Phonophoresis vs Iontophoresis Treatment
Several musculoskeletal conditions still remain without a definite treatment in modern medicine, but there are always advances in science trying to find the best alternatives to improve the symptoms of these patients with a lower incidence of side effects. Phonophoresis and iontophoresis are both therapeutic tools thought to alleviate pain in musculoskeletal conditions by delivering drugs into the organism faster than topical absorption by the skin and safer than intraarticular injections.
Phonophoresis and iontophoresis are used in debilitating and recurring musculoskeletal problems such as tennis elbow, also known as lateral epicondylitis. This condition features an intense and crippling pain in the outer side of the elbow that aggravates after using hand tools and performing certain actions that involve gripping and rotational movements. The etiology of this condition is not fully understood, which is why improvements with the current treatment are slow, and patients usually look for alternatives to improve their health condition.
But what is exactly phonophoresis, how is it different from iontophoresis, and which one is better? Are they safe alternatives to use in severe and recurring musculoskeletal problems as in tennis elbow?
What is phonophoresis?
Phonophoresis is a technique in physical therapy that involves using an ultrasound device and topical medications to promote faster dermal absorption of these drugs and improve various types of inflammatory conditions. It is often used in combination with anti-inflammatory medications, analgesics, and steroids meant to improve pain symptoms and regain the functional capacity of the articulation.
This type of treatment can be accompanied by other traditional therapies as well as lifestyle modifications to improve the quality of life of the patient. It is commonly used to improve joint symptoms, but may also enhance the function of muscles and ligaments.
In a typical session of phonophoresis, the doctor will apply gel or ointment previously prepared with drugs such as dexamethasone or lidocaine. After that, he will apply the transducer directly against the skin and adjust the wavelength of the ultrasound to promote absorption. The procedure does not hurt, and there are no known adverse reactions.
It is a popular alternative treatment to improve the episodic symptoms of knee osteoarthritis, lateral epicondylitis, tendinitis, various types of bursitis, and even certain conditions associated with the nervous system, as the carpal tunnel syndrome.
What is iontophoresis?
Similar to phonophoresis, iontophoresis is an alternative way to deliver drugs into the system, but instead of using ultrasound waves, it uses a mild form of electrical stimulation. It is a type of electrotherapy that creates a voltage gradient and charge the drug molecules, creating an ionized version of these substances. After becoming ions, they are transported through electro-osmosis into the skin, and the procedure is meant to deliver faster and more effectively the same substances that would otherwise be absorbed very slowly.
A typical session of iontophoresis requires a solution of dexamethasone or the drug that is meant to be delivered through the skin. The patient is instructed to sit and place the affected body area in a tray filled with this solution and connected to iontophoresis machine. Throughout the procedure, the patient may feel a tingling sensation as a mild electrical current is sent. It is not meant to be painful or cause any type of shock, and usually lasts a few minutes.
Iontophoresis is applied for the same reason as phonophoresis, but it is known to improve additional conditions, such as hyperhidrosis (excess sweating of the hands and feet). Iontophoresis is a safe procedure that has no reported side effects, it is known to be effective in improving pain symptoms, and it is one of the most popular alternative treatments for lateral epicondylitis or tennis elbow.
Effectiveness of phonophoresis vs. iontophoresis in clinical trials
According to clinical trials, both phonophoresis and iontophoresis are effective in treating pain associated with musculoskeletal conditions, as in lateral epicondylitis. However, a recent review that compares both types of treatment in the management of tennis elbow shows that, even though both improve pain symptoms, only iontophoresis is known to increase grip strength and fully restore the functional capacity of the articulation, at least for a limited period of time. However, it is difficult to evaluate the effectiveness of these procedures as a standalone therapy because the majority of studies apply these procedures in combination with other therapeutic options.
There are more studies on iontophoresis and only limited data on phonophoresis to treat lateral epicondylitis, and the available evidence is often not conclusive. A study published in the journal Physiotherapy evaluated ultrasound application by itself, and phonophoresis using hydrocortisone with and without an epicondylosis clasp. In this study, the pain only improved in patients with phonophoresis along with an epicondylosis clasp, suggesting that phonophoresis alone and ultrasound alone might not be really effective in improving tennis elbow symptoms. Similar results were reported in a study comparing phonophoresis and Cyriax physiotherapy for lateral epicondylitis.
Some studies that directly contrast the effects of phonophoresis and iontophoresis suggest that they are both associated with an improvement in symptoms, but the effect is further enhanced by performing stretching and strengthening exercises to improve grip strength and reduce pain. Other studies do not report any significant impact on the phonophoresis group and both functional and symptomatic improvements in the iontophoresis group. Moreover, studies comparing Cyriax physiotherapy and iontophoresis show that they are both equally effective in treating lateral epicondylitis.
Advantages and disadvantages of phonophoresis and iontophoresis
In a nutshell, there are diverging results about the effectiveness of phonophoresis and iontophoresis, but none of them suggests that phonophoresis is superior to iontophoresis in treating musculoskeletal conditions. Instead, evidence indicates that iontophoresis improves grip strength and other parameters that phonophoresis does not appear to change.
According to the scientific data, iontophoresis is equally effective than Cyriax physiotherapy, which includes a series of manual techniques to improve the function of the ligaments in lateral epicondylitis. However, another critical finding in both phonophoresis and iontophoresis is that they show better results when combined with stretching and strengthening exercises, lifestyle modifications, and other traditional treatments.