Acetic Acid Iontophoresis for 'Dissolving' the Heel Spur

Acetic acid iontophoresis is a non-invasive therapeutic procedure in which acetic acid (usually a 5% solution) is delivered into tissues using a low-voltage electric current. Negatively charged acetate ions are driven through the skin by the current, targeted to areas of calcification. The theoretical basis is that acetate ions react with otherwise insoluble calcium deposits (for example calcium carbonate), forming calcium acetate — a more soluble compound that can be removed by the bloodstream.

Acetic acid iontophoresis has been used for decades to treat conditions associated with calcification — the earliest reports date from 1955 and 1977 — including calcific shoulder tendinitis, myositis ossificans and calcifying bursitis. The goal is to increase calcium solubility, thereby dissolving or reducing painful calcifications.

The heel spur is a calcified outgrowth on the heel bone, often a consequence of chronic plantar fascia inflammation (plantar fasciitis). Although many heel spurs are asymptomatic, they more commonly cause severe, nagging pain. The theoretical aim of acetic acid iontophoresis for a heel spur is to reduce the size of the spur and alleviate the associated soft tissue inflammation. The procedure is usually applied using a sponge electrode and an adhesive electrode over the heel (the acetic acid is placed on the negative electrode). Treatments are performed once daily for a minimum of 20 days. The treatment appeared more effective when combined with other therapies, such as stretching, taping or ultrasound therapy. Ultrasound treatment is recommended after the iontophoresis session. The area over the spur should be treated for 5 minutes at medium intensity. The M-Sonic 950 device, for example, is suitable for this.

Clinical Studies

Case Reports

Early evidence for the use of acetic acid iontophoresis to treat calcaneal heel spurs comes from case reports. These are observational experiences and cannot be regarded as definitive clinical proof.

Japour et al. (1999) reported on 35 patients with chronic heel pain. This was an uncontrolled observational study, but the results were notable: 94% of patients reported complete or significant pain reduction after an average of 5.7 treatment sessions (~2.8 weeks). Patient pain scores (on a 0–10 scale) decreased from 7.5 to 1.8, and at long-term follow-up (mean 27 months later) the mean pain score was only 0.64. Furthermore, 94% said they would recommend the treatment to others.

Another case reported by Costa (2008) described a 15-year-old footballer treated for chronic plantar fasciitis that had not responded to other therapies. The patient received acetic acid iontophoresis for four weeks, supplemented with ultrasound and combined with an insole. Symptoms resolved within six weeks, and the patient returned fully to sport.

Nikhade et al. (2014) described a 29-year-old woman with an X-ray-confirmed 9×5 mm heel spur. The patient received five treatments per week for three weeks, then three treatments per week for a further three weeks, during which 80 mA·minute dose acetic acid iontophoresis and ultrasound were applied. At the end of treatment (~6 weeks, ~24 sessions) radiography showed approximately an 85% reduction in spur size, and her pain resolved completely (VAS 7/10 to 0/10).

Controlled Trials

An early randomized trial (Cairo University, 2001) investigated reducing spur size and relieving pain. Thirty patients were randomized into two groups: one group received acetic acid iontophoresis and stretching exercises, while the other group received ultrasound therapy and the same stretching. Both groups underwent nine treatments over three weeks. The results indicated that acetic acid iontophoresis produced greater pain relief than ultrasound, but spur size did not change significantly.

Osborne and Allison (2006) conducted a randomized, double-blind, placebo-controlled trial comparing acetic acid iontophoresis to dexamethasone iontophoresis and placebo iontophoresis. The study included 31 patients (42 affected feet) who received six treatments over two weeks. Results showed improvement in all groups (including placebo), but the acetic acid group achieved greater pain reduction and better morning mobility at four weeks.

Summary

Acetic acid iontophoresis can be considered a treatment option for heel pain associated with a heel spur.
According to some clinical teams, significant pain relief may be achieved within 2–4 weeks, although reduction in spur size is variable and not guaranteed. The therapy is best combined with other conservative measures, such as stretching exercises and ultrasound.
While acetic acid iontophoresis does not usually literally "melt" the spur, clinical studies support that it can be an effective tool to reduce pain and improve function.