BMI: body mass index

CGRP: calcitonin gene-related peptide

D5W: dextrose 5% water

FDL: flexor digitorum longus

FHL: flexor hallucis longus

RM score: Roles and Maudsley (RM) score

TN: tibialis nerve

TP: tibialis posterior

TRPV1: transient receptor potential vanilloid receptor 1

VAS: visual analog scale

Plantar fasciitis is a common worldwide source of heel pain, affecting subjects across ages. Treatment options varied; however, they were often unsatisfactory. Corticosteroid injection, one of the most popular intervention procedures, offers an early onset of effect but is often not sustainable and carries several risks of side effects.^[1,2]

The use of dextrose 5% water (D5W) injection in musculoskeletal pain is gaining popularity since it downregulates transient receptor potential vanilloid receptor 1 (TRPV1) which is involved in pain and inflammation.^[3,4] To enhance its safety and effectiveness in ameliorating pain, the ultrasound-guided hydrodissection D5W injection technique might be performed.^[5] This case series aimed to evaluate the efficacy and patient-reported outcomes of ultrasound-guided perineural tibial nerve (TN) D5W injection using the hydrodissection technique for the treatment of plantar fasciitis.

A 52-year-old active housewife sought a consultation at a pain clinic for 6 months of stabbing left heel pain when she stood up after sleeping or sitting down. She had no history of trauma. She had tried various treatment methods, including oral analgesics and landmark-guided steroid heel injections, with no complete relief of her pain; instead, she felt unpleasant pain during injection procedures. She had no history of chronic illness. Her body mass index (BMI) was 22.5 kg/m². Physical examination revealed tenderness at her left plantar medial calcaneal tuberosity. Plain radiography showed plantar calcaneal enthesophyte(Fig. 1a). Musculoskeletal ultrasound demonstrated an increase in thickness of the left plantar fascia, disruption of the compact fibular pattern, and increased hypoechogenicity, confirming the diagnosis of plantar fasciitis(Fig. 1b). She looked for a less painful, safe, and more durable treatment option. After consent, a three-milliliter out-of-plane ultrasound-guided D5W was injected perineural to TN using a hydrodissection technique and a 25-gauge one-inch needle, posterior to the medial malleolus with the patient lying in a supine position(Fig. 1c). No anesthetic agent was given. Two sessions of injection were conducted, one week apart, resulting in a significant pain reduction, with visual analog scale (VAS) scores improving from 6/10 to 1/10. Her Roles and Maudsley (RM) score was decreased from 4 to 1. She expressed great satisfaction with the present method due to less painful injections and effectiveness in relieving pain. She was advised to avoid high-heel footwear and wore appropriate footwear daily. A one-month follow-up showed no recurrence of pain (VAS 0/10) with a persistent RM score of 1 and no limitation in activity.

A 60-year-old overweight man presented to the clinic with on-and-off dull pain and stiffness at his left heel for 5 months. He was an active businessman and had no history of trauma prior to the symptoms. The pain interfered with his daily busy activities. He had sought a consult previously and been prescribed various oral analgesics with no significant improvement; instead, he had increased his creatinine level. He had undergone serial acupuncture treatments with no satisfactory relief in pain, yet he suffered unpleasant pain during heel puncture sessions. His comorbidities were dyslipidemia, chronic kidney disease, and hypertension. His blood pressure was 150/92 mmHg and stable with other vital signs. His serum creatinine was 1.4 mg/dl. During physical examination, local medial left heel pain with a VAS of 7/10 and an RM score of 4 was noted. The Tinel sign was negative. Plain radiography demonstrated plantar calcaneal enthesophyte(Fig. 2a). Musculoskeletal ultrasound showed an increase in left plantar fascia thickness (5.1 mm), increased structural hypoechogenicity, and disruption of the compact fibular pattern, supporting the diagnosis of plantar fasciitis(Fig. 2b). Seeking a safe, minimal pain, and more effective treatment option, he agreed to a perineural tibial nerve D5W injection. A three-milliliter dose of D5W was injected out-of-plane ultrasound-guided, perineural to TN using a hydrodissection technique with a 25-gauge one-inch needle, posterior to the medial malleolus(Fig. 2c). No anesthetic agent was given. The patient was in a supine position during the procedure. Two sessions with a week apart were performed, resulting in a significant pain alleviation to 1/10 in the VAS rate, and the RM score was 1. He was advised to avoid barefoot walking, wear appropriate daily footwear, and reduce weight. We also managed the medication for his comorbid diseases well, including candesartan 16 mg once daily (OD), rosuvastatin 10 mg OD, and bicarbonate 500 mg tablet twice a day. During the one-month follow-up, he happily reported no recurrence of heel pain (VAS 0/10, RM score 1) and no stiffness. He could perform his daily business activity without any limitation due to heel pain. His blood pressure was well controlled, and there was no increase in serum creatinine level.

