Achilles Tendinopathy; the Effect of Shockwave Treatment

July 1, 2026 updated by: Vastra Gotaland Region

Comparison of Two Treatment Methods for Achilles Tendon Pain With a Focus on Pain, Function, Vascular Ingrowth, Immune Cell Response, and Cell Composition

BACKGROUND Achilles tendinopathy-pain in the Achilles tendon-is a common and often long-lasting condition that limits physical activity and performance, and also affects work capacity and quality of life. The pain is localized either to the mid- portion of the tendon or at its insertion into the calcaneus. Although individually tailored exercise is the first-line treatment, symptoms persist in many patients, highlighting the need for adjunctive therapies.

AIM This interdisciplinary and innovative research project aims to evaluate the effect of shockwave therapy in Achilles tendinopathy, both in cases where the pain is located in the mid-portion of the tendon and where it is situated at the tendon's insertion. In addition to assessing effects on pain and function, the study will examine the impact on calcifications, neovascularization (evaluated via Doppler ultrasound), and-uniquely-systemic immunological effects, with a focus on NK cells in the blood, an area that remains largely unexplored. METHOD This is a randomized controlled trial (RCT) with four arms, including 200 patients divided into two groups based on pain location. Half of the participants will receive adjunctive shockwave therapy in six sessions, in addition to exercise following the protocol by Silbernagel et al. The primary outcome measure is self-reported pain assessed using the Numeric Rating Scale (NRS) 0-10 at 12 months.

Secondary outcomes include function, assessed through patient-reported outcomes (Victorian Institute of Sport Assessment-Achilles Swedish version, VISA-AS), calf muscle strength and endurance, and jumping ability using a validated test battery. Neovascularization and tendon cross-sectional area will be evaluated using ultrasound/Doppler.

In a sub-cohort, immune cell composition in blood will be analyzed using flow cytometry before and after treatment. For patients undergoing surgery, tissue samples will also be collected for cellular composition analysis.

SIGNIFICANCE This project has the potential to improve treatment strategies, reduce the need for surgery, and generate entirely new knowledge about the relationship between local tissue pathology and systemic immune responses.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

Pain in the Achilles tendon, Achilles tendinopathy, is a common musculoskeletal condition affecting adults of all ages. The condition is characterized by localized pain and swelling in the Achilles tendon, particularly during tendon loading, functional limitations, and, in chronic cases, pathological neovascularization. Achilles tendinopathy is considered a typical overuse injury, and the diagnosis is made clinically. The incidence is reported to be 2/1000 per year, which would mean that approximately 1,400 individuals are affected each year in the Gothenburg area alone. A recent study from the United Kingdom has also shown that the typical patient is not physically active-as many clinical guidelines are designed for-but rather between 50 and 60 years old, has a high BMI, and often presents with comorbidities such as hypertension and diabetes. This highlights the need to review current clinical guidelines and evaluate the evidence for alternative treatments.

The pain is usually load-related and located either in the midportion of the Achilles tendon or at its insertion on the calcaneus. The condition is often long-lasting despite adequate treatment, and in addition to limiting physical activity, it can also affect work ability and quality of life. Non-operative treatment with heel-raise exercises and load management-appropriately dosed exercise-is the first-line standard, although long-standing or treatment-resistant cases may require adjunct therapies. Among these, extracorporeal shockwave therapy (ESWT), administered either radially (rESWT) or focally (fESWT), has emerged as a promising intervention in several studies, although it has been questioned in others. Shockwave therapy targets both pain relief and restoration of function, but its effects on pain, function, tendon morphology, and immune cell levels remain largely unexplored.

Recent systematic reviews have emphasized the need for higher-quality studies to determine whether adding shockwave therapy is beneficial for patients with Achilles tendinopathy. Evidence remains limited regarding whether shockwave therapy provides comparable pain relief for midportion versus insertional pain. Furthermore, it is unclear whether shockwave therapy must be combined with heel-raise exercises and load management or whether it can function as a standalone treatment.

Doppler ultrasound is commonly used to quantify neovascularization in the tendon. Some studies have shown that shockwave therapy induces transient increases in neovascularization that coincide with clinical improvement, while others have found no effect on neovascularization. Tendon thickness and the effect of shockwave therapy on intratendinous calcifications have also been investigated, but no consensus has been reached. Much of this research area remains unexplored due to the small number of studies and limited sample sizes.

Despite a growing evidence base suggesting that appropriately dosed exercise combined with shockwave therapy may be beneficial for tendon injuries, several areas remain under-investigated. Notably, no publications have been found on whether the micro-injuries potentially induced by shockwave therapy may cause systemic effects and thereby alter immune cell levels. Unpublished data from our research group have shown that early loading of a ruptured Achilles tendon increases circulating NK-cell levels, but whether this also applies to a painful tendon with potential tendinosis changes is unknown.

