The arthroscopic syndesmotic assessment tool can differentiate between stable and unstable ankle syndesmoses

Abstract

Purpose Patients with stable isolated injuries of the ankle syndesmosis can be treated conservatively, while unstable injuries require surgical stabilisation. Although evaluating syndesmotic injuries using ankle arthroscopy is becoming more popular, differentiating between stable and unstable syndesmoses remains a topic of on‐going debate in the current literature. The purpose of this study was to quantify the degree of displacement of the ankle syndesmosis using arthroscopic measurements. The hypothesis was that ankle arthroscopy by measuring multiplanar fibular motion can determine syndesmotic instability. Methods Arthroscopic assessment of the ankle syndesmosis was performed on 22 fresh above knee cadaveric specimens, first with all syndesmotic and ankle ligaments intact and subsequently with sequential sectioning of the anterior inferior tibiofibular ligament, the interosseous ligament, the posterior inferior tibiofibular ligament, and deltoid ligaments. In all scenarios, four loading conditions were considered under 100N of direct force: (1) unstressed, (2) a lateral hook test, (3) anterior to posterior (AP) translation test, and (4) posterior to anterior (PA) translation test. Anterior and posterior coronal plane tibiofibular translation, as well as AP and PA sagittal plane translation, were arthroscopically measured. Results As additional ligaments of the syndesmosis were transected, all arthroscopic multiplanar translation measurements increased (p values ranging from p < 0.001 to p = 0.007). The following equation of multiplanar fibular motion relative to the tibia measured in millimeters: 0.76*AP sagittal translation + 0.82*PA sagittal translation + 1.17*anterior third coronal plane translation—0.20*posterior third coronal plane translation, referred to as the Arthroscopic Syndesmotic Assessment tool, was generated from our data. According to our results, an Arthroscopic Syndesmotic Assessment value equal or greater than 3.1 mm indicated an unstable syndesmosis. Conclusions This tool provides a more reliable opportunity in determining the presence of syndesmotic instability and can help providers decide whether syndesmosis injuries should be treated conservatively or operatively stabilized. The long‐term usefulness of the tool will rest on whether an unstable syndesmosis correlates with acute or chronic clinical symptoms.

Arthroscopic Assessment of Syndesmotic Instability in the Sagittal Plane in a Cadaveric Model

“…Anterior to posterior (AP) and posterior to anterior (PA) fibular translation relative to the central point of the incisura was assessed using a bone hook placed around the distal part of the fibula 5 cm proximal to ankle joint. 15 Using an electronic goniometer, a 100-N anteriorly and then posteriorly directed force was applied via the electronic force gauge (Figure 1). The 100-N force used in this study was based on a cadaveric study performed by Stoffel et al 27 who found that forces of more than 100 N did not show substantial increase in syndesmotic displacement.…”

“…Syndesmotic instability is multiplanar in nature, occurring in the coronal, sagittal, and rotational planes. 10,13,15,19,32 Historically, most studies have focused on the coronal plane, but recent studies suggest that syndesmotic instability may be more readily evident when measuring fibular translation in the sagittal plane. 3,15,17-19,30,34 With increased awareness of the long-term morbidity associated with untreated syndesmotic instability, arthroscopy has been increasingly used to diagnose subtle syndesmotic injuries that may not be as readily identifiable by other means.…”

“…10,13,15,19,32 Historically, most studies have focused on the coronal plane, but recent studies suggest that syndesmotic instability may be more readily evident when measuring fibular translation in the sagittal plane. 3,15,17-19,30,34 With increased awareness of the long-term morbidity associated with untreated syndesmotic instability, arthroscopy has been increasingly used to diagnose subtle syndesmotic injuries that may not be as readily identifiable by other means. 5,18,22,24,28 Radiographs have limited sensitivity, 2,23,25 and biomechanical studies further underscore that external rotation stress radiographs preferentially test the deltoid ligament rather than the syndesmosis.…”

Comparative CT with stress manoeuvres for diagnosing distal isolated tibiofibular syndesmotic injury in acute ankle sprain: a protocol for an accuracy- test prospective study

“… 9 16 The arthroscopic examination facilitates a correct diagnosis and treatment and is considered the best reference standard for syndesmotic injuries. 17 However, in this study, participant selection is based on the ankle sprain condition and physical examination, which has limited accuracy. 4 A significant proportion of uninjured syndesmosis will be selected with the alternative diagnoses of a lateral collateral ligament injury.…”

Computed tomography with stress maneuvers for diagnosing syndesmotic instability

“…Two studies compared the accuracy of MRI to that of arthroscopy and showed that MRI is highly sensitive and specific for evaluating syndesmotic injury (9,15) . The best reference standard for syndesmotic injuries is the arthroscopic examination, which enables correct diagnosis and treatment (16). However, in this study, the inclusion criteria are based on the ankle sprain context and physical examination, which have limited accuracy (4) .…”