Dry Needling Therapy as a Potential Treatment Option for Plantar Fasciitis

Plantar fasciitis is one of the most common causes of inferior heel pain and it affects individuals of all ages and activity levels. Estimates cite that plantar fasciitis accounts for approximately 1 million annual physician visits in the United States^1,2 with treatment costs estimated between $192 and $276 million.³
 
Clinically, plantar fasciitis is defined as insidious sharp pain and discomfort at the medial tubercle of the calcaneus that is worse with initial weight-bearing steps after long periods of inactivity.4 Although the word “fasciitis” suggests an inflammatory condition, research shows that the mechanism underlying the onset of plantar fasciitis may be more related to advanced fascial degeneration similar to tendinosis.⁵
 
Treatment for plantar fasciitis comprises different strategies that range from conservative intervention to corticosteroid injection to surgical intervention. According to clinical guidelines, conservative interventions are highly recommended as the first-line treatment for plantar fasciitis.⁶ Cadaveric studies have found plantar fascia strain to increase with gastrocnemius tension, with a significant correlation between passive gastrocnemius stiffness and pain intensity in individuals with plantar fasciitis.⁷ Therefore, calf stretches and plantar fascia-specific stretches are commonly recommended by health care providers to patients with plantar fasciitis to decrease tightness of the triceps surae muscles.⁶ Evidence shows that conservative treatment for plantar fasciitis is efficacious in up to 90% of the cases.⁸

How Dry Needling Works

For patients who do not experience improvement in their symptoms after continued stretching, there is a growing trend of patients seeking alternative or adjunctive treatments, including dry needling therapy (DNT), to alleviate symptoms associated with plantar fasciitis.
 
Due to improved accessibility and recognition by competitive and recreational athletes as well as individuals suffering from chronic pain, DNT is becoming more well-known as either an alternative or adjunctive strategy for the treatment and management of musculoskeletal pain disorders.⁹ DNT involves the insertion of thin, sharp needles in the muscle belly to reduce the number and sensitivity of muscle nodules, or myofascial trigger points (MTrPs), related to pain.⁷ MTrPs are commonly recognized as “muscle knots” that develop in response to repetitive stress on a specific muscle or muscle group, which can result from occupational and recreational activities.
 
A MTrP is identified by a hyperirritable taut band of hardened muscle that causes local pain, referred pain, referred tenderness, motor dysfunction, or autonomic phenomena.¹⁰ Light-microscopic studies have revealed that MTrPs present as segments of muscle fibers with contracted sarcomeres and increased diameter that prevents full lengthening and contraction of the muscle.⁸ Patients with MTrPs often have pain at either: the site of the MTrP itself, the origin or insertion of the affected muscle due to pulling by the muscle fibers that have been stretched by contraction knots, or referred pain outside the MTrP.¹¹ From peripheral sensitization of muscle nociceptors in MTrPs, patients with MTrPs experience tenderness to pressure on the muscle, or pain with movement or exercise.¹¹ MTrPs within the triceps surae have therefore been theorized to play a role in pain associated with plantar fasciitis by generating myofascial pain syndrome (MPS), a common condition associated with regional pain and muscle tenderness, without the need for associated pathology.¹²
 
There are various types of dry needling, which include deep dry needling with pistoning, deep dry needling with collagen stretching, neurological dry needling, electrical stimulation dry needling, and superficial dry needling. Deep dry needling with pistoning is commonly performed for the treatment of MTrPs in the triceps surae muscles (Figure 1).¹³ Once the palpating hand identifies the location of the MTrP, the needling hand places the needle and guide tube over the site and the needle is gently tapped into the epidermis. Using the dominant hand, the needle is pushed perpendicular and deep into the muscle to penetrate the MTrP. There are two options once the needle pierces the MTrP: leaving the needle in place for up to 20 minutes, or pistoning of the needle in and out of the muscle, causing a twitch response. As acetylcholine is depleted at the motor end plate with the pistoning technique, twitching will cease and the needle is then removed from the body.⁹
 

The therapeutic effects of DNT are maximized through correct identification of MTrPs, or hypersensitive nodules in the muscle belly, which are detected using flat palpation or pincer grip technique.^4,14 In Travell and Simons’ Myofascial Pain and Dysfunction: The Trigger Point Manual, the authors describe MTrPs in the gastrocnemius and soleus muscles to cause referred pain to the plantar aspect of the heel (Figures 2 and 3) and occasionally the ipsilateral sacroiliac joint.¹³ These MTrPs commonly found in the triceps surae muscles mimic the heel pain often associated with plantar fasciitis. Accordingly, treating plantar fasciitis symptoms alone without addressing the symptoms associated with MTrPs may potentially leave the primary issue unresolved.¹³
 

