SLR - August 2019 - Christine C. Palma

Defining Reference Values for the Normal Tibiofibular Syndesmosis in Adults Using Weight-Bearing CT

Reference: Patel S, Malhotra K, Cullen NP, Singh D, Goldberg AJ, Welck MJ. Defining Reference Values for the Normal Tibiofibular Syndesmosis in Adults Using Weight-Bearing CT. The Bone & Joint Journal. 2019 Mar;101(3):348-52.

Scientific Literature Review

Reviewed By: Christine C. Palma, DPM
Residency Program: University of Florida Health – Jacksonville, FL

Podiatric Relevance: The tibiofibular syndesmosis (TFS) plays a critical role in stabilization of the ankle joint. Injuries to this ligament can result in significant morbidity and often times are underdiagnosed on initial presentation. TFS injury can be evaluated with cross-sectional imaging using MRI and CT. Cone beam CT differs from conventional CT and MRI as it allows the subject to stand, thus allowing for imaging of the ankle in real-time under physiologic loading.

Methods: This is a retrospective review performed on 200 feet in 100 uninjured patients, 50 male, and 50 female, between June 2013 and July 2017. Inclusion criteria included patients aged 18 years and over who underwent bilateral, simultaneous, weight-bearing Cone beam CT imaging. Exclusion criteria included those with hindfoot pathology that could cause variations in syndesmotic anatomy. Images were analyzed in the axial plane at the level of the ankle joint perpendicular to the long axis of the tibia. 3 different calculated measures and one angle were used to establish the following: 1) normal reference measurements for the TFS; 2) if side to side variations exist in TFS measurements; 3) if age affects TFS anatomy; 4) if gender affects TFS anatomy.

Results: The upper limit of lateral translation of the fibula was 5.27mm. The anteroposterior rotation was 0.31 mm to 2.59 mm, and -1.48 mm to 3.44 mm, respectively. No difference was found between the left and right legs. Increasing age was associated with a reduction in lateral translation of the fibula. Male fibulae were significantly more externally, posteriorly, and laterally translated compared to females.

Conclusions: Reference values have been established for cross-sectional syndesmotic anatomy in healthy, uninjured patients. This is beneficial as it can aid in timely identification and intervention of syndesmotic injuries and avoid the potentially painful sequelae of misdiagnosis. It also stands as a reference point for future studies that can use this review to evaluate for new reference ranges when analyzing ankles with syndesmotic pathology. Age and gender should also be taken into account when diagnosing these patients as they have both been shown to have varying effects on syndesmotic anatomy. 

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