Radiographic Measurement of the Distal Tibiofibular Syndesmosis Has Limited Use

Abstract

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.

National Athletic Trainers' Association Position Statement: Conservative Management and Prevention of Ankle Sprains in Athletes

“…13 In addition, MRI can be useful in demonstrating any associated injuries that may delay complete recovery, such as osteochondral contusions in the ankle, which are prevalent after inversion sprains. 97 The ankle syndesmotic ligament complex includes the anterior inferior tibiofibular ligament, posterior inferior tibiofibular ligament, interosseus ligament, and interosseous membrane. For athletes suspected of sustaining a high ankle sprain, plain radiographs are recommended and may demonstrate widening of the ankle mortise when the injury is significant.…”

Syndesmosis injuries

“…Beumer et al [19] showed that there is no optimal radiographic parameter to assess syndesmotic injury. The most useful parameters are the presence of both loss of tibiofibular overlap and widening of the medial clear space, since absence of tibiofibular overlap may indicate syndesmosis widening and a medial clear space larger than a superior clear space indicates deltoid disruption [19]. Stress radiographs may be useful for diagnosing syndesmotic injury and defining indications for surgery.…”

“…Classically, syndesmotic injuries may be present if radiographs show increased tibiofibular clear space, decreased tibiofibular overlap, and/or increased medial clear space ( Fig. 2, Table 1) [19,20].…”

“…CT also readily allows measurement of the contralateral ankle for comparison. A displacement difference of 2 mm or more side to side is • Distance between the lateral border of the medial malleolus and the medial border of the talus, measured at the level of the talar dome • In the mortise view, MCS should be equal to or less than the superior clear space between the talar dome and the tibial plafond [19].…”

Comments on Hsu et al.: Surgical treatment of syndesmotic diastasis: emphasis on effect of syndesmotic screw on ankle function

“…Beumer et al stated that no optimal radiographic parameter exists to assess syndesmotic integrity, because all are dependent on the position of rotation. Except for unilateral absence of tibiofibular overlap and the combination of the medial and superior clear space, quantitative measurement of syndesmotic parameters in repeated ankle radiographs may be of little value [8]. 4.…”