Bilateral External Torque CT, a Novel Diagnostic Tool for Detection of Syndesmotic Insufficiency

Study population: the investigator set them sample size to 30 patients.

Primary endpoint (concerning both study questions): is the applied torque measurement in Newton meters (maximum up to 7.5 Nm) up to the pain tolerance limit. For the chronic injuries, a minimum of 5 Nm should be achieved. If this is not possible due to pain, an intra-articular infiltration into the upper ankle joint with 5ml Ropivacaine 2% is performed under sterile conditions.

In addition, fibula translation while exercising the maximum tolerated External Torque CT (maximum up to 7.5 Nm).

Secondary endpoint (1st study question): the comparison to stress fluoroscopy without anesthesia and under anesthesia.

Secondary endpoint (2nd study question): the comparison of patients with and without symptoms. Secondary endpoint in patients who received intra-articular infiltration is the increase in tolerated Newton meters.

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Key information

Conditions

Syndesmotic Injuries Ankle Injuries Leg Injuries Wounds and Injuries

Age range

18 year–75 year

Sex eligibility

All sexes

Study type

Observational

Primary location

Balgrist University Hospital

Zurich, 8008, Switzerland

About this study

Isolated injuries to the distal tibiofibular syndesmosis affect approximately 1-17% of all ankle sprains and up to 30% in "high impact" sports. If the injury is missed, chronic syndesmosis instability can lead to prolonged convalescence, pain, and osteoarthritis of the upper ankle. Therefore, early diagnosis is essential for safe and effective treatment.

The diagnosis of syndesmosis insufficiency presents a certain dilemma in foot surgery. Already the differentiation between a simple fibular ligament lesion (low ankle sprain) and a syndesmosis injury (high ankle sprain) is often clinically difficult and only suggests a syndesmosis injury but does not confirm it.

The investigators have developed an external torque device that allows bilateral stressing of the syndesmosis by external rotation. In this case, both lower legs are stabilized by a special knee brace (fibula remains free floating) or by the hip joints, which are end rotated on both sides, while an external rotation force of maximum 7.5Nm (respectively up to the respective pain limit) can be set on both sides by means of torque newton meters. A CT can then be performed under external rotation stress.

In two previous studies (cadaver study and study on healthy subjects) the investigators have seen on the one hand that bilateral external torque CT is able to reliably detect syndesmosis instabilities and on the other hand that in healthy subjects the two ankle joints are comparable.

Based on these results the investigators want to address the following further questions:

can "Bilateral External Torque CT" be reliably applied in patients with acute syndesmosis rupture?
how stable does a syndesmosis have to be after an injury?

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

Written informed consent
Patient age of ≥18 yr and ≤75 yr.
Proven acute (<4 weeks) syndesmosis injury (anterior and posterior) on MRI.
Proven chronic (>2 months) syndesmosis injury (anterior and posterior) on MRI with/without surgical stabilization performed.
Healthy opposite side

Exclusion criteria

A dependency between patient sponsor and/or project management
Pregnancy (contraindication for CT): in women of childbearing age, a pregnancy test is performed in any case
St.n. previous operation(s) of the affected lower extremity (specifically of the ankle joint).
Severe deformities (osteoarthritis with limited function upper and lower ankle joint, metatarsophalangeal joint).

Treatment and study plan

Bilateral external torque device

Device

The "External Torque Device" was developed, which allows bilateral stressing of the syndesmosis by external rotation. Both lower legs are stabilized by a special knee brace (the fibula remains free to float) or by the hip joints, which are end rotated on both sides, while an external rotation force of maximum 7.5Nm (or up to the respective pain threshold) can be set on both sides using torque newton meters. If no load is possible - which the examination of the syndesmosis generally does not allow - an intra-articular local anesthesia with 5ml ropivacaine 2mg/ml can be performed under sterile conditions after the patient's consent.

Primary outcomes

External torque CT

Time frame: 24 months

= the applied torque measurement in Newton meters (maximum up to 7.5 Nm) up to the pain tolerance limit. In the chronic injuries, at least 5 Nm should be achieved. If this is not possible due to pain, patients with chronic injuries are infiltrated intra-articularly into the upper ankle joint with 5ml ropivacaine 2% under sterile conditions.

Sponsors and collaborators

Lead sponsor

Balgrist University Hospital

Other

Registry information

Important dates

Study start: 2023
Primary completion: 2025
Study completion: 2025
First posted: Nov 23, 2022
Registry last updated: Jun 19, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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Completed