This measurement can be made on AP or mortise projections 5. The horizontal distance between the lateral margin of the anterior tubercle and the medial contour of the fibula is measured parallel and about 1 cm above the distal tibial plafond in a normal anteroposterior view of the ankle1-3.
Interpretation
In the context of an enlarged tibiofibular clear space and a widened medial clear space, a tibiofibular overlap of <0 mm is considered abnormal 1 although has been reported as a normal variant 6.
Practical points
Like with the tibiofibular clear space, there is some debate about the actual ability of those measures to really predict syndesmotic injury 1,2,4.
1. Hermans J, Wentink N, Beumer A et al. Correlation Between Radiological Assessment of Acute Ankle Fractures and Syndesmotic Injury on MRI. Skeletal Radiol. 2011;41(7):787-801. doi:10.1007/s00256-011-1284-2 - Pubmed
2. Yaradılmış Y. The Evaluation of Radiological Measurements Used in Diagnosis and Treatment of Syndesmosis Injury: A Regional Study in Turkey. Jt Dis Relat Surg. 2020;31(1):123-9. doi:10.5606/ehc.2020.71132 - Pubmed
3. Krähenbühl N, Weinberg M, Davidson N et al. Imaging in Syndesmotic Injury: A Systematic Literature Review. Skeletal Radiol. 2017;47(5):631-48. doi:10.1007/s00256-017-2823-2 - Pubmed
4. Nielson J, Gardner M, Peterson M et al. Radiographic Measurements Do Not Predict Syndesmotic Injury in Ankle Fractures: An MRI Study. Clin Orthop Relat Res. 2005;&NA;(436):216-21. doi:10.1097/01.blo.0000161090.86162.19 - Pubmed
5. Lau B, Allahabadi S, Palanca A, Oji D. Understanding Radiographic Measurements Used in Foot And... : JAAOS - Journal of the American Academy of Orthopaedic Surgeons. LWW. 2021;30(2):e139-54. doi:10.5435/JAAOS-D-20-00189
6. Shah A, Kadakia A, Tan G, Karadsheh M, Wolter T, Sabb B. Radiographic Evaluation of the Normal Distal Tibiofibular Syndesmosis. Foot Ankle Int. 2012;33(10):870-6. doi:10.3113/FAI.2012.0870 - Pubmed