Research in Focus: Effectiveness of ESWT for treating Chronic Insertional Achilles Tendinopathy

  •   March 9, 2020

Full Citation: Pinitkwamdee S, Laohajaroensombat S, Orapin J, Woratanarat P. Effectiveness of Extracorporeal Shockwave Therapy in the Treatment of Chronic Insertional Achilles Tendinopathy. American Orthopaedic Foot & Ankle Society. 2020. Doi: 10.1177/1071100719898461

Background

Achilles tendinopathy is a common overuse injury that can lead to decreased sports or activities of daily living (ADL) participation. It is characterized by tendon pain, swelling, and impaired performance. Extracorporeal Shockwave Therapy (ESWT) is thought to “stimulate nitric acid production, reduce pain, inflammation and substance P, and induce tenocyte proliferation.”1

ESWT has been proposed as a supplement to conservative treatment approaches for Achilles tendinopathy; however, research is limited and studies have not included a sham control group.1 The purpose of this study was to measure the effect of ESWT vs Sham in combination with conservative treatments in patients with chronic insertional Achilles tendinopathy.

Methods

  • Double-blind trial
    • Patients treated in prone, unable to see the application of the intervention.
    • Outcome assessors blinded to group allocation.
  • Intervention group
    • Radial shockwave
    • Applied at the point of maximum tenderness at the Achilles insertion
    • Treated once weekly for four treatments
    • Combined with standard conservative treatment (defined as rest, medication, activity modification, stretching exercise and heel lift orthosis)
  • Control group
    • Radial shockwave probe applied at Achilles insertion, with ultrasound gel
    • Probe was disconnected from the machine
    • Second probe (not in contact with the patient) was activated to “generate the shockwave sound”
    • Also received standard conservative treatment
  • Randomized allocation to intervention or control group
  • Inclusion Criteria
    • Patients aged 18-70
    • Diagnosis of insertional Achilles tendinopathy
    • Symptoms for > six months
    • “Failed” conservative treatment for three months
  • Exclusion criteria
    • Corticosteroid injection within four weeks of enrollment in the study
    • Non-insertional Achilles tendinopathy
    • Neurological deficit
    • History of foot and ankle infection or trauma
    • Foot and ankle deformity
    • History of foot and ankle surgery
    • Contraindication for shockwaves (hemophilia, coagulopathy, or foot and ankle malignancy)
  • Outcomes assessed
    • VAS (primary outcome) and VAS-FA Thai Version (secondary outcome, previously validated with the SF-36 Thai version)
    • Assessed at two, three, four, six, 12 and 24 weeks

Findings

  • Both ESWT and Sham groups showed significant reduction in VAS over time.
    • ESWT group showed statistically significant reduction in VAS at four, six and 12 weeks
    • Sham group showed statistically significant reduction in VAS at weeks 12 and 24
  • After repeated measurement analysis, there was no significant between group differences for VAS or VAS-FA at any time point
  • Four patients in the ESWT intervention group (N=16) experienced complications
    • Pain (N=2)
    • Failed ESWT, with referral for surgical intervention (N=2)
  • No complications were reported in the Sham control group

Analysis

Although the ESWT group demonstrated a reduction in VAS at earlier time points in the analysis, both groups demonstrated reduction in VAS over time. There were no statistically significant between group differences in the VAS or VAS-FA at any time. The authors did not report a between group clinically significant of reduction in VAS2 at any time.

Given the lack of between-group differences and the increased incidence of complications with ESWT versus Sham, further research is needed to determine the safety and effectiveness of ESWT in this patient population.

Limitations

  • Patient Sample
    • Convenience sample
    • Small sample size: the authors recruited a total of 31 patients for inclusion in the study
    • Average age of the sample was 60 years, therefore may not reflect the general population
  • Patient blinding
    • The authors employed Sham ESWT that generated a sound similar to ESWT, however, the Sham did include a pulsing tactile aspect characteristic of ESWT.
    • Previous treatment with ESWT (for Achilles tendinopathy or other) was not an exclusion criterion for the study.

Relevance to physiotherapy practice in Alberta

Despite limited evidence to support its use, ESWT is an intervention that many Alberta physiotherapists employ in practice for a range of conditions. Physiotherapists wishing to adopt emerging treatment methods must be aware of the nature and quality of the available evidence and must modify their clinical practice accordingly to demonstrate evidence-informed practice. Physiotherapists who adopt emerging interventions also have a professional responsibility to analyze the outcomes data from their own patient populations to critically assess the impact of interventions selected.

Disclaimer: The purpose of this summary is to highlight recently published research findings that are not openly accessible. Every effort is made to ensure accuracy and clarity of the summary. Readers are encouraged to review the published article in full for further information.


  1. Pinitkwamdee S, Laohajaroensombat S, Orapin J, Woratanarat P. Effectiveness of Extracorporeal Shockwave Therapy in the Treatment of Chronic Insertional Achilles Tendinopathy. American Orthopaedic Foot & Ankle Society. 2020. Doi: 10.1177/1071100719898461
  2. Sutton RM, McDonald EL, Shakked RJ, Fuchs D, Raikin SM. Determination of Minimum Clinically Important Difference (MCID) in Visual Analog Scale (VAS) Pain and Foot and Ankle Ability Measure (FAAM) Scores After Hallux Valgus Surgery. Foot & Ankle International 2019. 40(6):687-693.