Diagnostic imaging of ankle syndesmosis injuries: A general review

Twenty-five fresh-frozen cadaveric specimens were used to evaluate the role of the syndesmotic ligaments when the ankle is loaded with external rotation torque. An apparatus was constructed that allowed pure external-rotation torque to be applied through the ankle with the foot in neutral flexion. The apparatus provided solid fixation of the tibia while allowing free movement of the fibula in all planes. The syndesmotic ligaments were incrementally sectioned, and direct measurements of anatomical diastasis were made. Mortise and lateral radiographs were made at each increment under both loaded (5.0 newton-meters) and unloaded conditions. After all structures of the syndesmosis had been divided, the syndesmosis was reduced and was repaired with one or two screws. The strength of the repair was measured with incremental increases in torque of 1.0 newton-meter. The radiographs were measured by three independent observers in a blind fashion. In order to evaluate intraobserver error, each observer was randomly given forty radiographs to reinterpret. Diastasis and rotation were found to be related to the amount of injury of the ligament (p < 0.0001). After the entire syndesmosis had been divided, application of a 5.0-newton-meter torque resulted in a mean diastasis of 7.3 millimeters. The subsequent repair of the anterior tibiofibular ligament with suture failed at a mean of 2.0 newton-meters (range, 1.0 to 6.0 newton-meters) of torque. Repair with two screws was found to be stronger than repair with one, with the first construct failing at a mean of 11.0 newton-meters (range, 5.0 to 15.0 newton-meters) and the second, at a mean of 6.2 newton-meters (range, 2.0 to 10.0 newton-meters) (p = 0.0005). Failure of the screw fixation was not associated with the maximum previous diastasis (p = 0.13). Measurements of anatomical diastasis were compared with measurements made on the mortise and lateral radiographs. Measurements on the stress mortise radiographs had a weak correlation with diastasis (r = 0.41, p < 0.0001). However, measurements on the stress lateral radiographs had a higher correlation (r = 0.81, p < 0.0001). Additionally, interobserver correlation was significantly higher for the measurements on the lateral radiographs (r = 0.87, p < 0.0001) than for those on the mortise radiographs (r = 0.56, p < 0.0001). Intraobserver correlation for the three observers was poor with regard to the measurements on the mortise radiographs (r = 0.12, 0.42, and 0.25). The respective correlations for the measurements on the lateral radiographs were r = 0.81, 0.90, and 0.89.(ABSTRACT TRUNCATED AT 400 WORDS) Show more

Radiographs of 20 plastinated human cadaveric lower legs were obtained in 12 positions of rotation to determine the optimal parameter for reliable assessment of syndesmotic and ankle integrity, and to assess the effect of positioning of the ankle on this parameter. Three observers measured eight parameters twice after four repetitions of ankle positioning. Intraclass correlation coefficients and reproducibility were assessed. Some tibiofibular overlap was present in all radiographs in any position of rotation. The medial clear space was smaller than or equal to the superior clear space in all radiographs. Intraclass correlation coefficients of the other parameters were too weak for reliable quantitative measurements, as was shown with a mixed model analysis of variance. This resulted from the inability to reproduce ankle positioning, even under optimal laboratory circumstances. This study shows that no optimal radiographic parameter exists to assess syndesmotic integrity. Tibiofibular overlap and medial and superior clear space are the most useful, because one-sided traumatic absence of tibiofibular overlap may be an indication of syndesmotic injury, and a medial clear space larger than a superior clear space is indicative of deltoid injury. Additional quantitative measurement of all syndesmotic parameters with repeated radiographs of the ankle cannot be done reliably and therefore are of little value. Show more

To compare the use of magnetic resonance (MR) imaging with the use of arthroscopy for the diagnosis of tibiofibular syndesmotic injury. This study involved 58 patients who had ankle sprains or distal fibular fractures and underwent surgery. All patients were examined with MR imaging for diagnosis of tibiofibular syndesmotic injury. When MR imaging revealed ligament discontinuity (criterion 1) or either a wavy or curved ligament contour or nonvisualization of the ligament (criterion 2), the injury was considered to be a ligament disruption. After MR imaging, ankle arthroscopy was performed in all patients for a definitive diagnosis of ligament disruption. Arthroscopic findings showed anteroinferior tibiofibular ligament (AITFL) disruption in 28 patients and posteroinferior tibiofibular ligament (PITFL) disruption in five patients. When an MR imaging diagnosis was based on criterion 1 only, the diagnosis of AITFL disruption was made with a sensitivity of 100%, a specificity of 70%, and an accuracy of 84%, and the diagnosis of PITFL disruption was made with a sensitivity of 100%, a specificity of 94%, and an accuracy of 95%. When an MR imaging diagnosis was based on criteria 1 and 2, the diagnosis of AITFL disruption was made with a sensitivity of 100%, a specificity of 93%, and an accuracy of 97%, whereas the diagnosis of PITFL disruption was made with a sensitivity of 100%, a specificity of 100%, and an accuracy of 100%. MR imaging with use of both criteria is highly accurate for the diagnosis of tibiofibular syndesmotic disruption. Show more