Assessing Intratendinous Pressure and Its Correlation With Tendon Structure, Patient Characteristics, and Pain Symptoms in Individuals With and Without Midportion Achilles Tendinopathy

November 2, 2026 updated by: University Hospital, Ghent

Assessing Intratendinous Pressure and Its Correlation With Tendon Structure, Patient Characteristics, and Pain Symptoms in Individuals With and Without Midportion Achilles Tendinopathy: An Observational Study

Study type: Observational study

Aim: To assess intratendinous pressure in individuals with and without midportion Achilles tendinopathy and investigate its correlation with tendon structure, patient characteristics, and pain symptoms.

Intervention: This is a non-interventional, observational study. Intratendinous pressure is measured using an invasive measurement method (e.g., Compass Universal Hg), used in accordance with its intended purpose.

Participants: Adults aged 18-55, both male and female, including patients with clinically diagnosed Achilles tendinopathy and healthy control participants.

Outcome measures:

  • Primary: Intratendinous pressure (mm Hg)

  • Secondary:

    • Tendon structure (e.g., tendon thickness, cross-sectional area (CSA) (cm2), tendon volume (cm3) determined on ultrasound and MRI)
    • Clinical outcomes (VISA-A, TENDINS-A)
    • Patient characteristics (e.g., activity level, BMI, symptom duration, age,..)

Discussion: The study seeks to better understand whether intratendinous pressure is increased in symptomatic Achilles tendons compared to healthy individuals. It also examines whether there is an association with structural tendon changes, a range of patient-related factors and the clinical symptoms experienced by the patient. The findings may help refine the pathophysiological understanding of Achilles tendinopathy and support the development of future treatment strategies.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Not yet recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Achilles tendinopathy is a debilitating injury that is common among athletes, especially those involved in running sports. Around 30% of all runners exhibit Achilles tendinopathy with an annual incidence of 7-9%. Despite its high prevalence, the underlying pathophysiological mechanisms of Achilles tendinopathy remain incompletely understood. An emerging concept is the potential role of impaired intratendinous pressure homeostasis in the onset and progression of tendinopathy. A substantial body of in vitro and in vivo research concerning intratendinous pressure has already been conducted by Dr. Lauren Pringels, yet important knowledge gaps remain.

This observational study aims to investigate whether intratendinous pressure differs between individuals with and without Achilles tendinopathy. A secondary aim is to explore whether the intratendinous pressure correlates with tendon structure, patient characteristics, and pain symptoms.

Participants will be divided into two groups: patients clinically diagnosed with midportion Achilles tendinopathy, and asymptomatic healthy controls. The study aims to include approximately 25-30 participants per group. Participants will be recruited through sports physicians, physiotherapists, social media and study advertisements. All participants will undergo a standardized evaluation consisting of questionnaires, intratendinous pressure measurement, clinical examination and imaging assessments.

Patient-reported outcome measures will include:

  • VISA-A (Victorian Institute of Sport Assessment - Achilles)
  • TENDINS-A (TENDINopathy Severity Assessment - Achilles)

Patient characteristics such as age, sex, height, weight, BMI, activity level, and symptom duration will be recorded.

Intratendinous pressure measurement will be performed using a simple, directly invasive measurement method (e.g., Compass Universal Hg), in accordance with its intended clinical use. The patient is positioned prone on the examination table, with the foot supported in 30° plantar flexion. In this position, the tension on the tendon is virtually zero, representing the resting condition. The invasive measurement method is introduced under ultrasound guidance and the pressure is determined at the center of the tendon. Needle positioning is done at a 30° angle, in a distal direction and parallel to the collagen fibrils, to minimize tissue trauma.

In patients with Achilles tendinopathy, intratendinous pressure is measured at the point where the tendon is most swollen. In asymptomatic individuals, intratendinous pressure is measured at a fixed point.

Imaging assessments include B-mode ultrasound and MRI scans to assess tendon structure, including tendon thickness, cross-sectional area and tendon volume.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Observational

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
60

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • Belgium
      • Ghent, Belgium, 9000
        • Department of rehabilitation sciences
        • Contact:

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

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years to 55 years (Adult)

Accepts Healthy Volunteers

Yes

Genders Eligible for Study

All

Sampling Method

Non-Probability Sample

Study Population

Participants will be recruited from the outpatient clinics of UZ Gent and on the UGent campus, as well as through local physiotherapy practices and orthopedic clinics in the surrounding region. Recruitment methods include distribution of flyers, social media posts and direct referrals from healthcare providers. The study population consists of adults aged 18-55 years, including individuals with clinically diagnosed midportion Achilles tendinopathy and asymptomatic healthy controls.

Description

Inclusion Criteria healthy controls:

  • Participation in sports that strain the Achilles tendon (recreational or competitive) at least once a week
  • Age: 18-55 y/o

Exclusion Criteria healthy controls:

  • History of Achilles tendinopathy/rupture/surgery or other ankle pathology (e.g., arthritis)
  • Current pain/stiffness in the Achilles tendon (VISA-A < 100)
  • Underlying systemic diseases (rheumatological disorders, e.g., SpA, psoriatic arthritis; hypercholesterolemia; endocrine disorders)
  • Current pregnancy
  • Use of (fluoro)quinolones in the last 2 years
  • Coagulation disorders
  • Contraindication MRI scan

Inclusion Criteria patients with achilles tendinopathy:

  • Participation in sports that strain the Achilles tendon (recreational or competitive) at least once a week
  • Age: 18-55 y/o
  • Duration of symptoms: > 6 weeks and < 3 years
  • Midportion Achilles tendinopathy (a + b + c must be met) (a: Pain from 2.5 cm proximal to the posterosuperior calcaneal edge ; b: Pain during exercise anamnestic/single leg hop test (VAS-HOP) ; c: Ultrasound hypoechoic zones OR power Doppler signal OR increased APD)

