Interferential Therapy (IFT) for Achilles Tendonitis
Interferential therapy (IFT) does not provide clinically meaningful benefit for Achilles tendonitis and should not be used as a primary treatment modality. The evidence shows IFT fails to produce significant improvements in pain or inflammation, while proven alternatives like eccentric exercises demonstrate substantial efficacy.
Evidence Against IFT Effectiveness
A controlled study measuring Achilles tendon microcirculation found no significant changes in total hemoglobin or oxygen saturation after interferential current application, indicating IFT does not meaningfully alter tendon physiology or blood flow 1
This contrasts sharply with other physical modalities tested in the same study—ultrasound and vibration massage both significantly increased tendon microcirculation, while IFT produced no measurable effect 1
Recommended Evidence-Based Treatment Algorithm
First-Line Treatment (Weeks 0-8)
The American Academy of Family Physicians identifies eccentric strength training as the most effective treatment option for Achilles tendinopathy, with strong supporting evidence 2. This should be your primary intervention:
Eccentric heel-drop exercises: Perform for 6 weeks with each stretch maintained for at least 15 seconds, which reduces pain from a mean VAS of 7.2 to 2.9 (p<0.01), with 80% of patients rating satisfaction as excellent 3
Gastrocnemius-soleus stretching and deep friction massage are recommended as adjunctive interventions 2
Heel lift orthotics to unload the tendon for immediate pain relief 2
Shoe orthotics if overpronation or pes planus is present 2
Relative rest and icing as fundamental components 2
NSAIDs for acute pain relief only—recognize that the underlying pathology is degenerative (tendinosis), not inflammatory, so anti-inflammatory treatments provide only temporary relief [@3,4@]
Second-Line Treatment (After 6-8 Weeks Without Improvement)
Refer to a podiatric foot and ankle surgeon 2
Continue initial treatments while adding immobilization with a cast or fixed-ankle walker device 2
Consider extracorporeal shockwave therapy (ESWT): Evidence from 4 RCTs demonstrates ESWT reduces pain and improves function, with best results when combined with eccentric exercises and stretching 4
Third-Line Options (After 3-6 Months of Failed Conservative Treatment)
Approximately 80% of patients fully recover within 3-6 months with conservative treatment, meaning only 20% require advanced interventions 2
Surgical consultation may be warranted at this stage for the minority who fail comprehensive conservative care
Critical Pitfalls to Avoid
Never inject corticosteroids into or around the Achilles tendon—this significantly increases rupture risk and is specifically contraindicated by the American Academy of Family Physicians [@3,4@]
Do not pursue IFT or other unproven physical therapy modalities when evidence-based options (eccentric exercises, stretching, orthotics) have demonstrated efficacy 2
Do not rely on anti-inflammatory treatments alone—the pathology is degenerative tendinosis, not acute tendonitis, despite the common misnomer 2
Avoid calling this condition "tendonitis"—it should be labeled "tendinosis" or "tendinopathy" because most cases involve chronic degenerative changes rather than inflammation 2
Alternative Physical Modalities With Evidence
If you wish to augment eccentric exercises with adjunctive physical therapy:
Low-level laser therapy (904 nm, 5.4 J per point) significantly reduces prostaglandin E2 concentrations and increases pressure pain threshold compared to placebo (p=0.009 and p=0.012 respectively) 5
Therapeutic ultrasound (0.8-1.2 W/cm²) significantly increases tendon oxygen saturation and total hemoglobin, potentially supporting healing 1
Vibration massage applied directly to the Achilles tendon (not the calf muscle) significantly increases both microcirculation parameters 1
These modalities show physiological effects on tendon tissue, unlike IFT which demonstrates no measurable impact 1.