Injection Techniques for Common Chronic Pain Conditions of the Foot: A Comprehensive Review

Key points

• Foot and ankle pain affects one in five people over 50, limits mobility and daily activities and increases the risk of falls.
• Injections can relieve pain in several chronic foot conditions, but the evidence is limited and the benefit has been short-lived in most cases.
• Injection therapy is more likely to help when the cause is inflammatory, such as gout, osteoarthritis or rheumatoid arthritis, than when it is anatomical or compressive.
• In Morton's neuroma, steroid, alcohol and capsaicin injections give short-lived relief, while hyaluronic acid reduced pain for over a year in one study.
• Ultrasound guidance improves the accuracy of foot and ankle injections.

Overview

This comprehensive review in Pain and Therapy describes common chronic pain conditions of the foot and the injection techniques used for each: Morton's neuroma, Achilles tendinopathy, tarsal tunnel syndrome, plantar fasciitis, gout, ankle osteoarthritis, rheumatoid arthritis and posterior tibial tendon dysfunction. Chronic foot pain has traditionally been treated with costly surgery of variable efficacy; foot and ankle surgery for chronic pain has cost the US Medicare population around 11 billion dollars since 2000. The authors see injections as a financially attractive alternative but stress that larger studies of long-term effects are needed, and that the choice of technique should be made for each patient.

Morton's neuroma, Achilles tendinopathy and tarsal tunnel syndrome

Morton's neuroma is a bulging of the interdigital nerve, usually in the third intermetatarsal space. Corticosteroid injections improve symptoms only temporarily and may cause injection-site pain, skin and pigment changes and tissue atrophy. Alcohol injections work better at higher concentrations but should be used only if better-supported treatments fail; injected capsaicin relieved pain for at least 12 weeks; and an ultrasound-guided hyaluronic acid injection reduced pain for more than a year. In Achilles tendinopathy, injections are not yet sufficiently supported: a meta-analysis found no difference between platelet-rich plasma (PRP) and saline in VISA-A scores, and prolotherapy improved VISA-A scores by 79% compared with 73% with eccentric loading exercises, without a significant difference over time. Tarsal tunnel syndrome is a compressive neuropathy of the posterior tibial nerve that can cause permanent nerve injury; no randomised trials of injections exist, anaesthetic or steroid injections are used as initial therapy, and surgical release remains the definitive treatment when conservative care fails. In one study, six of nine patients had symptom relief after steroid injection, but only two showed improved nerve conduction.

Plantar fasciitis

Plantar fasciitis affects about 10% of the population. Injected corticosteroids improved heel pain within the first month but had no effect between one and six months. Results comparing PRP with corticosteroids conflict, and in a randomised trial with 36 months of follow-up, corticosteroid, PRP, shock wave therapy and prolotherapy each helped for a period, but none produced a long-term improvement in pain compared with baseline. These treatments were safe, with side effects limited to brief redness or throbbing pain; PRP was linked to fewer repeat injections or surgery but costs more.

Gout, osteoarthritis and rheumatoid arthritis

Intra-articular corticosteroids are recommended for gout by the European League Against Rheumatism and the American College of Rheumatology, although no randomised trials have tested them in foot gout; in one series of 21 patients, ultrasound-guided triamcinolone with lidocaine into the first metatarsophalangeal joint improved pain within 48 hours without adverse events. In foot and ankle osteoarthritis, ultrasound-guided injection into cadaveric midfoot joints was accurate in 64% of cases compared with 24% using landmarks alone. Evidence for corticosteroids in ankle osteoarthritis is limited to two studies; of 18 studies of hyaluronic acid, all seven randomised trials reported significant relief, and pooled data showed better pain relief than saline at six months. PRP gave relief for up to 24 weeks in one study and an average of 17.7 months in another, and a single study of mesenchymal stem cells in six patients reported marked improvement at 30 months. In rheumatoid arthritis of the ankle, intra-articular steroids relieved pain for one to 12 weeks, and in a study of 100 patients intra-articular methotrexate had a longer anti-inflammatory effect than corticosteroids.

Posterior tibial tendon dysfunction

Posterior tibial tendon dysfunction causes collapse of the medial longitudinal arch and affects about 3.3–10% of the population, most often women over 40. Lidocaine injection into the tendon sheath gave complete initial relief in all treated ankles in one study. Blind injection carried a risk of wrong placement (11%) or neurovascular injury, and ultrasound guidance improved accuracy for both anaesthetic and botulinum toxin injections.

Frequently asked questions

Do foot injections give lasting pain relief?

Usually not. Most reported benefits were short-lived, and in plantar fasciitis no injection treatment improved pain at 36 months compared with baseline.

When are foot injections most likely to help?

When the pain has an inflammatory cause, such as gout, osteoarthritis or treatment-resistant rheumatoid arthritis. In compressive conditions such as tarsal tunnel syndrome, injections may only bridge the time to surgery.

Is this a formal guideline?

No. It is a narrative review of published studies; most of the evidence comes from small trials, and the authors call for larger studies.

Source

Urits I, Smoots D, Franscioni H, et al. Injection Techniques for Common Chronic Pain Conditions of the Foot: A Comprehensive Review. Pain Ther 2020;9(1):145-160. DOI: 10.1007/s40122-020-00157-5. Open access. Summary prepared by Medpresso from the original publication; it is not a substitute for the full text or for medical advice.