Exclusion Criteria patients with achilles tendinopathy:

  • History of Achilles tendon rupture/surgery or other ankle pathology (e.g., arthritis)
  • Combination of midportion + insertional tendinopathy
  • Underlying systemic diseases (rheumatological disorders, e.g., SpA, psoriatic arthritis; hypercholesterolemia; endocrine disorders)
  • Current pregnancy
  • Use of (fluoro)quinolones in the last 2 years ; corticosteroid injection/sclerotherapy/ESWT < 3 months ago
  • Coagulation disorders
  • Contraindication MRI scan

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

  • Observational Models: CASE_CONTROL
  • Time Perspectives: CROSS_SECTIONAL

Cohorts and Interventions

Group / Cohort

Group / Cohort

A group or subgroup of participants in an observational study that is assessed for biomedical or health outcomes.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Healthy controls

Individuals without achilles tendinopathy
Diagnostic test: Intratendinous pressure measurement

Intratendinous pressure measurement will be performed using a simple, directly invasive measurement method (e.g., Compass Universal Hg), in accordance with its intended clinical use. The patient is positioned prone on the examination table, with the foot supported in 30° plantar flexion. In this position, the tension on the tendon is virtually zero, representing the resting condition. The invasive measurement method is introduced under ultrasound guidance and the pressure is determined at the center of the tendon. Needle positioning is done at a 30° angle, in a distal direction and parallel to the collagen fibrils, to minimize tissue trauma.
Patients with achilles tendinopathy

Patients with midportion achilles tendinopathy
Diagnostic test: Intratendinous pressure measurement

Intratendinous pressure measurement will be performed using a simple, directly invasive measurement method (e.g., Compass Universal Hg), in accordance with its intended clinical use. The patient is positioned prone on the examination table, with the foot supported in 30° plantar flexion. In this position, the tension on the tendon is virtually zero, representing the resting condition. The invasive measurement method is introduced under ultrasound guidance and the pressure is determined at the center of the tendon. Needle positioning is done at a 30° angle, in a distal direction and parallel to the collagen fibrils, to minimize tissue trauma.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Intratendinous pressure
Time Frame: Single measurement at baseline

Intratendinous pressure in the achilles tendon (mm Hg)
Single measurement at baseline

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Patient reported outcome measures
Time Frame: Single measurement at baseline

VISA-A (Victorian Institute of Sport Assessment - Achilles) questionnaire ; score from 0-100 (higher score is better with 100 = no dysfunction, no pain)
Single measurement at baseline
Patient reported outcome measures
Time Frame: Single measurement at baseline

TENDINS-A (TENDINopathy Severity Assessment - Achilles) questionnaire ; score ranging from 0-100 (higher score is worse with 0 = no dysfunction, no pain)
Single measurement at baseline
Patient characteristics
Time Frame: Recorded at baseline

Collection of demographic and clinical variables including: age in years
Recorded at baseline
Patient characteristics
Time Frame: Recorded at baseline

Collection of demographic and clinical variables including: sex (M/V/X)
Recorded at baseline
Patient characteristics
Time Frame: Recorded at baseline

Collection of demographic and clinical variables including: height in cm
Recorded at baseline
Patient characteristics
Time Frame: Recorded at baseline

Collection of demographic and clinical variables including: weight in kg
Recorded at baseline
Patient characteristics
Time Frame: Recorded at baseline

Collection of demographic and clinical variables including: weight and height will be combined to report BMI in kg/m²
Recorded at baseline
Patient characteristics
Time Frame: Recorded at baseline

Collection of demographic and clinical variables including: profession
Recorded at baseline
Patient characteristics
Time Frame: Recorded at baseline

Collection of demographic and clinical variables including: physical activity level (using a 6-point likert scale)
Recorded at baseline
Patient characteristics
Time Frame: Recorded at baseline

Collection of demographic and clinical variables including: duration of symptoms in weeks
Recorded at baseline
Tendon structure
Time Frame: Single measurement at baseline

Assessment of tendon characteristics using ultrasound including: tendon thickness (anteroposterior diameter in cm)
Single measurement at baseline
Tendon structure
Time Frame: Single measurement at baseline

Assessment of tendon characteristics using ultrasound including: cross-sectional area (cm²)
Single measurement at baseline
Tendon structure
Time Frame: Single measurement at baseline

Assessment of tendon characteristics using ultrasound including: vascularity (color and power doppler signal)
Single measurement at baseline
Tendon structure
Time Frame: Single measurement at baseline

Assessment of tendon characteristics using ultrasound including: tendon thickening (= anteroposterior diameter at thickest part of the tendon (cm) - anteroposterior diameter at 2cm proximal from calcaneal notch (cm))
Single measurement at baseline
Tendon structure
Time Frame: Single measurement at baseline

Assessment of tendon characteristics using MRI including: tendon volume (cm²)
Single measurement at baseline
Tendon structure
Time Frame: Single measurement at baseline

Assessment of tendon characteristics using MRI including: T2/T2* mapping
Single measurement at baseline
Perfusion pressure
Time Frame: Single measurement at baseline

Assessment of blood pressure to calculate perfusion pressure: ((diastolic pressure + 1/3 × [systolic pressure - diastolic pressure]) - intratendinous pressure)
Single measurement at baseline

Collaborators and Investigators

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

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
University Hospital, Ghent

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)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
October 28, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
December 1, 2026

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
December 1, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
November 14, 2025

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
November 2, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
November 9, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
November 9, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
November 2, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
November 1, 2026

More Information

Terms related to this study

Keywords

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • ONZ-2025-0357

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

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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