The aim of this project is to evaluate two different treatment methods for patients with Achilles tendinopathy-appropriately dosed exercise alone or appropriately dosed exercise combined with shockwave therapy-with a focus on:

Pain and muscle function

Neovascularization and calcifications in the tendon

Systemic changes in immune cell composition in the blood, with a focus on NK cells and CD8+ T cells

Hypotheses Appropriately dosed exercise combined with shockwave therapy leads to reduced pain and improved function compared with appropriately dosed exercise alone.

Appropriately dosed exercise combined with shockwave therapy reduces neovascularization and calcifications in the tendon.

Appropriately dosed exercise combined with shockwave therapy induces micro-injuries in the tendon that generate a systemic immune response (higher levels of NK cells and CD8+ T cells).

Appropriately dosed exercise combined with shockwave therapy has similar effects regardless of whether the pain is located in the midportion of the Achilles tendon or at its insertion.

Significance This project has the potential to improve the treatment of Achilles tendinopathy by identifying which patients benefit from shockwave therapy and by increasing the understanding of the biological effects of different treatment methods. The results may contribute to more individualized treatment and reduce the need for surgical interventions.

Study Type

Interventional

Enrollment (Estimated)

200

Phase

  • Not Applicable

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Women and men over 18 years of age who seek care for load-related pain in the midportion of the Achilles tendon or at the Achilles tendon insertion at a Physiotherapy Clinic in Primary Care, at the Physiotherapy Department at Sahlgrenska University Hospital/Mölndal, or at the Orthopedic Department at Sahlgrenska University Hospital/Mölndal.
  • Symptoms must have been present for one month or longer.
  • Symptoms may be present in one or both Achilles tendons.

Exclusion Criteria:

  • Unwillingness to receive shockwave therapy.
  • Previous shockwave therapy for Achilles tendon pain within the past year.
  • Neurological disease, significant cardiac conditions, increased bleeding tendency, treatment with anticoagulant medication, pregnancy, or presence of a tumor in the foot.
  • Corticosteroid injection in the foot within the past six months.
  • Reduced sensation, acute inflammation, or any wound around the heel.
  • Inability to understand or speak Swedish.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Achilles Tendinopathy, exercise therapy and additional treatment with shockwave
Patients with Achilles Tendinopathy receiving exercise therapy with regular follow-ups and additional treatment with shockwave.
Device: individually tailored exercises and Radial Shockwave
Shockwave: 5-6 treatments with radial shockwave, 10 bar, 2000-4000 pulses as an additional treatment to individually tailored exercises.
Active Comparator: Achilles Tendinopathy, exercise therapy
Patients with Achilles Tendinopathy receiving exercise therapy with regular follow-ups
Other: Individually tailored exercises
Individually tailored exercises
Experimental: Insertional Achilles Tendinopathy, exercise therapy and additional treatment with shockwave
Patients with Insertional Achilles Tendinopathy receiving exercise therapy with regular follow-ups and additional treatment with shockwave.
Device: individually tailored exercises and Radial Shockwave
Shockwave: 5-6 treatments with radial shockwave, 10 bar, 2000-4000 pulses as an additional treatment to individually tailored exercises.
Active Comparator: Insertional Achilles Tendinopathy, exercise therapy
Patients with Insertional Achilles Tendinopathy receiving exercise therapy with regular follow-ups
Other: Individually tailored exercises
Individually tailored exercises

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in self-reported pain from baseline to 12 months after treatment start
Time Frame: At baseline and after 12 months after enrollment
Zero is equivalent to no pain and 10 indicates the worst possible pain.
At baseline and after 12 months after enrollment

