
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Delivers drugs locally with minimal systemic absorption
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Enhances patient compliance
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Reduces oral NSAID dosage requirements
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Synergistic with active exercise therapy
Limitations and Considerations
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Requires compatible medicated gels
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Results depend on ultrasound parameters and therapist skill
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Effectiveness decreases with thick or scarred skin
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Contraindicated over open wounds, malignancy, or pregnancy
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Cost and drug availability can limit use in resource-poor settings
Safety Profile
All three studies reported no adverse effects, confirming phonophoresis as a safe physiotherapeutic intervention when applied with standard precautions.
Evidence-Based Summary
| Parameter | Exercise Only | Ultrasound | Phonophoresis |
|---|---|---|---|
| Pain Reduction | Moderate | Strong | Very Strong |
| Disability Improvement | Moderate | Strong | Very Strong |
| Muscle Strength | Minimal | Improved | Improved |
| Quality of Life | Minimal | Improved | Superior |
| Depression/Mood | Minor change | Moderate improvement | Significant improvement |
| Clinical Safety | Safe | Safe | Safe and Effective |
My Final Conclusion
The cumulative evidence demonstrates that phonophoresis is an effective and evidence-supported therapy for both acute and chronic low back pain.
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In chronic nonspecific LBP, Lofnac Gel phonophoresis significantly reduces pain and disability compared to ultrasound alone.
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In acute LBP, diclofenac + thiocolchicoside phonophoresis yields faster pain relief and functional recovery.
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For chronic specific pain, phonophoresis performs as well as ultrasound, and both should be complemented with strengthening and postural exercises.
Therefore:
Yes, Phonophoresis is effective and should be considered a valuable therapy in the comprehensive physiotherapy management of low back pain, rather than using ultrasound therapy alone.
Highlights
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Phonophoresis enhances transdermal delivery of NSAIDs and myorelaxants.
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It offers superior pain and disability reduction versus ultrasound alone.
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Exercise remains essential - modalities alone are insufficient.
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The therapy is safe, cost-effective, and suitable for outpatient rehabilitation.
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Optimal results require appropriate gel selection and correct ultrasound parameters.
Frequently Asked Questions (FAQs)
1. Is phonophoresis more effective than ultrasound therapy?
Yes, especially when medicated gels like diclofenac + thiocolchicoside or Lofnac Gel are used. It produces faster and greater pain reduction.
2. Can phonophoresis replace exercise therapy?
No. Phonophoresis complements but does not substitute strengthening and stretching exercises.
3. How many sessions are needed for noticeable improvement?
Most studies show significant results after 10-12 sessions over 4-6 weeks.
4. Which drugs are most effective for phonophoresis in low back pain?
Topical agents containing diclofenac, methyl salicylate, or thiocolchicoside are commonly supported by research.
5. Is phonophoresis safe for everyone?
Yes, except for patients with contraindications such as pregnancy, open wounds, or active infections at the treatment site.
More:
(1) 15 Physiotherapy Exercises for Lower Back Pain: Guide by a Physiotherapist