Correlation Between Weber Classification of Ankle Fractures and Medial Clear Space Widening on Radiography

Background/Objective: There is a growing interest in deltoid ligament injury and repair. The integrity of the deltoid ligament is indirectly assessed through medial clear space widening. The objective of this study was to quantify the degree of medial clear space widening in Weber A, B, and C ankle fractures. Methods: Weber A, B, and C ankle fracture radiographs were retrospectively evaluated for the medial, lateral, and superior clear spaces and data gathered on associated injuries to the medial and posterior malleoli. Multivariable regression analysis was performed with the goal of assessing whether there were significant differences among the Weber fracture types for medial, lateral, and superior clear space widening. Results: A total of 473 radiographs with lateral malleolar fractures were retrospectively evaluated with 127 being Weber A, 216 Weber B, and 130 Weber C, with an additional 89 with associated fracture of the medial malleolus and 62 of the posterior malleolus. The mean medial clear space for Weber A fractures was 3.3 ± 1.1 mm, Weber B fractures 4.3 ± 2.4 mm, and Weber C fractures 5.7 ± 3.6 mm. Weber C fractures demonstrated significantly greater medial and lateral clear space distances than Weber A or B fractures. Additional fractures of the medial or posterior malleoli were also associated with greater medial and lateral clear space distances. Conclusions: Medial clear space is significantly increased in Weber C fractures and when additional medial or posterior malleolar fractures also occur. This sheds light on the biomechanics of ankle fractures and their impact on the medial ligamentous instability.