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in self-reported pain 3 and 6 months after treatment start
Time Frame: At baseline and after 3 and 6 months after enrollment
Zero is equivalent to no pain and 10 indicates the worst possible pain.
At baseline and after 3 and 6 months after enrollment
Rate of blood vessels in the Achilles tendon
Time Frame: At baseline and after 3, 6, and 12 month
Rate of blood vessels (n) (neovascularization) will be measured with Ultrasound in Doppler mode and compared with the healthy side.
At baseline and after 3, 6, and 12 month
Achilles Tendon cross-sectional area
Time Frame: At baseline and after 3, 6 and 12 months
Achilles Tendon cross-sectional area in square centimeters will be evaluated with ultrasound in the midportion of the tendon
At baseline and after 3, 6 and 12 months
Physical Activity Scale (PAS)
Time Frame: At baseline and after 3,6 and 12 months
A patient reported outcome used for the purpose to evaluate the patients self estimated physical activity level. The scale is from 1 to 6 and the higher score, the better outcome.
At baseline and after 3,6 and 12 months
VISA-AS
Time Frame: At baseline and after 3, 6 and 12 months
A valid and reliable questionnaire developed for patients with an Achilles Tendinopathy with a purpose to evaluate patient reported outcome in terms of symptoms and function. The values can be between 0 and 100 and the higher score, the better outcome
At baseline and after 3, 6 and 12 months
Heel-rise height during heel-rise work test
Time Frame: At baseline and after 3, 6 and 12 months
Evaluation of heel-rise height (cm) during heel-rise work test. Comparison between groups in heel-rise height Limb Symmetry Index (LSI) - injured side/healthy side *100 expressed in percent. The range in LSI is between 0-100% and the higher value, the better outcome
At baseline and after 3, 6 and 12 months
Evaluation of lower leg endurance with heel-rise work (Joule)
Time Frame: At baseline and after 3, 6 and 12 months
Evaluation of lower leg endurance with heel-rise work (Joule) during heel-rise work test. Comparison between groups in heel-rise work Limb Symmetry Index (LSI) - injured side/healthy side *100 expressed in percent. The range in LSI is between 0-100% and the higher value, the better outcome
At baseline and after 3, 6 and 12 months
Numbers of heel-rises during heel-rise work test
Time Frame: At baseline and after 3, 6 and 12 months
Evaluation of numbers of heel-rises during heel-rise work test. Comparison between groups in numbers of heel-rises Limb Symmetry Index (LSI) - injured side/healthy side *100 expressed in percent. The range in LSI is between 0-100% and the higher value, the better outcome
At baseline and after 3, 6 and 12 months
Calf muscle power
Time Frame: At baseline and after 3, 6 and 12 months
Evaluation of calf muscle power in a weight training machine expressed in watt (Newton x meter /seconds). Comparison will be performed between groups and limbs in power (LSI)- injured side/healthy side *100 expressed in percent.The range in LSI is between 0-100% and the higher value, the better outcome
At baseline and after 3, 6 and 12 months
Drop Countermovement Jump
Time Frame: At baseline and after 3, 6 and 12 months
Drop Countermovement Jump: Evaluation of vertical jumping height after jumping from a 20 cm high box. The outcome will be measured as the height the patient can perform in jump height after landing in cm. Comparison between groups and limbs in jump height will be presented as Limb Symmetry Index (LSI)- injured side/healthy side *100 expressed in percent. The range in LSI is between 0-100% and the higher value, the better outcome.
At baseline and after 3, 6 and 12 months
Hopping
Time Frame: At baseline and after 3, 6 and 12 months
Evaluation of series of jumps as in jumping ropes. The outcome measurement will be mean jumping height in cm and elasticity ratio in 20 jumps. Comparison between groups and limbs in jump height and elasticity ratio will be presented as Limb Symmetry Index (LSI)- injured side/healthy side *100 expressed in percent. The range in LSI is between 0-100% and the higher value, the better outcome
At baseline and after 3, 6 and 12 months
Range of motion in the ankle
Time Frame: At baseline and after 3, 6 and 12 months
Range of motion in both ankles will be measured with an inclinometer in degrees both with the knee bent and with the knee straight. Comparison between groups and limbs in jump height will be presented as Limb Symmetry Index (LSI)- injured side/healthy side *100 expressed in percent. The range in LSI is between 0-100% and the higher value, the better outcome.
At baseline and after 3, 6 and 12 months

Other Outcome Measures

Outcome Measure
Measure Description
Time Frame
Blood samples will be collected to assess changes in immune cell composition, focusing on NK and CD8+ T cells.
Time Frame: At baseline and after 4-6 weeks
10 ml blood will be collected at two times from a cohort of the population. Flow cytometry and antibody staining will be used for immune profiling.
At baseline and after 4-6 weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Vastra Gotaland Region

Collaborators

Göteborg University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

September 1, 2026

Primary Completion (Estimated)

December 31, 2029

Study Completion (Estimated)

December 31, 2031

Study Registration Dates

First Submitted

June 25, 2026

First Submitted That Met QC Criteria

July 1, 2026

First Posted (Actual)

July 6, 2026

Study Record Updates

Last Update Posted (Actual)

July 6, 2026

Last Update Submitted That Met QC Criteria

July 1, 2026

Last Verified

June 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 2026-01721-01 (Other Identifier: The Swedish Ethical Review Authority)
  • P2026-0030 (Other Grant/Funding Number: Swedish Research Council for Sport Science)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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