The D5W acts by inhibiting capsaicin-sensitive calcium channel receptors TRPV1, a prototypical nociceptive channel that is responsible for releasing neuroinflammatory mediators such as substance P and calcitonin gene-related peptide (CGRP). Desensitizing TRPV1 exhibited pain relief and anti-inflammatory effects.^[4,6]

Some studies reported the use of D5W with various techniques in musculoskeletal cases.^[7-11] There are studies of dextrose injection in treating plantar fascia, mostly as prolotherapy at the plantar fascia, reported in two meta-analyses of randomized controlled trial studies by Lai et al. and Chutumstid et al.^[12,13] Conway et al. reported the effectiveness of D5W injection perineural to the saphenous nerve at the adductor canal and deep TN at the bifurcation of the gastrocnemius muscles in treating plantar fasciitis; however, it was landmark-guided injection in quite a long period (injection every week for 8 consecutive weeks).^[14] In 2024, Darmawan et al. reported one case of plantar fasciitis successfully treated with perineural TND5W injection with a shorter treatment period (2 sessions with a week apart). Mechanistically, perineural injection is different with prolotherapy. The first focuses on neuromodulation, restoring nerve function, and the latter aims at soft tissue repairment and stimulating tissue (tendon, ligament) regeneration. This technique has the advantage of directing the most nearby nerve innervating the lesion with a less painful effect than direct plantar fascia injection. The dextrose itself might amend the hypoglycemic microenvironment around the nociceptive nerve fiber in a chronic pain condition.^[15] Moreover, perineural TND5W using the hydrodissection technique^[5] is safer than conventional plantar corticosteroid injection, for the latter carries the risk of fat pad atrophy and has short-term relief in pain. Our case series supports the positive outcome of perineural TND5W using the hydrodissection technique injection in treating plantar fasciitis and adds data on D5W safety in subjects with hypertension and chronic kidney disease.

Although no study yet compares the effectiveness of perineural TND5W injection with conventional corticosteroid injection at the heel, the meta-analysis by Lai et al. reported better long-term pain improvement in dextrose plantar fascia dextrose prolotherapy compared with corticosteroid injection. Our report has limitations in the small sample size, no long-term follow-up, and potential complication assessment. We cannot rule out the potential placebo effect since there is no comparison with a sham procedure. Further randomized controlled studies with larger sample sizes are needed to establish and generalize the effectiveness and safety of this technique and to define appropriate patients’ criteria mostly suitable for this technique.

Ultrasound-guided perineural TND5W injection using the hydrodissection technique appears to be a safe, effective, and less painful treatment modality for plantar fasciitis. Additional large randomized control trials with longer follow-up and validated outcome measures are required to strongly support the benefit of this technique.

The authors declared that no clinical trials were used in the present study.

The authors declared that no experiments on humans or human tissues were performed for the present study.

The authors certify that appropriate patient consents for publication have been obtained.

The authors declared that no experiments on animals were performed for the present study.

The authors declared that no commercially available immortalised human and animal cell lines were used in the present study.

The authors declare no conflict of interest.

This research received no external funding.

No use of AI was reported.

All data used are referenced or included in the article.

All authors made equal significant contribution to this paper.