Plantar fasciitis pain is often correlated with increased plantar fascia thickness and lower plantar fascia echogenicity, which are commonly assessed in podiatric practice using ultrasound before and after conservative treatment to determine treatment efficacy.^4,14 DNT of the triceps surae muscles has been found to cause a significant reduction in plantar fascia thickness and heel pain without significant impact on ankle dorsiflexion and plantarflexion range of motion.^11,16
 
A randomized controlled trial conducted by Salehi and colleagues suggests that a combination of dry needling and stretching exercises, compared to stretching alone, is more effective for improving pain and function in patients with plantar fasciitis after 6 weeks of intervention.⁴ Plantar fascia thickness and echogenicity were measured at 2 points and 2 regions, respectively, to ensure that changes were not influenced by measurement location as the plantar fascia is thicker proximally than distally. After the intervention, the study noted a significant difference in plantar fascia thickness and echogenicity favoring the group that received dry needling and stretching exercises versus the group that only did stretching exercises. The results of this study suggest that the combination of dry needling exercises has a high efficacy for decreasing plantar fascia thickness at the insertion and a moderate to high efficacy for increasing plantar fascia echogenicity. However, the muscles of the lower extremity that received DNT were not standardized among patients as different lower extremity muscles were selected based on the locations of MTrPs found on each patient. The muscles that were treated with DNT included the abductor hallucis, quadratus plantae, soleus, flexor digitorum brevis, gastrocnemius, and tibialis posterior muscles. Further research is warranted to investigate the effectiveness of DNT on the various lower extremity muscles.⁴
 

Corticosteroid injections (CSI) are widely used to treat the symptoms of plantar fasciitis due to the anti-inflammatory effect that results from down-regulation of pro-inflammatory cytokines and corticosteroid are recommended as a tier 1 treatment option by the American College of Foot and Ankle Surgeons (ACFAS).^17,18 Although CSI is a safe intervention with post-injection pain as the only reported short-term adverse effect, the long-term results of CSI for plantar fasciitis must be considered because studies have found an increased risk of plantar fascia rupture after CSI which may result in long term sequelae that is difficult to resolve.^19,20 When comparing pain as a primary outcome of CSI versus DNT, a systematic review reveals that CSI appears to be superior to DNT for reducing musculoskeletal pain and disability in short- and medium-term conditions (≤6 weeks).¹⁷ However, DNT appears to be more effective than CSI in the long-term (≥6 weeks).¹⁷ It is important to note that these findings are based off low-quality evidence, and large randomized control trials with higher methodological quality are required to draw more definite conclusions.
 
There is considerable variability in the literature for the efficacy of DNT as a treatment option for plantar fasciitis due to the small sample size and heterogeneity in DNT techniques used among clinical trials. A high risk of bias is also prevalent among DNT research given the lack of double blind randomized controlled trials, and only one study blinded plantar fasciitis participants through a sham dry needling intervention.²² Success of DNT is largely dependent on one’s technical experience. Moreover, insufficient standardization of DNT protocol further contributes to the lack of conducive evidence to support DNT as an effective treatment for plantar fasciitis.²² As with all procedures, appropriate patient selection is essential prior to either rendering or referring patients for DNT.
 
The following patients should not be considered for dry needling treatment: Patients currently on anticoagulant therapy (except acetylsalicylic acid at doses up to 325 mg/day); those with coagulopathy; patients with dermatological disease in the area of needling; patients with lymphedema in the limb of concern; and those who are at risk of adverse effects.²³

In Conclusion

Plantar fasciitis is a common pedal condition that accounts for an estimated 11–15% of all foot complaints requiring professional care in adults.²⁴ The cause of plantar fasciitis is multifactorial and MPS may be another potential etiology to be considered by health care providers when treating patients with plantar fasciitis. While the majority of plantar fasciitis is successfully treated with conservative care, DNT may serve as an alternative or adjunctive treatment modality in patients who have not experienced pain relief with calf stretches. Research shows that DNT for plantar fasciitis is most effective when performed in conjunction with stretching exercises, versus DNT or stretching alone.⁴ However, further research is still necessary to establish the efficacy of DNT for heel pain.
 
Sonia Chuang, BS is a third year student at the Dr. William M. Scholl College of Podiatric Medicine. All illustrations in this feature are her original work.

Noah Rosenblatt, PhD is Associate Professor, Podiatric Medicine and Surgery and Associate Dean of Research, Dr. William M. Scholl College of Podiatric Medicine at Rosalind Franklin University of Medicine and Science.
 
Stephanie Wu, DPM, MSc, FACFAS is the Dean, Professor of Surgery, and Professor of Stem Cell and Regenerative Medicine at Dr. William M. Scholl College of Podiatric Medicine at Rosalind Franklin University of Medicine and Science.

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